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Sample records for insecticide treated mosquito

  1. Effect of insecticide-treated bed nets on house-entry by malaria mosquitoes

    NARCIS (Netherlands)

    Spitzen, Jeroen; Koelewijn, Teun; Mukabana, W.R.; Takken, Willem

    2017-01-01

    Insecticide-treated nets are currently a major tool to reduce malaria transmission. Their level of repellency affects contact of the mosquito with the net, but may also influence the mosquito's entry into the house. The response of host-seeking malaria mosquitoes approaching the eave of an

  2. Scepticism towards insecticide treated mosquito nets for malaria control in a rural community in northwestern Tanzania

    DEFF Research Database (Denmark)

    Nnko, Soori; Whyte, Susan Reynolds; Geissler, Wenzel

    2012-01-01

    in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional...... who could afford the prices of ITNs and who knew where to obtain the insecticides did not necessarily buy them. This suggests that, although people tend to report costrelated factors as a barrier against the use of ITNs, there are other critical concerns at work. Without underestimating the practical...

  3. 1 Scepticism towards insecticide treated mosquito nets for malaria ...

    African Journals Online (AJOL)

    This paper is based on a study conducted in a rural community along the shores of ... that, the majority of people who could afford the prices of ITNs and who knew .... POs included school compounds, health facility settings and in drug shops, .... the villagers curiously asked our field assistant: '[W]e are told treated nets are ...

  4. Interplay between insecticide-treated bed-nets and mosquito demography: implications for malaria control.

    Science.gov (United States)

    Ngonghala, Calistus N; Mohammed-Awel, Jemal; Zhao, Ruijun; Prosper, Olivia

    2016-05-21

    Although malaria prevalence has witnessed a significant reduction within the past decade, malaria still constitutes a major health and economic problem, especially to low-income countries. Insecticide-treated nets (ITNs) remain one of the primary measures for preventing the malignant disease. Unfortunately, the success of ITN campaigns is hampered by improper use and natural decay in ITN-efficacy over time. Many models aimed at studying malaria transmission and control fail to account for this decay, as well as mosquito demography and feeding preferences exhibited by mosquitoes towards humans. Omitting these factors can misrepresent disease risk, while understanding their effects on malaria dynamics can inform control policy. We present a model for malaria dynamics that incorporates these factors, and a systematic analysis, including stability and sensitivity analyses of the model under different conditions. The model with constant ITN-efficacy exhibits a backward bifurcation emphasizing the need for sustained control measures until the basic reproduction number, R0, drops below a critical value at which control is feasible. The infectious and partially immune human populations and R0 are highly sensitive to the probability that a mosquito feeds successfully on a human, ITN coverage and the maximum biting rate of mosquitoes, irrespective of whether ITN-efficacy is constant or declines over time. This implies that ITNs play an important role in disease control. When ITN-efficacy wanes over time, we identify disease risks and corresponding ITN coverage, as well as feeding preference levels for which the disease can be controlled or eradicated. Our study leads to important insights that could assist in the design and implementation of better malaria control strategies. We conclude that ITNs that can retain their effectiveness for longer periods will be more appropriate in the fight against malaria and that making more ITNs available to highly endemic regions is

  5. Behavioural responses of females of two anopheline mosquito species to human-occupied, insecticide-treated and untreated bed nets

    Science.gov (United States)

    2014-01-01

    Background Insecticide-treated bed nets (ITNs), used extensively to reduce human exposure to malaria, work through physical and chemical means to block or deter host-seeking mosquitoes. Despite the importance of ITNs, very little is known about how host-seeking mosquitoes behave around occupied bed nets. As a result, evidence-based evaluations of the effects of physical damage on bed net effectiveness are not possible and there is a dearth of knowledge on which to base ITN design. Methods The dispersion of colony-raised female Anopheles gambiae and Anopheles albimanus was observed in 2-hr laboratory experiments in which up to 200 mosquitoes were released inside a mosquito-proof 3 m × 3 m tent housing a bed net arrayed with 18 30 cm × 30 cm sticky screen squares on the sides, ends and roof. Numbers of mosquitoes caught on the sticky squares were interpreted as the ‘mosquito pressure’ on that part of the net. Results Presence of a human subject in the bed net significantly increased total mosquito pressure on the net for both species and significantly re-oriented An. gambiae to the roof of the net. Anopheles albimanus pressure was greatest on the bed net roof in both host-present and no-host conditions. The effects of different human subjects in the bed net, of different ambient conditions (dry, cool conditions vs warm, humid conditions) and of bed net treatment (deltamethrin-treated or no insecticide) on mosquito pressure patterns were tested for both species. Species-specific pressure patterns did not vary greatly as a result of any of these factors though some differences were noted that may be due the size of the different human subjects. Conclusions As a result of the interaction between host-seeking responses and the convective plume from the net occupant, species-specific mosquito pressure patterns manifest more or less predictably on the bed net. This has implications for bed net design and suggests that current methods of assessing damaged

  6. Impact of insecticide-treated materials on filaria transmission by the various species of vector mosquito in Africa.

    Science.gov (United States)

    Pedersen, E M; Mukoko, D A

    2002-12-01

    Nocturnally periodic bancroftian filariasis is maintained by three mainly endophilic vectors in East Africa: Culex quinquefasciatus, Anopheles funestus and the An. gambiae complex. Permethrin-impregnated bednets provide considerable protection against these mosquitoes, but the species respond differently. The degree of protection conferred by treated bednets was determined in Kenyan communities where all three vectors actively transmit Wuchereria bancrofti. The annual transmission potential in the communities (i.e. an estimate of the number of human infective, third-stage larvae of W. bancrofti inoculated into each villager each year) was reduced by 92%, through the nets' impact on vector biting rates (reduced by 22%) and their cumulative impact on the annual infective biting rate (reduced by 95%). Thus a modest reduction in the numbers of mosquitoes biting humans, attributable to the use of the insecticide-treated nets, strongly suppressed the risk of W. bancrofti transmission.

  7. Median knock-down time as a new method for evaluating insecticide-treated textiles for mosquito control.

    Science.gov (United States)

    Skovmand, Ole; Bonnet, Julien; Pigeon, Olivier; Corbel, Vincent

    2008-06-27

    Insecticide treated bed nets are major tools for the Roll Back Malaria campaign. There are two types of Long-Lasting Insecticide-treated Nets (LNs) on the market: coated nets and insecticide-incorporated nets. Nets provided to this market need a recommendation from the World Health Organization to be purchased by donors and NGOs. During laboratory study (phase I), the first step consists in evaluating the wash resistance of a new LN product. When insecticide-incorporated nets are washed, it takes time to regenerate the insecticidal activity, i.e. insecticide must migrate to the net surface to be accessible to mosquitoes. The interval of time required for regeneration must be carefully determined to ensure the accuracy of further results. WHOPES procedures currently recommend the determination of the regeneration time by using mortality data. However, as mortality cannot exceed 100%, a LN that regenerates a surface concentration exceeding the dosage for 100% mortality, will have its regeneration time underestimated. The Median Knock Down Time (MKDT) was determined as function of insecticide dosage on an inert surface, glass, and on polyester nettings using an acetone solution or a simple emulsion. Dosage response was also established for mortality data. The same method was then applied to a commercially polyethylene netting, currently under WHOPES evaluation, to determine the dynamics of regeneration as function of repeated washings. The deltamethrin content of these nets was estimated by Capillary Gas Chromatography (GC-ECD). MKDT was a linear function of log insecticide dosage on glass as on nettings. Mortality data were either 0 or 100% for most concentrations except for a narrow range. MKDT was log linear function of total deltamethrin content in a commercial polyethylene net exposed to washings. The regeneration time of this net increased with the number of washes and MKDT became higher. A new, easy and rapid method to determine MKDT is suggested. The MKDT is

  8. Effect of insecticide-treated bed nets on house-entry by malaria mosquitoes: The flight response recorded in a semi-field study in Kenya.

    Science.gov (United States)

    Spitzen, Jeroen; Koelewijn, Teun; Mukabana, W Richard; Takken, Willem

    2017-08-01

    Insecticide-treated nets are currently a major tool to reduce malaria transmission. Their level of repellency affects contact of the mosquito with the net, but may also influence the mosquito's entry into the house. The response of host-seeking malaria mosquitoes approaching the eave of an experimental house was recorded within a large screen house. We compared entry- and exit rates in relation to the presence in the house of different insecticide-treated bed nets (ITNs) with an untreated net. Mosquitoes were lured towards the house by dispensing a synthetic host-odour blend from within the net in the house. Complementary WHO bioassays revealed that the treated nets caused high knock-down- and mortality responses to the Anopheles gambiae sensu stricto strain tested. The proportion of mosquitoes that came into view of the cameras and subsequently entered the house did not differ between treated nets and the untreated net. Treated nets did not affect proportions of mosquitoes that exited the house and departed from view around the eave. However, the percentage of house-leaving and re-entering mosquitoes when an insecticide- treated net was present, was lower than in the presence of an untreated net. Our results indicated that there was no spatial repellent effect from pyrethroid-treated nets that influences house-entry at eave level. It is argued that the toxic effect of treated bed nets resulted in a reduced number of mosquitoes re-entering the house, which could thereby affect malaria transmission in neighbouring, unprotected houses. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Frequent blood feeding enables insecticide-treated nets to reduce transmission by mosquitoes that bite predominately outdoors.

    Science.gov (United States)

    Russell, Tanya L; Beebe, Nigel W; Bugoro, Hugo; Apairamo, Allan; Chow, Weng K; Cooper, Robert D; Collins, Frank H; Lobo, Neil F; Burkot, Thomas R

    2016-03-10

    The effectiveness of vector control on malaria transmission by long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) depends on the vectors entering houses to blood feed and rest when people are inside houses. In the Solomon Islands, significant reductions in malaria have been achieved in the past 20 years with insecticide-treated bed nets, IRS, improved diagnosis and treatment with artemisinin combination therapies; despite the preference of the primary vector, Anopheles farauti, to feed outdoors and early in the evening and thereby avoid potential exposure to insecticides. Rational development of tools to complement LLINs and IRS by attacking vectors outdoor requires detailed knowledge of the biology and behaviours of the target species. Malaria transmission in Central Province, Solomon Islands was estimated by measuring the components comprising the entomological inoculation rate (EIR) as well as the vectorial capacity of An. farauti. In addition, the daily and seasonal biting behaviour of An. farauti, was examined and the duration of the feeding cycle was estimated with a mark-release-recapture experiment. Anopheles farauti was highly exophagic with 72% captured by human landing catches (HLC) outside of houses. Three-quarters (76%) of blood feeding on humans was estimated to occur before 21.00 h. When the hourly location of humans was considered, the proportion of exposure to mosquito bites on humans occurring indoors (πi) was only 0.130 ± 0.129. Peak densities of host seeking An. farauti occurred between October and January. The annual EIR was estimated to be 2.5 for 2012 and 33.2 for 2013. The length of the feeding cycle was 2.1 days. The short duration of the feeding cycle by this species offers an explanation for the substantial control of malaria that has been achieved in the Solomon Islands by LLINs and IRS. Anopheles farauti is primarily exophagic and early biting, with 13% of mosquitoes entering houses to feed late at night during

  10. Remote Effect of Insecticide-Treated Nets and the Personal Protection against Malaria Mosquito Bites

    Science.gov (United States)

    Chandre, Fabrice; Hougard, Jean-Marc; Corbel, Vincent; Pennetier, Cédric

    2017-01-01

    Experimental huts are part of the WHO process for testing and evaluation of Insecticide Treated Nets (ITN) in semi-field conditions. Experimental Hut Trials (EHTs) mostly focus on two main indicators (i.e., mortality and blood feeding reduction) that serve as efficacy criteria to obtain WHO interim recommendation. However, several other outputs that rely on counts of vectors collected in the huts are neglected although they can give useful information about vectors’ behavior and personal protection provided by ITNs. In particular, EHTs allow to measure the deterrent effect and personal protection of ITNs. To provide a better assessment of ITNs efficacy, we performed a retrospective analysis of the deterrence and the personal protection against malaria transmission for 12 unwashed and 13 washed ITNs evaluated through EHTs conducted in West Africa. A significant deterrent effect was shown for six of the 12 unwashed ITNs tested. When washed 20 times, only three ITNs had significant deterrent effect (Rate Ratios (RR)1; p0.05). Current WHO efficacy criteria do not sufficiently take into account the deterrence effect of ITNs. Moreover, the deterrence variability is rarely discussed in EHT’s reports. Our findings highlighted the long-range effect (deterrent or attractive) of ITNs that may have significant consequences for personal/community protection against malaria transmission. Indicators measuring the deterrence should be further considered for the evaluation of ITNs. PMID:28129371

  11. Preventing childhood malaria in Africa by protecting adults from mosquitoes with insecticide-treated nets.

    Directory of Open Access Journals (Sweden)

    Gerry F Killeen

    2007-07-01

    Full Text Available BACKGROUND: Malaria prevention in Africa merits particular attention as the world strives toward a better life for the poorest. Insecticide-treated nets (ITNs represent a practical means to prevent malaria in Africa, so scaling up coverage to at least 80% of young children and pregnant women by 2010 is integral to the Millennium Development Goals (MDG. Targeting individual protection to vulnerable groups is an accepted priority, but community-level impacts of broader population coverage are largely ignored even though they may be just as important. We therefore estimated coverage thresholds for entire populations at which individual- and community-level protection are equivalent, representing rational targets for ITN coverage beyond vulnerable groups. METHODS AND FINDINGS: Using field-parameterized malaria transmission models, we show that high (80% use but exclusively targeted coverage of young children and pregnant women (representing <20% of the population will deliver limited protection and equity for these vulnerable groups. In contrast, relatively modest coverage (35%-65% use, with this threshold depending on ecological scenario and net quality of all adults and children, rather than just vulnerable groups, can achieve equitable community-wide benefits equivalent to or greater than personal protection. CONCLUSIONS: Coverage of entire populations will be required to accomplish large reductions of the malaria burden in Africa. While coverage of vulnerable groups should still be prioritized, the equitable and communal benefits of wide-scale ITN use by older children and adults should be explicitly promoted and evaluated by national malaria control programmes. ITN use by the majority of entire populations could protect all children in such communities, even those not actually covered by achieving existing personal protection targets of the MDG, Roll Back Malaria Partnership, or the US President's Malaria Initiative.

  12. Insecticide susceptibility status of human biting mosquitoes in ...

    African Journals Online (AJOL)

    Matowo Pc

    al., 1999). The occurrence of insecticide resistant Culex mosquitoes has also been reported in Wete, ... Emerged pupae were sucked from the larval containers .... Key: aWHO criteria for assessing susceptibility to insecticides of mosquitoes; ...

  13. Experimental hut evaluation of bednets treated with an organophosphate (chlorpyrifos-methyl or a pyrethroid (lambdacyhalothrin alone and in combination against insecticide-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes

    Directory of Open Access Journals (Sweden)

    Corbel Vincent

    2005-05-01

    Full Text Available Abstract Background Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is important to identify alternative insecticides which, if necessary, could be used to replace or supplement the pyrethroids for use on treated nets. Certain compounds of an earlier generation of insecticides, the organophosphates may have potential as net treatments. Methods Comparative studies of chlorpyrifos-methyl (CM, an organophosphate with low mammalian toxicity, and lambdacyhalothrin (L, a pyrethroid, were conducted in experimental huts in Côte d'Ivoire, West Africa. Anopheles gambiae and Culex quinquefasciatus mosquitoes from the area are resistant to pyrethroids and organophosphates (kdr and insensitive acetylcholinesterase Ace.1R. Several treatments and application rates on intact or holed nets were evaluated, including single treatments, mixtures, and differential wall/ceiling treatments. Results and Conclusion All of the treatments were effective in reducing blood feeding from sleepers under the nets and in killing both species of mosquito, despite the presence of the kdr and Ace.1R genes at high frequency. In most cases, the effects of the various treatments did not differ significantly. Five washes of the nets in soap solution did not reduce the impact of the insecticides on A. gambiae mortality, but did lead to an increase in blood feeding. The three combinations performed no differently from the single insecticide treatments, but the low dose mixture performed encouragingly well indicating that such combinations might be used for controlling insecticide resistant mosquitoes. Mortality of mosquitoes that carried both Ace.1R and Ace.1S genes did not differ significantly from mosquitoes that carried only Ace.1S genes on any of the treated nets, indicating that the Ace.1R allele does not confer effective resistance to chlorpyrifos-methyl under the realistic conditions of an experimental hut.

  14. The impact of pyrethroid resistance on the efficacy of insecticide-treated bed nets against African anopheline mosquitoes: systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Clare Strode

    2014-03-01

    Full Text Available Pyrethroid insecticide-treated bed nets (ITNs help contribute to reducing malaria deaths in Africa, but their efficacy is threatened by insecticide resistance in some malaria mosquito vectors. We therefore assessed the evidence that resistance is attenuating the effect of ITNs on entomological outcomes.We included laboratory and field studies of African malaria vectors that measured resistance at the time of the study and used World Health Organization-recommended impregnation regimens. We reported mosquito mortality, blood feeding, induced exophily (premature exit of mosquitoes from the hut, deterrence, time to 50% or 95% knock-down, and percentage knock-down at 60 min. Publications were searched from 1 January 1980 to 31 December 2013 using MEDLINE, Cochrane Central Register of Controlled Trials, Science Citation Index Expanded, Social Sciences Citation Index, African Index Medicus, and CAB Abstracts. We stratified studies into three levels of insecticide resistance, and ITNs were compared with untreated bed nets (UTNs using the risk difference (RD. Heterogeneity was explored visually and statistically. Included were 36 laboratory and 24 field studies, reported in 25 records. Studies tested and reported resistance inconsistently. Based on the meta-analytic results, the difference in mosquito mortality risk for ITNs compared to UTNs was lower in higher resistance categories. However, mortality risk was significantly higher for ITNs compared to UTNs regardless of resistance. For cone tests: low resistance, risk difference (RD 0.86 (95% CI 0.72 to 1.01; moderate resistance, RD 0.71 (95% CI 0.53 to 0.88; high resistance, RD 0.56 (95% CI 0.17 to 0.95. For tunnel tests: low resistance, RD 0.74 (95% CI 0.61 to 0.87; moderate resistance, RD 0.50 (95% CI 0.40 to 0.60; high resistance, RD 0.39 (95% CI 0.24 to 0.54. For hut studies: low resistance, RD 0.56 (95% CI 0.43 to 0.68; moderate resistance, RD 0.39 (95% CI 0.16 to 0.61; high resistance, RD 0

  15. Use of insecticide-treated mosquito nets for children under five years in an urban area of Lagos State, Nigeria.

    Science.gov (United States)

    Okafor, I P; Odeyemi, K A

    2012-01-01

    Insecticide-treated nets (ITNs) have proven to be one of the most effective means of reducing malaria morbidity and mortality in children and pregnant women. This study is carried out to determine the practice and determinants of ITN use for children under five years among care givers in an urban area of Lagos State. A community-based, cross sectional study was carried out in Lagos State in April 2007 among three hundred and forty (340) care givers primarily responsible for child care at home. They were selected by a multi-stage sampling method using a pre-tested, interviewer-administered, structured questionnaire. ITN use rate for under-fives was high (61.8%) and this was significantly determined by care giver's marital status (P level of care giver and occupation of head of the household were not significant determinants. There is need for health campaigns on ITNs targeted at unmarried care givers of young children. In addition, we also recommend social marketing of modern family planning methods to reduce family size, thereby increasing chances of ITN use among children less than five years to reduce malaria burden.

  16. Assessing the Health Effects of Long-Term Exposure to Insecticide-Treated Mosquito Nets in the Control of Malaria in Endemic Regions

    Directory of Open Access Journals (Sweden)

    Ebere C. Anyanwu

    2004-01-01

    Full Text Available Malaria is a protozoan disease caused in humans by the genus Plasmodium of which four species are known: P. falciparum, P. vivax, P. ovale, and P. malariae. It is transmitted through the bite of infected female mosquitoes of the genus Anopheles. Malaria is endemic in tropical and subtropical regions of the world. It is characterized by extreme exhaustion associated with paroxysms of high fever, sweating, shaking chills, and anemia. Approximately 40% of the world's population, mostly those living in the poorest nations, are at risk. Much of the deaths due to malaria occur in Africa, mostly among children. The search for prevention and control interventions that are effective and sustainable remains an abiding challenge for national governments and international health agencies. To this end, the World Health Organization and several nongovernmental organizations are investing in the use of insecticide-treated mosquito nets (ITMNs as a viable option. Trials of ITMNs in the 1980s and 1990s showed that they reduce deaths in young children by an average of 20% and multilateral agencies, spearheaded by Roll Back Malaria (RBM, seek to have 60% of the populations at risk sleeping under ITMNs by 2005. All pesticides are toxic by nature and present risks of adverse effects that depend on toxicity of the chemical and the degree of exposure. While there is agreement that ITMNs can be effective in reducing malaria morbidity and mortality under field trials, a number of factors relating to their sustainability and contribution to health improvement in less-developed countries have yet to be determined. In particular, the adverse effects associated with their long-term use and misuse has yet to be fully evaluated. Although this paper examines potential neurotoxic and neurobehavioral effects of long-term use of ITMNs and discusses priority public health actions for protecting the health of users, it forms the basis for further research.

  17. Oviposition and olfaction responses of Aedes aegypti mosquitoes to insecticides.

    Science.gov (United States)

    Canyon, D V; Muller, R

    2013-12-01

    Insecticide applications are not particularly effective on Aedes aegypti mosquitoes which has been attributed to their 'closet' behaviour, or ability to rest in places that remain unexposed to insecticides. Some researchers have suggested that insecticides repel mosquitoes, which would result in less exposure and increased dispersal. If repellence due to insecticides is a fact, acquiring a vector-borne disease, such as dengue, could legitimately be attributed to local vector control efforts and this would lead to restitution claims. This study thus investigated the effect of insecticide presence on mosquito behaviour indirectly via oviposition and directly via olfactory response. In all experiments, oviposition in each insecticide compared to its water and ethanol controls was not significantly different. This indicates that Ae. aegypti mosquitoes are not affected by insecticide presence and that increased dispersal is unlikely to be caused by vector control spraying.

  18. DEET mosquito repellent sold through social marketing provides personal protection against malaria in an area of all-night mosquito biting and partial coverage of insecticide-treated nets: a case-control study of effectiveness.

    Science.gov (United States)

    Rowland, Mark; Freeman, Tim; Downey, Gerald; Hadi, Abdul; Saeed, Mohammed

    2004-03-01

    DEET (diethyl-3-methylbenzamide), the widely used mosquito repellent, has the potential to prevent malarial infection but hitherto there has been no study demonstrating this possibility during normal everyday use. Mosbar, a repellent soap containing DEET, was promoted through social marketing in villages in eastern Afghanistan. This was followed up with a case-control study of effectiveness against malarial infection conducted through local clinics. Mosbar was purchased by 43% of households. Reported use of insecticide-treated nets (ITNs) was 65% among the control group. There was a strong association between Mosbar use and ITN use, as 81% of Mosbar users also possessed ITN. The use of Mosbar was associated with a 45% reduction in the odds of malaria (95% CI: -11% to 72%, P=0.08) after adjusting for ITN and other unmatched factors. Ownership of ITNs was associated with a 46% reduction in the odds of malaria (95% CI: 12% to 67%, P=0.013) after adjusting for Mosbar and other unmatched factors. The greatest reduction in the odds of malaria was associated with combined use of Mosbar and ITN (69% reduction, 95% CI: 28% to 87%, P=0.007). The association between recalled use of Mosbar 10 days ago (nearer the time of infection) and reduction in malarial infections (adjusted odds ratio 0.08, 95% CI: 0.01-0.61, P=0.001) was significantly stronger than that shown by current use of Mosbar. Most purchasers of Mosbar were satisfied with the product (74%), although a minority said they preferred to use only ITN (8%). The local mosquito vectors, Anopheles stephensi and A. nigerrimus, started biting shortly after dusk and continued biting until early morning. It was shown that Mosbar prevented biting throughout this period. In regions where mosquito vectors bite during evening and night, repellents could have a useful supplementary role to ITN and their use should be more widely encouraged.

  19. Human exposure to anopheline mosquitoes occurs primarily indoors, even for users of insecticide-treated nets in Luangwa Valley, South-east Zambia

    Directory of Open Access Journals (Sweden)

    Seyoum Aklilu

    2012-05-01

    Full Text Available Abstract Background Current front line malaria vector control methods such as indoor residual spraying (IRS and long-lasting insecticidal nets (LLINs, rely upon the preference of many primary vectors to feed and/or rest inside human habitations where they can be targeted with domestically-applied insecticidal products. We studied the human biting behaviour of the malaria vector Anopheles funestus Giles and the potential malaria vector Anopheles quadriannulatus Theobald in Luangwa valley, south-east Zambia. Methods Mosquitoes were collected by human landing catch in blocks of houses with either combined use of deltamethrin-based IRS and LLINs or LLINs alone. Human behaviour data were collected to estimate how much exposure to mosquito bites indoors and outdoors occurred at various times of the night for LLIN users and non-users. Results Anopheles funestus and An. quadriannulatus did not show preference to bite either indoors or outdoors: the proportions [95% confidence interval] caught indoors were 0.586 [0.303, 0.821] and 0.624 [0.324, 0.852], respectively. However, the overwhelming majority of both species were caught at times when most people are indoors. The proportion of mosquitoes caught at a time when most people are indoors were 0.981 [0.881, 0.997] and 0.897 [0.731, 0.965], respectively, so the proportion of human exposure to both species occuring indoors was high for individuals lacking LLINs (An. funestus: 0.983 and An. quadriannulatus: 0.970, respectively. While LLIN users were better protected, more than half of their exposure was nevertheless estimated to occur indoors (An. funestus: 0.570 and An. quadriannulatus: 0.584. Conclusions The proportion of human exposure to both An. funestus and An. quadriannulatus occuring indoors was high in the area and hence both species might be responsive to further peri-domestic measures if these mosquitoes are susceptible to insecticidal products.

  20. Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study

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    Irish SR

    2008-06-01

    Full Text Available Abstract Background An important advantage of pyrethroid-treated nets over untreated nets is that once nets become worn or holed a pyrethroid treatment will normally restore protection. The capacity of pyrethroids to kill or irritate any mosquito that comes into contact with the net and prevent penetration of holes or feeding through the sides are the main reasons why treated nets continue to provide protection despite their condition deteriorating over time. Pyrethroid resistance is a growing problem among Anopheline and Culicine mosquitoes in many parts of Africa. When mosquitoes become resistant the capacity of treated nets to provide protection might be diminished, particularly when holed. An experimental hut trial against pyrethroid-resistant Culex quinquefasciatus was therefore undertaken in southern Benin using a series of intact and holed nets, both untreated and treated, to assess any loss of protection as nets deteriorate with use and time. Results There was loss of protection when untreated nets became holed; the proportion of mosquitoes blood feeding increased from 36.2% when nets were intact to between 59.7% and 68.5% when nets were holed to differing extents. The proportion of mosquitoes blood feeding when treated nets were intact was 29.4% which increased to 43.6–57.4% when nets were holed. The greater the number of holes the greater the loss of protection regardless of whether nets were untreated or treated. Mosquito mortality in huts with untreated nets was 12.9–13.6%; treatment induced mortality was less than 12%. The exiting rate of mosquitoes into the verandas was higher in huts with intact nets. Conclusion As nets deteriorate with use and become increasingly holed the capacity of pyrethroid treatments to restore protection is greatly diminished against resistant Culex quinquefasciatus mosquitoes.

  1. Fungal infection counters insecticide resistance in African malaria mosquitoes

    NARCIS (Netherlands)

    Farenhorst, M.; Mouatcho, J.C.; Kikankie, C.K.; Brooke, B.D.; Hunt, R.H.; Thomas, M.B.; Koekemoer, L.L.; Knols, B.G.J.; Coetzee, M.

    2009-01-01

    The evolution of insecticide resistance in mosquitoes is threatening the effectiveness and sustainability of malaria control programs in various parts of the world. Through their unique mode of action, entomopathogenic fungi provide promising alternatives to chemical control. However, potential

  2. Fungal infection counters insecticide resistance in African malaria mosquitoes

    NARCIS (Netherlands)

    Farenhorst, M.; Mouatcho, J.C.; Kikankie, C.K.; Brooke, B.D.; Hunt, R.H.; Thomas, M.B.; Koekemoer, L.L.; Knols, B.G.J.; Coetzee, M.

    2009-01-01

    The evolution of insecticide resistance in mosquitoes is threatening the effectiveness and sustainability of malaria control programs in various parts of the world. Through their unique mode of action, entomopathogenic fungi provide promising alternatives to chemical control. However, potential inte

  3. Susceptibility of Adult Mosquitoes to Insecticides in Aqueous Sucrose Baits

    Science.gov (United States)

    2011-06-01

    of the lack of ingestion as a result of repellency due to high survival of water-deprived control mosquitoes at 24 hr and the abundance of abdomens...Vol. 36, no. 1 Journal of Vector Ecology 59 Susceptibility of adult mosquitoes to insecticides in aqueous sucrose baits Sandra A. Allan Center for...2010 ABSTRACT: Mosquitoes characteristically feed on plant-derived carbohydrates and honeydew just after emergence and intermittently during their

  4. Do insecticide-treated bednets have an effect on malaria vectors?

    NARCIS (Netherlands)

    Takken, W.

    2002-01-01

    The use of insecticide-treated bednets (ITNs) has been widely adopted as an important method for malaria control. Few data exist on effects of ITNs on mosquito biology and ecology, other than the development of insecticide resistance against the insecticides used. There is no hard evidence that the

  5. Energetic cost of insecticide resistance in Culex pipiens mosquitoes.

    Science.gov (United States)

    Rivero, A; Magaud, A; Nicot, A; Vézilier, J

    2011-05-01

    The extensive use of insecticides to control vector populations has lead to the widespread development of different mechanisms of insecticide resistance. Mutations that confer insecticide resistance are often associated to fitness costs that prevent them from spreading to fixation. In vectors, such fitness costs include reductions in preimaginal survival, adult size, longevity, and fecundity. The most commonly invoked explanation for the nature of such pleiotropic effects of insecticide resistance is the existence of resource-based trade-offs. According to this hypothesis, insecticide resistance would deplete the energetic stores of vectors, reducing the energy available for other biological functions and generating trade-offs between insecticide resistance and key life history traits. Here we test this hypothesis by quantifying the energetic resources (lipids, glycogen, and glucose) of larvae and adult females of the mosquito Culex pipiens L. resistant to insecticides through two different mechanisms: esterase overproduction and acetylcholinesterase modification. We find that, as expected from trade-off theory, insecticide resistant mosquitoes through the overproduction of esterases contain on average 30% less energetic reserves than their susceptible counterparts. Acetylcholinesterase-modified mosquitoes, however, also showed a significant reduction in energetic resources (20% less). We suggest that, in acetylcholinesterase-modified mosquitoes, resource depletion may not be the result of resource-based trade-offs but a consequence of the hyperactivation of the nervous system. We argue that these results not only provide a mechanistic explanation for the negative pleiotropic effects of insecticide resistance on mosquito life history traits but also can have a direct effect on the development of parasites that depend on the vector's energetic reserves to fulfil their own metabolic needs.

  6. Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

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    Carnevale Pierre

    2010-11-01

    Full Text Available Abstract Background The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs, chlorpyrifos and diazinon, and insect growth regulator (IGR, pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures. Methods Mosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2 on different commonly used surfaces: porous (cement and stucco and non-porous (softwood and hard plastic. Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces. Results After treatment, delayed mortality was high (87-100% even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p -3. A reduction in fecundity was still observed nine months after treatment at both doses (p -3 and adult emergence was reduced at the higher dose (p -3. Conclusions High mortality rates were observed against laboratory strains of the pest mosquito Cx. quinquefasciatus susceptible and resistant to insecticides. Long-term killing remained equally important on non-porous surfaces regardless the resistance status for over 12 months. The paint's effect on fecundity, fertility and

  7. Adulticidal & larvicidal efficacy of three neonicotinoids against insecticide susceptible & resistant mosquito strains

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    Sreehari Uragayala

    2015-01-01

    Interpretation & conclusions: The present study indicated that insecticide resistant strains of mosquito species tested showed more susceptibility to the three neonicotinoids tested, and the possibility of using neonicotinoids for the control of resistant mosquitoes should be explored.

  8. The potential role of the educational system in addressing the effect of inadequate knowledge of mosquitoes on use of insecticide-treated nets in Ghana.

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    Kudom, Andreas A; Mensah, Ben A

    2010-09-15

    Since 2001, there has been a tremendous increase in number of households protected by ITN and IRS in Ghana. However, there has not been evidence of a reduction in malaria cases as expected and reported deaths have rather increased since 2007. As a result, this study was undertaken to get a better understanding of perceptions of malaria, knowledge on mosquitoes and the value attached to ITNs among secondary and tertiary students in Cape Coast. Structured questionnaires were administered randomly to gather data on demographic characteristics of students, knowledge of mosquitoes and ITNs and attitude towards the use of ITN in seven public high schools and four tertiary institutions in Cape Coast metropolis. In addition, curriculums of science courses common to all students from junior high school to the university were carefully examined. A total of 492 students took part in this study and more than 90% of them had high knowledge of malaria transmission and ITN, but little knowledge of mosquito life history. Only 1% in secondary and 2.1% in tertiary institutions had seen or knew about all the development stages of mosquitoes. In high school and tertiary institutions, 24.2% and 10.8% of respondents, respectively, were able to mention other genera of mosquitoes, apart from Anopheles. Though 93.9% in senior high school and 86.7% in the tertiary institutions knew that ITNs are either used to protect oneself from mosquito bites or to prevent malaria, 32.7% of the respondents in secondary and 21.9% in tertiary institutions who owned ITN did not use them. The study reveals that respondents did not have adequate knowledge on the biology and behaviour of mosquitoes. This appears to weaken their knowledge of the link between the use of ITN and malaria control; the effect of this is that a significant number owned ITNs but did not use them. The implication is that if people will really accept and use ITN or other mosquito control interventions, then just creating awareness of

  9. Insecticidal activity and expression of cytochrome P450 family 4 genes in Aedes albopictus after exposure to pyrethroid mosquito coils.

    Science.gov (United States)

    Avicor, Silas W; Wajidi, Mustafa F F; El-Garj, Fatma M A; Jaal, Zairi; Yahaya, Zary S

    2014-10-01

    Mosquito coils are insecticides commonly used for protection against mosquitoes due to their toxic effects on mosquito populations. These effects on mosquitoes could induce the expression of metabolic enzymes in exposed populations as a counteractive measure. Cytochrome P450 family 4 (CYP4) are metabolic enzymes associated with a wide range of biological activities including insecticide resistance. In this study, the efficacies of three commercial mosquito coils with different pyrethroid active ingredients were assessed and their potential to induce the expression of CYP4 genes in Aedes albopictus analyzed by real-time quantitative PCR. Coils containing 0.3 % D-allethrin and 0.005 % metofluthrin exacted profound toxic effects on Ae. albopictus, inducing high mortalities (≥90 %) compared to the 0.2 % D-allethrin reference coil. CYP4H42 and CYP4H43 expressions were significantly higher in 0.3 % D-allethrin treated mosquitoes compared to the other treated populations. Short-term (KT50) exposure to mosquito coils induced significantly higher expression of both genes in 0.005 % metofluthrin exposed mosquitoes. These results suggest the evaluated products provided better protection than the reference coil; however, they also induced the expression of metabolic genes which could impact negatively on personal protection against mosquito.

  10. Efficacy of the Olyset Duo net against insecticide-resistant mosquito vectors of malaria.

    Science.gov (United States)

    Ngufor, Corine; N'Guessan, Raphael; Fagbohoun, Josias; Todjinou, Damien; Odjo, Abibath; Malone, David; Ismail, Hanafy; Akogbeto, Martin; Rowland, Mark

    2016-09-14

    Olyset Duo is a new long-lasting insecticidal net treated with permethrin (a pyrethroid) and pyriproxyfen, an insect growth regulator that disrupts the maturation of oocytes in mosquitoes exposed to the net. We tested the Olyset Duo net against pyrethroid-resistant Anopheles gambiae mosquitoes, which transmit malaria parasites, in laboratory bioassays and in a trial in Benin using experimental huts that closely resemble local habitations. Host-seeking mosquitoes that entered to feed were free to contact the occupied nets and were collected the next morning from exit traps. Surviving blood-fed mosquitoes were observed for effects on reproduction. Control nets were treated with pyrethroid only or pyriproxyfen only, and nets were tested unwashed and after 20 standardized washes. The Olyset Duo net showed improved efficacy and wash resistance relative to the pyrethroid-treated net in terms of mosquito mortality and prevention of blood feeding. The production of offspring among surviving blood-fed A. gambiae in the hut trial was reduced by the pyriproxyfen-treated net and the Olyset Duo net both before washing (90 and 71% reduction, respectively) and after washing (38 and 43% reduction, respectively). The degree of reproductive suppression in the hut trial was predicted by laboratory tunnel tests but not by cone bioassays. The overall reduction in reproductive rate of A. gambiae with the Olyset Duo net in the trial was 94% with no washing and 78% after 20 washes. The Olyset Duo net has the potential to provide community control of mosquito populations and reduce malaria transmission in areas of high insecticide resistance.

  11. Delayed action insecticides and their role in mosquito and malaria control.

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    Wang, Chuncheng; Gourley, Stephen A; Liu, Rongsong

    2014-01-01

    There is considerable interest in the management of insecticide resistance in mosquitoes. One possible approach to slowing down the evolution of resistance is to use late-life-acting (LLA) insecticides that selectively kill only the old mosquitoes that transmit malaria, thereby reducing selection pressure favoring resistance. In this paper we consider an age-structured compartmental model for malaria with two mosquito strains that differ in resistance to insecticide, using an SEI approach to model malaria in the mosquitoes and thereby incorporating the parasite developmental times for the two strains. The human population is modeled using an SEI approach. We consider both conventional insecticides that target all adult mosquitoes, and LLA insecticides that target only old mosquitoes. According to linearised theory the potency of the insecticide affects mainly the speed of evolution of resistance. Mutations that confer resistance can also affect other parameters such as mean adult life span and parasite developmental time. For both conventional and LLA insecticides the stability of the malaria-free equilibrium, with only the resistant mosquito strain present, depends mainly on these other parameters. This suggests that the main long term role of an insecticide could be to induce genetic changes that have a desirable effect on a vital parameter such as adult life span. However, when this equilibrium is unstable, numerical simulations suggest that a potent LLA insecticide can slow down the spread of malaria in humans but that the timing of its action is very important.

  12. Health Effects of Long-Term Exposure to Insecticide-Treated Mosquito Nets in the Control of Malaria in Endemic Regions, Revised

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    Ebere C. Anyanwu

    2006-01-01

    Full Text Available The endemicity of malaria in tropical areas of the world persists, especially in countries south of Saharan Africa. The efforts and concerns invested by the World Health Organization and other health agencies to eradicate malaria are commendable. However, in spite of all these efforts, the loss in economic and human resources continues. In a previous report, the long-term health effects of insecticide-impregnated bednet (IIBN use were highlighted with the expectation of attracting serious thoughts and further research on the issue. This present paper is an update on that expectation. Results from a comprehensive literature search show that not much work has been done on the effects of long-term exposure to IIBNs in combating malarial infection. The efficacy of IIBNs is not in question. What is in question is whether long-term exposure to IIBNs have any health effects. The aims and outcomes of the research found in the literature on the subject to date seem to support only the efficacy of the temporal use of plain bednets, but not the use of IIBNs, and do not tell much about the long-term effects of IIBN exposure. All pesticides are toxic by nature and present risks of adverse effects. While there is agreement that IIBNs can be effective in reducing malarial morbidity and mortality under field trials, a number of factors relating to their long-term-exposure health effects have yet to be determined. Further reliable research projects are recommended urgently. However, some of the anticipated behavioral effects caused by insecticidal use will be avoided by the use of untreated nets instead.

  13. Susceptibility Status of Anopheles sundaicus Mosquitoes Against Insecticides Cypermethrin in Garut Regency

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    Nunung Seniawati

    2010-06-01

    Full Text Available At the time of high vector populations and malaria transmission is in progress, it is necessary to use insecticides to control vector using the house spraying. To get the results as objective the eradication of the vector that is able to suppress the vector population so that no longer play a role in malaria transmission, the insecticide used should be effective against mosquitoes and the mosquitoes are still susceptible to the insecticide used. To determine the level of malaria vector mosquito susceptibility to insecticides, in the terri-tory of Garut district has conducted susceptibility tests of Anopheles sundaicus mosquitoes to insecticides Cypermethrin held in November up to December 2008. Mosquitoes tested were captured in the form of larvae from ponds and estuaries in Karyamukti Cibalong Garut, and then reared in the field insektarium. The adult level were then tested for their susceptibility. Mosquito susceptibility tests conducted using the WHO Susceptibility Test Kit as many as four repetitions performed simultaneously, while the insecticide used in the form of imprag-nated paper with a dose of 0.05%. From tests it is known that mosquito mortality rate up to 100% test. This indicates that the mosquito An. sundaicus in Garut regency of West Java, is still susceptible to the insecticide Cypermenthrin. Therefore, it can still be used in the eradication of malaria vectors in the recommended dosage of 0.20 g/m2.

  14. Optimal control of Aedes aegypti mosquitoes by the sterile insect technique and insecticide.

    Science.gov (United States)

    Thomé, Roberto C A; Yang, Hyun Mo; Esteva, Lourdes

    2010-01-01

    We present a mathematical model to describe the dynamics of mosquito population when sterile male mosquitoes (produced by irradiation) are introduced as a biological control, besides the application of insecticide. In order to analyze the minimal effort to reduce the fertile female mosquitoes, we search for the optimal control considering the cost of insecticide application, the cost of the production of irradiated mosquitoes and their delivery as well as the social cost (proportional to the number of fertilized females mosquitoes). The optimal control is obtained by applying the Pontryagin's Maximum Principle. Copyright 2009 Elsevier Inc. All rights reserved.

  15. Contrasting patterns of tolerance between chemical and biological insecticides in mosquitoes exposed to UV-A.

    Science.gov (United States)

    Tetreau, Guillaume; Chandor-Proust, Alexia; Faucon, Frédéric; Stalinski, Renaud; Akhouayri, Idir; Prud'homme, Sophie M; Raveton, Muriel; Reynaud, Stéphane

    2013-09-15

    Mosquitoes are vectors of major human diseases, such as malaria, dengue or yellow fever. Because no efficient treatments or vaccines are available for most of these diseases, control measures rely mainly on reducing mosquito populations by the use of insecticides. Numerous biotic and abiotic factors are known to modulate the efficacy of insecticides used in mosquito control. Mosquito breeding sites vary from opened to high vegetation covered areas leading to a large ultraviolet gradient exposure. This ecological feature may affect the general physiology of the insect, including the resistance status against insecticides. In the context of their contrasted breeding sites, we assessed the impact of low-energetic ultraviolet exposure on mosquito sensitivity to biological and chemical insecticides. We show that several mosquito detoxification enzyme activities (cytochrome P450, glutathione S-transferases, esterases) were increased upon low-energy UV-A exposure. Additionally, five specific genes encoding detoxification enzymes (CYP6BB2, CYP6Z7, CYP6Z8, GSTD4, and GSTE2) previously shown to be involved in resistance to chemical insecticides were found over-transcribed in UV-A exposed mosquitoes, revealed by RT-qPCR experiments. More importantly, toxicological bioassays revealed that UV-exposed mosquitoes were more tolerant to four main chemical insecticide classes (DDT, imidacloprid, permethrin, temephos), whereas the bioinsecticide Bacillus thuringiensis subsp. israelensis (Bti) appeared more toxic. The present article provides the first experimental evidence of the capacity of low-energy UV-A to increase mosquito tolerance to major chemical insecticides. This is also the first time that a metabolic resistance to chemical insecticides is linked to a higher susceptibility to a bioinsecticide. These results support the use of Bti as an efficient alternative to chemical insecticides when a metabolic resistance to chemicals has been developed by mosquitoes. Copyright

  16. Chlorfenapyr: a pyrrole insecticide for the control of pyrethroid or DDT resistant Anopheles gambiae (Diptera: Culicidae) mosquitoes.

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    N'Guessan, R; Boko, P; Odjo, A; Akogbéto, M; Yates, A; Rowland, M

    2007-04-01

    Owing to the development and spread of pyrethroid resistance in Anopheles gambiae in Africa there is an urgent need to develop alternative insecticides to supplement the pyrethroids. Chlorfenapyr is a pyrrole insecticide first commercialized for the control of agricultural pests and termites. Performance against An. gambiae bearing kdr (pyrethroid and DDT resistance) or Ace-1(R) insensitive acetylcholinesterase (organophosphate and carbamate resistance) mechanisms was studied using a variety of adult bioassay tests including a simulated-experimental hut system (tunnel tests) that allows uninhibited mosquito behaviour/insecticide interactions. Strains resistant to pyrethroids and organophosphates showed no cross resistance to chlorfenapyr. In cone bioassays on treated netting the mortality of adult mosquitoes showed an unexpected curvilinear response, with highest mortality occurring at intermediate dosages. Adults expressed irritability to chlorfenapyr at higher dosages, which might explain the dosage-mortality trend. Toxic activity of chlorfenapyr was slow compared to conventional neurotoxic insecticides and additional mortality occurred between 24h and 72 h. In tunnel tests, the dosage-mortality trend showed a more typical sigmoid response and most mortality occurred during the first 24h. Mosquito penetration through the holed, treated netting showed only limited inhibition and blood-feeding was not inhibited. Mortality rates in the kdr strain exposed to chlorfenapyr treated netting in tunnel tests were much higher than with permethrin treated netting over the same 100-500 mg/m(2) dosage range. Chlorfenapyr has potential for malaria control in treated-net or residual spraying applications in areas where mosquitoes are pyrethroid resistant. For treated-net applications chlorfenapyr might be combined with pyrethroid as a mixture to provide personal protection as well as to give control of resistant mosquitoes.

  17. Lack of insecticidal effect of mosquito coils containing either metofluthrin or esbiothrin on Anopheles gambiae sensu lato mosquitoes.

    Science.gov (United States)

    Lukwa, Nzira; Chiwade, Tonderai

    2008-12-01

    Use of mosquito coils for personal protection against malaria and mosquito nuisance is advocated under mosquito and malaria control programmes. We performed field studies of mosquito coils containing either metofluthrin or esbiothrin in experimental huts situated in Kamhororo village, Gokwe district, Zimbabwe. All tests were performed on 3-5 day old reared female Anopheles gambiae sensu lato mosquitoes. The burning times were 9hr 20min for mosquito coils containing metofluthrin and 8 hr for those containing esbiothrin and the results were significantly different (p = metofluthrin was 90% and that for esbiothrin was 73.3% and the results were significantly different (p = 0.00). Mosquito coils containing metofluthrin had a mean repellence of 92.7% as compared to 85.4% for esbiothrin and the results were not significantly different (p=0.27). The protection time as required by EPA (1999) was 6 hr for mosquito coils containing metofluthrin and 5 hr for those containing esbiothrin. The mean insecticidal effect of mosquito coils containing metofluthrin was 84% as compared to 83% for those containing esbiothrin and the results were not significantly different (p = 0.56). Both mosquito formulations could not be classified as having insecticidal effect since none of them met the 95% mortality rate criteria.

  18. Insecticide resistance in malaria vector mosquitoes at four localities in Ghana, West Africa

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    Kaiser Maria L

    2011-06-01

    Full Text Available Abstract Background Malaria vector control programmes that rely on insecticide-based interventions such as indoor house spraying with residual insecticides or insecticide treated bed nets, need to base their decision-making process on sound baseline data. More and more commercial entities in Africa, such as mining companies, are realising the value to staff productivity of controlling malaria transmission in their areas of operation. This paper presents baseline entomological data obtained during surveys conducted for four mining operations in Ghana, West Africa. Results The vast majority of the samples were identified as Anopheles gambiae S form with only a few M form specimens being identified from Tarkwa. Plasmodium falciparum infection rates ranged from 4.5 to 8.6% in An. gambiae and 1.81 to 8.06% in An. funestus. High survival rates on standard WHO bioassay tests were recorded for all insecticide classes except the organophosphates that showed reasonable mortality at all locations (i.e. > 90%. The West African kdr mutation was detected and showed high frequencies in all populations. Conclusions The data highlight the complexity of the situation prevailing in southern Ghana and the challenges facing the malaria vector control programmes in this region. Vector control programmes in Ghana need to carefully consider the resistance profiles of the local mosquito populations in order to base their resistance management strategies on sound scientific data.

  19. First report of the infection of insecticide-resistant malaria vector mosquitoes with an entomopathogenic fungus under field conditions

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    Akogbéto Martin

    2011-02-01

    Full Text Available Abstract Background Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control malaria vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecticide-resistant mosquitoes under laboratory conditions. The goal of this study was to see whether entomopathogenic fungi could be used to infect insecticide-resistant malaria vectors under field conditions, and to see whether the virulence and viability of the fungal conidia decreased after exposure to ambient African field conditions. Methods This study used the fungus Beauveria bassiana to infect the insecticide-resistant malaria vector Anopheles gambiae s.s (Diptera: Culicidae VKPER laboratory colony strain. Fungal conidia were applied to polyester netting and kept under West African field conditions for varying periods of time. The virulence of the fungal-treated netting was tested 1, 3 and 5 days after net application by exposing An. gambiae s.s. VKPER mosquitoes in WHO cone bioassays carried out under field conditions. In addition, the viability of B. bassiana conidia was measured after up to 20 days exposure to field conditions. Results The results show that B. bassiana infection caused significantly increased mortality with the daily risk of dying being increased by 2.5× for the fungus-exposed mosquitoes compared to the control mosquitoes. However, the virulence of the B. bassiana conidia decreased with increasing time spent exposed to the field conditions, the older the treatment on the net, the lower the fungus-induced mortality rate. This is likely to be due to the climate because laboratory trials found no such decline within the same trial time period. Conidial viability also decreased with increasing exposure to the net and natural abiotic environmental conditions. After 20 days field exposure the conidial viability was 30%, but

  20. First report of the infection of insecticide-resistant malaria vector mosquitoes with an entomopathogenic fungus under field conditions

    Science.gov (United States)

    2011-01-01

    Background Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control malaria vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecticide-resistant mosquitoes under laboratory conditions. The goal of this study was to see whether entomopathogenic fungi could be used to infect insecticide-resistant malaria vectors under field conditions, and to see whether the virulence and viability of the fungal conidia decreased after exposure to ambient African field conditions. Methods This study used the fungus Beauveria bassiana to infect the insecticide-resistant malaria vector Anopheles gambiae s.s (Diptera: Culicidae) VKPER laboratory colony strain. Fungal conidia were applied to polyester netting and kept under West African field conditions for varying periods of time. The virulence of the fungal-treated netting was tested 1, 3 and 5 days after net application by exposing An. gambiae s.s. VKPER mosquitoes in WHO cone bioassays carried out under field conditions. In addition, the viability of B. bassiana conidia was measured after up to 20 days exposure to field conditions. Results The results show that B. bassiana infection caused significantly increased mortality with the daily risk of dying being increased by 2.5× for the fungus-exposed mosquitoes compared to the control mosquitoes. However, the virulence of the B. bassiana conidia decreased with increasing time spent exposed to the field conditions, the older the treatment on the net, the lower the fungus-induced mortality rate. This is likely to be due to the climate because laboratory trials found no such decline within the same trial time period. Conidial viability also decreased with increasing exposure to the net and natural abiotic environmental conditions. After 20 days field exposure the conidial viability was 30%, but the viability of control

  1. First report of the infection of insecticide-resistant malaria vector mosquitoes with an entomopathogenic fungus under field conditions

    NARCIS (Netherlands)

    Howard, A.F.V.; N'Guessan, R.; Koenraadt, C.J.M.; Asidi, A.; Farenhorst, M.; Akogbeto, M.; Knols, B.G.J.; Takken, W.

    2011-01-01

    Background - Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control malaria vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecti

  2. The Effect of Early Mosquito Insecticides Exposure on Spraque Dawley Rat Testis: A Histopathological Feature Towards Malignancy?

    Science.gov (United States)

    Indah Winarni, Tri; Auzan Aziman, Milzam; Abshar Andar, Anindyo; Pawitra, Ika

    2017-02-01

    The incidence of health problems associated with endocrine-disruption have increased. Many studies suggesting that endocrine disruptor chemicals (EDC) do contribute to cancer through estrogen-related receptors. Many chemicals have EDCs properties including insecticides. Early life exposure to EDCs can increased the risk of testicular cancer have been reported in the last decade. This study was aimed to determine the effect of insecticides exposure on histopathological tumor cell development of germ and Leydig cell. True experiment research design with posttest only control group design was applied. Sprague Dawley (SD) rat (n = 25) were randomly divided into 5 groups (control group, 25 mg β estradiol 3-benzoate, spiral mosquito coil repellent, 3 ml of liquid mosquito repellent, and 4 ml of liquid mosquito repellent). The exposure were administered for 20 days started at aged 3 days. At the age of 100 days (older adult), testis was stained using Hematoxyllin Eosin (HE) and histological features predicting malignancy were observed. The number of tumor cell development in both testicular germ cells and Leydig cells significantly increased in all treated group compared to those of control and the changes towards malignancy were also observed in all treated group. Exposure to mosquito insecticides causes significant changes in testicular germ and Leydig cell histological features that leads to malignancy.

  3. Synergy in efficacy of fungal entomopathogens and permethrin against West African insecticide-resistant Anopheles gambiae mosquitoes

    NARCIS (Netherlands)

    Farenhorst, M.; Knols, B.G.J.; Thomas, M.B.; Howard, A.F.V.; Takken, W.; Rowland, M.; N'Guessan, R.

    2010-01-01

    Background Increasing incidences of insecticide resistance in malaria vectors are threatening the sustainable use of contemporary chemical vector control measures. Fungal entomopathogens provide a possible additional tool for the control of insecticide-resistant malaria mosquitoes. This study invest

  4. Synergy in Efficacy of Fungal Entomopathogens and Permethrin against West African Insecticide-Resistant Anopheles gambiae Mosquitoes

    NARCIS (Netherlands)

    Farenhorst, M.; Knols, B.G.J.; Thomas, M.B.; Howard, A.F.V.; Takken, W.; Rowland, M.; N'Guessan, R.

    2010-01-01

    Background: Increasing incidences of insecticide resistance in malaria vectors are threatening the sustainable use of contemporary chemical vector control measures. Fungal entomopathogens provide a possible additional tool for the control of insecticide-resistant malaria mosquitoes. This study

  5. Synergy in efficacy of fungal entomopathogens and permethrin against West African insecticide-resistant Anopheles gambiae mosquitoes

    NARCIS (Netherlands)

    Farenhorst, M.; Knols, B.G.J.; Thomas, M.B.; Howard, A.F.V.; Takken, W.; Rowland, M.; N'Guessan, R.

    2010-01-01

    Background Increasing incidences of insecticide resistance in malaria vectors are threatening the sustainable use of contemporary chemical vector control measures. Fungal entomopathogens provide a possible additional tool for the control of insecticide-resistant malaria mosquitoes. This study

  6. Role of cytochrome P450s in insecticide resistance: impact on the control of mosquito-borne diseases and use of insecticides on Earth

    Science.gov (United States)

    David, Jean-Philippe; Ismail, Hanafy Mahmoud; Chandor-Proust, Alexia; Paine, Mark John Ingraham

    2013-01-01

    The fight against diseases spread by mosquitoes and other insects has enormous environmental, economic and social consequences. Chemical insecticides remain the first line of defence but the control of diseases, especially malaria and dengue fever, is being increasingly undermined by insecticide resistance. Mosquitoes have a large repertoire of P450s (over 100 genes). By pinpointing the key enzymes associated with insecticide resistance we can begin to develop new tools to aid the implementation of control interventions and reduce their environmental impact on Earth. Recent technological advances are helping us to build a functional profile of the P450 determinants of insecticide metabolic resistance in mosquitoes. Alongside, the cross-responses of mosquito P450s to insecticides and pollutants are also being investigated. Such research will provide the means to produce diagnostic tools for early detection of P450s linked to resistance. It will also enable the design of new insecticides with optimized efficacy in different environments. PMID:23297352

  7. Role of cytochrome P450s in insecticide resistance: impact on the control of mosquito-borne diseases and use of insecticides on Earth.

    Science.gov (United States)

    David, Jean-Philippe; Ismail, Hanafy Mahmoud; Chandor-Proust, Alexia; Paine, Mark John Ingraham

    2013-02-19

    The fight against diseases spread by mosquitoes and other insects has enormous environmental, economic and social consequences. Chemical insecticides remain the first line of defence but the control of diseases, especially malaria and dengue fever, is being increasingly undermined by insecticide resistance. Mosquitoes have a large repertoire of P450s (over 100 genes). By pinpointing the key enzymes associated with insecticide resistance we can begin to develop new tools to aid the implementation of control interventions and reduce their environmental impact on Earth. Recent technological advances are helping us to build a functional profile of the P450 determinants of insecticide metabolic resistance in mosquitoes. Alongside, the cross-responses of mosquito P450s to insecticides and pollutants are also being investigated. Such research will provide the means to produce diagnostic tools for early detection of P450s linked to resistance. It will also enable the design of new insecticides with optimized efficacy in different environments.

  8. Evaluation of organophosphorus and synthetic pyrethroid insecticides against six vector mosquitoe species

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    Montada Dorta Domingo

    1993-01-01

    Full Text Available Three organophosphorus compounds- malathion, folithion and temephos- and two synthetic pyrethroids- alphamethrin and deltamethrin- were used for monitoring the susceptibility status of larvae and adults of six vector mosquitoe species: Culex quinquefasciatus (Filariasis and Aedes albopictus (Dengue (both laboratory and field strains; laboratory strains of Aedes aegypti (Dengue, Anopheles slephensi and Anopheles culicifacies (Malaria, and Culex tritaeniorhynchus (Japanese encephalitis in India. From the LC50 values obtained for these insecticides, it was found that all mosquito species including the field strains of Cx. quinquefasciatus and Ae. albopictus were highly susceptible Except for Cx. quinquefasciatus (field strain against malathion, 100% mortality was observed at the discriminating dosages recommended by World Health Organization. The residual effect of alphamethrin, deltamethrin, malathion and folithion at 25 mg (ai/m² on different surfaces against six species of vector mosquitoes showed that alphamethrin was the most effective on all four treated surfaces (mud, plywood, cement and thatch. Nevertheless, residual efficacy lasted longer on thatch than on the other surfaces. Therefore, synthetic pyrethroids such as alphamethrin can be effectively employed in integrated vector control operations.

  9. Evaluation of organophosphorus and synthetic pyrethroid insecticides against six vector mosquitoe species

    Directory of Open Access Journals (Sweden)

    Domingo Montada Dorta

    1993-12-01

    Full Text Available Three organophosphorus compounds- malathion, folithion and temephos- and two synthetic pyrethroids- alphamethrin and deltamethrin- were used for monitoring the susceptibility status of larvae and adults of six vector mosquitoe species: Culex quinquefasciatus (Filariasis and Aedes albopictus (Dengue (both laboratory and field strains; laboratory strains of Aedes aegypti (Dengue, Anopheles slephensi and Anopheles culicifacies (Malaria, and Culex tritaeniorhynchus (Japanese encephalitis in India. From the LC50 values obtained for these insecticides, it was found that all mosquito species including the field strains of Cx. quinquefasciatus and Ae. albopictus were highly susceptible Except for Cx. quinquefasciatus (field strain against malathion, 100% mortality was observed at the discriminating dosages recommended by World Health Organization. The residual effect of alphamethrin, deltamethrin, malathion and folithion at 25 mg (ai/m² on different surfaces against six species of vector mosquitoes showed that alphamethrin was the most effective on all four treated surfaces (mud, plywood, cement and thatch. Nevertheless, residual efficacy lasted longer on thatch than on the other surfaces. Therefore, synthetic pyrethroids such as alphamethrin can be effectively employed in integrated vector control operations.

  10. The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control.

    Science.gov (United States)

    Oxborough, Richard M; N'Guessan, Raphael; Jones, Rebecca; Kitau, Jovin; Ngufor, Corine; Malone, David; Mosha, Franklin W; Rowland, Mark W

    2015-03-24

    The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of experiments explored whether standard World Health Organization (WHO) guidelines for evaluation of long-lasting insecticidal nets, developed through testing of pyrethroid insecticides, are suitable for evaluation of non-neurotoxic insecticides. The efficacy of WHO recommended cone, cylinder and tunnel tests was compared for pyrethroids and chlorfenapyr. To establish bioassay exposure times predictive of insecticide-treated net (ITN) efficacy in experimental hut trials, standard three-minute bioassays of pyrethroid and chlorfenapyr ITNs were compared with longer exposures. Mosquito behaviour and response to chlorfenapyr ITN in bioassays conducted at night were compared to day and across a range of temperatures representative of highland and lowland transmission. Standard three-minute bioassay of chlorfenapyr produced extremely low levels of mortality compared to pyrethroids. Thirty-minute day-time bioassay produced mortality closer to hut efficacy of chlorfenapyr ITN but still fell short of the WHO threshold. Overnight tunnel test with chlorfenapyr produced 100% mortality and exceeded the WHO threshold of 80%. The endogenous circadian activity rhythm of anophelines results in inactivity by day and raised metabolism and flight activity by night. A model which explains improved toxicity of chlorfenapyr ITN when tested at night, and during the day at higher ambient temperature, is that activation of chlorfenapyr and disruption of respiratory pathways is enhanced when the insect is more metabolically

  11. Mosquito nets treated with a mixture of chlorfenapyr and alphacypermethrin control pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes in West Africa.

    Science.gov (United States)

    N'Guessan, Raphael; Ngufor, Corine; Kudom, Andreas A; Boko, Pelagie; Odjo, Abibathou; Malone, David; Rowland, Mark

    2014-01-01

    The effectiveness of insecticide treated nets is under threat across Africa south of the Sahara from the selection of pyrethroid resistance in Anopheles gambiae mosquitoes. To maintain progress against malaria it is necessary to identify alternative residual insecticides for mosquito nets. Mixtures of pyrethroid and insecticides with novel mode of action provide scope for both improved control and management of resistance through concurrent exposure to unrelated insecticides. The pyrrole chlorfenapyr and the pyrethroid alphacypermethrin were tested individually and as a mixture on mosquito nets in an experimental hut trial in southern Benin against pyrethroid resistant An gambiae and Culex quinquefasciatus mosquitoes. The nets were deliberately holed to simulate the effect of wear and tear. The nets treated with the mixture of chlorfenapyr 200 mg/m² and alphacypermethrin 25 mg/m² killed a proportion of An gambiae (77%, 95%CI: 66-86%) significantly greater than nets treated with alphacypermethrin 25 mg/m(2) (30%, 95%CI: 21-41%) but not significantly different from nets treated with chlorfenapyr 200 mg/m² (69%, 95%CI: 57-78%). The nets treated with the mixtures procured personal protection against An gambiae biting(58-62%) by a greater margin than the alphacypermethrin treated net (39%), whereas the chlorfenapyr treated net was not protective. A similar trend in mortality and blood feeding inhibition between treatments was observed in Cx quinquefasciatus to that seen in An. gambiae, although the effects were lower. A mixture of alphacypermethrin with chlorfenapyr applied at 100 mg/m² had an effect similar to the mixture with chlorfenapyr at 200 mg/m². The effectiveness of ITNs against pyrethroid resistant mosquitoes was restored by the mixture: the alphacypermethrin component reduced human-vector contact while the chlorfenapyr controlled pyrethroid-resistant mosquitoes. The complementary action of these unrelated insecticides demonstrates that the combination on

  12. Evaluation of insecticide impregnated baits for control of mosquito larvae in land crab burrows on French Polynesian atolls.

    Science.gov (United States)

    Lardeux, Frederic; Sechan, Yves; Faaruia, Marc

    2002-07-01

    Land crab burrows are larval mosquito habitats of major significance in the Pacific region. They are constituted by a sinuous tunnel leading to a chamber in contact with the water table, where mosquito larvae proliferate. Controlling larvae in these sites is difficult, because the configuration of burrows prevents the use of standard techniques. An experiment was carried out in French Polynesia to control Aedes polynesiensis Marks and Culex spp. breeding in burrows of the land crab Cardisoma carnifex (Herbst). The technique was based on the crab's behavior, which involves the crab carrying food into its burrow. It was shown that appetizing baits impregnated with an insecticide were carried by crabs into the flooded chamber of their burrows. A field treatment of burrows was carried out by sowing insecticide impregnated baits on the ground. The treatment coverage was almost perfect and the easy implementation of the technique enabled large areas to be treated in a short time. The bait was developed by compacting various flours, which easily incorporate a large variety of insecticide formulations. Although the baits can be easily stocked, a reliable insecticide is still to be found. The results indicate that our technique could be a method of choice for treating crab burrows.

  13. Chemical and biological insecticides select distinct gene expression patterns in Aedes aegypti mosquito.

    Science.gov (United States)

    Després, Laurence; Stalinski, Renaud; Faucon, Frédéric; Navratil, Vincent; Viari, Alain; Paris, Margot; Tetreau, Guillaume; Poupardin, Rodolphe; Riaz, Muhammad Asam; Bonin, Aurélie; Reynaud, Stéphane; David, Jean-Philippe

    2014-12-01

    Worldwide evolution of mosquito resistance to chemical insecticides represents a major challenge for public health, and the future of vector control largely relies on the development of biological insecticides that can be used in combination with chemicals (integrated management), with the expectation that populations already resistant to chemicals will not become readily resistant to biological insecticides. However, little is known about the metabolic pathways affected by selection with chemical or biological insecticides. Here we show that Aedes aegypti, a laboratory mosquito strain selected with a biological insecticide (Bacillus thuringiensis israelensis, Bti) evolved increased transcription of many genes coding for endopeptidases while most genes coding for detoxification enzymes were under-expressed. By contrast, in strains selected with chemicals, genes encoding detoxification enzymes were mostly over-expressed. In all the resistant strains, genes involved in immune response were under-transcribed, suggesting that basal immunity might be a general adjustment variable to compensate metabolic costs caused by insecticide selection. Bioassays generally showed no evidence for an increased susceptibility of selected strains towards the other insecticide type, and all chemical-resistant strains were as susceptible to Bti as the unselected parent strain, which is a good premise for sustainable integrated management of mosquito populations resistant to chemicals.

  14. Control of pyrethroid and DDT-resistant Anopheles gambiae by application of indoor residual spraying or mosquito nets treated with a long-lasting organophosphate insecticide, chlorpyrifos-methyl

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    Chabi Joseph

    2010-02-01

    Full Text Available Abstract Background Scaling up of long-lasting insecticidal nets (LLINs and indoor residual spraying (IRS with support from the Global Fund and President's Malaria Initiative is providing increased opportunities for malaria control in Africa. The most cost-effective and longest-lasting residual insecticide DDT is also the most environmentally persistent. Alternative residual insecticides exist, but are too short-lived or too expensive to sustain. Dow Agrosciences have developed a microencapsulated formulation (CS of the organophosphate chlorpyrifos methyl as a cost-effective, long-lasting alternative to DDT. Methods Chlorpyrifos methyl CS was tested as an IRS or ITN treatment in experimental huts in an area of Benin where Anopheles gambiae and Culex quinquefasiactus are resistant to pyrethroids, but susceptible to organophosphates. Efficacy and residual activity was compared to that of DDT and the pyrethroid lambdacyalothrin. Results IRS with chlorpyrifos methyl killed 95% of An. gambiae that entered the hut as compared to 31% with lambdacyhalothrin and 50% with DDT. Control of Cx. quinquefasciatus showed a similar trend; although the level of mortality with chlorpyrifos methyl was lower (66% it was still much higher than for DDT (14% or pyrethroid (15% treatments. Nets impregnated with lambdacyhalothrin were compromized by resistance, killing only 30% of An. gambiae and 8% of Cx. quinquefasciatus. Nets impregnated with chlorpyrifos methyl killed more (45% of An gambiae and 15% of Cx. quinquefasciatus, but its activity on netting was of short duration. Contact bioassays on the sprayed cement-sand walls over the nine months of monitoring showed no loss of activity of chlorpyrifos methyl, whereas lambdacyhalothrin and DDT lost activity within a few months of spraying. Conclusion As an IRS treatment against pyrethroid resistant mosquitoes chlorpyrifos methyl CS outperformed DDT and lambdacyhalothrin. In IRS campaigns, chlorpyrifos methyl CS should

  15. Wash resistance of insecticide-treated materials.

    Science.gov (United States)

    Ordóñez González, José; Kroeger, Axel; Aviña, Ana Isabel; Pabón, Eulides

    2002-01-01

    The effectiveness of insecticide-treated materials (ITMs) for malaria control is reduced by washing them. This research in Colombia and Bolivia investigated the resistance of different insecticide formulations and, in particular, a commercially available impregnated bednet (PermaNet) which provides chemical protection for the insecticide. The fabrics studied were all polyester; the pyrethroids used for impregnation were deltamethrin (tablet and suspension concentrate both at 25 mg/m2 target dose), lambdacyhalothrin (capsule suspension at 15 mg/m2; laboratory study only), alphacypermethrin (suspension concentrate at 40 mg/m2) and, in the case of PermaNet, deltamethrin (55 mg/m2). The indicator of wash resistance was Anopheles spp. mortality (using the bioassay cone method) before and after different numbers and intensities of washing. When the fabrics were washed under controlled conditions, gently with water and a bar of soap, the wash resistance of all formulations was good (100% Anopheles mortality after 3 washes). However, when the impregnated nets were soaked for 30-60 min and washed with soap powder and tap water by local women in the usual way, the mortality after 4 washes declined considerably (43.5% and 41.3% for deltamethrin tablets and liquid respectively when washing every second day). Alphacypermethrin showed slightly better results after 3 washes every 7th day compared to deltamethrin tablets (63.8% and 43.3% mortality, respectively). The wash resistance offered by PermaNet was much better and longer lasting: Anopheles mortality after 4 washes was 92.6%, after 10 washes 83.7% and after 20 washes 87.1%. The limitations of commercially available wash-resistant nets are, however, their limited accessibility and the difficulty of replacing all existing bednets with a new product.

  16. The mosquito ultra-low volume dispersion model for estimating environmental concentrations of insecticides used for adult mosquito management.

    Science.gov (United States)

    Schleier, Jerome J; Peterson, Robert K D

    2014-09-01

    Computer models for pesticide drift are widely used tools by regulatory agencies to estimate the deposition of pesticides beyond the intended target area. Currently, there is no model in use that has been validated or verified as an accurate means of estimating concentrations of insecticides after ground-based ultra-low volume (ULV) applications used for adult mosquito management. To address the need for a validated model we created a spreadsheet-based model called Mosquito Ultra-Low Volume Dispersion (MULV-Disp) to aid in the adoption and to provide easier use of a validated model. We explain the origin, use, and utility of MULV-Disp, which can be used by regulatory agencies and other interested parties to estimate deposition of ULV insecticides.

  17. Evaluation of Olyset™ insecticide-treated nets distributed seven years previously in Tanzania

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    Mshinda Hassan

    2004-06-01

    Full Text Available Abstract Background Insecticide-treated nets represent currently a key malaria control strategy, but low insecticide re-treatment rates remain problematic. Olyset™ nets are currently one of two long-lasting insecticidal nets recommended by WHO. An assessment was carried out of the effect of Olyset™ nets after seven years of use in rural Tanzania. Methods A survey of Olyset™ nets was conducted in two Tanzanian villages to examine their insecticide dosage, bioassay efficacy and desirability compared with ordinary polyester nets. Results Of 103 randomly selected nets distributed in 1994 to 1995, 100 could be traced. Most nets were in a condition likely to offer protection against mosquito biting. Villagers appreciated mainly the durability of Olyset™ nets and insecticide persistence. People disliked the small size of these nets and the light blue colour and preferred a smaller mesh size, features that can easily be modified. At equal price, 51% said they would prefer to buy an Olyset™ net and 49% opted for an ordinary polyester net. The average permethrin content was 33%-41% of the initial insecticide dose of 20,000 mg/Kg. Bioassay results indicated high knock-down rates at 60 minutes, but the mosquito mortality after 24 hours was rather low (mean: 34%. No significant correlation was found between bioassay results and insecticide concentration in and on the net. Conclusions Olyset™ nets are popular, durable and with a much longer insecticide persistence than ordinary polyester nets. Hence, Olyset™ nets are one of the best choices for ITN programmes in rural malaria-endemic areas.

  18. Quantifying behavioural interactions between humans and mosquitoes: Evaluating the protective efficacy of insecticidal nets against malaria transmission in rural Tanzania

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    Mathenge Evan

    2006-11-01

    Full Text Available Abstract Background African malaria vectors bite predominantly indoors at night so sleeping under an Insecticide-Treated Net (ITN can greatly reduce malaria risk. Behavioural adaptation by mosquitoes to increasing ITN coverage could allow vector mosquitoes to bite outside of peak sleeping hours and undermine efficacy of this key malaria prevention measure. Methods High coverage with largely untreated nets has been achieved in the Kilombero Valley, southern Tanzania through social marketing programmes. Direct surveys of nightly biting activity by An. gambiae Giles were conducted in the area before (1997 and after (2004 implementation of ITN promotion. A novel analytical model was applied to estimate the effective protection provided by an ITN, based on published experimental hut trials combined with questionnaire surveys of human sleeping behaviour and recorded mosquito biting patterns. Results An. gambiae was predominantly endophagic and nocturnal in both surveys: Approximately 90% and 80% of exposure occurred indoors and during peak sleeping hours, respectively. ITNs consistently conferred >70% protection against exposure to malaria transmission for users relative to non-users. Conclusion As ITN coverage increases, behavioural adaptation by mosquitoes remains a future possibility. The approach described allows comparison of mosquito biting patterns and ITN efficacy at multiple study sites and times. Initial results indicate ITNs remain highly effective and should remain a top-priority intervention. Combined with recently developed transmission models, this approach allows rapid, informative and cost-effective preliminary comparison of diverse control strategies in terms of protection against exposure before more costly and intensive clinical trials.

  19. Insecticide susceptibility of Anopheles coluzzii and Anopheles gambiae mosquitoes in Ibadan, Southwest Nigeria.

    Science.gov (United States)

    Okorie, P N; Ademowo, O G; Irving, H; Kelly-Hope, L A; Wondji, C S

    2015-03-01

    The emergence of insecticide resistance in Anopheles (Diptera: Culicidae) mosquitoes has great implications for malaria control in Nigeria. This study aimed to determine the dynamics of insecticide susceptibility levels and the frequency of knock-down resistance (kdr) mutations (L1014F) in wild Anopheles coluzzii Coetzee & Wilkerson sp. n. and Anopheles gambiae Giles from the Ojoo and Bodija areas of Ibadan, in southwest Nigeria. Insecticide susceptibility to pyrethroids, organophosphates, carbamates and organochlorines was assessed using World Health Organization (WHO) bioassays. A subset of the mosquitoes exposed to pyrethroids and DDT was used for species and molecular form identification; kdr genotyping was determined using the TaqMan real-time polymerase chain reaction assay. The mosquitoes were resistant to pyrethroids and DDT but completely susceptible to organophosphates and carbamates. Bodija samples (n = 186) consisted of An. gambiae (91.4%) and An. coluzzii (8.1%) and included one An. coluzzii/An. gambiae hybrid specimen. All mosquitoes screened in Ojoo (n = 26) were An. gambiae. The 1014F kdr mutation was detected at frequencies of 24.5 and 5.8% in Bodija and Ojoo, respectively. No correlation was observed between kdr genotypes and resistance phenotypes. The results indicate that metabolic resistance probably plays an important role in the development of resistance and highlight the need to implement insecticide resistance management strategies.

  20. Profile of the population use of household insecticides against mosquitoes

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    Luzilene Barbosa Oliveira

    2015-11-01

    Full Text Available This study described the use of household insecticides in Picos (Piauí, Brazil, identify which are the most used types of insecticides and describes the incidence of poisoning and environmental awareness of the population. After home visits (n = 700, it was seen that the majority of respondents was represented by women (75%, with 31-55 years-old (49%, incomplete primary education (38.1% and income between 1-2 earnings (64%. Most homes have between 1-3 residents (48%, 85% of the persons use insecticides mainly chosen in TV and radio and only 54% of them read the label before employing the product. The most used form of presentation is the aerosol (70.7%. Majority (79% recognizes that insecticides are harmful to health, but 74% do not use any Personal Protective Equipment (PPE. Symptoms of toxicity were reported by 27% of people interviewed. Two women reported irritation, dizziness and respiratory problems and need for medical intervention and hospitalization. All interviewed discard the package as regular trash, since Picos does not has selective collection. In conclusion, most people use insecticides, know about the individual and collective risks to which they are exposed but do not use PPE, though they believe insecticides are toxic. It was noted that acquisition of knowledge does not necessarily result in behavioral changes, since learning does not translate into appropriate preventive attitudes and practices, emphasizing the requirement for awareness campaigns about toxicity and environmental risks, preparation of professionals and surveillance policy against indiscriminate sale.

  1. The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control

    OpenAIRE

    Oxborough, RM; N'Guessan, R.; Jones, R.; Kitau, J; Ngufor, C; Malone, D; Mosha, FW; Rowland, MW

    2015-01-01

    Background\\ud The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of exper...

  2. Silica nanoparticle: a potential new insecticide for mosquito vector control.

    Science.gov (United States)

    Barik, Tapan K; Kamaraju, Raghavendra; Gowswami, Arunava

    2012-09-01

    Presently, there is a need for increased efforts to develop newer and effective methods to control mosquito vectors as the existing chemical and biological methods are not as effective as in earlier period owing to different technical and operational reasons. The use of nanomaterial products in various sectors of science including health increased during the last decade. We tested three types of nanosilica, namely lipophilic, hydrophilic and hydrophobic, to assess their larvicidal, pupicidal and growth inhibitor properties and also their influence on oviposition behaviour (attraction/deterrence) of mosquito species that transmit human diseases, namely malaria (Anopheles), yellow fever, chickungunya and dengue (Aedes), lymphatic filariasis and encephalitis (Culex and Aedes). Application of hydrophobic nanosilica at 112.5 ppm was found effective against mosquito species tested. The larvicidal effect of hydrophobic nanosilica on mosquito species tested was in the order of Anopheles stephensi > Aedes aegypti > Culex quinquefasciatus, and the pupicidal effect was in the order of A. stephensi > C. quinquefasciatus > Ae. aegypti. Results of combined treatment of hydrophobic nanosilica with temephos in larvicidal test indicated independent toxic action without any additive effect. This is probably the first report that demonstrated that nanoparticles particularly nanosilica could be used in mosquito vector control.

  3. Environmental fate model for ultra-low-volume insecticide applications used for adult mosquito management.

    Science.gov (United States)

    Schleier, Jerome J; Peterson, Robert K D; Irvine, Kathryn M; Marshall, Lucy M; Weaver, David K; Preftakes, Collin J

    2012-11-01

    One of the more effective ways of managing high densities of adult mosquitoes that vector human and animal pathogens is ultra-low-volume (ULV) aerosol applications of insecticides. The U.S. Environmental Protection Agency uses models that are not validated for ULV insecticide applications and exposure assumptions to perform their human and ecological risk assessments. Currently, there is no validated model that can accurately predict deposition of insecticides applied using ULV technology for adult mosquito management. In addition, little is known about the deposition and drift of small droplets like those used under conditions encountered during ULV applications. The objective of this study was to perform field studies to measure environmental concentrations of insecticides and to develop a validated model to predict the deposition of ULV insecticides. The final regression model was selected by minimizing the Bayesian Information Criterion and its prediction performance was evaluated using k-fold cross validation. Density of the formulation and the density and CMD interaction coefficients were the largest in the model. The results showed that as density of the formulation decreases, deposition increases. The interaction of density and CMD showed that higher density formulations and larger droplets resulted in greater deposition. These results are supported by the aerosol physics literature. A k-fold cross validation demonstrated that the mean square error of the selected regression model is not biased, and the mean square error and mean square prediction error indicated good predictive ability.

  4. Environmental fate model for ultra-low-volume insecticide applications used for adult mosquito management

    Science.gov (United States)

    Schleier, Jerome J.; Peterson, Robert K.D.; Irvine, Kathryn M.; Marshall, Lucy M.; Weaver, David K.; Preftakes, Collin J.

    2012-01-01

    One of the more effective ways of managing high densities of adult mosquitoes that vector human and animal pathogens is ultra-low-volume (ULV) aerosol applications of insecticides. The U.S. Environmental Protection Agency uses models that are not validated for ULV insecticide applications and exposure assumptions to perform their human and ecological risk assessments. Currently, there is no validated model that can accurately predict deposition of insecticides applied using ULV technology for adult mosquito management. In addition, little is known about the deposition and drift of small droplets like those used under conditions encountered during ULV applications. The objective of this study was to perform field studies to measure environmental concentrations of insecticides and to develop a validated model to predict the deposition of ULV insecticides. The final regression model was selected by minimizing the Bayesian Information Criterion and its prediction performance was evaluated using k-fold cross validation. Density of the formulation and the density and CMD interaction coefficients were the largest in the model. The results showed that as density of the formulation decreases, deposition increases. The interaction of density and CMD showed that higher density formulations and larger droplets resulted in greater deposition. These results are supported by the aerosol physics literature. A k-fold cross validation demonstrated that the mean square error of the selected regression model is not biased, and the mean square error and mean square prediction error indicated good predictive ability.

  5. The entomopathogenic fungus Beauveria bassiana reduces instantaneous blood feeding in wild multi-insecticide-resistant Culex quinquefasciatus mosquitoes in Benin, West Africa

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    Howard Annabel FV

    2010-09-01

    Full Text Available Abstract Background Mosquito-borne diseases are still a major health risk in many developing countries, and the emergence of multi-insecticide-resistant mosquitoes is threatening the future of vector control. Therefore, new tools that can manage resistant mosquitoes are required. Laboratory studies show that entomopathogenic fungi can kill insecticide-resistant malaria vectors but this needs to be verified in the field. Methods The present study investigated whether these fungi will be effective at infecting, killing and/or modifying the behaviour of wild multi-insecticide-resistant West African mosquitoes. The entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were separately applied to white polyester window netting and used in combination with either a permethrin-treated or untreated bednet in an experimental hut trial. Untreated nets were used because we wanted to test the effect of fungus alone and in combination with an insecticide to examine any potential additive or synergistic effects. Results In total, 1125 female mosquitoes were collected during the hut trial, mainly Culex quinquefasciatus Say. Unfortunately, not enough wild Anopheles gambiae Giles were collected to allow the effect the fungi may have on this malaria vector to be analysed. None of the treatment combinations caused significantly increased mortality of Cx. quinquefasciatus when compared to the control hut. The only significant behaviour modification found was a reduction in blood feeding by Cx. quinquefasciatus, caused by the permethrin and B. bassiana treatments, although no additive effect was seen in the B. bassiana and permethrin combination treatment. Beauveria bassiana did not repel blood foraging mosquitoes either in the laboratory or field. Conclusions This is the first time that an entomopathogenic fungus has been shown to reduce blood feeding of wild mosquitoes. This behaviour modification indicates that B. bassiana could potentially be a new

  6. Mosquito nets treated with a mixture of chlorfenapyr and alphacypermethrin control pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes in West Africa.

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    Raphael N'Guessan

    Full Text Available BACKGROUND: The effectiveness of insecticide treated nets is under threat across Africa south of the Sahara from the selection of pyrethroid resistance in Anopheles gambiae mosquitoes. To maintain progress against malaria it is necessary to identify alternative residual insecticides for mosquito nets. Mixtures of pyrethroid and insecticides with novel mode of action provide scope for both improved control and management of resistance through concurrent exposure to unrelated insecticides. METHODS: The pyrrole chlorfenapyr and the pyrethroid alphacypermethrin were tested individually and as a mixture on mosquito nets in an experimental hut trial in southern Benin against pyrethroid resistant An gambiae and Culex quinquefasciatus mosquitoes. The nets were deliberately holed to simulate the effect of wear and tear. RESULTS: The nets treated with the mixture of chlorfenapyr 200 mg/m² and alphacypermethrin 25 mg/m² killed a proportion of An gambiae (77%, 95%CI: 66-86% significantly greater than nets treated with alphacypermethrin 25 mg/m(2 (30%, 95%CI: 21-41% but not significantly different from nets treated with chlorfenapyr 200 mg/m² (69%, 95%CI: 57-78%. The nets treated with the mixtures procured personal protection against An gambiae biting(58-62% by a greater margin than the alphacypermethrin treated net (39%, whereas the chlorfenapyr treated net was not protective. A similar trend in mortality and blood feeding inhibition between treatments was observed in Cx quinquefasciatus to that seen in An. gambiae, although the effects were lower. A mixture of alphacypermethrin with chlorfenapyr applied at 100 mg/m² had an effect similar to the mixture with chlorfenapyr at 200 mg/m². CONCLUSION: The effectiveness of ITNs against pyrethroid resistant mosquitoes was restored by the mixture: the alphacypermethrin component reduced human-vector contact while the chlorfenapyr controlled pyrethroid-resistant mosquitoes. The complementary action of these

  7. Toxicities of Organophosphate and Carbamat Insecticide Against Culex quinquefasciatus Mosquito Larvae

    OpenAIRE

    Endang Puji Astuti; Yuneu Yuliasih; Titin Delia; Marliah Santi

    2009-01-01

    Culex quinquefasciatus mosquito is increasing problem of public health, being the vector responsible for West Nile Virus and Filariasis. Chlorpirifos (Organofosfat) and Metonil (Carbamat) were known to posses insecticide activity against insect. The study was aimed to examine effectiveness of Klorpirifos and Metonil as larvicide against C. quinquefasciatus larval. Chlorpirifos a significantly higher larvicidal activity against 3th-4th instar larvae of C. quinquefasciatus than Metonil. The lar...

  8. Synergy in efficacy of fungal entomopathogens and permethrin against West African insecticide-resistant Anopheles gambiae mosquitoes.

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    Marit Farenhorst

    Full Text Available BACKGROUND: Increasing incidences of insecticide resistance in malaria vectors are threatening the sustainable use of contemporary chemical vector control measures. Fungal entomopathogens provide a possible additional tool for the control of insecticide-resistant malaria mosquitoes. This study investigated the compatibility of the pyrethroid insecticide permethrin and two mosquito-pathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, against a laboratory colony and field population of West African insecticide-resistant Anopheles gambiae s.s. mosquitoes. METHODOLOGY/FINDINGS: A range of fungus-insecticide combinations was used to test effects of timing and sequence of exposure. Both the laboratory-reared and field-collected mosquitoes were highly resistant to permethrin but susceptible to B. bassiana and M. anisopliae infection, inducing 100% mortality within nine days. Combinations of insecticide and fungus showed synergistic effects on mosquito survival. Fungal infection increased permethrin-induced mortality rates in wild An. gambiae s.s. mosquitoes and reciprocally, exposure to permethrin increased subsequent fungal-induced mortality rates in both colonies. Simultaneous co-exposure induced the highest mortality; up to 70.3+/-2% for a combined Beauveria and permethrin exposure within a time range of one gonotrophic cycle (4 days. CONCLUSIONS/SIGNIFICANCE: Combining fungi and permethrin induced a higher impact on mosquito survival than the use of these control agents alone. The observed synergism in efficacy shows the potential for integrated fungus-insecticide control measures to dramatically reduce malaria transmission and enable control at more moderate levels of coverage even in areas where insecticide resistance has rendered pyrethroids essentially ineffective.

  9. Differential expression of salivary proteins between susceptible and insecticide-resistant mosquitoes of Culex quinquefasciatus.

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    Innocent Djegbe

    Full Text Available BACKGROUND: The Culex quinquefasciatus mosquito, a major pest and vector of filariasis and arboviruses in the tropics, has developed multiple resistance mechanisms to the main insecticide classes currently available in public health. Among them, the insensitive acetylcholinesterase (ace-1(R allele is widespread worldwide and confers cross-resistance to organophosphates and carbamates. Fortunately, in an insecticide-free environment, this mutation is associated with a severe genetic cost that can affect various life history traits. Salivary proteins are directly involved in human-vector contact during biting and therefore play a key role in pathogen transmission. METHODS AND RESULTS: An original proteomic approach combining 2D-electrophoresis and mass spectrometry was adopted to compare the salivary expression profiles of two strains of C. quinquefasciatus with the same genetic background but carrying either the ace-1(R resistance allele or not (wild type. Four salivary proteins were differentially expressed (>2 fold, P<0.05 in susceptible (SLAB and resistant (SR mosquito strains. Protein identification indicated that the D7 long form, a major salivary protein involved in blood feeding success, presented lower expression in the resistant strain than the susceptible strain. In contrast, three other proteins, including metabolic enzymes (endoplasmin, triosephosphate isomerase were significantly over-expressed in the salivary gland of ace-1(R resistant mosquitoes. A catalogue of 67 salivary proteins of C. quinquefasciatus sialotranscriptome was also identified and described. CONCLUSION: The "resistance"-dependent expression of salivary proteins in mosquitoes may have considerable impact on biting behaviour and hence on the capacity to transmit parasites/viruses to humans. The behaviour of susceptible and insecticide-resistant mosquitoes in the presence of vertebrate hosts and its impact on pathogen transmission urgently requires further

  10. Identifying genomic changes associated with insecticide resistance in the dengue mosquito Aedes aegypti by deep targeted sequencing.

    Science.gov (United States)

    Faucon, Frederic; Dusfour, Isabelle; Gaude, Thierry; Navratil, Vincent; Boyer, Frederic; Chandre, Fabrice; Sirisopa, Patcharawan; Thanispong, Kanutcharee; Juntarajumnong, Waraporn; Poupardin, Rodolphe; Chareonviriyaphap, Theeraphap; Girod, Romain; Corbel, Vincent; Reynaud, Stephane; David, Jean-Philippe

    2015-09-01

    The capacity of mosquitoes to resist insecticides threatens the control of diseases such as dengue and malaria. Until alternative control tools are implemented, characterizing resistance mechanisms is crucial for managing resistance in natural populations. Insecticide biodegradation by detoxification enzymes is a common resistance mechanism; however, the genomic changes underlying this mechanism have rarely been identified, precluding individual resistance genotyping. In particular, the role of copy number variations (CNVs) and polymorphisms of detoxification enzymes have never been investigated at the genome level, although they can represent robust markers of metabolic resistance. In this context, we combined target enrichment with high-throughput sequencing for conducting the first comprehensive screening of gene amplifications and polymorphisms associated with insecticide resistance in mosquitoes. More than 760 candidate genes were captured and deep sequenced in several populations of the dengue mosquito Ae. aegypti displaying distinct genetic backgrounds and contrasted resistance levels to the insecticide deltamethrin. CNV analysis identified 41 gene amplifications associated with resistance, most affecting cytochrome P450s overtranscribed in resistant populations. Polymorphism analysis detected more than 30,000 variants and strong selection footprints in specific genomic regions. Combining Bayesian and allele frequency filtering approaches identified 55 nonsynonymous variants strongly associated with resistance. Both CNVs and polymorphisms were conserved within regions but differed across continents, confirming that genomic changes underlying metabolic resistance to insecticides are not universal. By identifying novel DNA markers of insecticide resistance, this study opens the way for tracking down metabolic changes developed by mosquitoes to resist insecticides within and among populations.

  11. Identifying genomic changes associated with insecticide resistance in the dengue mosquito Aedes aegypti by deep targeted sequencing

    Science.gov (United States)

    Faucon, Frederic; Dusfour, Isabelle; Gaude, Thierry; Navratil, Vincent; Boyer, Frederic; Chandre, Fabrice; Sirisopa, Patcharawan; Thanispong, Kanutcharee; Juntarajumnong, Waraporn; Poupardin, Rodolphe; Chareonviriyaphap, Theeraphap; Girod, Romain; Corbel, Vincent; Reynaud, Stephane; David, Jean-Philippe

    2015-01-01

    The capacity of mosquitoes to resist insecticides threatens the control of diseases such as dengue and malaria. Until alternative control tools are implemented, characterizing resistance mechanisms is crucial for managing resistance in natural populations. Insecticide biodegradation by detoxification enzymes is a common resistance mechanism; however, the genomic changes underlying this mechanism have rarely been identified, precluding individual resistance genotyping. In particular, the role of copy number variations (CNVs) and polymorphisms of detoxification enzymes have never been investigated at the genome level, although they can represent robust markers of metabolic resistance. In this context, we combined target enrichment with high-throughput sequencing for conducting the first comprehensive screening of gene amplifications and polymorphisms associated with insecticide resistance in mosquitoes. More than 760 candidate genes were captured and deep sequenced in several populations of the dengue mosquito Ae. aegypti displaying distinct genetic backgrounds and contrasted resistance levels to the insecticide deltamethrin. CNV analysis identified 41 gene amplifications associated with resistance, most affecting cytochrome P450s overtranscribed in resistant populations. Polymorphism analysis detected more than 30,000 variants and strong selection footprints in specific genomic regions. Combining Bayesian and allele frequency filtering approaches identified 55 nonsynonymous variants strongly associated with resistance. Both CNVs and polymorphisms were conserved within regions but differed across continents, confirming that genomic changes underlying metabolic resistance to insecticides are not universal. By identifying novel DNA markers of insecticide resistance, this study opens the way for tracking down metabolic changes developed by mosquitoes to resist insecticides within and among populations. PMID:26206155

  12. Differential expression of salivary proteins between susceptible and insecticide-resistant mosquitoes of Culex quinquefasciatus.

    Science.gov (United States)

    Djegbe, Innocent; Cornelie, Sylvie; Rossignol, Marie; Demettre, Edith; Seveno, Martial; Remoue, Franck; Corbel, Vincent

    2011-03-23

    The Culex quinquefasciatus mosquito, a major pest and vector of filariasis and arboviruses in the tropics, has developed multiple resistance mechanisms to the main insecticide classes currently available in public health. Among them, the insensitive acetylcholinesterase (ace-1(R) allele) is widespread worldwide and confers cross-resistance to organophosphates and carbamates. Fortunately, in an insecticide-free environment, this mutation is associated with a severe genetic cost that can affect various life history traits. Salivary proteins are directly involved in human-vector contact during biting and therefore play a key role in pathogen transmission. An original proteomic approach combining 2D-electrophoresis and mass spectrometry was adopted to compare the salivary expression profiles of two strains of C. quinquefasciatus with the same genetic background but carrying either the ace-1(R) resistance allele or not (wild type). Four salivary proteins were differentially expressed (>2 fold, Pmosquito strains. Protein identification indicated that the D7 long form, a major salivary protein involved in blood feeding success, presented lower expression in the resistant strain than the susceptible strain. In contrast, three other proteins, including metabolic enzymes (endoplasmin, triosephosphate isomerase) were significantly over-expressed in the salivary gland of ace-1(R) resistant mosquitoes. A catalogue of 67 salivary proteins of C. quinquefasciatus sialotranscriptome was also identified and described. The "resistance"-dependent expression of salivary proteins in mosquitoes may have considerable impact on biting behaviour and hence on the capacity to transmit parasites/viruses to humans. The behaviour of susceptible and insecticide-resistant mosquitoes in the presence of vertebrate hosts and its impact on pathogen transmission urgently requires further investigation. All proteomic data will be deposited at PRIDE (http://www.ebi.ac.uk/pride/).

  13. Use of insecticide-treated clothes for personal protection against malaria: a community trial

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    Kuria Isabel W

    2006-07-01

    Full Text Available Abstract Background The study sought to determine the effect of using insecticide-treated clothes (ITCs on personal protection against malaria infection. The specific objectives were to determine the effect of using ITCs on the rate of infection with malaria parasites and the effect on indoor mosquito density. Methods This study was done in Dadaab refugee camps, North Eastern Province Kenya between April and August 2002, and involved a total of 198 participants, all refugees of Somali origin. The participants were selected through multi-stage cluster sampling. Half of the participants (treatment group had their personal clothes worn on a daily basis (Diras, Saris, Jalbaabs, Ma'awis and shirts and their bedding (sheets and blankets treated with insecticide (permethrin. The other half (comparison group had their clothes treated with placebo (plain water. Indoor mosquito density was determined from twelve households belonging to the participants; six in the treatment block and six in the comparison block. During pre-test and post-test, laboratory analysis of blood samples was done, indoor mosquito density determined and questionnaires administered. Using STATA statistical package, tests for significant difference between the two groups were conducted. Results Use of ITCs reduced both malaria infection rates and indoor mosquito density significantly. The odds of malaria infection in the intervention group were reduced by about 70 percent. The idea of using ITCs for malaria infection control was easily accepted among the refugees and they considered it beneficial. No side effects related to use of the ITCs were observed from the participants. Conclusion The use of ITCs reduces malaria infection rate and has potential as an appropriate method of malaria control. It is recommended, therefore, that this strategy be considered for use among poor communities like slum dwellers and other underprivileged communities, such as street children and refugees

  14. Identification of genes involved in pyrethroid-, propoxur-, and dichlorvos- insecticides resistance in the mosquitoes, Culex pipiens complex (Diptera: Culicidae).

    Science.gov (United States)

    Li, Chun-xiao; Guo, Xiao-xia; Zhang, Ying-mei; Dong, Yan-de; Xing, Dan; Yan, Ting; Wang, Gang; Zhang, Heng-duan; Zhao, Tong-yan

    2016-05-01

    Culex pipiens pallens and Cx. p. quinquefasciatus are important vectors of many diseases, such as West Nile fever and lymphatic filariasis. The widespread use of insecticides to control these disease vectors and other insect pests has led to insecticide resistance becoming common in these species. In this study, high throughout Illumina sequencing was used to identify hundreds of Cx. p. pallens and Cx. p. quinquefasciatus genes that were differentially expressed in response to insecticide exposure. The identification of these genes is a vital first step for more detailed investigation of the molecular mechanisms involved in insecticide resistance in Culex mosquitoes.

  15. Optimal Control of Malaria Transmission using Insecticide Treated Nets and Spraying

    Science.gov (United States)

    Athina, D.; Bakhtiar, T.; Jaharuddin

    2017-03-01

    In this paper, we consider a model of the transmission of malaria which was developed by Silva and Torres equipped with two control variables, namely the use of insecticide treated nets (ITN) to reduce the number of human beings infected and spraying to reduce the number of mosquitoes. Pontryagin maximum principle was applied to derive the differential equation system as optimality conditions which must be satisfied by optimal control variables. The Mangasarian sufficiency theorem shows that Pontryagin maximum principle is necessary as well as sufficient conditions for optimization problem. The 4th-order Runge Kutta method was then performed to solve the differential equations system. The numerical results show that both controls given at once can reduce the number of infected individuals as well as the number of mosquitoes which reduce the impact of malaria transmission.

  16. Challenges in estimating insecticide selection pressures from mosquito field data.

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    Susana Barbosa

    2011-11-01

    Full Text Available Insecticide resistance has the potential to compromise the enormous effort put into the control of dengue and malaria vector populations. It is therefore important to quantify the amount of selection acting on resistance alleles, their contributions to fitness in heterozygotes (dominance and their initial frequencies, as a means to predict the rate of spread of resistance in natural populations. We investigate practical problems of obtaining such estimates, with particular emphasis on Mexican populations of the dengue vector Aedes aegypti. Selection and dominance coefficients can be estimated by fitting genetic models to field data using maximum likelihood (ML methodology. This methodology, although widely used, makes many assumptions so we investigated how well such models perform when data are sparse or when spatial and temporal heterogeneity occur. As expected, ML methodologies reliably estimated selection and dominance coefficients under idealised conditions but it was difficult to recover the true values when datasets were sparse during the time that resistance alleles increased in frequency, or when spatial and temporal heterogeneity occurred. We analysed published data on pyrethroid resistance in Mexico that consists of the frequency of a Ile1,016 mutation. The estimates for selection coefficient and initial allele frequency on the field dataset were in the expected range, dominance coefficient points to incomplete dominance as observed in the laboratory, although these estimates are accompanied by strong caveats about possible impact of spatial and temporal heterogeneity in selection.

  17. Adaptation and evaluation of the bottle assay for monitoring insecticide resistance in disease vector mosquitoes in the Peruvian Amazon

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    Brogdon William G

    2009-09-01

    Full Text Available Abstract Background The purpose of this study was to establish whether the "bottle assay", a tool for monitoring insecticide resistance in mosquitoes, can complement and augment the capabilities of the established WHO assay, particularly in resource-poor, logistically challenging environments. Methods Laboratory reared Aedes aegypti and field collected Anopheles darlingi and Anopheles albimanus were used to assess the suitability of locally sourced solvents and formulated insecticides for use with the bottle assay. Using these adapted protocols, the ability of the bottle assay and the WHO assay to discriminate between deltamethrin-resistant Anopheles albimanus populations was compared. The diagnostic dose of deltamethrin that would identify resistance in currently susceptible populations of An. darlingi and Ae. aegypti was defined. The robustness of the bottle assay during a surveillance exercise in the Amazon was assessed. Results The bottle assay (using technical or formulated material and the WHO assay were equally able to differentiate deltamethrin-resistant and susceptible An. albimanus populations. A diagnostic dose of 10 μg a.i./bottle was identified as the most sensitive discriminating dose for characterizing resistance in An. darlingi and Ae. aegypti. Treated bottles, prepared using locally sourced solvents and insecticide formulations, can be stored for > 14 days and used three times. Bottles can be stored and transported under local conditions and field-assays can be completed in a single evening. Conclusion The flexible and portable nature of the bottle assay and the ready availability of its components make it a potentially robust and useful tool for monitoring insecticide resistance and efficacy in remote areas that require minimal cost tools.

  18. Time-of-day specific changes in metabolic detoxification and insecticide resistance in the malaria mosquito Anopheles gambiae.

    Science.gov (United States)

    Balmert, Nathaniel J; Rund, Samuel S C; Ghazi, John P; Zhou, Peng; Duffield, Giles E

    2014-05-01

    Mosquitoes exhibit ∼24 h rhythms in physiology and behavior, regulated by the cooperative action of an endogenous circadian clock and the environmental light:dark cycle. Here, we characterize diel (observed under light:dark conditions) time-of-day changes in metabolic detoxification and resistance to insecticide challenge in Anopheles gambiae mosquitoes. A better understanding of mosquito chronobiology will yield insights into developing novel control strategies for this important disease vector. We have previously identified >2000 rhythmically expressed An. gambiae genes. These include metabolic detoxification enzymes peaking at various times throughout the day. Especially interesting was the identification of rhythmic genes encoding enzymes capable of pyrethroid and/or DDT metabolism (CYP6M2, CYP6P3, CYP6Z1, and GSTE2). We hypothesized that these temporal changes in gene expression would confer time-of-day specific changes in metabolic detoxification and responses to insecticide challenge. An. gambiae mosquitoes (adult female Pimperena and Mali-NIH strains) were tested by gene expression analysis for diel rhythms in key genes associated with insecticidal resistance. Biochemical assays for total GST, esterase, and oxidase enzymatic activities were undertaken on time-specific mosquito head and body protein lysates. To determine for rhythmic susceptibility to insecticides by survivorship, mosquitoes were exposed to DDT or deltamethrin across the diel cycle. We report the occurrence of temporal changes in GST activity in samples extracted from the body and head with a single peak at late-night to dawn, but no rhythms were detected in oxidase or esterase activity. The Pimperena strain was found to be resistant to insecticidal challenge, and subsequent genomic analysis revealed the presence of the resistance-conferring kdr mutation. We observed diel rhythmicity in key insecticide detoxification genes in the Mali-NIH strain, with peak phases as previously reported in

  19. Toxicities of Organophosphate and Carbamat Insecticide Against Culex quinquefasciatus Mosquito Larvae

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    Endang Puji Astuti

    2009-06-01

    Full Text Available Culex quinquefasciatus mosquito is increasing problem of public health, being the vector responsible for West Nile Virus and Filariasis. Chlorpirifos (Organofosfat and Metonil (Carbamat were known to posses insecticide activity against insect. The study was aimed to examine effectiveness of Klorpirifos and Metonil as larvicide against C. quinquefasciatus larval. Chlorpirifos a significantly higher larvicidal activity against 3th-4th instar larvae of C. quinquefasciatus than Metonil. The larval mortality was observed after 24-h exposure. The LC95 value of Chlorpirifos and Metonil were 3,139 mg/lt and 9,045 mg/lt, against C. quinquefasciatus. The mixed of both insecticide was LC95 value 2,823 mg/lt. The result of this study suggested that Chlorpirifos more effective larvicide against C. quinquefasciatus than Metonil.

  20. Comparative analysis of response to selection with three insecticides in the dengue mosquito Aedes aegypti using mRNA sequencing.

    Science.gov (United States)

    David, Jean-Philippe; Faucon, Frédéric; Chandor-Proust, Alexia; Poupardin, Rodolphe; Riaz, Muhammad Asam; Bonin, Aurélie; Navratil, Vincent; Reynaud, Stéphane

    2014-03-05

    Mosquito control programmes using chemical insecticides are increasingly threatened by the development of resistance. Such resistance can be the consequence of changes in proteins targeted by insecticides (target site mediated resistance), increased insecticide biodegradation (metabolic resistance), altered transport, sequestration or other mechanisms. As opposed to target site resistance, other mechanisms are far from being fully understood. Indeed, insecticide selection often affects a large number of genes and various biological processes can hypothetically confer resistance. In this context, the aim of the present study was to use RNA sequencing (RNA-seq) for comparing transcription level and polymorphism variations associated with adaptation to chemical insecticides in the mosquito Aedes aegypti. Biological materials consisted of a parental susceptible strain together with three child strains selected across multiple generations with three insecticides from different classes: the pyrethroid permethrin, the neonicotinoid imidacloprid and the carbamate propoxur. After ten generations, insecticide-selected strains showed elevated resistance levels to the insecticides used for selection. RNA-seq data allowed detecting over 13,000 transcripts, of which 413 were differentially transcribed in insecticide-selected strains as compared to the susceptible strain. Among them, a significant enrichment of transcripts encoding cuticle proteins, transporters and enzymes was observed. Polymorphism analysis revealed over 2500 SNPs showing > 50% allele frequency variations in insecticide-selected strains as compared to the susceptible strain, affecting over 1000 transcripts. Comparing gene transcription and polymorphism patterns revealed marked differences among strains. While imidacloprid selection was linked to the over transcription of many genes, permethrin selection was rather linked to polymorphism variations. Focusing on detoxification enzymes revealed that permethrin

  1. Insecticidal and repellent activity of Hiptage benghalensis L. Kruz (Malpighiaceae) against mosquito vectors.

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    Lalrotluanga; Ngente, Lalchawimawii; Nachimuthu, Senthil Kumar; Guruswami, Gurusubramanian

    2012-09-01

    Plant-based insecticides for vector control are urgently needed for Anopheles barbirostris, Culex quinquefasciatus, and Aedes albopictus which are the primary vectors of malaria, lymphatic filariasis, and dengue, respectively, in India and other South East Asian countries. In the present study, larvicidal, adulticidal, and repellent activities of acetone root bark extract of Hiptage benghalensis were tested against the larvae and adults of the three mosquito vectors. The acetone root bark extracts of H. benghalensis was more effective as larvicides with low LC(50) (11.15-16.78 ppm) and LT50 (1.25-4.84 h at 200 and 400 ppm) values. Results of log probit analysis (at 95 % confidence level) and regression analysis of crude acetone root bark extract of H. benghalensis revealed that lethal concentration (LC(50)) values gradually decreased with the exposure periods; lethal time (LT(50)) decreased with the concentration, and the mortality is positively correlated with the concentration. The order of susceptibility of the three mosquito species was as follows: A. albopictus > A. barbirostris > C. quinquefascitus. Biochemical changes were also evidenced in third instar larvae of three mosquito species following a sublethal exposure for 24 h. The level of sugar, glycogen, lipids, and proteins was significantly (P larvicide against A. albopictus, A. barbirostris, and C. quinquefascitus, which can be recommended to control these mosquito species on its breeding site. However, further investigations are needed to confirm the lethal effects of H. benghalensis in field conditions and its impact on the nontarget organisms.

  2. Enhanced Tolerance of House Mosquito to Different Insecticides due to Agricultural and Household Pesticides in Sewage System of Tehran, Iran

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    H Vatandoost, L Ezeddinloo, A H Mahvi, M R Abai, EB Kia, I Mobedi

    2004-07-01

    Full Text Available Different insecticides are being used for household and agricultural pest control in the capital city of Iran, Tehran. An investigation was carried out in order to evaluate the susceptibility level of laboratory and field collected mosquito, Culex quinquefasciatusin to different insecticides. Field strain was collected from sewage system of the city. Adult females were subjected to the diagnostic dose of different insecticides as recommended by WHO. Results showed that laboratory strains only exhibit resistant to DDT 4%, and susceptible to other insecticides. By using WHO criteria, field strain is resistant to DDT 4%, bendiocarb 0.1%, and tolerant to malathion 5%, permethrin 0.75%, deltamethrin 0.05%, lambdacyhalothrin 0.05% and etofenprox 5%. The field strain is still susceptible to cyfluthrin 0.15%.This findings indicate that routine use of pesticides in household and agricultural pest control may cause resistant in the wastewater mosquito, Culex quinquefasciatus.

  3. Pharmacological and Genetic Evidence for Gap Junctions as Potential New Insecticide Targets in the Yellow Fever Mosquito, Aedes aegypti.

    Science.gov (United States)

    Calkins, Travis L; Piermarini, Peter M

    2015-01-01

    The yellow fever mosquito Aedes aegypti is an important vector of viral diseases that impact global health. Insecticides are typically used to manage mosquito populations, but the evolution of insecticide resistance is limiting their effectiveness. Thus, identifying new molecular and physiological targets in mosquitoes is needed to facilitate insecticide discovery and development. Here we test the hypothesis that gap junctions are valid molecular and physiological targets for new insecticides. Gap junctions are intercellular channels that mediate direct communication between neighboring cells and consist of evolutionarily distinct proteins in vertebrate (connexins) and invertebrate (innexins) animals. We show that the injection of pharmacological inhibitors of gap junctions (i.e., carbenoxolone, meclofenamic acid, or mefloquine) into the hemolymph of adult female mosquitoes elicits dose-dependent toxic effects, with mefloquine showing the greatest potency. In contrast, when applied topically to the cuticle, carbenoxolone was the only inhibitor to exhibit full efficacy. In vivo urine excretion assays demonstrate that both carbenoxolone and mefloquine inhibit the diuretic output of adult female mosquitoes, suggesting inhibition of excretory functions as part of their mechanism of action. When added to the rearing water of 1st instar larvae, carbenoxolone and meclofenamic acid both elicit dose-dependent toxic effects, with meclofenamic acid showing the greatest potency. Injecting a double-stranded RNA cocktail against innexins into the hemolymph of adult female mosquitoes knock down whole-animal innexin mRNA expression and decreases survival of the mosquitoes. Taken together these data indicate that gap junctions may provide novel molecular and physiological targets for the development of insecticides.

  4. Pharmacological and Genetic Evidence for Gap Junctions as Potential New Insecticide Targets in the Yellow Fever Mosquito, Aedes aegypti.

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    Travis L Calkins

    Full Text Available The yellow fever mosquito Aedes aegypti is an important vector of viral diseases that impact global health. Insecticides are typically used to manage mosquito populations, but the evolution of insecticide resistance is limiting their effectiveness. Thus, identifying new molecular and physiological targets in mosquitoes is needed to facilitate insecticide discovery and development. Here we test the hypothesis that gap junctions are valid molecular and physiological targets for new insecticides. Gap junctions are intercellular channels that mediate direct communication between neighboring cells and consist of evolutionarily distinct proteins in vertebrate (connexins and invertebrate (innexins animals. We show that the injection of pharmacological inhibitors of gap junctions (i.e., carbenoxolone, meclofenamic acid, or mefloquine into the hemolymph of adult female mosquitoes elicits dose-dependent toxic effects, with mefloquine showing the greatest potency. In contrast, when applied topically to the cuticle, carbenoxolone was the only inhibitor to exhibit full efficacy. In vivo urine excretion assays demonstrate that both carbenoxolone and mefloquine inhibit the diuretic output of adult female mosquitoes, suggesting inhibition of excretory functions as part of their mechanism of action. When added to the rearing water of 1st instar larvae, carbenoxolone and meclofenamic acid both elicit dose-dependent toxic effects, with meclofenamic acid showing the greatest potency. Injecting a double-stranded RNA cocktail against innexins into the hemolymph of adult female mosquitoes knock down whole-animal innexin mRNA expression and decreases survival of the mosquitoes. Taken together these data indicate that gap junctions may provide novel molecular and physiological targets for the development of insecticides.

  5. Multi-function oxidases are responsible for the synergistic interactions occurring between repellents and insecticides in mosquitoes

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    Duchon Stéphane

    2009-04-01

    Full Text Available Abstract Background With the spread of pyrethroid resistance in mosquitoes, the combination of an insecticide (carbamate or organophosphate with a repellent (DEET is considered as a promising alternative strategy for the treatment of mosquito nets and other relevant materials. The efficacy of these mixtures comes from the fact that they reproduce pyrethroid features and that positive interactions occur between insecticides and repellent. To better understand the mechanisms involved and assess the impact of detoxifying enzymes (oxidases and esterases in these interactions, bioassays were carried out in the laboratory against the main dengue vector Aedes aegypti. Methods Topical applications of DEET and propoxur (carbamate, used alone or as a mixture, were carried out on female mosquitoes, using inhibitors of the two main detoxification pathways in the insect. PBO, an inhibitor of multi-function oxidases, and DEF, an inhibitor of esterases, were applied one hour prior to the main treatment. Results Results showed that synergism between DEET and propoxur disappeared in the presence of PBO but not with DEF. This suggests that oxidases, contrary to esterases, play a key role in the interactions occurring between DEET and cholinesterase inhibitors in mosquitoes. Conclusion These findings are of great interest for the implementation of "combination nets" in the field. They support the need to combine insecticide with repellent to overcome insecticide resistance in mosquitoes of public health importance.

  6. Predicting the impact of insecticide-treated bed nets on malaria transmission: the devil is in the detail

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    Novak Robert J

    2009-11-01

    Full Text Available Abstract Background Insecticide-treated bed nets (ITNs, including long-lasting insecticidal nets (LLINs, play a primary role in global campaigns to roll back malaria in tropical Africa. Effectiveness of treated nets depends on direct impacts on individual mosquitoes including killing and excite-repellency, which vary considerably among vector species due to variations in host-seeking behaviours. While monitoring and evaluation programmes of ITNs have focuses on morbidity and all-cause mortality in humans, local entomological context receives little attention. Without knowing the dynamics of local vector species and their responses to treated nets, it is difficult to predict clinical outcomes when ITN applications are scaled up across African continent. Sound model frameworks incorporating intricate interactions between mosquitoes and treated nets are needed to develop the predictive capacity for scale-up applications of ITNs. Methods An established agent-based model was extended to incorporate the direct outcomes, e.g. killing and avoidance, of individual mosquitoes exposing to ITNs in a hypothetical village setting with 50 houses and 90 aquatic habitats. Individual mosquitoes were tracked throughout the life cycle across the landscape. Four levels of coverage, i.e. 40, 60, 80 and 100%, were applied at the household level with treated houses having only one bed net. By using Latin hypercube sampling scheme, parameters governing killing, diverting and personal protection of net users were evaluated for their relative roles in containing mosquito populations, entomological inoculation rates (EIRs and malaria incidence. Results There were substantial gaps in coverage between households and individual persons, and 100% household coverage resulted in circa 50% coverage of the population. The results show that applications of ITNs could give rise to varying impacts on population-level metrics depending on values of parameters governing interactions of

  7. Disruptive Technology for Vector Control: the Innovative Vector Control Consortium and the US Military Join Forces to Explore Transformative Insecticide Application Technology for Mosquito Control Programmes

    Science.gov (United States)

    2015-09-26

    Control Consortium and the US Military join forces to explore transformative insecticide application technology for  mosquito control programmes...opment of new insecticides to fight growing mosquito resistance to the current chemicals [6]. However, it is essential to match the next generation of...technological advancements made in recent decades to modernize the tools used to target, control, and monitor mosquito populations. This paper summarizes the

  8. Insecticide treated bednet strategy in rural settings: can we exploit women's decision making power?

    Science.gov (United States)

    Tilak, Rina; Tilak, V W; Bhalwar, R

    2007-01-01

    Use of insecticide treated bednets in prevention of malaria is a widely propagated global strategy, however, its use has been reported to be influenced and limited by many variables especially gender bias. A cross sectional field epidemiological study was conducted in a rural setting with two outcome variables, 'Bednet use'(primary outcome variable) and 'Women's Decision Making Power' which were studied in reference to various predictor variables. Analysis reveals a significant effect on the primary outcome variable 'Bednet use' of the predictor variables- age, occupation, bednet purchase decision, women's decision making power, husband's education and knowledge about malaria and its prevention. The study recommends IEC on treated bednets to be disseminated through TV targeting the elderly women who have better decision making power and mobilizing younger women who were found to prefer bednets for prevention of mosquito bites for optimizing the use of treated bednets in similar settings.

  9. The entomopathogenic fungus Beauveria bassiana reduces instantaneous blood feeding in wild multi-insecticide-resistant Culex quinquefasciatus mosquitoes in Benin, West Africa

    NARCIS (Netherlands)

    Howard, A.F.V.; N'Guessan, R.; Koenraadt, C.J.M.; Asidi, A.; Farenhorst, M.; Akogbéto, M.; Thomas, M.B.; Knols, B.G.J.; Takken, W.

    2010-01-01

    Background Mosquito-borne diseases are still a major health risk in many developing countries, and the emergence of multi-insecticide-resistant mosquitoes is threatening the future of vector control. Therefore, new tools that can manage resistant mosquitoes are required. Laboratory studies show that

  10. The entomopathogenic fungus Beauveria bassiana reduces instantaneous blood feeding in wild multi-insecticide-resistant Culex quinquefasciatus mosquitoes in Benin, West Africa

    NARCIS (Netherlands)

    Howard, A.F.V.; N'Guessan, R.; Koenraadt, C.J.M.; Asidi, A.; Farenhorst, M.; Akogbeto, M.; Thomas, M.B.; Knols, B.G.J.; Takken, W.

    2010-01-01

    Background: Mosquito-borne diseases are still a major health risk in many developing countries, and the emergence of multi-insecticide-resistant mosquitoes is threatening the future of vector control. Therefore, new tools that can manage resistant mosquitoes are required. Laboratory studies show tha

  11. Biorational insecticides for control of mosquitoes and black flies in Sinaloa

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    Cipriano García Gutiérrez

    2012-09-01

    Full Text Available In Sinaloa Mexico the presence of mosquitoes is a important health problem, and each spring-summer season appear several species which include: Aedes aegypti (Linneus, Anopheles albimanus (Wiedemann, Culex quinquefasciatus (Say and black flies of the Simulidae family. The control of larvae and adults of these insects are usually performed with chemical insecticides, so the use of biorational insecticides for control of these insects is novel, due to that have low environment impact. The objective of this work is to give known to the different biorational insecticides and their biological effects (inhibitor, insect repellent, larvicide, adulticide, that can be used to combat to different development stages of these insects. As well as show the progress of a study on the effectiveness of neem extracts, garlic, cinnamon, albahaca and cypermethrin at low doses (0.25,0.5 and 1ml/L, for control of larvae and adults of black flies in the unicipality of El Fuerte, Sinaloa. By the mode of action, the biorational that can doing use for the control of theseinsects were: Spinosad, and Bacillus thuringiensis (Berliner var. israeliensis for larvae control, Spinosad and Beauveria bassiana (Vuill. for adults; as well as extracts of neem, garlic, cinnamon and albahaca for both stages. The preliminary results of the study showed that the effectiveness application in tourist sites, through aerial spraying of cypermethrin at low doses and the plants extracts, allow low the index of larvae and infestation of mosquitoes and blackflies, decreasing the discomfort caused by these insects in the place of study.

  12. Modeling the effects of integrating larval habitat source reduction and insecticide treated nets for malaria control.

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    Laith Yakob

    Full Text Available Integrated vector management for malaria control has received a lot of recent interest. Attacking multiple points in the transmission cycle is hoped to act synergistically and improve upon current single-tool interventions based on the use of insecticide-treated bed nets (ITNs. In the present study, we theoretically examined the application of larval habitat source reduction with ITNs in reducing malaria transmission. We selected this type of environmental management to complement ITNs because of a potential secondary mode of action that both control strategies share. In addition to increasing vector mortality, ITNs reduce the rate at which female mosquitoes locate human hosts for blood feeding, thereby extending their gonotrophic cycle. Similarly, while reducing adult vector emergence and abundance, source reduction of larval habitats may prolong the cycle duration by extending delays in locating oviposition sites. We found, however, that source reduction of larval habitats only operates through this secondary mode of action when habitat density is below a critical threshold. Hence, we illustrate how this strategy becomes increasingly effective when larval habitats are limited. We also demonstrate that habitat source reduction is better suited to human populations of higher density and in the presence of insecticide resistance or when the insecticidal properties of ITNs are depleted.

  13. Insecticide-Treated Nets and Protection against Insecticide-Resistant Malaria Vectors in Western Kenya.

    Science.gov (United States)

    Ochomo, Eric; Chahilu, Mercy; Cook, Jackie; Kinyari, Teresa; Bayoh, Nabie M; West, Philippa; Kamau, Luna; Osangale, Aggrey; Ombok, Maurice; Njagi, Kiambo; Mathenge, Evan; Muthami, Lawrence; Subramaniam, Krishanthi; Knox, Tessa; Mnavaza, Abraham; Donnelly, Martin James; Kleinschmidt, Immo; Mbogo, Charles

    2017-05-01

    Insecticide resistance might reduce the efficacy of malaria vector control. In 2013 and 2014, malaria vectors from 50 villages, of varying pyrethroid resistance, in western Kenya were assayed for resistance to deltamethrin. Long-lasting insecticide-treated nets (LLIN) were distributed to households at universal coverage. Children were recruited into 2 cohorts, cleared of malaria-causing parasites, and tested every 2 weeks for reinfection. Infection incidence rates for the 2 cohorts were 2.2 (95% CI 1.9-2.5) infections/person-year and 2.8 (95% CI 2.5-3.0) infections/person-year. LLIN users had lower infection rates than non-LLIN users in both low-resistance (rate ratio 0.61, 95% CI 0.42-0.88) and high-resistance (rate ratio 0.55, 95% CI 0.35-0.87) villages (p = 0.63). The association between insecticide resistance and infection incidence was not significant (p = 0.99). Although the incidence of infection was high among net users, LLINs provided significant protection (p = 0.01) against infection with malaria parasite regardless of vector insecticide resistance.

  14. The excito –repellency effect of pyrethroid insecticide-treated bednets on An. stephensi under laboratory condition

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    Hamzeh Ali Pour

    2006-02-01

    Full Text Available Background: The excito-repellency effect due to the application of some insecticides is important in interrupting the malaria transmission cycle. The repellency effect of some insecticides also inhibits the entry of mosquitoes into sprayed houses, which in long-term causes alteration in endophilic and exophilic rates. Methods: In this study, a modified excito-repellency (E-R test box was used. In order to standardize this system, a number of methods and techniques were considered to evaluate the mosquitoes’ reaction to pyrethroid-impregnated nets. A cylindrical guinea – pig holder made up of aluminum mesh was placed within the exposure chamber. Treated and untreated nets covered this holder so that the guinea pig was available to mosquito for bloodfeeding. An exit trap was devised on the rear side of the exposure chamber. Nets were impregnated with lambdacyhalothrin insecticide at the concentrations of 12.5, 25 and 50 mg/m2, deltamethrin at 12.5, 25 and 50 mg/m2 and cyfluthrin at 40, 80 and 100 mg/m2 or unimpregnated in laboratory by standard dipping procedure. The bloodfeeding rate, exit rate, survival rate, mortality rate and recovery rate of mosquitoes were considered. Results: The results obtained using one-way analysis of variance (ANOVA reflects a significant difference in excito-repellency of tested insecticides (p<0.05. The bloodfeeding rate of exposed mosquitoes to nets treated with lambdacyhalothrin, deltamethrin and cyfluthrin at standard dose of 25 mg/m2 were 15%, 5.3%and 9.3% respectively the exit rates were also 18.2%, 11.2% and 19.7%, and it was 98.9 % in the control group. The survival rate of mosquitoes was 63.2%, 34.9% and 67%, respectively. The bloodfeeding and exit rates for control group were 41.3% and 1.4%, respectively. Conclusion: The excito-repellency evaluation revealed that the deltamethrin-impregnated net was more effective on An. stephensi than lambdacyhalothrin and cyfluthrin insecticides, under laboratory

  15. Sustainable control of mosquito larvae in the field by the combined actions of the biological insecticide Bti and natural competitors.

    Science.gov (United States)

    Kroeger, Iris; Liess, Matthias; Dziock, Frank; Duquesne, Sabine

    2013-06-01

    Integrated management of mosquitoes is becoming increasingly important, particularly in relation to avoiding recolonization of ponds after larvicide treatment. We conducted for the first time field experiments that involved exposing natural populations of the mosquito species Culex pipiens to: a) application of the biological insecticide Bacillus thuringiensis israelensis (Bti), b) the introduction of natural competitors (a crustacean community composed mainly of Daphnia spp.), or c) a combined treatment that involved both introduction of a crustacean community and the application of Bti. The treatment that involved only the introduction of crustaceans had no significant effect on mosquito larval populations, while treatment with Bti alone caused only a significant reduction in the abundance of mosquito larvae in the short-term (within 3-10 days after treatment). In contrast, the combined treatment rapidly reduced the abundance of mosquito larvae, which remained low throughout the entire observation period of 28 days. Growth of the introduced crustacean communities was favored by the immediate reduction in the abundance of mosquito larvae following Bti administration, thus preventing recolonization of ponds by mosquito larvae at the late period (days 14-28 after treatment). Both competition and the temporal order of establishment of different species are hence important mechanisms for efficient and sustainable mosquito control.

  16. Cost-effectiveness of long-lasting insecticide-treated hammocks in preventing malaria in South-central Vietnam.

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    Chantal M Morel

    Full Text Available BACKGROUND: Despite much success in reducing the burden of malaria in Vietnam, pockets of malaria persist and eliminating them remains an important development goal. In central Vietnam, insecticide-treated hammocks have recently been introduced to help counter the disease in the highly forested, mountainous areas, where other measures have so far been unsuccessful. This study assesses the cost-effectiveness of using long-lasting insecticide-treated hammocks in this area. METHODS AND FINDINGS: This cost-effectiveness study was run alongside a randomized control trial testing the efficacy of the long-lasting insecticide-treated hammocks. Data were collected through an exit survey, a household survey, expenditure records and key informant interviews. The study estimates that under normal (non-trial conditions the total net societal cost per malaria episode averted in using long-lasting insecticide-treated hammocks in this area was 126 USD. Cost per hammock, including insecticidal netting, sewing, transport, and distribution was found to be approximately 11.76 USD per hammock. Average savings per episode averted were estimated to be $14.60 USD for the health system and 14.37 USD for households (including both direct and indirect cost savings. The study estimates that the annual financial outlay required of government to implement this type of programme to be 3.40 USD per person covered per year. CONCLUSION: The study finds that the use of a hammock intervention could represent good value for money to help prevent malaria in more remote areas, where traditional control measures such as insecticide-treated bednets and indoor residual spraying are insufficient or inappropriate to control malaria. However, the life span of the hammock-the number of years over which it effectively deters mosquitoes-has a significant impact on the cost-effectiveness of the intervention and study results should be interpreted in light of the evidence on effectiveness

  17. Turning cigarette butt waste into an alternative control tool against an insecticide-resistant mosquito vector.

    Science.gov (United States)

    Dieng, Hamady; Rajasaygar, Sudha; Ahmad, Abu Hassan; Ahmad, Hamdan; Rawi, Che Salmah Md; Zuharah, Wan Fatma; Satho, Tomomitsu; Miake, Fumio; Fukumitsu, Yuki; Saad, Ahmad Ramli; Ghani, Idris Abd; Vargas, Ronald Enrique Morales; Majid, Abdul Hafiz Ab; Abubakar, Sazaly

    2013-12-01

    Annually, 4.5 trillion cigarette butts (CBs) are flicked into our environment. Evidence exists that CB waste is deadly to aquatic life, but their lethality to the aquatic life of the main dengue vector is unknown. CBs are full of toxicants that occur naturally, during planting and manufacturing, which may act as larvicidal agents. We assessed Aedes aegypti vulnerability to Marlboro butts during its development. Overall, CBs showed insecticidal activities against larvae. At early phases of development, mortality rates were much higher in two CBs solution (2CBSol) and 3CBSol microcosms (MICRs). Larval survival gradually decreased with development in 1CBSol-MICRs. However, in great presence of CBs, mortality was high even for the late developmental stages. These results suggest that A. aegypti larvae are vulnerable to CB presence in their habitats, but this effect was seen most during the early developmental phases and in the presence of increased amounts of cigarette remnants. CB filters are being used as raw material in many sectors, i.e., brick, art, fashion, plastic industries, as a practical solution to the pollution problem, the observed butt waste toxicity to mosquito larvae open new avenues for the identification of novel insecticide products.

  18. Deltamethrin-mediated survival, behavior, and oenocyte morphology of insecticide-susceptible and resistant yellow fever mosquitos (Aedes aegypti).

    Science.gov (United States)

    Marriel, Nadja Biondine; Tomé, Hudson Vaner Ventura; Guedes, Raul Carvalho Narciso; Martins, Gustavo Ferreira

    2016-06-01

    Insecticide use is the prevailing control tactic for the mosquito Aedes aegypti, a vector of several human viruses, which leads to ever-increasing problems of insecticide resistance in populations of this insect pest species. The underlying mechanisms of insecticide resistance may be linked to the metabolism of insecticides by various cells, including oenocytes. Oenocytes are ectodermal cells responsible for lipid metabolism and detoxification. The goal of this study was to evaluate the sublethal effects of deltamethrin on survival, behavior, and oenocyte structure in the immature mosquitoes of insecticide-susceptible and resistant strains of A. aegypti. Fourth instar larvae (L4) of both strains were exposed to different concentrations of deltamethrin (i.e., 0.001, 0.003, 0.005, and 0.007 ppm). After exposure, L4 were subjected to behavioral bioassays. Insecticide effects on cell integrity after deltamethrin exposure (at 0.003 or 0.005 ppm) were assessed by processing pupal oenocytes for transmission electron microscopy or TUNEL reaction. The insecticide resistant L4 survived all the tested concentrations, whereas the 0.007-ppm deltamethrin concentration had lethal effects on susceptible L4. Susceptible L4 were lethargic and exhibited less swimming activity than unexposed larvae, whereas the resistant L4 were hyperexcited following exposure to 0.005 ppm deltamethrin. No sublethal effects and no significant cell death were observed in the oenocytes of either susceptible or resistant insects exposed to deltamethrin. The present study illustrated the different responses of susceptible and resistant strains of A. aegypti following exposure to sublethal concentration of deltamethrin, and demonstrated how the behavior of the immature stage of the two strains varied, as well as oenocyte structure following insecticide exposure.

  19. Factors Associated with Correct and Consistent Insecticide Treated Curtain Use in Iquitos, Peru.

    Science.gov (United States)

    Paz-Soldan, Valerie A; Bauer, Karin; Morrison, Amy C; Cordova Lopez, Jhonny J; Izumi, Kiyohiko; Scott, Thomas W; Elder, John P; Alexander, Neal; Halsey, Eric S; McCall, Philip J; Lenhart, Audrey

    2016-03-01

    Dengue is an arthropod-borne virus of great public health importance, and control of its mosquito vectors is currently the only available method for prevention. Previous research has suggested that insecticide treated curtains (ITCs) can lower dengue vector infestations in houses. This observational study investigated individual and household-level socio-demographic factors associated with correct and consistent use of ITCs in Iquitos, Peru. A baseline knowledge, attitudes, and practices (KAP) survey was administered to 1,333 study participants, and ITCs were then distributed to 593 households as part of a cluster-randomized trial. Follow up KAP surveys and ITC-monitoring checklists were conducted at 9, 18, and 27 months post-ITC distribution. At 9 months post-distribution, almost 70% of ITCs were hanging properly (e.g. hanging fully extended or tied up), particularly those hung on walls compared to other locations. Proper ITC hanging dropped at 18 months to 45.7%. The odds of hanging ITCs correctly and consistently were significantly greater among those participants who were housewives, knew three or more correct symptoms of dengue and at least one correct treatment for dengue, knew a relative or close friend who had had dengue, had children sleeping under a mosquito net, or perceived a change in the amount of mosquitoes in the home. Additionally, the odds of recommending ITCs in the future were significantly greater among those who perceived a change in the amount of mosquitoes in the home (e.g. perceived the ITCs to be effective). Despite various challenges associated with the sustained effectiveness of the selected ITCs, almost half of the ITCs were still hanging at 18 months, suggesting a feasible vector control strategy for sustained community use.

  20. Impact of insecticide-treated nets on wild pyrethroid resistant Anopheles epiroticus population from southern Vietnam tested in experimental huts

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    Trung Ho

    2009-10-01

    Full Text Available Abstract Background In this study, the efficacy of insecticide-treated nets was evaluated in terms of deterrence, blood-feeding inhibition, induced exophily and mortality on a wild resistant population of Anopheles epiroticus in southern Vietnam, in order to gain insight into the operational consequences of the insecticide resistance observed in this malaria vector in the Mekong delta. Method An experimental station, based on the model of West Africa and adapted to the behaviour of the target species, was built in southern Vietnam. The study design was adapted from the WHO phase 2 guidelines. The study arms included a conventionally treated polyester net (CTN with deltamethrin washed just before exhaustion, the WHO recommended long-lasting insecticidal net (LLIN PermaNet 2.0® unwashed and 20 times washed and PermaNet 3.0®, designed for the control of pyrethroid resistant vectors, unwashed and 20 times washed. Results The nets still provided personal protection against the resistant An. epiroticus population. The personal protection ranged from 67% for deltamethrin CTN to 85% for unwashed PermaNet 3.0. Insecticide resistance in the An. epiroticus mosquitoes did not seem to alter the deterrent effect of pyrethroids. A significant higher mortality was still observed among the treatment arms despite the fact that the An. epiroticus population is resistant against the tested insecticides. Conclusion This study shows that CTN and LLINs still protect individuals against a pyrethroid resistant malaria vector from the Mekong region, where insecticide resistance is caused by a metabolic mechanism. In the light of a possible elimination of malaria from the Mekong region these insights in operational consequences of the insecticide resistance on control tools is of upmost importance.

  1. Increase in susceptibility to insecticides with aging of wild Anopheles gambiae mosquitoes from Côte d’Ivoire

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    Chouaibou Mouhamadou S

    2012-09-01

    Full Text Available Abstract Background Appropriate monitoring of vector insecticide susceptibility is required to provide the rationale for optimal insecticide selection in vector control programs. Methods In order to assess the influence of mosquito age on susceptibility to various insecticides, field-collected larvae of An. gambiae s.l. from Tiassalé were reared to adults. Females aged 1, 2, 3, 5 and 10 days were exposed to 5 insecticides (deltamethrin, permethrin, DDT, malathion and propoxur using WHO susceptibility test kits. Outcome measures included the LT50 (exposure time required to achieve 50% knockdown, the RR (resistance ratio, i.e. a calculation of how much more resistant the wild population is compared with a standard susceptible strain and the mortality rate following 1 hour exposure, for each insecticide and each mosquito age group. Results There was a positive correlation between the rate of knockdown and mortality for all the age groups and for all insecticides tested. For deltamethrin, the RR50 was highest for 2 day old and lowest for 10 day old individuals. Overall, mortality was lowest for 2 and 3 day old individuals and significantly higher for 10 day old individuals (P 50 was highest for 1 to 3 day old individuals and lowest for 10 day old individuals and mortality was lowest for 1 to 3 day old individuals, intermediate for 5 day old and highest for 10 day old individuals. DDT did not display any knockdown effect and mortality was low for all mosquito age groups (50 was low (1.54 - 2.77 and mortality was high (>93% for all age groups. With propoxur, no knockdown effect was observed for 1, 2 and 3 day old individuals and a very low level of mortality was observed ( Conclusion Results indicate that for An. gambiae s.l. adults derived from wild-collected larvae, there was an influence of age on insecticide susceptibility status, with younger individuals (1 to 3 days old more resistant than older mosquitoes. This

  2. Using Adult Mosquitoes to Transfer Insecticides to Aedes Aegypti Larval Habitats

    Science.gov (United States)

    2009-07-14

    indoor residual applications, insecticide-treated materials (ITMs) such as cur- tains and bed nets, and the application of larvicides to aquatic...and posttreatment periods we ran 3 trials in each avenue. After each test, all deployment, collecting, and monitoring materials were discarded to...Salud, the Laboratorio de Salud Publica, and the Comité de Investigaciones in Peru gave written consent for the trials and associated protocols. Sra

  3. Genome analysis of cytochrome P450s and their expression profiles in insecticide resistant mosquitoes, Culex quinquefasciatus.

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    Ting Yang

    Full Text Available Here we report a study of the 204 P450 genes in the whole genome sequence of larvae and adult Culex quinquefasciatus mosquitoes. The expression profiles of the P450 genes were compared for susceptible (S-Lab and resistant mosquito populations, two different field populations of mosquitoes (HAmCq and MAmCq, and field parental mosquitoes (HAmCq(G0 and MAmCq(G0 and their permethrin selected offspring (HAmCq(G8 and MAmCq(G6. While the majority of the P450 genes were expressed at a similar level between the field parental strains and their permethrin selected offspring, an up- or down-regulation feature in the P450 gene expression was observed following permethrin selection. Compared to their parental strains and the susceptible S-Lab strain, HAmCq(G8 and MAmCq(G6 were found to up-regulate 11 and 6% of total P450 genes in larvae and 7 and 4% in adults, respectively, while 5 and 11% were down-regulated in larvae and 4 and 2% in adults. Although the majority of these up- and down-regulated P450 genes appeared to be developmentally controlled, a few were either up- or down-regulated in both the larvae and adult stages. Interestingly, a different gene set was found to be up- or down-regulated in the HAmCq(G8 and MAmCq(G6 mosquito populations in response to insecticide selection. Several genes were identified as being up- or down-regulated in either the larvae or adults for both HAmCq(G8 and MAmCq(G6; of these, CYP6AA7 and CYP4C52v1 were up-regulated and CYP6BY3 was down-regulated across the life stages and populations of mosquitoes, suggesting a link with the permethrin selection in these mosquitoes. Taken together, the findings from this study indicate that not only are multiple P450 genes involved in insecticide resistance but up- or down-regulation of P450 genes may also be co-responsible for detoxification of insecticides, insecticide selection, and the homeostatic response of mosquitoes to changes in cellular environment.

  4. Site-directed mutagenesis of an acetylcholinesterase gene from the yellow fever mosquito Aedes aegypti confers insecticide insensitivity.

    Science.gov (United States)

    Vaughan, A; Rocheleau, T; ffrench-Constant, R

    1997-11-01

    Insecticide resistance is a serious problem facing the effective control of insect vectors of disease. Insensitive acetylcholinesterase (AChE) confers resistance to organophosphorus (OP) and carbamate insecticides and is a widespread resistance mechanism in vector mosquitoes. Although the point mutations that underlie AChE insensitivity have been described from Drosophila, the Colorado potato beetle, and house flies, no resistance associated mutations have been documented from mosquitoes to date. We are therefore using a cloned acetylcholinesterase gene from the yellow fever mosquito Aedes aegypti as a model in which to perform site directed mutagenesis in order to understand the effects of potential resistance associated mutations. The same resistance associated amino-acid replacements as found in other insects also confer OP and carbamate resistance to the mosquito enzyme. Here we describe the levels of resistance conferred by different combinations of these mutations and the effects of these mutations on the kinetics of the AChE enzyme. Over-expression of these constructs in baculovirus will facilitate purification of each of the mutant enzymes and a more detailed analysis of their associated inhibition kinetics.

  5. Insecticidal and repellent activity of Clausena dentata (Rutaceae) plant extracts against Aedes aegypti and Culex quinquefasciatus mosquitoes (Diptera: Culicidae).

    Science.gov (United States)

    Ramkumar, Govindaraju; Karthi, Sengodan; Muthusamy, Ranganathan; Natarajan, Devarajan; Shivakumar, Muthugounder Subramanian

    2015-03-01

    Mosquito control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol agents. The present study is to evaluate adulticidal activity of Clausena dentata plant extract against Aedes aegypti and Culex quinquefasciatus mosquitoes. The adult mortality was observed after 24 h of exposure. The highest mortality was found in acetone extracts against Ae. aegypti and Cx. quinquefasciatus with the LC50 and LC90 4.1783 mg/ml (3.8201-7.1026), 9.3884 mg/ml (7. 8258-13.1820) and 4.2451 mg/ml (3.8547-8.0254), 12.3214 mg/ml (10.9287-16.2220), respectively. Smoke toxicity was observed at 10-min interval for 40 min, and the mortality data were recorded. Result shows that Ae. aegypti and Cx. quinquefasciatus are 85 ± 2 and 89 ± 1.5, respectively. A mortality of 100 % was recorded in the commercial mosquito control. These results suggest that the leaf extracts of C. dentata have a potential to be used as an ideal eco-friendly approach for the control of mosquitoes.

  6. Delivering insecticide-treated nets for malaria prevention: innovative strategies

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    Krezanoski PJ

    2016-09-01

    Full Text Available Paul J Krezanoski1–3 1Department of Medicine, 2Department of Pediatrics, Massachusetts General Hospital, 3Medicine and Pedatrics, Harvard Medical School, Boston, MA, USA Abstract: The wide-scale adoption of insecticide-treated nets (ITNs has led to significant reductions in malaria morbidity and mortality worldwide. Delivery of ITNs to the 3.2 billion people at risk of malaria requires multiple steps in diverse settings. The effectiveness of the delivery of ITNs in order to prevent malaria relies on activities that include ITN manufacturing and design, integration into national and international malaria prevention policies, supplying and distributing ITNs to households and individuals, and, finally, programs focused on spurring demand for and use of ITNs by individuals at risk. This paper reviews some recent innovative strategies for ITN delivery across these four domains, places these innovations within the context of the history of ITN deployment, and identifies opportunities to further improve the effectiveness of this ubiquitous public health tool. Keywords: malaria, insecticide-treated bed nets, prevention, access, ownership, use, policies

  7. Pharmacological validation of an inward-rectifier potassium (Kir channel as an insecticide target in the yellow fever mosquito Aedes aegypti.

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    Matthew F Rouhier

    Full Text Available Mosquitoes are important disease vectors that transmit a wide variety of pathogens to humans, including those that cause malaria and dengue fever. Insecticides have traditionally been deployed to control populations of disease-causing mosquitoes, but the emergence of insecticide resistance has severely limited the number of active compounds that are used against mosquitoes. Thus, to improve the control of resistant mosquitoes there is a need to identify new insecticide targets and active compounds for insecticide development. Recently we demonstrated that inward rectifier potassium (Kir channels and small molecule inhibitors of Kir channels offer promising new molecular targets and active compounds, respectively, for insecticide development. Here we provide pharmacological validation of a specific mosquito Kir channel (AeKir1 in the yellow fever mosquito Aedes aegypti. We show that VU590, a small-molecule inhibitor of mammalian Kir1.1 and Kir7.1 channels, potently inhibits AeKir1 but not another mosquito Kir channel (AeKir2B in vitro. Moreover, we show that a previously identified inhibitor of AeKir1 (VU573 elicits an unexpected agonistic effect on AeKir2B in vitro. Injection of VU590 into the hemolymph of adult female mosquitoes significantly inhibits their capacity to excrete urine and kills them within 24 h, suggesting a mechanism of action on the excretory system. Importantly, a structurally-related VU590 analog (VU608, which weakly blocks AeKir1 in vitro, has no significant effects on their excretory capacity and does not kill mosquitoes. These observations suggest that the toxic effects of VU590 are associated with its inhibition of AeKir1.

  8. Use of insecticide-treated school uniforms for prevention of dengue in schoolchildren: a cost-effectiveness analysis.

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    Yesim Tozan

    Full Text Available BACKGROUND: Dengue-related illness is a leading cause of hospitalization and death, particularly among children. Practical, acceptable and affordable measures are urgently needed to protect this age group. Schools where children spend most of their day is proposed as an ideal setting to implement preventive strategies against day-biting Aedes mosquitoes. The use of insecticide-treated school uniforms is a promising strategy currently under investigation. METHODS: Using a decision-analytic model, we evaluated the cost-effectiveness of the use of insecticide-treated school uniforms for prevention of dengue, compared with a "do-nothing" alternative, in schoolchildren from the societal perspective. We explored how the potential economic value of the intervention varied under various scenarios of intervention effectiveness and cost, as well as dengue infection risk in school-aged children, using data specific to Thailand. RESULTS: At an average dengue incidence rate of 5.8% per year in school-aged children, the intervention was cost-effective (ICER≤$16,440 in a variety of scenarios when the intervention cost per child was $5.3 or less and the intervention effectiveness was 50% or higher. In fact, the intervention was cost saving (ICER$16,440. CONCLUSIONS: Our results present the potential economic value of the use of insecticide-treated uniforms for prevention of dengue in schoolchildren in a typical dengue endemic setting and highlight the urgent need for additional research on this intervention.

  9. Use of butterflies as nontarget insect test species and the acute toxicity and hazard of mosquito control insecticides.

    Science.gov (United States)

    Hoang, Tham C; Pryor, Rachel L; Rand, Gary M; Frakes, Robert A

    2011-04-01

    Honeybees are the standard insect test species used for toxicity testing of pesticides on nontarget insects for the U.S. Environmental Protection Agency (U.S. EPA) under the Federal Insecticide Fungicide and Rodenticide Act (FIFRA). Butterflies are another important insect order and a valued ecological resource in pollination. The current study conducted acute toxicity tests with naled, permethrin, and dichlorvos on fifth larval instar (caterpillars) and adults of different native Florida, USA, butterfly species to determine median lethal doses (24-h LD50), because limited acute toxicity data are available with this major insect group. Thorax- and wing-only applications of each insecticide were conducted. Based on LD50s, thorax and wing application exposures were acutely toxic to both caterpillars and adults. Permethrin was the most acutely toxic insecticide after thorax exposure to fifth instars and adult butterflies. However, no generalization on acute toxicity (sensitivity) of the insecticides could be concluded based on exposures to fifth instars versus adult butterflies or on thorax versus wing exposures of adult butterflies. A comparison of LD50s of the butterflies from this study (caterpillars and adults) with honeybee LD50s for the adult mosquito insecticides on a µg/organism or µg/g basis indicates that several butterfly species are more sensitive to these insecticides than are honeybees. A comparison of species sensitivity distributions for all three insecticides shows that permethrin had the lowest 10th percentile. Using a hazard quotient approach indicates that both permethrin and naled applications in the field may present potential acute hazards to butterflies, whereas no acute hazard of dichlorvos is apparent in butterflies. Butterflies should be considered as potential test organisms when nontarget insect testing of pesticides is suggested under FIFRA. Copyright © 2011 SETAC.

  10. Managing insecticide resistance in malaria vectors by combining carbamate-treated plastic wall sheeting and pyrethroid-treated bed nets

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    Pennetier Cédric

    2009-10-01

    Full Text Available Abstract Background Pyrethroid resistance is now widespread in Anopheles gambiae, the major vector for malaria in sub-Saharan Africa. This resistance may compromise malaria vector control strategies that are currently in use in endemic areas. In this context, a new tool for management of resistant mosquitoes based on the combination of a pyrethroid-treated bed net and carbamate-treated plastic sheeting was developed. Methods In the laboratory, the insecticidal activity and wash resistance of four carbamate-treated materials: a cotton/polyester blend, a polyvinyl chloride tarpaulin, a cotton/polyester blend covered on one side with polyurethane, and a mesh of polypropylene fibres was tested. These materials were treated with bendiocarb at 100 mg/m2 and 200 mg/m2 with and without a binding resin to find the best combination for field studies. Secondly, experimental hut trials were performed in southern Benin to test the efficacy of the combined use of a pyrethroid-treated bed net and the carbamate-treated material that was the most wash-resistant against wild populations of pyrethroid-resistant An. gambiae and Culex quinquefasciatus. Results Material made of polypropylene mesh (PPW provided the best wash resistance (up to 10 washes, regardless of the insecticide dose, the type of washing, or the presence or absence of the binding resin. The experimental hut trial showed that the combination of carbamate-treated PPW and a pyrethroid-treated bed net was extremely effective in terms of mortality and inhibition of blood feeding of pyrethroid-resistant An. gambiae. This efficacy was found to be proportional to the total surface of the walls. This combination showed a moderate effect against wild populations of Cx. quinquefasciatus, which were strongly resistant to pyrethroid. Conclusion These preliminary results should be confirmed, including evaluation of entomological, parasitological, and clinical parameters. Selective pressure on resistance

  11. The effect of deltamethrin-treated net fencing around cattle enclosures on outdoor-biting mosquitoes in Kumasi, Ghana.

    Science.gov (United States)

    Maia, Marta Ferreira; Abonuusum, Ayimbire; Lorenz, Lena Maria; Clausen, Peter-Henning; Bauer, Burkhard; Garms, Rolf; Kruppa, Thomas

    2012-01-01

    Classic vector control strategies target mosquitoes indoors as the main transmitters of malaria are indoor-biting and -resting mosquitoes. However, the intensive use of insecticide-treated bed-nets (ITNs) and indoor residual spraying have put selective pressure on mosquitoes to adapt in order to obtain human blood meals. Thus, early-evening and outdoor vector activity is becoming an increasing concern. This study assessed the effect of a deltamethrin-treated net (100 mg/m(2)) attached to a one-meter high fence around outdoor cattle enclosures on the number of mosquitoes landing on humans. Mosquitoes were collected from four cattle enclosures: Pen A - with cattle and no net; B - with cattle and protected by an untreated net; C - with cattle and protected by a deltamethrin-treated net; D - no cattle and no net. A total of 3217 culicines and 1017 anophelines were collected, of which 388 were Anopheles gambiae and 629 An. ziemanni. In the absence of cattle nearly 3 times more An. gambiae (p<0.0001) landed on humans. The deltamethrin-treated net significantly reduced (nearly three-fold, p<0.0001) culicine landings inside enclosures. The sporozoite rate of the zoophilic An. ziemanni, known to be a secondary malaria vector, was as high as that of the most competent vector An. gambiae; raising the potential of zoophilic species as secondary malaria vectors. After deployment of the ITNs a deltamethrin persistence of 9 months was observed despite exposure to African weather conditions. The outdoor use of ITNs resulted in a significant reduction of host-seeking culicines inside enclosures. Further studies investigating the effectiveness and spatial repellence of ITNs around other outdoor sites, such as bars and cooking areas, as well as their direct effect on vector-borne disease transmission are needed to evaluate its potential as an appropriate outdoor vector control tool for rural Africa.

  12. The central role of mosquito cytochrome P450 CYP6Zs in insecticide detoxification revealed by functional expression and structural modelling.

    Science.gov (United States)

    Chandor-Proust, Alexia; Bibby, Jaclyn; Régent-Kloeckner, Myriam; Roux, Jessica; Guittard-Crilat, Emilie; Poupardin, Rodolphe; Riaz, Muhammad Asam; Paine, Mark; Dauphin-Villemant, Chantal; Reynaud, Stéphane; David, Jean-Philippe

    2013-10-01

    The resistance of mosquitoes to chemical insecticides is threatening vector control programmes worldwide. Cytochrome P450 monooxygenases (CYPs) are known to play a major role in insecticide resistance, allowing resistant insects to metabolize insecticides at a higher rate. Among them, members of the mosquito CYP6Z subfamily, like Aedes aegypti CYP6Z8 and its Anopheles gambiae orthologue CYP6Z2, have been frequently associated with pyrethroid resistance. However, their role in the pyrethroid degradation pathway remains unclear. In the present study, we created a genetically modified yeast strain overexpressing Ae. aegypti cytochrome P450 reductase and CYP6Z8, thereby producing the first mosquito P450-CPR (NADPH-cytochrome P450-reductase) complex in a yeast recombinant system. The results of the present study show that: (i) CYP6Z8 metabolizes PBAlc (3-phenoxybenzoic alcohol) and PBAld (3-phenoxybenzaldehyde), common pyrethroid metabolites produced by carboxylesterases, producing PBA (3-phenoxybenzoic acid); (ii) CYP6Z8 transcription is induced by PBAlc, PBAld and PBA; (iii) An. gambiae CYP6Z2 metabolizes PBAlc and PBAld in the same way; (iv) PBA is the major metabolite produced in vivo and is excreted without further modification; and (v) in silico modelling of substrate-enzyme interactions supports a similar role of other mosquito CYP6Zs in pyrethroid degradation. By playing a pivotal role in the degradation of pyrethroid insecticides, mosquito CYP6Zs thus represent good targets for mosquito-resistance management strategies.

  13. Personal protection of long lasting insecticide-treated nets in areas of Anopheles gambiae s.s. resistance to pyrethroids

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    Paré-Toé Léa

    2006-02-01

    Full Text Available Abstract Background The development of mosquito nets pre-treated with insecticide, Long Lasting Impregnated Nets (LLINs that last the life span of the net, is a solution to the difficulty of the re-impregnation of conventional nets. Even if they showed a good efficacy in control conditions, their efficacy in the field, particularly in areas with resistance of Anopheles gambiae to pyrethroids, is not well documented. This study compares wide (Olyset® and small (Permanet® mesh LLINs in field conditions, using entomological parameters. Methods The two LLINs were tested in a rice-growing area of south-western Burkina Faso (West Africa with year around high density of the main malaria vector An. gambiae s.s. In the study village (VK6, there is a mixed population of two molecular forms of An. gambiae, the S-form which dominates during the rainy season and the M-form which dominates the rest of the year. The two LLINs Olyset® and Permanet® were distributed in the village and 20 matched houses were selected for comparison with four houses without treated nets. Results Mosquito entrance rate was ten fold higher in control houses than in houses with LLINs and there was no difference between the two net types. Among mosquitoes found in the houses, 36 % were dead in LLIN houses compared to 0% in control houses. Blood feeding rate was 80 % in control houses compared to 43 % in LLIN houses. The type of net did not significantly impact any of these parameters. No mosquitoes were found inside Permanet®, whereas dead or dying mosquitoes were collected inside the Olyset®. More than 60% of mosquitoes found on top or inside the nets had had blood meals from cattle, as shown by ELISA analysis. Conclusion The percentage of blood-fed mosquitoes in a bed net study does not necessarily determine net success. The efficacy of the two types of LLINs was comparable, during a period when the S-form of An. gambiae was carrying the kdr gene. Significantly higher numbers

  14. New Insecticides and Repellents For Use on Mosquitoes and Sand Flies

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    The major emphasis of our research is on the discovery and development of new insecticides for personal protection. The insecticide discovery effort involves structure-activity modeling to correlate molecular structure and electronic properties with repellent and/or insecticidal activity. Models a...

  15. Susceptibility of Culicidae Mosquitoes to Some Insecticides Recommended by WHO in a Malaria Endemic Area of Southeastern Iran

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    Mousa Fathian

    2015-10-01

    Full Text Available Background: According to the national strategy plan on monitoring of insecticides resistance, this study was carried out to determine the base line susceptibility of the Culicidae mosquitoes to the WHO-recommended insecticides in an endemic focus of malaria in southeastern Iran.Methods: Larval collection was carried out by dipping method and adult collection occurred by suction tube from January to December 2010. The susceptibility test was assessed to DDT 4 %, malathion 5 %, propoxur 0.1 %, deltamethrin 0.05 %, lambda-cyhalothrin 0.05 %, and cyfluthrin 0.15 % at different interval times (discriminative dose followed by 24 h recovery period . The LT50 and LT90 values were calculated for plotting the regression line using Microsoft office Excel software ver. 2007.Results: Anopheles stephensi was quite resistant to DDT and showed susceptible or tolerant to other insecticides. The LT50 and LT90 values to DDT in this species were 29.07, and 98.26 minutes, respectively. Anopheles culicifacies and Anopheles dthali were found susceptible or tolerant to insecticides. Culex pipiens was found resistance to DDT, propoxur, lambda-cyhalothrin and cyfluthrin whereas observed susceptible to malathion and tolerant to deltamethrin. Ochlerotatus caspius sl. was resistant to DDT, whereas found susceptible to other insecticides. Culisita longiareolatawas susceptible to deltamethrin, whereas tolerant to other insecticides. The LT50 and LT90 values of Cs. longiareolata to DDT were 17.82, and 51.26 minutes.Conclusion: We suggested the same study in different parts of the country for monitoring and evaluation of control measures.

  16. Evaluation of organophosphorus and synthetic pyrethroid insecticides against six vector mosquitoe species Avaliação de inseticidas organofosforados e piretroides sintéticos contra seis mosquitos vetores

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    Domingo Montada Dorta

    1993-12-01

    Full Text Available Three organophosphorus compounds- malathion, folithion and temephos- and two synthetic pyrethroids- alphamethrin and deltamethrin- were used for monitoring the susceptibility status of larvae and adults of six vector mosquitoe species: Culex quinquefasciatus (Filariasis and Aedes albopictus (Dengue (both laboratory and field strains; laboratory strains of Aedes aegypti (Dengue, Anopheles slephensi and Anopheles culicifacies (Malaria, and Culex tritaeniorhynchus (Japanese encephalitis in India. From the LC50 values obtained for these insecticides, it was found that all mosquito species including the field strains of Cx. quinquefasciatus and Ae. albopictus were highly susceptible Except for Cx. quinquefasciatus (field strain against malathion, 100% mortality was observed at the discriminating dosages recommended by World Health Organization. The residual effect of alphamethrin, deltamethrin, malathion and folithion at 25 mg (ai/m² on different surfaces against six species of vector mosquitoes showed that alphamethrin was the most effective on all four treated surfaces (mud, plywood, cement and thatch. Nevertheless, residual efficacy lasted longer on thatch than on the other surfaces. Therefore, synthetic pyrethroids such as alphamethrin can be effectively employed in integrated vector control operations.Três compostos organo-fosforados - malation, folition e temefos -e dois piretroides sintéticos - alfametrina e deltametrina - foram usados para controlar o estado da susceptibilidade das larvas e adultos de seis mosquitos vetores na Índia. Foram utilizadas cepas de laboratório e área de Culex quinquefasciatus (filariasis e Aedes albopictus (Dengue e cepas de laboratório de Aedes aegypti (Dengue, Anopheles stephensi e Anopheles culicifacies (Malária e Culex tritaenorhynchus (encefalite japonesa. Os valores de C1(50 obtidos para esses inseticidas mostram que todas as espécies incluindo as cepas de área foram muito susceptíveis. Nos

  17. Made-to-measure malaria vector control strategies: rational design based on insecticide properties and coverage of blood resources for mosquitoes.

    Science.gov (United States)

    Killeen, Gerry F; Seyoum, Aklilu; Gimnig, John E; Stevenson, Jennifer C; Drakeley, Christopher J; Chitnis, Nakul

    2014-04-16

    Eliminating malaria from highly endemic settings will require unprecedented levels of vector control. To suppress mosquito populations, vector control products targeting their blood hosts must attain high biological coverage of all available sources, rather than merely high demographic coverage of a targeted resource subset, such as humans while asleep indoors. Beyond defining biological coverage in a measurable way, the proportion of blood meals obtained from humans and the proportion of bites upon unprotected humans occurring indoors also suggest optimal target product profiles for delivering insecticides to humans or livestock. For vectors that feed only occasionally upon humans, preferred animal hosts may be optimal targets for mosquito-toxic insecticides, and vapour-phase insecticides optimized to maximize repellency, rather than toxicity, may be ideal for directly protecting people against indoor and outdoor exposure. However, for vectors that primarily feed upon people, repellent vapour-phase insecticides may be inferior to toxic ones and may undermine the impact of contact insecticides applied to human sleeping spaces, houses or clothing if combined in the same time and place. These concepts are also applicable to other mosquito-borne anthroponoses so that diverse target species could be simultaneously controlled with integrated vector management programmes. Measurements of these two crucial mosquito behavioural parameters should now be integrated into programmatically funded, longitudinal, national-scale entomological monitoring systems to inform selection of available technologies and investment in developing new ones.

  18. The knockdown resistance mutation and knockdown time in Anopheles gambiae collected from Mali evaluated through a bottle bioassay and a novel insecticide-treated net bioassay.

    Science.gov (United States)

    Fryxell, Rebecca T Trout; Seifert, Stephanie N; Lee, Yoosook; Sacko, Adama; Lanzaro, Gregory; Cornel, Anthony

    2012-06-01

    Successful malaria management in Mali includes the use of pyrethroids and insecticide-treated nets (ITNs) for mosquito control; however, management is threatened by the spread of insecticide resistance detected via the knockdown resistance (kdr) allele. In a preliminary study, we compared the knockdown times of Anopheles gambiae from Mali using a novel ITN bioassay and the World Health Organization (WHO) bottle bioassay. Additionally, the frequency and relationship between kdr genotypes, molecular forms, and pyrethroid resistance were analyzed. The S molecular form was predominant and accounted for 76% of the assayed population. Both kdr resistant alleles, West Africa resistant (kdr-w) and East Africa resistant (kdr-e), were observed. There was no significant difference in knockdown time based on kdr genotype or molecular form of individual mosquitoes, but mosquitoes in the ITN bioassay homozygous for the kdr-w allele were knocked down significantly faster than those in the WHO bottle bioassay. The ITN bioassay provides an additional indicator of insecticide efficacy because ITNs, frequently used within homes, are the most common form of vector control and malaria prevention, and the ITN bioassays can evaluate seasonal field effects.

  19. Evidence of carbamate resistance in urban populations of Anopheles gambiae s.s. mosquitoes resistant to DDT and deltamethrin insecticides in Lagos, South-Western Nigeria

    Science.gov (United States)

    2012-01-01

    Background Resistance monitoring is essential in ensuring the success of insecticide based vector control programmes. This study was carried out to assess the susceptibility status of urban populations of Anopheles gambiae to carbamate insecticide being considered for vector control in mosquito populations previously reported to be resistant to DDT and permethrin. Methods Two – three day old adult female Anopheles mosquitoes reared from larval collections in 11 study sites from Local Government Areas of Lagos were exposed to test papers impregnated with DDT 4%, deltamethrin 0.05% and propoxur 0.1% insecticides. Additional tests were carried out to determine the susceptibility status of the Anopheles gambiae population to bendiocarb insecticide. Members of the A. gambiae complex, the molecular forms, were identified by PCR assays. The involvement of metabolic enzymes in carbamate resistance was assessed using Piperonyl butoxide (PBO) synergist assays. The presence of kdr-w/e and ace-1R point mutations responsible for DDT-pyrethroid and carbamate resistance mechanisms was also investigated by PCR. Results Propoxur resistance was found in 10 out of the 11 study sites. Resistance to three classes of insecticides was observed in five urban localities. Mortality rates in mosquitoes exposed to deltamethrin and propoxur did not show any significant difference (P > 0.05) but was significantly higher (P insecticide resistance management strategies to combat the multiple resistance identified. PMID:22686575

  20. Coverage-Dependent Effect of Insecticide-Treated Curtains for Dengue Control in Thailand

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    Vanlerberghe, Veerle; Trongtokit, Yuwadee; Jirarojwatana, Somchai; Jirarojwatana, Ravisara; Lenhart, Audrey; Apiwathnasorn, Chamnarn; McCall, Philip J.; Van der Stuyft, Patrick

    2013-01-01

    Evidence on the effectiveness of insecticide-treated curtains (ITCs) for reducing densities of Aedes mosquitoes, the principal vectors of dengue, is scarce. In Laem Chabang southeast of Bangkok, Thailand, the Breteau Index (BI) (number of positive containers/100 houses) was 45 in October 2006. In March 2007, we distributed long-lasting ITCs in 22 clusters (2,032 houses) and selected 66 control clusters (661 houses). Routine control activities continued in all clusters. Six months after distribution, the BI was 25.8 and 77.6 in intervention and control areas, respectively (P < 0.001). Eighteen months after distribution, the BI was 21.8 and 23.8, respectively (P = 0.28). The average number of ITCs/house at cluster level was associated with the BI (P < 0.01) after six months, when 70.5% of households still used ITCs, but not at 18 months, when ITC coverage had decreased to 33.2%. Deployment of ITCs can result in considerable reductions in Aedes infestation levels, but the effect is coverage dependent. PMID:23669233

  1. Evidence for a useful life of more than three years for a polyester-based long-lasting insecticidal mosquito net in Western Uganda

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    Atieli Francis

    2011-10-01

    Full Text Available Abstract Background Long-lasting insecticidal nets (LLIN are now standard for the prevention of malaria. However, only products with recommendation for public use from the World Health Organization should be used and this evaluation includes the assessment of net effectiveness after three years of field use. Results for one of the polyester-based products, Interceptor® is presented. Methods In five villages, 190 LLIN and 90 nets conventionally treated with the insecticide alpha-cypermethrin at 25 mg/m2 were distributed randomly and used by the families. Following a baseline household survey a net survey was carried out every six months to capture use, washing habits and physical condition of the nets. Randomly selected nets were collected after 6, 12, 24, 36 and 42 months and tested for remaining insecticide content and ability to knock-down and kill malaria transmitting mosquitoes. Results During the three and a half years of observation only 16 nets were lost to follow-up resulting in an estimated attrition rate of 12% after three and 20/% after 3.5 years. Nets were used regularly and washed on average 1.5 times per year. After three and a half years 29% of the nets were still in good condition while 13% were seriously torn with no difference between the LLIN and control nets. The conventionally treated nets quickly lost insecticide and after 24 months only 7% of the original dose remained (1.6 mg/m2. Baseline median concentration of alpha-cypermethrin for LLIN was 194.5 mg/m2 or 97% of the target dose with between and within net variation of 11% and 4% respectively (relative standard deviation. On the LLIN 73.8 mg/m2 alpha-cypermethrin remained after three years of use and 56.2 mg/m2 after three and a half and 94% and 81% of the LLIN still had > 15 mg/m2 left respectively. Optimal effectiveness in bio-assays (≥95% 60 minute knock-down or ≥ 80% 24 hour mortality was found in 83% of the sampled LLIN after three and 71% after three and a

  2. Synergistic action of octopamine receptor agonists on the activity of selected novel insecticides for control of dengue vector Aedes aegypti (Diptera: Culicidae) mosquito.

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    Ahmed, Mohamed Ahmed Ibrahim; Vogel, Christoph Franz Adam

    2015-05-01

    Studying insecticide resistance in mosquitoes has attracted the attention of many scientists to elucidate the pathways of resistance development and to design novel strategies in order to prevent or minimize the spread and evolution of resistance. Here, we tested the synergistic action of piperonyl butoxide (PBO) and two octopamine receptor (OR) agonists, amitraz (AMZ) and chlordimeform (CDM) on selected novel insecticides to increase their lethal action on the fourth instar larvae of Aedes aegypti L. However, chlorfenapyr was the most toxic insecticide (LC50 = 193, 102, and 48 ng/ml, after 24, 48, and 72 h exposure, respectively) tested. Further, PBO synergized all insecticides and the most toxic combinatorial insecticide was nitenpyram even after 48 and 72 h exposure. In addition, OR agonists significantly synergized most of the selected insecticides especially after 48 and 72 h exposure. The results imply that the synergistic effects of amitraz are a promising approach in increasing the potency of certain insecticides in controlling the dengue vector Ae. aegypti mosquito.

  3. Relative potency of various insecticides for use in ATSBs against mosquitoes and sand flies

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    Mosquitoes and sand flies are important throughout the world as nuisance pests and vectors of a variety of human and livestock diseases. Control efforts are limited often to adulticide sprays and larvicides, however, environmental concerns restrict their use. Both mosquitoes and sand flies need to...

  4. Knowledge, attitude and practice on malaria: a study in a tribal belt of Orissa state, India with reference to use of long lasting treated mosquito nets.

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    Vijayakumar, K N; Gunasekaran, K; Sahu, S S; Jambulingam, P

    2009-11-01

    Local knowledge and practice related to malaria is important for the implementation of culturally appropriate, sustainable and effective interventions. In this context, to know people's knowledge, attitude and practice on malaria and its prevention, a study was carried out in two districts viz., Malkangiri and Koraput of Orissa state in India, the former with ongoing insecticide treated mosquito nets (ITNs) programme and the latter without such programme (non-ITNs). Both qualitative and quantitative methods were used for data collection. The local concepts used for malaria describe only the biomedical symptoms of the disease although a few by meaning in local language reflect people's misconceptions about the cause of malaria. About 63% of the respondents mentioned mosquito bite as the cause for this disease and 65% considered malaria as a serious problem. Qualitative data showed that people from remote villages seek treatment from traditional healers, Disharis. About 64% of the respondents stated that avoiding mosquito bites could prevent malaria. Majority (99%) of the people reported using personal protection measures to avoid mosquito bites. Although, majority of the people were aware of the cause and prevention of malaria (about 70% stated sleeping under mosquito net prevents malaria), a sizable proportion still had misconceptions and hence appropriate communication strategies should be developed and imparted alongside ITNs/LLINs distribution for a behaviour change to adopt such preventive measures. Since, the tribes are habituated to seek treatment from traditional healers; they could be involved in motivating people to use ITNs/LLINs to protect from mosquito bites and malaria.

  5. Characterization of Bacillus thuringiensis soil isolates from Cuba, with insecticidal activity against mosquitoes

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    Aileen González

    2011-09-01

    Full Text Available Chemical insecticides may be toxic and cause environmental degradation. Consequently, biological control for insects represents an alternative with low ecological impact. In this work, three soil isolates (A21, A51 and C17 from different regions of the Cuban archipelago were identified, characterized and evaluated against Aedes aegypti and Culex quinquefasciatus. The new isolates were compared with reference IPS82 strain and two strains isolated from biolarvicides Bactivec and Bactoculicida, respectively. The differentiation was done by morphological, biochemical, bioassays activity and molecular methods (SDS-PAGE, plasmid profile and random amplified polymorphic analysis. All isolates were identified as Bacillus thuringiensis. The A21, A51 and C17 isolates showed higher larvicide activity than Bactivec’s isolated reference strain, against both A. aegypti and C. quinquefasciatus. A21 isolate had a protein profile similar to IPS82 and Bactivec strain. A51 and C17 isolates produced a characteristic proteins pattern. A21 and A51 isolates had plasmid patterns similar to IPS82 standard strain, while C17 isolate had different both plasmid profile and protein bands. All the studied isolates showed a diverse RAPD patterns and were different from the strains previously used in biological control in Cuba. Rev. Biol. Trop. 59 (3: 1007-1016. Epub 2011 September 01.El uso prolongado de insecticidas ha conducido al desarrollo de resistencia en diferentes especies de mosquitos y al incremento de la degradación del ambiente. El control biológico de insectos ha devenido como una alternativa útil y de bajo impacto ambiental. En nuestro estudio fueron identificados, caracterizados tres aislamientos de suelos procedentes de diferentes regiones del archipiélago cubano y comparados con cepas de referencia: aisladas de los biolarvicidas Bactivec y Bactoculicida, además de IPS82. La diferenciación de los mismos se llevó a cabo mediante métodos morfol

  6. The infectivity of the entomopathogenic fungus Beauveria bassiana to insecticide-resistant and susceptible Anopheles arabiensis mosquitoes at two different temperatures

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    Koekemoer Lizette L

    2010-03-01

    Full Text Available Abstract Background Control of the major African malaria vector species continues to rely extensively on the application of residual insecticides through indoor house spraying or bed net impregnation. Insecticide resistance is undermining the sustainability of these control strategies. Alternatives to the currently available conventional chemical insecticides are, therefore, urgently needed. Use of fungal pathogens as biopesticides is one such possibility. However, one of the challenges to the approach is the potential influence of varied environmental conditions and target species that could affect the efficacy of a biological 'active ingredient'. An initial investigation into this was carried out to assess the susceptibility of insecticide-susceptible and resistant laboratory strains and wild-collected Anopheles arabiensis mosquitoes to infection with the fungus Beauveria bassiana under two different laboratory temperature regimes. Methods Insecticide susceptibility to all four classes of insecticides recommended by WHO for vector control was tested on laboratory and wild-caught An. arabiensis, using standard WHO bioassay protocols. Mosquito susceptibility to fungus infection was tested using dry spores of B. bassiana under two temperature regimes (21 ± 1°C or 25 ± 2°C representative of indoor conditions observed in western Kenya. Cox regression analysis was used to assess the effect of fungal infection on mosquito survival and the effect of insecticide resistance status and temperature on mortality rates following fungus infection. Results Survival data showed no relationship between insecticide susceptibility and susceptibility to B. bassiana. All tested colonies showed complete susceptibility to fungal infection despite some showing high resistance levels to chemical insecticides. There was, however, a difference in fungus-induced mortality rates between temperature treatments with virulence significantly higher at 25°C than 21

  7. Characteristics and Efficacy of Three Commercial Handheld Thermal Foggers with Pyrethroid Insecticides Against Three Species of Mosquitoes.

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    Fulcher, Ali; Farooq, Muhammad; Richardson, Alec G; Smith, Michael L; Scott, Jodi M; Gaines, Marcia K; Xue, Rui-De

    2016-03-01

    The field study's objectives were to compare the physical characteristics as well as efficacy with multiple insecticides for Bonide(®) Fog Rx Insect Fogger, Black Flag(®) Propane Insect Fogger, and Burgess(®) Outdoor Propane Insect Fogger. Evaluations were conducted with 7 machine chemical combinations, 3 depths of spray, and 3 species of laboratory-reared mosquitoes, Anopheles quadrimaculatus, Culex quinquefasciatus, and Aedes aegypti. Combinations of these factors were analyzed in conjunction with environmental parameters. Data showed statistical significance between all machines. The Bonide machine maintained integrity and durability for the longest period of time compared with the other 2 machines. When evaluating the 3 machines with DUET™, mortality was highest with the Bonide and lowest with the Burgess machine.

  8. The seed physiological potential of hybrid corn treated with insecticides and store in two environmental conditions

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    Rosane Fátima Baldiga Tonin

    2014-03-01

    Full Text Available Seed treatment is a widely disseminated practice in Brazilian cultural areas, which linked to other cultural practices, has contributed to the increase in productivity, cost reduction, final product improvement, environmental damage reduction as well as good seed protection in the field level and storage. The work had the objective to check the insecticide effect on the germination and vigor of the hybrid maize seeds, stored in two environmental conditions. The seeds were treated with three insecticides, identified as: Insecticide one (Thiametoxan; Insecticide two (Neonicotinoide and Insecticide three [Neonicotinoide + (Imidaclopride+thiodicarbe]. After being treated, the seeds were stored for a period of 270 days, in two different places, one with (10ºC temperature and relative humidity (60% and another under normal condition of storage. During this period evaluations were accomplished every 45 days, through germination and vigor tests. In addition to germination and cooling tests, sanitation analysis, seedling emergency and seed inoculation were carried out. After that the seeds were stored for a period of 30 days in environmental places with and without control of air condition. The results obtained allow to conclude that the maintenance of seed quality of hybrid maize, treated with insecticides, depends on the hybrid and chemical product used in their treatment and that the reduction in feasibility and vigor of seeds treated with thiametoxan is intensified due to the storage period extension.

  9. A qualitative study on the acceptability and preference of three types of long-lasting insecticide-treated bed nets in Solomon Islands: implications for malaria elimination

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    Appleyard Bridget

    2009-06-01

    Full Text Available Abstract Background In March 2008, the Solomon Islands and Vanuatu governments raised the goal of their National Malaria Programmes from control to elimination. Vector control measures, such as indoor residual spraying (IRS and long-lasting insecticidal bed nets (LLINs are key integral components of this programme. Compliance with these interventions is dependent on their acceptability and on the socio-cultural context of the local population. These factors need to be investigated locally prior to programme implementation. Method Twelve focus group discussions (FGDs were carried out in Malaita and Temotu Provinces, Solomon Islands in 2008. These discussions explored user perceptions of acceptability and preference for three brands of long-lasting insecticide-treated bed nets (LLINs and identified a number of barriers to their proper and consistent use. Results Mosquito nuisance and perceived threat of malaria were the main determinants of bed net use. Knowledge of malaria and the means to prevent it were not sufficient to guarantee compliance with LLIN use. Factors such as climate, work and evening social activities impact on the use of bed nets, particularly in men. LLIN acceptability plays a varying role in compliance with their use in villages involved in this study. Participants in areas of reported high and year round mosquito nuisance and perceived threat of malaria reported LLIN use regardless of any reported unfavourable characteristics. Those in areas of low or seasonal mosquito nuisance were more likely to describe the unfavourable characteristics of LLINs as reasons for their intermittent or non-compliance. The main criterion for LLIN brand acceptability was effectiveness in preventing mosquito bites and malaria. Discussions highlighted considerable confusion around LLIN care and washing which may be impacting on their effectiveness and reducing their acceptability in Solomon Islands. Conclusion Providing LLINs that are acceptable

  10. Geographical/Ecological Differentials in Insecticide-Treated Net Use among Under-Five Children in Somolu Local Government Area, Lagos State.

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    Ojo, Oreoluwa O; Ajayi, IkeOluwapo O; Awolola, Taiwo S

    2014-01-01

    Malaria control efforts currently lay emphasis on reducing transmission by limiting human-vector contact. More studies have been carried out on mosquito avoidance practices in the rural areas, leaving the urban areas understudied. This study was conducted to identify knowledge of malaria transmission and to investigate geographical/ecological differentials in the use of insecticide-treated nets (ITNs) among caregivers of under-fives in Somolu Local Government Area, Lagos State. A household survey was conducted by interviewing 394 female caregivers of under-fives selected using the WHO Lot Quality Technique from communities stratified based on level of planning and drainage. The mean age of the respondents was 33.6 ± 7.7 years. Malaria transmission was attributed mostly to mosquito bites in all strata: S1 (58.3%), S2 (56.1%) and S3 (61.4%). Mosquito net was mentioned as a preventive measure by: 59.3% (S1), 80.7% (S2) and 64.3% (S3). Ownership of long-lasting insecticidal nets was: 76.0% (S1), 75.4% (S2) and 68.6% (S3), and of these, 73.1% (S1), 70.7% (S2) and 72.4% (S3) reported that their child slept under the net the night before the survey. There is a need to reinforce education on transmission and ownership of ITNs especially among caregivers in unplanned, poorly drained communities.

  11. Insecticide-treated net (ITN) ownership, usage, and malaria transmission in the highlands of western Kenya.

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    Atieli, Harrysone E; Zhou, Guofa; Afrane, Yaw; Lee, Ming-Chieh; Mwanzo, Isaac; Githeko, Andrew K; Yan, Guiyun

    2011-06-18

    Insecticide-treated bed nets (ITNs) are known to be highly effective in reducing malaria morbidity and mortality. However, usage varies among households, and such variations in actual usage may seriously limit the potential impact of nets and cause spatial heterogeneity on malaria transmission. This study examined ITN ownership and underlying factors for among-household variation in use, and malaria transmission in two highland regions of western Kenya. Cross-sectional surveys were conducted on ITN ownership (possession), compliance (actual usage among those who own ITNs), and malaria infections in occupants of randomly sampled houses in the dry and the rainy seasons of 2009. Despite ITN ownership reaching more than 71%, compliance was low at 56.3%. The compliance rate was significantly higher during the rainy season compared with the dry season (62% vs. 49.6%). Both malaria parasite prevalence (11.8% vs. 5.1%) and vector densities (1.0 vs.0.4 female/house/night) were significantly higher during the rainy season than during the dry season. Other important factors affecting the use of ITNs include: a household education level of at least primary school level, significantly high numbers of nuisance mosquitoes, and low indoor temperatures. Malaria prevalence in the rainy season was about 30% lower in ITN users than in non-ITN users, but this percentage was not significantly different during the dry season. In malaria hypo-mesoendemic highland regions of western Kenya, the gap between ITNownership and usage is generally high with greater usage recorded during the high transmission season. Because of the low compliance among those who own ITNs, there is a need to sensitize households on sustained use of ITNs in order to optimize their role as a malaria control tool.

  12. Insecticidal potential of Ocimum canum plant extracts against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus larval and adult mosquitoes (Diptera: Culicidae).

    Science.gov (United States)

    Murugan, Jimmantiyur Madhappan; Ramkumar, Govindaraju; Shivakumar, Muthugoundar Subramanian

    2016-01-01

    Mosquitoes have developed resistance to various synthetic insecticides, making their control increasingly difficult. Insecticides of botanical origin may serve as suitable natural control. This study evaluates the toxic potential of Ocimum canum (Sims) leaf extract and powder against Anopheles stephensi (Liston), Aedes aegypti (Lin) and Culex quinquefasciatus (Say) larval and adult mosquitoes. Larval mortality was observed after 24 h recovery period and adult smoke toxicity observed for 40 min duration at 10 min interval. Methanol extract of O. canum showed highest larval mortality against the larvae of C. quinquefasciatus LC50 = 28.3225, LC90 = 44.1150; Ae. aegypti LC50 = 43.327, LC90 = 61.249; and An. stephensi LC50 = 30.2001, LC90 = 48.2866 ppm. The smoke toxicities were 93% mortality in C. quinquefasciatus, 74% in Ae. aegypti and 79% in An. stephensi adults, respectively, whereas 100% mortality was recorded in the commercial mosquito control. Our results suggest that O. canum leaf extract and powder are natural insecticide, and ideal eco friendly approach for mosquito control.

  13. Barriers in access to insecticide-treated bednets for malaria prevention: An analysis of Cambodian DHS data

    Directory of Open Access Journals (Sweden)

    Kevin Welch & Melissa Fuster

    2012-03-01

    Full Text Available Background & objectives: The distribution of insecticide-treated bednets (ITNs, as an alternative to untreatedbednets or no bednet at all, not only directly prevents the mosquito from biting an individual, but kills themosquito as well. This reduces the mosquito infestation at the household and community levels. However,barriers may exist limiting the effectiveness of malaria prevention by these tactics. Objectives of the studywere to assess current disparities in access to ITNs, what factors may be associated with disparities in accessand the progress of antimalaria interventions.Methods: This study examined disparities in access to intervention resources between rural and urban locationsby assessing the percentage of households in each area that has at least one ITN. Demographic Health Survey(DHS 2005 data from 16,823 survey respondents from Cambodia were explored, examining the ratio ofhouseholds with at least one ITN according to various socioeconomic determinants. Statistical analysis wasdone using Chi-square and logistic regression with SPSS.Results: Problematic distance from ITN distributors, rural location, and poverty were all associated withgreater unlikelihood of possession of least one household ITN.Conclusion: In order to effectively combat high malaria prevalence, interventions need to be refocused onincreasing accessibility to ITNs. The limitations of this study require further investigation into alternativesocioeconomic determinants.

  14. Towards a Casa Segura: a consumer product study of the effect of insecticide-treated curtains on Aedes aegypti and dengue virus infections in the home.

    Science.gov (United States)

    Loroño-Pino, María Alba; García-Rejón, Julián E; Machain-Williams, Carlos; Gomez-Carro, Salvador; Nuñez-Ayala, Guadalupe; Nájera-Vázquez, Maria del Rosario; Losoya, Arturo; Aguilar, Lyla; Saavedra-Rodriguez, Karla; Lozano-Fuentes, Saul; Beaty, Meaghan K; Black, William C; Keefe, Thomas J; Eisen, Lars; Beaty, Barry J

    2013-08-01

    The home, or domicile, is the principal environment for transmission of dengue virus (DENV) between humans and mosquito vectors. Community-wide distribution of insecticide-treated curtains (ITCs), mimicking vector control program-driven interventions, has shown promise to reduce DENV infections. We conducted a Casa Segura consumer product intervention study in Mérida, Mexico to determine the potential to reduce intradomicillary DENV transmission through ITC use in individual homes. Dengue virus infections in mosquitoes and in humans were reduced in homes with ITCs in one of two study subareas. Overall, ITCs reduced intradomicillary DENV transmission; ITC homes were significantly less likely to experience multiple DENV infections in humans than NTC homes. Dengue virus-infected Aedes aegypti females were reduced within the ITC homes where curtain use was highest. Some homes yielded up to nine infected Ae. aegypti females. This study provides insights regarding best practices for Casa Segura interventions to protect homes from intradomicillary DENV transmission.

  15. Towards a Casa Segura: A Consumer Product Study of the Effect of Insecticide-Treated Curtains on Aedes aegypti and Dengue Virus Infections in the Home

    Science.gov (United States)

    Loroño-Pino, María Alba; García-Rejón, Julián E.; Machain-Williams, Carlos; Gomez-Carro, Salvador; Nuñez-Ayala, Guadalupe; del Rosario Nájera-Vázquez, Maria; Losoya, Arturo; Aguilar, Lyla; Saavedra-Rodriguez, Karla; Lozano-Fuentes, Saul; Beaty, Meaghan K.; Black, William C.; Keefe, Thomas J.; Eisen, Lars; Beaty, Barry J.

    2013-01-01

    The home, or domicile, is the principal environment for transmission of dengue virus (DENV) between humans and mosquito vectors. Community-wide distribution of insecticide-treated curtains (ITCs), mimicking vector control program-driven interventions, has shown promise to reduce DENV infections. We conducted a Casa Segura consumer product intervention study in Mérida, Mexico to determine the potential to reduce intradomicillary DENV transmission through ITC use in individual homes. Dengue virus infections in mosquitoes and in humans were reduced in homes with ITCs in one of two study subareas. Overall, ITCs reduced intradomicillary DENV transmission; ITC homes were significantly less likely to experience multiple DENV infections in humans than NTC homes. Dengue virus–infected Aedes aegypti females were reduced within the ITC homes where curtain use was highest. Some homes yielded up to nine infected Ae. aegypti females. This study provides insights regarding best practices for Casa Segura interventions to protect homes from intradomicillary DENV transmission. PMID:23732254

  16. Interactive effects of mosquito control insecticide toxicity, hypoxia, and increased carbon dioxide on larval and juvenile eastern oysters and hard clams.

    Science.gov (United States)

    Garcia, R N; Chung, K W; Key, P B; Burnett, L E; Coen, L D; Delorenzo, M E

    2014-04-01

    Mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. Few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased CO2 (low pH), are less understood. Toxicity was assessed at 4 and 21 days for larval and juvenile stages of the Eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, using two pyrethroids (resmethrin and permethrin), an organophosphate (naled), and a juvenile growth hormone mimic (methoprene). Acute toxicity (4-day LC50) values ranged from 1.59 to >10 mg/L. Overall, clams were more susceptible to mosquito control insecticides than oysters. Naled was the most toxic compound in oyster larvae, whereas resmethrin was the most toxic compound in clam larvae. Mortality for both species generally increased with chronic insecticide exposure (21-day LC50 values ranged from 0.60 to 9.49 mg/L). Insecticide exposure also caused sublethal effects, including decreased swimming activity after 4 days in larval oysters (4-day EC50 values of 0.60 to 2.33 mg/L) and decreased growth (shell area and weight) in juvenile clams and oysters after 21 days (detected at concentrations ranging from 0.625 to 10 mg/L). Hypoxia, hypercapnia, and a combination of hypoxia and hypercapnia caused mortality in larval clams and increased resmethrin toxicity. These data will benefit both shellfish mariculture operations and environmental resource agencies as they manage the use of mosquito control insecticides near coastal ecosystems.

  17. Evidence of carbamate resistance in urban populations of Anopheles gambiae s.s. mosquitoes resistant to DDT and deltamethrin insecticides in Lagos, South-Western Nigeria

    Directory of Open Access Journals (Sweden)

    Oduola Adedayo O

    2012-06-01

    Full Text Available Abstract Background Resistance monitoring is essential in ensuring the success of insecticide based vector control programmes. This study was carried out to assess the susceptibility status of urban populations of Anopheles gambiae to carbamate insecticide being considered for vector control in mosquito populations previously reported to be resistant to DDT and permethrin. Methods Two – three day old adult female Anopheles mosquitoes reared from larval collections in 11 study sites from Local Government Areas of Lagos were exposed to test papers impregnated with DDT 4%, deltamethrin 0.05% and propoxur 0.1% insecticides. Additional tests were carried out to determine the susceptibility status of the Anopheles gambiae population to bendiocarb insecticide. Members of the A. gambiae complex, the molecular forms, were identified by PCR assays. The involvement of metabolic enzymes in carbamate resistance was assessed using Piperonyl butoxide (PBO synergist assays. The presence of kdr-w/e and ace-1R point mutations responsible for DDT-pyrethroid and carbamate resistance mechanisms was also investigated by PCR. Results Propoxur resistance was found in 10 out of the 11 study sites. Resistance to three classes of insecticides was observed in five urban localities. Mortality rates in mosquitoes exposed to deltamethrin and propoxur did not show any significant difference (P > 0.05 but was significantly higher (P A. gambiae s.s (M form. The kdr -w point mutation at allelic frequencies between 45%-77% was identified as one of the resistant mechanisms responsible for DDT and pyrethroid resistance. Ace-1R point mutation was absent in the carbamate resistant population. However, the possible involvement of metabolic resistance was confirmed by synergistic assays conducted. Conclusion Evidence of carbamate resistance in A. gambiae populations already harbouring resistance to DDT and permethrin is a clear indication that calls for the implementation of

  18. Development of Wuchereria bancrofti in Culex pipiens L. (Diptera: Culicidae) exposed in the larval instar to sublethal dosages of insecticides and one insect growth regulator and their influence on reproduction of filaria-infected mosquitoes.

    Science.gov (United States)

    Seif, A I; Husseiny, I M; Soliman, B A; Soliman, M A; el-Kady, M A

    1997-12-01

    The effects of exposure of Culex pipiens larvae to sublethel concentrations of larvicides on uptake, development of Wuchereria bancrofti, survival rate and reproduction of filaria-infected mosquitoes were investigated. Fourth instar larvae of Cx. pipiens were exposed to LC40 of the surfactant Triton X-100, the insect growth regulator DPX alone or combined with LC10 of the surfactant and permethrin alone or combined with LC10 of the surfactant. Adults that survived insecticide treatments and controls were infected by allowing them to feed on microfilaremic volunteers. Significant reduction in the uptake of microfilaria was observed in groups treated with Triton X-100 alone or combined either with permethrin or DPX when compared to control. The overall infection and infective rates were significantly reduced in mosquitoes treated with Triton X-100 either alone or combined with permethrin. Treatment with Triton X-100 and DPX prolonged the extrinsic incubation period (EIP) and retarded the development of filarial larvae, while permethrin either alone or combined with Triton X-100 and DPX combined with Triton X-100 shortened the EIP. All larvicides reduced the number of infective larvae (L3)/mosquito and induced deformities among he different parasite stages, especially in mosquitoes treated with combination of permethrin and Triton X-100 or mixture of DPX and Triton X-100 where 36% and 54.9% respectively of L3S were deformed. In treated mosquitoes, a low percentage of L3S was detected in the head and proboscis region while the majority was trapped in the thoracic region. The survival rates of mosquitoes were reduced in cases treated with permethrin, DPX and Triton X-100 while treatment with mixture of DPX and Triton X-100 induced higher rate of mortalities when compared to control. Egg production of filaria- infected Cx. pipiens was significantly reduced in mosquitoes treated with DPX and Triton X-100. It was observed that the addition of Triton X-100 to DPX or to

  19. Combining indoor residual spraying and insecticide-treated nets for malaria control in Africa: a review of possible outcomes and an outline of suggestions for the future

    Directory of Open Access Journals (Sweden)

    Okumu Fredros O

    2011-07-01

    Full Text Available Abstract Insecticide-treated nets (ITNs and indoor residual spraying (IRS are currently the preferred methods of malaria vector control. In many cases, these methods are used together in the same households, especially to suppress transmission in holoendemic and hyperendemic scenarios. Though widespread, there has been limited evidence suggesting that such co-application confers greater protective benefits than either ITNs or IRS when used alone. Since both methods are insecticide-based and intradomicilliary, this article hypothesises that outcomes of their combination would depend on effects of the candidate active ingredients on mosquitoes that enter or those that attempt to enter houses. It is suggested here that enhanced household level protection can be achieved if the ITNs and IRS have divergent yet complementary properties, e.g. highly deterrent IRS compounds coupled with highly toxic ITNs. To ensure that the problem of insecticide resistance is avoided, the ITNs and IRS products should preferably be of different insecticide classes, e.g. pyrethroid-based nets combined with organophosphate or carbamate based IRS. The overall community benefits would however depend also on other factors such as proportion of people covered by the interventions and the behaviour of vector species. This article concludes by emphasizing the need for basic and operational research, including mathematical modelling to evaluate IRS/ITN combinations in comparison to IRS alone or ITNs alone.

  20. The effectiveness of a nationwide universal coverage campaign of insecticide-treated bed nets on childhood malaria in Malawi.

    Science.gov (United States)

    Zamawe, Collins O F; Nakamura, Kanan; Shibanuma, Akira; Jimba, Masamine

    2016-10-18

    Although the universal coverage campaign of insecticide-treated mosquito bed nets (ITNs) has been associated with improved malaria outcomes, recent reports indicate that the campaign is losing its sparkle in some countries. In Malawi, the universal coverage campaign was implemented in 2012, but its impacts are yet to be ascertained. Thus, this study examined the effects of the campaign on malaria morbidity among children in Malawi. This is a repeated cross-sectional study. The study used nationally-representative malaria indicator survey (MIS) data collected in 2012 and 2014. In total, the analysis included 4193 children between the ages of 6 and 59 months (2171 from 2012 MIS and 2022 from 2014 MIS). ITNs coverage and malaria morbidity before (2012 = pre-test/control) and after (2014 = post-test/treated) the universal coverage campaign of ITNs were compared. The treated and control samples were matched on measured relevant covariates using propensity scores. The mean number of ITNs per household improved significantly from 1.1 (SD 1.0) in 2012 to 1.4 (SD 1.1) in 2014 (p universal coverage campaign of ITNs was not associated with a reduced burden of malaria among children in Malawi. This was likely due to increased insecticide resistance, inconsistent use of bed nets and under-utilization of other methods of malaria control. This calls for a multifaceted approach in the fight against malaria instead of simple dependence on ITNs. In particular, local or community level malaria interventions should go hand in hand with the universal coverage campaign.

  1. Factors Associated with Sustained Use of Long-Lasting Insecticide-Treated Nets Following a Reduction in Malaria Transmission in Southern Zambia.

    Science.gov (United States)

    Pinchoff, Jessie; Hamapumbu, Harry; Kobayashi, Tamaki; Simubali, Limonty; Stevenson, Jennifer C; Norris, Douglas E; Colantuoni, Elizabeth; Thuma, Philip E; Moss, William J

    2015-11-01

    Understanding factors influencing sustained use of long-lasting insecticide-treated nets (LLIN) in areas of declining malaria transmission is critical to sustaining control and may facilitate elimination. From 2008 to 2013, 655 households in Choma District, Zambia, were randomly selected and residents were administered a questionnaire and malaria rapid diagnostic test. Mosquitoes were collected concurrently by light trap. In a multilevel model, children and adolescents of 5-17 years of age were 55% less likely to sleep under LLIN than adults (odds ratio [OR] = 0.45; 95% confidence interval [CI] = 0.35, 0.58). LLIN use was 80% higher during the rainy season (OR = 1.8; CI = 1.5, 2.2) and residents of households with three or more nets were over twice as likely to use a LLIN (OR = 2.1; CI = 1.4, 3.1). For every increase in 0.5 km from the nearest health center, the odds of LLIN use decreased 9% (OR = 0.9; CI = 0.88, 0.98). In a second multilevel model, the odds of LLIN use were more than twice high if more than five mosquitoes (anopheline and culicine) were captured in the house compared with households with no mosquitoes captured (OR = 2.1; CI = 1.1, 3.9). LLIN use can be sustained in low-transmission settings with continued education and distributions, and may be partially driven by the presence of nuisance mosquitoes.

  2. Behavioral Differentiation Induced by Insecticide Lambda-Cyhalothrin in Mosquito Fish, Gambusia affinis

    Directory of Open Access Journals (Sweden)

    Utku GÜNER

    2016-04-01

    Full Text Available Test toxic material, one of most used pesticide, the Lambda cyhalothrin (LCY (TEKVANDO 5EC belongs to a group of chemicals called synthetic pyrethroids and pesticides and potential toxic pollutant contaminating aquatic ecosystems, was investigated in the present study for behavioral toxicology. Mosquito fish, Gambusia affinis (Baird & Girard, 1853 were selected for responses of Lambda cyhalothrin by Using to video-based movement analysis system. Selected 3 different doses 0.1, 0.5 and 0.75 ppm were used analyzed behavioral changes according to control group. The following behaviors were measured: total distance, travelled and average speed for treatment and control groups, maximum and average speed and time moving away from the dose applied point. This suggests that LCY contamination has the potential to significantly affect (p<0.05 the behavior of Mosquito fish, G. affinis.

  3. Environmental Fate Model for Ultra-Low-Volume Insecticide Applications Used for Adult Mosquito Management

    Science.gov (United States)

    2012-01-01

    drift hazard (Hewitt, 2008; Teske et al., 2000). Little is currently known about the deposition and drift of small droplets such as those used during...ULV applications for adult mosquito management ( Teske et al., 2000). Droplets smaller than 50 μm have very low settling velocities, and have similar...risk and regulatory assessments have used models like ISCST3, AgDrift® (Stewart Agricultural Research Services, Macon, MO, USA) ( Teske et al., 2002), and

  4. 蚊虫抗药性分子机制研究进展%Advances in the molecular mechanisms of mosquito resistance to insecticides

    Institute of Scientific and Technical Information of China (English)

    刘宏美; 代玉华; 公茂庆

    2012-01-01

    蚊虫是重要的医学昆虫,可以通过叮咬传播疾病(例如疟疾、丝虫病、登革热等),其行为与人类生活息息相关.由于长久以来大量、广泛地使用杀虫剂,使蚊虫抗性日益严重.蚊虫的抗性机制主要有靶标抗性(包括神经轴突钠离子通道、乙酰胆碱酯酶和γ-氨基丁酸受体氯离子通道的突变)和代谢抗性(包括非特异性羧酸酯酶、细胞色素P450和谷胱甘肽-S-转移酶的活性增加)两方面.现对这些机制的研究进展进行综述,试图全面了解大量、广泛使用杀虫剂之后蚊虫抗性产生的分子机制.%Mosquitoes, which act as important medical insects, can transmit diseases such as malaria, fiariasis and dengue fever, etc. by bites, being harmful to humans. For a long period of time, due to the extensive use of chemical insecticides, the insecticide resistance in mosquitoes is becoming more and more serious. The mechanisms of resistance can be classified into two groups, knockdown resistance (such as saltations in sodium channel, Acetylcholinesterase and 7-aminobutyric acid) and metabolic resistance (such as augmentations in carboxylesterase, cytochrome P450 and glutathione-S-transferase). In this article, recent research advances in the resistance of mosquitoes to chemical insecticides are reviewed for better understanding of the molecular mechanism of mosquito resistance to the extensively used chemical insecticides.

  5. Efficacy of Two Common Methods of Application of Residual Insecticide for Controlling the Asian Tiger Mosquito, Aedes albopictus (Skuse, in Urban Areas.

    Directory of Open Access Journals (Sweden)

    Lorenzo Marini

    Full Text Available After its first introduction in the 1980's the Asian tiger mosquito, Aedes albopictus (Skuse, has spread throughout Southern Europe. Ae. albopictus is considered an epidemiologically important vector for the transmission of many viral pathogens such as the yellow fever virus, dengue fever and Chikungunya fever, as well as several filarial nematodes such as Dirofilaria immitis or D. repens. It is therefore crucial to develop measures to reduce the risks of disease transmission by controlling the vector populations. The aim of the study was to compare the efficacy of two application techniques (mist vs. stretcher sprayer and two insecticides (Etox based on the nonester pyrethroid Etofenprox vs. Microsin based on the pyrethroid type II Cypermetrin in controlling adult tiger mosquito populations in highly populated areas. To test the effect of the two treatments pre- and post-treatment human landing rate counts were conducted for two years. After one day from the treatment we observed a 100% population decrease in mosquito abundance with both application methods and both insecticides. However, seven and 14 days after the application the stretcher sprayer showed larger population reductions than the mist sprayer. No effect of insecticide type after one day and 14 days was found, while Etox caused slightly higher population reduction than Microsin after seven days. Emergency measures to locally reduce the vector populations should adopt adulticide treatments using stretcher sprayers. However, more research is still needed to evaluate the potential negative effects of adulticide applications on non-target organisms.

  6. Identification of chemical constituents of Zanthoxylum heitzii stem bark and their insecticidal activity against the malaria mosquito Anopheles gambiae.

    Science.gov (United States)

    Moussavi, Nastaran; Malterud, Karl Egil; Mikolo, Bertin; Dawes, Dag; Chandre, Fabrice; Corbel, Vincent; Massamba, Daniel; Overgaard, Hans J; Wangensteen, Helle

    2015-10-01

    Zanthoxylum heitzii bark extracts have insecticidal properties and have been reported to be used against malaria in Western Africa. Previously, it has been shown that a hexane extract of the bark is toxic to adult females of the mosquito Anopheles gambiae, a malaria vector. As part of our project on the control of malaria vectors using plant extracts, the phytochemistry of Z. heitzii bark hexane extract has been investigated with the aim to identify the major components with adulticidal and larvicidal effects on An. gambiae. Z. heitzii stem bark was extracted with hexane, and the extract was fractionated to isolate major components from the bark, identified by NMR spectroscopy. Isolated compounds were tested for toxicity towards adult female An. gambiae mosquitoes and for larvicidal effects towards An. gambiae. The alkaloid dihydronitidine, the sesquiterpenoid caryophyllene oxide, the amide pellitorine and the lignan sesamin were identified as the major constituents in Z. heitzii bark. Pellitorine was toxic to both adult insects (LD50 50 ng/mg insect) and larvae (LD50 13 μg/ml). None of the other compounds were toxic to adults, but caryophyllene oxide and sesamin exhibited moderate larvicidal effects (LD50 > 150 μg/ml). A mixture of the four compounds in the same ratio as in the hexane extract showed higher toxicity (LD50 34 ng/mg insect) towards adult insects than the pure compounds. The toxicity of Z. heitzii bark hexane extract to An. gambiae is mostly due to pellitorine, although interactions between pellitorine and other, inactive constituents may enhance the activity of the extract.

  7. [Prospects for treating mosquito-borne flavivirus encephalitides].

    Science.gov (United States)

    Platonov, A E; Karan', L S; Vengerov, Iu Ia; Galimzianov, Kh M

    2009-01-01

    The Japanese encephalitis virus and West Nile virus belong to the family Flaviviridae, genus Flavivirus; they have a similar transmission cycle, with birds serving as the natural vertebrate host and mosquitoes, primarily, Culex species, both serving as the enzootic vectors and infecting humans. These arboviruses have caused more human cases of severe neuroinvasive disease worldwide during the past decade than other mosquito-borne flaviviruses. The current data and concepts on the clinical manifestations, pathogenesis, diagnosis, and treatment of infections caused by West Nile virus and Japanese encephalitis virus, are considered. The need for developing innovative approaches to etiotropic therapy for West Nile fever and Japanese encephalitis is emphasized; these approaches should be based on the comprehensive insight and extensive studies of the pathogenesis of flaviviral infections.

  8. Effect of insecticide treated nets fence in protect- ing cattle against ...

    African Journals Online (AJOL)

    A field trial was carried out to assess the effect of insecticide treated net in pro- tecting cattle ... Tsetse flies invade vast areas of the fertile and well rain-fed lowlands of south- western ..... Taylor, D.B., Moon, R.D., and Mark, D.R., 2012. Economic ...

  9. Insecticide Treated Camouflage Sceening Reduces Sand Fly Numbers in Leishmania-Endemic Regions in Kenya

    Science.gov (United States)

    Current U.S. military operations in deserts face persistent threats from sand flies that transmit human Leishmania. In this study we investigated the efficacy of artificial barriers treated with residual insecticide to potentially reduce the risk of human infection from leishmaniasis by reducing the...

  10. Juvenile hormone (JH esterase of the mosquito Culex quinquefasciatus is not a target of the JH analog insecticide methoprene.

    Directory of Open Access Journals (Sweden)

    Shizuo G Kamita

    Full Text Available Juvenile hormones (JHs are essential sesquiterpenes that control insect development and reproduction. JH analog (JHA insecticides such as methoprene are compounds that mimic the structure and/or biological activity of JH. In this study we obtained a full-length cDNA, cqjhe, from the southern house mosquito Culex quinquefasciatus that encodes CqJHE, an esterase that selectively metabolizes JH. Unlike other recombinant esterases that have been identified from dipteran insects, CqJHE hydrolyzed JH with specificity constant (k(cat/K(M ratio and V(max values that are common among JH esterases (JHEs. CqJHE showed picomolar sensitivity to OTFP, a JHE-selective inhibitor, but more than 1000-fold lower sensitivity to DFP, a general esterase inhibitor. To our surprise, CqJHE did not metabolize the isopropyl ester of methoprene even when 25 pmol of methoprene was incubated with an amount of CqJHE that was sufficient to hydrolyze 7,200 pmol of JH to JH acid under the same assay conditions. In competition assays in which both JH and methoprene were available to CqJHE, methoprene did not show any inhibitory effects on the JH hydrolysis rate even when methoprene was present in the assay at a 10-fold higher concentration relative to JH. Our findings indicated that JHE is not a molecular target of methoprene. Our findings also do not support the hypothesis that methoprene functions in part by inhibiting the action of JHE.

  11. 蚊虫抗药性分子机制研究进展%Progress in molecular mechanisms of mosquito resistance to insecticides

    Institute of Scientific and Technical Information of China (English)

    史琦琪; 程鹏; 公茂庆

    2016-01-01

    蚊虫抗药性机制的研究对抗药性监测、治理及新的卫生杀虫剂研制具有重要意义。现已对与蚊虫杀虫剂抗性的相关行为、生理代谢活动及作用靶标等进行了全面研究。目前证实蚊虫抗药性与行为、生理功能改变、解毒功能增强和靶标不敏感性等有关。近年来,随着分子生物学、基因组学以及遗传学的发展,蚊虫抗药性的分子机制有了新的研究进展,已发现并克隆了一些靶标基因,与抗药性相关的基因突变也得到普遍验证。该文综述了蚊虫的抗药性机制在分子生物学水平的研究进展,重点阐述了与蚊虫抗药性相关基因的扩增、表达及基因结构的改变等。%Studies on the mechanisms of insecticide resistance is very important to develop effective strategies for monitoring and managing insecticide resistance as well as new pesticide research. In the past several decades, a great deal of studies on insecticide resistance mechanisms, such as behavior, physiological function, metabolic action and target⁃site have been reported. It has been proven correct that mechanisms of insecticide resistance were confirmed by changed behavior, modified physiological function, enhanced detoxification and target⁃site insensitivity. Recently, with the development of the molecular biology, insect genomes and genetics, the molecular mechanism of insect resistance has been elucidated to much greater details. Some target genes have been identified and cloned in many mosquitoes. Some insecticide resistance related mutations have been screened out in some mosquitoes. This paper reviewed the progress in molecular mechanisms of mosquito resistance to insecticides. The alterations in genes related to insecticide resistance including amplification, over⁃expression and structure change were introduced in details.

  12. Evaluation of indoor residual spraying with the pyrrole insecticide chlorfenapyr against pyrethroid-susceptible Anopheles arabiensis and pyrethroid-resistant Culex quinquefasciatus mosquitoes.

    Science.gov (United States)

    Oxborough, R M; Kitau, J; Matowo, J; Mndeme, R; Feston, E; Boko, P; Odjo, A; Metonnou, C G; Irish, S; N'guessan, R; Mosha, F W; Rowland, M W

    2010-10-01

    Chlorfenapyr is a pyrrole insecticide with a unique non-neurological mode of action. Laboratory bioassays of chlorfenapyr comparing the mortality of pyrethroid-susceptible and -resistant Anopheles gambiae s.s. and Culex quinquefasciatus mosquitoes indicated that operational cross-resistance is unlikely to occur (resistance ratio ranged between 0 and 2.1). Three trials of chlorfenapyr indoor residual spraying were undertaken in experimental huts in an area of rice irrigation in northern Tanzania that supports breeding of A. arabiensis. Daily mosquito collections were undertaken to assess product performance primarily in terms of mortality. In the second trial, 250mg/m(2) and 500mg/m(2) chlorfenapyr were tested for residual efficacy over 6 months. Both dosages killed 54% of C. quinquefasciatus, whilst for A. arabiensis 250mg/m(2) killed 48% compared with 41% for 500mg/m(2); mortality was as high at the end of the trial as at the beginning. In the third trial, 250mg/m(2) chlorfenapyr was compared with the pyrethroid alpha-cypermethrin dosed at 30mg/m(2). Chlorfenapyr performance was equivalent to the pyrethroid against A. arabiensis, with both insecticides killing 50% of mosquitoes. Chlorfenapyr killed a significantly higher proportion of pyrethroid-resistant C. quinquefasciatus (56%) compared with alpha-cypermethrin (17%). Chlorfenapyr has the potential to be an important addition to the limited arsenal of public health insecticides for indoor residual control of A. arabiensis and pyrethroid-resistant species of mosquito. Copyright © 2010 Royal Society of Tropical Medicine and Hygiene.

  13. 传疟按蚊抗药性研究进展%Research advance on insecticide resistance of malaria vector mosquito Anopheles

    Institute of Scientific and Technical Information of China (English)

    秦茜; 闫桂云; 陈晓光

    2014-01-01

    In May 2010,the Ministry of Health and Chinese Government issued Action Plan of China Malaria Elimination (2010-2020),aiming at complete elimination of malaria in P.R.China by 2020.Vector control is a fundamental element of the existing global strategy to fight malaria.Anopheles is the main malaria vector mosquito.However,rapidly increasing insecticide resistance of mosquitoes threatens current malaria vector control efforts.In order to understand current status of mosquito resistance to insecticide and resistance mechanisms of the malaria vector,the current status of insecticide resistance in malaria vector mosquito Anopheles,the resistance mechanisms and the detection methods on resistance were reviewed in this paper.%我国卫生部于2010年5月印发《中国消除疟疾行动计划(2010-2020年)》,提出在2020年,将全面彻底消除疟疾.控制及消除疟疾的关键在于传播媒介的控制,而按蚊为疟疾主要传播媒介,传疟媒介对杀虫剂的抗药性直接导致了疟疾发病的死灰复燃.为了全面了解疟疾蚊媒的抗药性现状和产生机制,该文对国内外传疟按蚊抗药性现状、产生机制和检测方法进行综述.

  14. Long-term field performance of a polyester-based long-lasting insecticidal mosquito net in rural Uganda

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    Atieli Francis

    2008-03-01

    Full Text Available Abstract Background In order to evaluate whether criteria for LLIN field performance (phase III set by the WHO Pesticide Evaluation Scheme are met, first and second generations of one of these products, PermaNet®, a polyester net using the coating technology were tested. Methods A randomized, double blinded study design was used comparing LLIN to conventionally treated nets and following LLIN for three years under regular household use in rural conditions. Primary outcome measures were deltamethrin residue and bioassay performance (60 minute knock-down and 24 hour mortality after a three minute exposure using a strain of Anopheles gambiae s.s. sensitive to pyrethroid insecticides. Results Baseline concentration of deltamethrin was within targets for all net types but was rapidly lost in conventionally treated nets and first generation PermaNet® with median of 0.7 and 2.5 mg/m2 after six months respectively. In contrast, second generation PermaNet® retained insecticide well and had 41.5% of baseline dose after 36 months (28.7 mg/m2. Similarly, vector mortality and knockdown dropped to 18% and 70% respectively for first generation LLIN after six months but remained high (88.5% and 97.8% respectively for second generation PermaNet® after 36 months of follow up at which time 90.0% of nets had either a knockdown rate ≥ 95% or mortality rate ≥ 80%. Conclusion Second generation PermaNet® showed excellent results after three years of field use and fulfilled the WHOPES criteria for LLIN. Loss of insecticide on LLIN using coating technology under field conditions was far more influenced by factors associated with handling rather than washing.

  15. Insecticidal potency of Aspergillus terreus against larvae and pupae of three mosquito species Anopheles stephensi, Culex quinquefasciatus, and Aedes aegypti.

    Science.gov (United States)

    Ragavendran, Chinnasamy; Natarajan, Devarajan

    2015-11-01

    Microbial control agents offer alternatives to chemical pest control, as they can be more selective than chemical insecticides. The present study evaluates the mosquito larvicidal and pupicidal potential of fungus mycelia using ethyl acetate and methanol solvent extracts produced by Aspergillus terreus against Anopheles stephensi, Culex quinquefasciatus, and Aedes aegypti. The A. terreus mycelia were extracted after 15 days from Sabouraud dextrose broth medium. The ethyl acetate extracts showed lethal concentration that kills 50% of the exposed larvae (LC50) and lethal concentration that kills 90% of the exposed larvae (LC90) values of the first, second, third, and fourth instar larvae of An. stephensi (LC50 = 97.410, 102.551, 29.802, and 8.907; LC90 = 767.957, 552.546, 535.474, and 195.677 μg/ml), Cx. quinquefasciatus (LC50 = 89.584, 74.689, 68.265, and 67.40; LC90 = 449.091, 337.355, 518.793, and 237.347 μg/ml), and Ae. aegypti (LC50 = 83.541, 84.418, 80.407, and 95.926; LC90 = 515.464, 443.167, 387.910, and 473.998 μg/ml). Pupicidal activity of mycelium extracts was tested against An. stephensi (LC50 = 25.228, LC90 = 140.487), Cx. quinquefasciatus (LC50 = 54.525, LC90 = 145.366), and Ae. aegypti (LC50 = 10.536, LC90 = 63.762 μg/ml). At higher concentration (500 μg/ml), mortality starts within the first 6 h of exposure. One hundred percent mortality occurs at 24-h exposure. The overall result observed that effective activity against selected mosquito larvae and pupae after 24 h was a dose and time-dependent activity. These ensure that the resultant mosquito population reduction is substantial even where the larvicidal and pupicidal potential is minimal. The FTIR spectra of ethyl acetate extract reflect prominent peaks (3448.32, 3000.36, 2914.59, 2118.73, 1668.21, 1436.87, 1409.02, 954.33, 901.13, and 704.67 cm(-1)). The spectra showed a sharp absorption band at 1314.66 cm(-1) assigned to wagging vibration of

  16. A single crossing-over event in voltage-sensitive Na+ channel genes may cause critical failure of dengue mosquito control by insecticides.

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    Koichi Hirata

    2014-08-01

    Full Text Available The voltage-sensitive sodium (Na+ channel (Vssc is the target site of pyrethroid insecticides. Pest insects develop resistance to this class of insecticide by acquisition of one or multiple amino acid substitution(s in this channel. In Southeast Asia, two major Vssc types confer pyrethroid resistance in the dengue mosquito vector Aedes aegypti, namely, S989P+V1016G and F1534C. We expressed several types of Vssc in Xenopus oocytes and examined the effect of amino acid substitutions in Vssc on pyrethroid susceptibilities. S989P+V1016G and F1534C haplotypes reduced the channel sensitivity to permethrin by 100- and 25-fold, respectively, while S989P+V1016G+F1534C triple mutations reduced the channel sensitivity to permethrin by 1100-fold. S989P+V1016G and F1534C haplotypes reduced the channel sensitivity to deltamethrin by 10- and 1-fold (no reduction, respectively, but S989P+V1016G+F1534C triple mutations reduced the channel sensitivity to deltamethrin by 90-fold. These results imply that pyrethroid insecticides are highly likely to lose their effectiveness against A. aegypti if such a Vssc haplotype emerges as the result of a single crossing-over event; thus, this may cause failure to control this key mosquito vector. Here, we strongly emphasize the importance of monitoring the occurrence of triple mutations in Vssc in the field population of A. aegypti.

  17. Analysis of population structure and insecticide resistance in mosquitoes of the genus Culex, Anopheles and Aedes from different environments of Greece with a history of mosquito borne disease transmission.

    Science.gov (United States)

    Fotakis, Emmanouil A; Chaskopoulou, Alexandra; Grigoraki, Linda; Tsiamantas, Alexandros; Kounadi, Stella; Georgiou, Loukas; Vontas, John

    2017-10-01

    Greece has been recently affected by several mosquito borne diseases with the West Nile Virus (WNV) outbreak in 2010 being one of the largest reported in Europe. Currently at the epicenter of an economic and refugee crisis and visited by over 16 million tourists a year the integrated management of diseases transmitted by mosquitoes is a public health and economic priority. Vector control programs rely mainly on insecticides, however data on insecticide resistance and the mosquito fauna is essential for successful applications. We determined the mosquito species composition and population dynamics in areas of increased vulnerability to vector borne disease transmission, as well as investigated the resistance status of major nuisance and disease vectors to insecticides. High mosquito densities were recorded in Thessaloniki and Evros, with Aedes caspius, a nuisance species, Culex pipiens, a known vector of WNV and Anopheles hyrcanus a potential vector of malaria being among the most prevalent species. Both vector species populations reached their peak in late summer. Aedes albopictus was recorded at high densities in Thessaloniki, but not in Evros. Notably, Cx. pipiens hybrids, which show an opportunistic biting behavior and are suspected to be involved in the transmission of the WNV, were recorded in considerable numbers in Thessaloniki and Attica. Culex pipiens and An. hyrcanus, but not Ae. caspius mosquitoes, showed moderate levels of resistance to deltamethrin. The presence of resistance in areas not exposed to vector control indicates that other factors could be selecting for resistance, i.e. pesticide applications for agriculture. Both L1014F and L101C kdr mutations were detected in Cx. pipiens populations. Anopheles hyrcanus resistance was not associated with mutations at the L1014 site. The Ace-1 mutations conferring insensitivity to organophosphates and carbamates were detected at low frequencies in all Cx. pipiens populations. Increased activity of P450s and

  18. CYP6 P450 enzymes and ACE-1 duplication produce extreme and multiple insecticide resistance in the malaria mosquito Anopheles gambiae.

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    Constant V Edi

    2014-03-01

    Full Text Available Malaria control relies heavily on pyrethroid insecticides, to which susceptibility is declining in Anopheles mosquitoes. To combat pyrethroid resistance, application of alternative insecticides is advocated for indoor residual spraying (IRS, and carbamates are increasingly important. Emergence of a very strong carbamate resistance phenotype in Anopheles gambiae from Tiassalé, Côte d'Ivoire, West Africa, is therefore a potentially major operational challenge, particularly because these malaria vectors now exhibit resistance to multiple insecticide classes. We investigated the genetic basis of resistance to the most commonly-applied carbamate, bendiocarb, in An. gambiae from Tiassalé. Geographically-replicated whole genome microarray experiments identified elevated P450 enzyme expression as associated with bendiocarb resistance, most notably genes from the CYP6 subfamily. P450s were further implicated in resistance phenotypes by induction of significantly elevated mortality to bendiocarb by the synergist piperonyl butoxide (PBO, which also enhanced the action of pyrethroids and an organophosphate. CYP6P3 and especially CYP6M2 produced bendiocarb resistance via transgenic expression in Drosophila in addition to pyrethroid resistance for both genes, and DDT resistance for CYP6M2 expression. CYP6M2 can thus cause resistance to three distinct classes of insecticide although the biochemical mechanism for carbamates is unclear because, in contrast to CYP6P3, recombinant CYP6M2 did not metabolise bendiocarb in vitro. Strongly bendiocarb resistant mosquitoes also displayed elevated expression of the acetylcholinesterase ACE-1 gene, arising at least in part from gene duplication, which confers a survival advantage to carriers of additional copies of resistant ACE-1 G119S alleles. Our results are alarming for vector-based malaria control. Extreme carbamate resistance in Tiassalé An. gambiae results from coupling of over-expressed target site allelic

  19. CYP6 P450 enzymes and ACE-1 duplication produce extreme and multiple insecticide resistance in the malaria mosquito Anopheles gambiae.

    Science.gov (United States)

    Edi, Constant V; Djogbénou, Luc; Jenkins, Adam M; Regna, Kimberly; Muskavitch, Marc A T; Poupardin, Rodolphe; Jones, Christopher M; Essandoh, John; Kétoh, Guillaume K; Paine, Mark J I; Koudou, Benjamin G; Donnelly, Martin J; Ranson, Hilary; Weetman, David

    2014-03-01

    Malaria control relies heavily on pyrethroid insecticides, to which susceptibility is declining in Anopheles mosquitoes. To combat pyrethroid resistance, application of alternative insecticides is advocated for indoor residual spraying (IRS), and carbamates are increasingly important. Emergence of a very strong carbamate resistance phenotype in Anopheles gambiae from Tiassalé, Côte d'Ivoire, West Africa, is therefore a potentially major operational challenge, particularly because these malaria vectors now exhibit resistance to multiple insecticide classes. We investigated the genetic basis of resistance to the most commonly-applied carbamate, bendiocarb, in An. gambiae from Tiassalé. Geographically-replicated whole genome microarray experiments identified elevated P450 enzyme expression as associated with bendiocarb resistance, most notably genes from the CYP6 subfamily. P450s were further implicated in resistance phenotypes by induction of significantly elevated mortality to bendiocarb by the synergist piperonyl butoxide (PBO), which also enhanced the action of pyrethroids and an organophosphate. CYP6P3 and especially CYP6M2 produced bendiocarb resistance via transgenic expression in Drosophila in addition to pyrethroid resistance for both genes, and DDT resistance for CYP6M2 expression. CYP6M2 can thus cause resistance to three distinct classes of insecticide although the biochemical mechanism for carbamates is unclear because, in contrast to CYP6P3, recombinant CYP6M2 did not metabolise bendiocarb in vitro. Strongly bendiocarb resistant mosquitoes also displayed elevated expression of the acetylcholinesterase ACE-1 gene, arising at least in part from gene duplication, which confers a survival advantage to carriers of additional copies of resistant ACE-1 G119S alleles. Our results are alarming for vector-based malaria control. Extreme carbamate resistance in Tiassalé An. gambiae results from coupling of over-expressed target site allelic variants with

  20. Characterization of Bacillus thuringiensis soil isolates from Cuba, with insecticidal activity against mosquitoes.

    Science.gov (United States)

    González, Aileen; Díaz, Raúl; Díaz, Manuel; Borrero, Yainais; Bruzón, Rosa Y; Carreras, Bertha; Gato, René

    2011-09-01

    Chemical insecticides may be toxic and cause environmental degradation. Consequently, biological control for insects represents an alternative with low ecological impact. In this work, three soil isolates (A21, A51 and C17) from different regions of the Cuban archipelago were identified, characterized and evaluated against Aedes aegypti and Culex quinquefasciatus. The new isolates were compared with reference IPS82 strain and two strains isolated from biolarvicides Bactivec and Bactoculicida, respectively. The differentiation was done by morphological, biochemical, bioassays activity and molecular methods (SDS-PAGE, plasmid profile and random amplified polymorphic analysis). All isolates were identified as Bacillus thuringiensis. The A21, A51 and C17 isolates showed higher larvicide activity than Bactivec's isolated reference strain, against both A. aegypti and C. quinquefasciatus. A21 isolate had a protein profile similar to IPS82 and Bactivec strain. A51 and C17 isolates produced a characteristic proteins pattern. A21 and A51 isolates had plasmid patterns similar to IPS82 standard strain, while C17 isolate had different both plasmid profile and protein bands. All the studied isolates showed a diverse RAPD patterns and were different from the strains previously used in biological control in Cuba.

  1. Characterization of Bacillus thuringiensis soil isolates from Cuba, with insecticidal activity against mosquitoes

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    Aileen González

    2011-09-01

    Full Text Available Chemical insecticides may be toxic and cause environmental degradation. Consequently, biological control for insects represents an alternative with low ecological impact. In this work, three soil isolates (A21, A51 and C17 from different regions of the Cuban archipelago were identified, characterized and evaluated against Aedes aegypti and Culex quinquefasciatus. The new isolates were compared with reference IPS82 strain and two strains isolated from biolarvicides Bactivec and Bactoculicida, respectively. The differentiation was done by morphological, biochemical, bioassays activity and molecular methods (SDS-PAGE, plasmid profile and random amplified polymorphic analysis. All isolates were identified as Bacillus thuringiensis. The A21, A51 and C17 isolates showed higher larvicide activity than Bactivec’s isolated reference strain, against both A. aegypti and C. quinquefasciatus. A21 isolate had a protein profile similar to IPS82 and Bactivec strain. A51 and C17 isolates produced a characteristic proteins pattern. A21 and A51 isolates had plasmid patterns similar to IPS82 standard strain, while C17 isolate had different both plasmid profile and protein bands. All the studied isolates showed a diverse RAPD patterns and were different from the strains previously used in biological control in Cuba. Rev. Biol. Trop. 59 (3: 1007-1016. Epub 2011 September 01.

  2. Mosquitocidal properties of Calotropis gigantea (Family: Asclepiadaceae) leaf extract and bacterial insecticide, Bacillus thuringiensis, against the mosquito vectors.

    Science.gov (United States)

    Kovendan, Kalimuthu; Murugan, Kadarkarai; Prasanna Kumar, Kanagarajan; Panneerselvam, Chellasamy; Mahesh Kumar, Palanisamy; Amerasan, Duraisamy; Subramaniam, Jayapal; Vincent, Savariar

    2012-08-01

    Calotropis gigantea leaf extract and Bacillus thuringiensis were tested first to fourth-instar larvae and pupae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The medicinal plants were collected from the area around Bharathiar University, Coimbatore, India. Calotropis gigantea leaf was washed with tap water and shade-dried at room temperature. An electrical blender powdered the dried plant materials (leaves). The powder 500 g of the leaf was extracted with 1.5 L of organic solvents of methanol for 8 h using a Soxhlet apparatus and filtered. The crude leaf extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal and pupicidal effects after 24 h of exposure; no mortality was observed in the control group. For Calotropis gigantea, the median lethal concentration values (LC(50)) observed for the larvicidal and pupicidal activities against mosquito vector species Anopheles stephensi I to IV larval instars and pupae were 73.77, 89.64, 121.69, 155.49, and 213.79 ppm; Aedes aegypti values were 92.27, 106.60, 136.48, 164.01, and 202.56 ppm; and Culex quinquefasciatus values were 104.66, 127.71, 173.75, 251.65, and 314.70 ppm, respectively. For B. thuringiensis, the LC(50) values of I to IV larval instars and pupae of Anopheles stephensi were 37.24, 45.41, 57.82, 80.09, and 98.34 ppm; Aedes aegypti values were 42.38, 51.90, 71.02, 96.17, and 121.59 ppm; and Culex quinquefasciatus values were 55.85, 68.07, 94.11, 113.35, and 133.87 ppm, respectively. The study proved that the methanol leaf extract of Calotropis gigantea and bacterial insecticide B. thuringiensis has mosquitocidal property and was evaluated as target species of mosquito vectors. This is an ideal ecofriendly approach for the control of vector control programs.

  3. Increasing coverage of insecticide-treated nets in rural Nigeria: implications of consumer knowledge, preferences and expenditures for malaria prevention

    Science.gov (United States)

    Onwujekwe, Obinna; Uzochukwu, Benjamin; Ezumah, Nkoli; Shu, Elvis

    2005-01-01

    Background The coverage of insecticide-treated nets (ITNs) remains low despite existing distribution strategies, hence, it was important to assess consumers' preferences for distribution of ITNs, as well as their perceptions and expenditures for malaria prevention and to examine the implications for scaling-up ITNs in rural Nigeria. Methods Nine focus group discussions (FGDs) and questionnaires to 798 respondents from three malaria hyper-endemic villages from Enugu state, south-east Nigeria were the study tools. Results There was a broad spectrum of malaria preventive tools being used by people. The average monthly expenditure on malaria prevention per household was 55.55 Naira ($0.4). More than 80% of the respondent had never purchased any form of untreated mosquito net. People mostly preferred centralized community-based sales of the ITNS, with instalment payments. Conclusion People were knowledgeable about malaria and the beneficial effects of using nets to protect themselves from the disease. The mostly preferred community-based distribution of ITNs implies that the strategy is a potential untapped additional channel for scaling-up ITNs in Nigeria and possibly other parts of sub-Saharan Africa. PMID:16026623

  4. Increasing coverage of insecticide-treated nets in rural Nigeria: implications of consumer knowledge, preferences and expenditures for malaria prevention

    Directory of Open Access Journals (Sweden)

    Ezumah Nkoli

    2005-07-01

    Full Text Available Abstract Background The coverage of insecticide-treated nets (ITNs remains low despite existing distribution strategies, hence, it was important to assess consumers' preferences for distribution of ITNs, as well as their perceptions and expenditures for malaria prevention and to examine the implications for scaling-up ITNs in rural Nigeria. Methods Nine focus group discussions (FGDs and questionnaires to 798 respondents from three malaria hyper-endemic villages from Enugu state, south-east Nigeria were the study tools. Results There was a broad spectrum of malaria preventive tools being used by people. The average monthly expenditure on malaria prevention per household was 55.55 Naira ($0.4. More than 80% of the respondent had never purchased any form of untreated mosquito net. People mostly preferred centralized community-based sales of the ITNS, with instalment payments. Conclusion People were knowledgeable about malaria and the beneficial effects of using nets to protect themselves from the disease. The mostly preferred community-based distribution of ITNs implies that the strategy is a potential untapped additional channel for scaling-up ITNs in Nigeria and possibly other parts of sub-Saharan Africa.

  5. Determinants of Ownership and Utilization of Insecticide-Treated Bed Nets for Malaria Control in Eastern Ethiopia

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    Sibhatu Biadgilign

    2012-01-01

    Full Text Available Background. Malaria remains a major cause of mortality and morbidity in the world, and particularly in sub-Saharan Africa. Objectives. The aim of this study was to determine ownership and utilization of ITNs among households with children under five in the previous night. Methods. A community based cross-sectional study was conducted in Gursum district in Eastern Ethiopia. A total of 335 households were surveyed using a pretested structured questionnaire administered though house-to-house interviews. Results. Household ownership for at least one mosquito net and use of nets were 62.4% (95% CI 57.2–67.6% and 21.5% (95% CI 17.1–25.9%, respectively. Households who received or were told about ITN in the last 6 months were three times more likely to have used it than those who were not (OR 3.25; 95% CI 1.5–7.10. Households whose heads were engaged as a farmer (adjusted OR 0.137; 95% CI: 0.04–0.50 and housewife (OR 0.26; 95% CI: 0.08–0.82 were less likely to use ITN than those of other occupations. Conclusion. The findings indicate low ITN ownership and utilization among the households. Intensive health education and community mobilization effort should be employed to increase the possession and proper utilization of insecticide treated bed nets.

  6. Synergy between repellents and non-pyrethroid insecticides strongly extends the efficacy of treated nets against Anopheles gambiae

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    N'Guessan Raphaël

    2007-03-01

    Full Text Available Abstract Background To manage the kdr pyrethroid-resistance in Anopheline malaria vectors, new compounds or new strategies are urgently needed. Recently, mixing repellents (DEET and a non-pyrethroid insecticide (propoxur was shown to be as effective as deltamethrin, a standard pyrethroid, under laboratory conditions, because of a strong synergy between the two compounds. In the present study, the interactions between two repellents (DEET and KBR 3023 and a non-pyrethroid insecticide (pyrimiphos methyl or PM on netting were investigated. The residual efficacy and the inhibition of blood feeding conferred by these mixtures were assessed against Anopheles gambiae mosquitoes. Methods DEET and KBR 3023 were mixed with pyrimiphos methyl (PM, a organophosphate (OP insecticide. The performance of mono- and bi-impregnated nets against adult mosquitoes was assessed using a miniaturized, experimental hut system (laboratory tunnel tests that allows expression of behavioural responses to insecticide, particularly the mortality and blood feeding effects. Results Both mixtures (PM+DEET and PM+KBR3023 induced 95% mortality for more than two months compared with less than one week for each compound used alone, then reflecting a strong synergy between the repellents and PM. A similar trend was observed with the blood feeding rates, which were significantly lower for the mixtures than for each component alone. Conclusion Synergistic interactions between organophosphates and repellents may be of great interest for vector control as they may contribute to increase the residual life of impregnated materials and improve the control of pyrethroid-resistance mosquitoes. These results prompt the need to evaluate the efficacy of repellent/non-pyrethroid insecticide mixtures against field populations of An. gambiae showing high level of resistance to Ops and pyrethroids.

  7. Decreased motivation in the use of insecticide-treated nets in a malaria endemic area in Burkina Faso

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    Doannio Julien

    2009-07-01

    Full Text Available Abstract Background The use of insecticide-treated nets (ITN is an important tool in the Roll Back Malaria (RBM strategy. For ITNs to be effective they need to be used correctly. Previous studies have shown that many factors, such as wealth, access to health care, education, ethnicity and gender, determine the ownership and use of ITNs. Some studies showed that free distribution and public awareness campaigns increased the rate of use. However, there have been no evaluations of the short- and long-term impact of such motivation campaigns. A study carried out in a malaria endemic area in south-western Burkina Faso indicated that this increased use declined after several months. The reasons were a combination of the community representation of malaria, the perception of the effectiveness and usefulness of ITNs and also the manner in which households are organized by day and by night. Methods PermaNet 2.0® and Olyset® were distributed in 455 compounds at the beginning of the rainy season. The community was educated on the effectiveness of nets in reducing malaria and on how to use them. To assess motivation, qualitative tools were used: one hundred people were interviewed, two hundred houses were observed directly and two houses were monitored monthly throughout one year. Results The motivation for the use of bednets decreased after less than a year. Inhabitants' conception of malaria and the inconvenience of using bednets in small houses were the major reasons. Acceptance that ITNs were useful in reducing malaria was moderated by the fact that mosquitoes were considered to be only one of several factors which caused malaria. The appropriate and routine use of ITNs was adversely affected by the functional organization of the houses, which changed as between day and night. Bednets were not used when the perceived benefits of reduction in mosquito nuisance and of malaria were considered not to be worth the inconvenience of daily use. Conclusion In

  8. Bio-efficacy of new long-lasting insecticide-treated bed nets against Anopheles funestus and Anopheles gambiae from central and northern Mozambique.

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    Abílio, Ana Paula; Marrune, Pelágio; de Deus, Nilsa; Mbofana, Francisco; Muianga, Pedro; Kampango, Ayubo

    2015-09-17

    Long-lasting insecticide-treated nets (LLINs) are one of the main methods used for controlling malaria transmission in Mozambique. The proliferation of several types of LLINs and the re-emergence of insecticide resistance in the local vector populations poses challenges to the local malaria control programme on selecting suitable insecticide-based vector control products. Therefore, this study evaluated the insecticide susceptibility and bio-efficacy of selected new LLINs against wild populations of Anopheles funestus sensu lato and A. gambiae s.l. from Northern and Central Mozambique. The study also investigated whether the insecticide contents on the LINNs fabrics were within the WHOPES recommended target range. The susceptibility of 2-5 day old wild female A. funestus and A. gambiae sensu stricto against the major classes of insecticides used for vector control, viz: deltamethrin (0.05 %), permethrin (0.75 %), propoxur (0.1 %), bendiocarb (0.1 %) and DDT (4 %), was determined using WHO cylinder susceptibility tests. WHO cone bioassays were conducted to determine the bio-efficacy of both pyrethroid-only LLINs (Olyset(®), Permanet 2.0(®), NetProtect(®) and Interceptor(®)) and, Permanet 3.0(®) a combination LLIN against A. funestus s.s, from Balama, Mocuba and Milange districts, respectively. The bio-efficacy of LLINs against the insectary-susceptible A. arabiensis (Durban strain) was assessed, as well. Untreated bed net swatches were used as negative controls. Chemical analyses, by high performance liquid chromatography, were undertaken to assess whether the insecticide contents on the LLINs fabrics fell within recommended target dose ranges. The frequency of kdr gene mutations was determined from a random sample of A. gambiae s.s. from both WHO susceptibility and cone bioassay experiments. Anopheles funestus from Balama district showed resistance to deltamethrin and possible resistance to permethrin, propoxur and bendiocarb, whilst A. gambiae from

  9. Pyrethroid resistance in mosquitoes

    Institute of Scientific and Technical Information of China (English)

    NANNAN LIU; QIANG XU; FANG ZHU; LEE ZHANG

    2006-01-01

    Repeated blood feedings throughout their life span have made mosquitoes ideal transmitters of a wide variety of disease agents. Vector control is a very important part of the current global strategy for the control of mosquito-associated diseases and insecticide application is the most important component in this effort. Pyrethroids, which account for 25% of the world insecticide market, are currently the most widely used insecticides for the indoor control of mosquitoes and are the only chemical recommended for the treatment of mosquito nets, the main tool for preventing malaria in Africa. However, mosquito-borne diseases are now resurgent, largely because of insecticide resistance that has developed in mosquito vectors and the anti-parasite drug resistance of parasites. This paper reviews our current knowledge of the molecular mechanisms governing metabolic detoxification and the development of target site insensitivity that leads to pyrethroid resistance in mosquitoes.

  10. Effective control of dengue vectors with curtains and water container covers treated with insecticide in Mexico and Venezuela: cluster randomised trials

    Science.gov (United States)

    Kroeger, Axel; Lenhart, Audrey; Ochoa, Manuel; Villegas, Elci; Levy, Michael; Alexander, Neal; McCall, P J

    2006-01-01

    Objectives To measure the impact on the dengue vector population (Aedes aegypti) and disease transmission of window curtains and water container covers treated with insecticide. Design Cluster randomised controlled trial based on entomological surveys and, for Trujillo only, serological survey. In addition, each site had a non-randomised external control. Setting 18 urban sectors in Veracruz (Mexico) and 18 in Trujillo (Venezuela). Participants 4743 inhabitants (1095 houses) in Veracruz and 5306 inhabitants (1122 houses) in Trujillo. Intervention Sectors were paired according to entomological indices, and one sector in each pair was randomly allocated to receive treatment. In Veracruz, the intervention comprised curtains treated with lambdacyhalothrin and water treatment with pyriproxyfen chips (an insect growth regulator). In Trujillo, the intervention comprised curtains treated with longlasting deltamethrin (PermaNet) plus water jar covers of the same material. Follow-up surveys were conducted at intervals, with the final survey after 12 months in Veracruz and nine months in Trujillo. Main outcome measures Reduction in entomological indices, specifically the Breteau and house indices. Results In both study sites, indices at the end of the trial were significantly lower than those at baseline, though with no significant differences between control and intervention arms. The mean Breteau index dropped from 60% (intervention clusters) and 113% (control) to 7% (intervention) and 12% (control) in Veracruz and from 38% to 11% (intervention) and from 34% to 17% (control) in Trujillo. The pupae per person and container indices showed similar patterns. In contrast, in nearby communities not in the trial the entomological indices followed the rainfall pattern. The intervention reduced mosquito populations in neighbouring control clusters (spill-over effect); and houses closer to treated houses were less likely to have infestations than those further away. This created a

  11. The effectiveness of a nationwide universal coverage campaign of insecticide-treated bed nets on childhood malaria in Malawi

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    Collins O. F. Zamawe

    2016-10-01

    Full Text Available Abstract Background Although the universal coverage campaign of insecticide-treated mosquito bed nets (ITNs has been associated with improved malaria outcomes, recent reports indicate that the campaign is losing its sparkle in some countries. In Malawi, the universal coverage campaign was implemented in 2012, but its impacts are yet to be ascertained. Thus, this study examined the effects of the campaign on malaria morbidity among children in Malawi. Methods This is a repeated cross-sectional study. The study used nationally-representative malaria indicator survey (MIS data collected in 2012 and 2014. In total, the analysis included 4193 children between the ages of 6 and 59 months (2171 from 2012 MIS and 2022 from 2014 MIS. ITNs coverage and malaria morbidity before (2012 = pre-test/control and after (2014 = post-test/treated the universal coverage campaign of ITNs were compared. The treated and control samples were matched on measured relevant covariates using propensity scores. Results The mean number of ITNs per household improved significantly from 1.1 (SD 1.0 in 2012 to 1.4 (SD 1.1 in 2014 (p < 0.001. Nonetheless, the prevalence of malaria among children increased considerably from 27.7 % (2012 to 32.0 % (2014 (p = 0.002. The risk of malaria was also significantly higher in 2014 compared to 2012 (RR = 1.14; 95 % CI 1.01–1.29. Besides, the use of bed nets was not significantly associated with malaria morbidity in 2014 (RR = 0.92; 95 % CI 0.76–1.12, but it was in 2012 (RR = 0.83; 95 % CI 0.70–1.00. Conclusions The universal coverage campaign of ITNs was not associated with a reduced burden of malaria among children in Malawi. This was likely due to increased insecticide resistance, inconsistent use of bed nets and under-utilization of other methods of malaria control. This calls for a multifaceted approach in the fight against malaria instead of simple dependence on ITNs. In particular, local or community level

  12. Discovery of Rigidified α,β-Unsaturated Imines as New Resistance-breaking Insecticides for Malaria Vector Control.

    Science.gov (United States)

    Arlt, Alexander; Böhnke, Niels; Horstmann, Sebastian; Vermeer, Arnoldus W P; Werner, Stefan; Velten, Robert

    2016-10-01

    During our continuous search for new resistance-breaking insecticides applicable to malaria vector control, a new class of α,β-unsaturated imines was identified by applying the principle of conformational rigidification as a powerful tool for compound optimisation. Herein we describe the successful synthesis of these compounds and their biological test results. Our lead compound 16 from this insecticidal class outperforms market standards, notably for the control of mosquito strains that exhibit either metabolic or target-site resistance to these established insecticides. In our model system for insecticide-treated mosquito nets the compound reveals long-lasting efficacy for up to several months.

  13. Best practices for an insecticide-treated bed net distribution programme in sub-Saharan eastern Africa

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    Sexton Alexis R

    2011-06-01

    Full Text Available Abstract Insecticide-treated bed nets are the preeminent malaria control means; though there is no consensus as to a best practice for large-scale insecticide-treated bed net distribution. In order to determine the paramount distribution method, this review assessed literature on recent insecticide treated bed net distribution programmes throughout sub-Saharan Eastern Africa. Inclusion criteria were that the study had taken place in sub-Saharan Eastern Africa, targeted malaria prevention and control, and occurred between 1996 and 2007. Forty-two studies were identified and reviewed. The results indicate that distribution frameworks varied greatly; and consequently so did outcomes of insecticide-treated bed net use. Studies revealed consistent inequities between urban and rural populations; which were most effectively alleviated through a free insecticide-treated bed net delivery and distribution framework. However, cost sharing through subsidies was shown to increase programme sustainability, which may lead to more long-term coverage. Thus, distribution should employ a catch up/keep up programme strategy. The catch-up programme rapidly scales up coverage, while the keep-up programme maintains coverage levels. Future directions for malaria should include progress toward distribution of long-lasting insecticide-treated nets.

  14. The Field Practices of Lambdacyhalothrin and Deltamethrin Insecticides Against Adult Mosquitoes of Anopheles stephensi as the Main Vector of Malaria: Residual Effects

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    Mousa Khosravani

    2017-04-01

    Full Text Available Background Various chemical control methods have adopted in anti-malaria interventions. Indoor residual spraying (IRS has been proven as a candidate in elimination program. On the other hand, resistance to multiple insecticides was implicated as a concern issue in these polices. Pesticides should be evaluated to identify probable resistant and make decision to choose a technique against vectors. Methods In this cross-sectional study, Bioassay test applied on lambdacyhalothrin WP 10% (0.05 mg a.i. /m2 and deltamethrin WP 5% (0.05 mg a.i./m2 on two surfaces (cement and plaster against adult mosquitoes of Anopheles stephensi according to WHO criteria to measure the residual activity in Saravan county, southern Iran. Overall, 3960 mosquitoes was used in our research. The mortality rates of An.stephensi Liston (Diptera: Culicidae measured between selected surfaces and insecticides in several times. Data analyzed by Mann-Whitney (nonparametric test using SPSS v22 statistic software. Results This paper illustrated that maximal course of residual efficacy was about 3 months. No statistically significant different was exhibited between type of surface within mortality rates of An. Stephensi (P = 0.724 but lambdacyhalothrin has more durability than deltamethrin Conclusions We established that lambdacyhalothrin can be used into control and elimination setting of malaria with two rounds of spray at an interval of 3-4 months in south of Iran.

  15. Disrupting Mosquito Reproduction and Parasite Development for Malaria Control.

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    Lauren M Childs

    2016-12-01

    Full Text Available The control of mosquito populations with insecticide treated bed nets and indoor residual sprays remains the cornerstone of malaria reduction and elimination programs. In light of widespread insecticide resistance in mosquitoes, however, alternative strategies for reducing transmission by the mosquito vector are urgently needed, including the identification of safe compounds that affect vectorial capacity via mechanisms that differ from fast-acting insecticides. Here, we show that compounds targeting steroid hormone signaling disrupt multiple biological processes that are key to the ability of mosquitoes to transmit malaria. When an agonist of the steroid hormone 20-hydroxyecdysone (20E is applied to Anopheles gambiae females, which are the dominant malaria mosquito vector in Sub Saharan Africa, it substantially shortens lifespan, prevents insemination and egg production, and significantly blocks Plasmodium falciparum development, three components that are crucial to malaria transmission. Modeling the impact of these effects on Anopheles population dynamics and Plasmodium transmission predicts that disrupting steroid hormone signaling using 20E agonists would affect malaria transmission to a similar extent as insecticides. Manipulating 20E pathways therefore provides a powerful new approach to tackle malaria transmission by the mosquito vector, particularly in areas affected by the spread of insecticide resistance.

  16. Candidate genes revealed by a genome scan for mosquito resistance to a bacterial insecticide: sequence and gene expression variations

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    David Jean-Philippe

    2009-11-01

    Full Text Available Abstract Background Genome scans are becoming an increasingly popular approach to study the genetic basis of adaptation and speciation, but on their own, they are often helpless at identifying the specific gene(s or mutation(s targeted by selection. This shortcoming is hopefully bound to disappear in the near future, thanks to the wealth of new genomic resources that are currently being developed for many species. In this article, we provide a foretaste of this exciting new era by conducting a genome scan in the mosquito Aedes aegypti with the aim to look for candidate genes involved in resistance to Bacillus thuringiensis subsp. israelensis (Bti insecticidal toxins. Results The genome of a Bti-resistant and a Bti-susceptible strains was surveyed using about 500 MITE-based molecular markers, and the loci showing the highest inter-strain genetic differentiation were sequenced and mapped on the Aedes aegypti genome sequence. Several good candidate genes for Bti-resistance were identified in the vicinity of these highly differentiated markers. Two of them, coding for a cadherin and a leucine aminopeptidase, were further examined at the sequence and gene expression levels. In the resistant strain, the cadherin gene displayed patterns of nucleotide polymorphisms consistent with the action of positive selection (e.g. an excess of high compared to intermediate frequency mutations, as well as a significant under-expression compared to the susceptible strain. Conclusion Both sequence and gene expression analyses agree to suggest a role for positive selection in the evolution of this cadherin gene in the resistant strain. However, it is unlikely that resistance to Bti is conferred by this gene alone, and further investigation will be needed to characterize other genes significantly associated with Bti resistance in Ae. aegypti. Beyond these results, this article illustrates how genome scans can build on the body of new genomic information (here, full

  17. Wash durability and optimal drying regimen of four brands of long-lasting insecticide-treated nets after repeated washing under tropical conditions

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    Atieli Francis K

    2010-08-01

    Full Text Available Abstract Background The current study was undertaken to determine the optimal wash-drying regimen and the effects of different washing procedures on the efficacy, and durability of four brands of newly introduced long-lasting insecticide-treated nets (LLINs under tropical conditions. Methods In the current study, the following four LLINs were tested: Olyset®, PermaNet ®2.0, BASF® and TNT®. Nets were divided into three sets; one set was washed by hand rubbing and air-dried either hanging or spread on the ground in direct sunlight or hanging or spread on the ground under the shade. A second set was washed using the WHO protocol (machine and the third set was washed by beating the nets on rocks. The biological activities of the nets were assessed by a three-minute bioassay cone test and the residual insecticide contents were determined using high performance liquid chromatography (HPLC procedure. Results Nets that were dried hanging under the shade retained more insecticide, 62.5% and recorded higher mortality compared to nets which were dried lying on the ground in direct sunlight 58.8%, nets dried under the shade spread on the ground 56.3%, and 57.8% for nets dried hanging in direct sunlight. It was also observed that nets washed by the standard WHO protocol, retained more insecticide and were more effective in killing mosquitoes compared to nets washed by local methods of hand rubbing and beating on rocks. There were significant differences between drying regimens (p ® and TNT there were no significant differences observed between the four drying regimens (p = 0.7944 and 0.4703 respectively. For BASF and Olyset, the differences were significant (p 0.0001. Conclusion The results of this study suggest that washing and drying regimen influence the insecticidal activity of LLINs. The standard WHOPES washing protocol underestimates the amount of insecticide washed from LLINs compared to the abrasive washing procedures that are used in the field

  18. Laboratory evaluation of insecticide-treated sugar baits for control of phlebotomine sand flies (Diptera: Psychodidae).

    Science.gov (United States)

    Mascari, T M; Foil, L D

    2010-12-01

    The purpose of this study was to evaluate the use of boric acid, imidacloprid, ivermectin, or abamectin incorporated into sugar baits as oral toxicants for adult phlebotomine sand flies. Variable toxicity of insecticide-sugar bait solutions to adult male and female sand flies was demonstrated, based on male female median lethal concentration values of 0.10-0.08, 6.13-9.53, and 9.03-18.11 mg/liter of imidacloprid, ivermectin, and abamectin, respectively. Complete control of sand flies could not be achieved with as high as 40 g/liter of boric acid in sugar bait solution; concentrations >40 g/liter were found repellent to the sand flies. Uranine O (a fluorescent tracer dye that can be used to measure the ingestion of sugar baits by sand flies) did not interact negatively with imidacloprid, ivermectin, or abamectin when it was combined with the insecticides in a sugar bait. Also, incorporation of imidacloprid, ivermectin, or abamectin into sugar baits did not reduce the effect whether adult male and female sand flies fed on these sugar baits. We propose that imidacloprid, ivermectin, or abamectin could be used to control adult sand fly populations with targeted use of insecticide-treated sugar baits.

  19. Levels of insecticide resistance to deltamethrin, malathion, and temephos, and associated mechanisms in Aedes aegypti mosquitoes from the Guadeloupe and Saint Martin islands (French West Indies).

    Science.gov (United States)

    Goindin, Daniella; Delannay, Christelle; Gelasse, Andric; Ramdini, Cédric; Gaude, Thierry; Faucon, Frédéric; David, Jean-Philippe; Gustave, Joël; Vega-Rua, Anubis; Fouque, Florence

    2017-02-10

    In the Guadeloupe and Saint Martin islands, Aedes aegypti mosquitoes are the only recognized vectors of dengue, chikungunya, and Zika viruses. For around 40 years, malathion was used as a mosquito adulticide and temephos as a larvicide. Since the European Union banned the use of these two insecticide molecules in the first decade of the 21st century, deltamethrin and Bacillus thuringiensis var. israelensis are the remaining adulticide and larvicide, respectively, used in Guadeloupe. In order to improve the management of vector control activities in Guadeloupe and Saint Martin, we investigated Ae. aegypti resistance to and mechanisms associated with deltamethrin, malathion, and temephos. Ae. aegypti mosquitoes were collected from six different localities of Guadeloupe and Saint Martin. Larvae were used for malathion and temephos bioassays, and adult mosquitoes for deltamethrin bioassays, following World Health Organization recommendations. Knockdown resistance (Kdr) genotyping for V1016I and F1534C mutations, and expression levels of eight enzymes involved in detoxification mechanisms were examined in comparison with the susceptible reference Bora Bora strain. Resistance ratios (RR50) calculated for Ae. aegypti larvae showed high resistance levels to temephos (from 8.9 to 33.1-fold) and low resistance levels to malathion (from 1.7 to 4.4-fold). Adult females displayed moderate resistance levels to deltamethrin regarding the time necessary to affect 50% of individuals, varying from 8.0 to 28.1-fold. Molecular investigations on adult mosquitoes showed high resistant allele frequencies for V1016I and F1534C (from 85 to 96% and from 90 to 98%, respectively), as well as an overexpression of the glutathione S-transferase gene, GSTe2, the carboxylesterase CCEae3a, and the cytochrome genes 014614, CYP6BB2, CYP6M11, and CYP9J23. Ae. aegypti populations from Guadeloupe and Saint Martin exhibit multiple resistance to organophosphates (temephos and malathion), and pyrethroids

  20. Influence of insecticide Bacillus thuringiensis subsp. israelensis treatments on resistance and enzyme activities in Aedes rusticus larvae (Diptera : Culicidae)

    OpenAIRE

    Boyer, Sébastien; M. Paris(LANL); JEGO S.; Lempérière, Guy; Ravanel, P.

    2012-01-01

    The bacterio-insecticide Bacillus thuringiensis subsp. israelensis (Bti) represents currently a safe alternative to chemical insecticides in mosquito-borne diseases control and is intensively used worldwide. In the French Rhone-alpine mosquito Aedes rusticus Rossi, several genomic signatures of selection were detected in populations treated for more than 15 years with Bti. In this study we investigated whether detoxifying enzyme activities such as cytochromes P450, esterases and glutathione S...

  1. 3D mosquito screens to create window double screen traps for mosquito control.

    Science.gov (United States)

    Khattab, Ayman; Jylhä, Kaisa; Hakala, Tomi; Aalto, Mikko; Malima, Robert; Kisinza, William; Honkala, Markku; Nousiainen, Pertti; Meri, Seppo

    2017-08-29

    Mosquitoes are vectors for many diseases such as malaria. Insecticide-treated bed nets and indoor residual spraying of insecticides are the principal malaria vector control tools used to prevent malaria in the tropics. Other interventions aim at reducing man-vector contact. For example, house screening provides additive or synergistic effects to other implemented measures. We used commercial screen materials made of polyester, polyethylene or polypropylene to design novel mosquito screens that provide remarkable additional benefits to those commonly used in house screening. The novel design is based on a double screen setup made of a screen with 3D geometric structures parallel to a commercial mosquito screen creating a trap between the two screens. Owing to the design of the 3D screen, mosquitoes can penetrate the 3D screen from one side but cannot return through the other side, making it a unidirectional mosquito screen. Therefore, the mosquitoes are trapped inside the double screen system. The permissiveness of both sides of the 3D screens for mosquitoes to pass through was tested in a wind tunnel using the insectary strain of Anopheles stephensi. Among twenty-five tested 3D screen designs, three designs from the cone, prism, or cylinder design groups were the most efficient in acting as unidirectional mosquito screens. The three cone-, prism-, and cylinder-based screens allowed, on average, 92, 75 and 64% of Anopheles stephensi mosquitoes released into the wind tunnel to penetrate the permissive side and 0, 0 and 6% of mosquitoes to escape through the non-permissive side, respectively. A cone-based 3D screen fulfilled the study objective. It allowed capturing 92% of mosquitoes within the double screen setup inside the wind tunnel and blocked 100% from escaping. Thus, the cone-based screen effectively acted as a unidirectional mosquito screen. This 3D screen-based trap design could therefore be used in house screening as a means of avoiding infective bites and

  2. Multicentre studies of insecticide-treated durable wall lining in Africa and South-East Asia: entomological efficacy and household acceptability during one year of field use

    Directory of Open Access Journals (Sweden)

    Messenger Louisa A

    2012-10-01

    Full Text Available Abstract Background Indoor residual spraying (IRS is a primary method of malaria vector control, but its potential impact is constrained by several inherent limitations: spraying must be repeated when insecticide residues decay, householders can tire of the annual imposition and campaign costs are recurrent. Durable lining (DL can be considered an advanced form of long-lasting IRS where insecticide is gradually released from an aesthetically attractive wall lining material to provide vector control for several years. A multicentre trial was carried out in Equatorial Guinea, Ghana, Mali, South Africa and Vietnam to assess the feasibility, durability, bioefficacy and household acceptability of DL, compared to conventional IRS or insecticide-treated curtains (LLITCs, in a variety of operational settings. Methods This study was conducted in 220 households in traditional rural villages over 12-15 months. In all sites, rolls of DL were cut to fit house dimensions and fixed to interior wall surfaces (usually with nails and caps by trained teams. Acceptability was assessed using a standardized questionnaire covering such topics as installation, exposure reactions, entomology, indoor environment, aesthetics and durability. Bioefficacy of interventions was evaluated using WHO cone bioassay tests at regular intervals throughout the year. Results The deltamethrin DL demonstrated little to no decline in bioefficacy over 12-15 months, supported by minimal loss of insecticide content. By contrast, IRS displayed a significant decrease in bioactivity by 6 months and full loss after 12 months. The majority of participants in DL households perceived reductions in mosquito density (93% and biting (82%, but no changes in indoor temperature (83%. Among those households that wanted to retain the DL, 73% cited protective reasons, 20% expressed a desire to keep theirs for decoration and 7% valued both qualities equally. In Equatorial Guinea, when offered a choice of

  3. Efficacy of topical mosquito repellent (picaridin) plus long-lasting insecticidal nets versus long-lasting insecticidal nets alone for control of malaria : A cluster randomised controlled trial

    NARCIS (Netherlands)

    Sluydts, V.; Durnez, L.; Heng, S.; Gryseels, C.; Canier, L.; Kim, S.; Van Roey, K.; Kerkhof, K.; Khim, N.; Mao, S.; Menard, D.; Coosemans, M.

    2016-01-01

    Background Although effective topical repellents provide personal protection against malaria, whether mass use of topical repellents in addition to long-lasting insecticidal nets can contribute to a further decline of malaria is not known, particularly in areas where outdoor transmission occurs. We

  4. Impact of insecticide-treated nets on wild pyrethroid resistant Anopheles epiroticus population from southern Vietnam tested in experimental huts

    OpenAIRE

    Trung Ho; Speybroeck Niko; Berkvens Dirk; Chinh Vu; Van Bortel Wim; Coosemans Marc

    2009-01-01

    Abstract Background In this study, the efficacy of insecticide-treated nets was evaluated in terms of deterrence, blood-feeding inhibition, induced exophily and mortality on a wild resistant population of Anopheles epiroticus in southern Vietnam, in order to gain insight into the operational consequences of the insecticide resistance observed in this malaria vector in the Mekong delta. Method An experimental station, based on the model of West Africa and adapted to the behaviour of the target...

  5. Socio-cultural factors influencing insecticide treated bed net utilization in a malaria endemic city in north-central Nigeria

    Institute of Scientific and Technical Information of China (English)

    Jombo GTA; Akosu JT; Mbaawuaga EM; Gyuse AN; Enenebeaku MNO; Okwori EE; Peters EJ; Akpan S; Odey F; Etukumana EA

    2010-01-01

    Objective: To ascertain the socio-cultural factors influencing the rate of utilization of insecticide treated bed nets (ITNs) in a malaria endemic city of Makurdi, north central Nigeria. Methods:The study was cross-sectional in nature using systematic sampling method to identify households. Both quantitative and qualitative data was generated from adult women using structured and semi structured questionnaires, and focused group discussions (FGDs) to obtain information on rate and patterns of utilization of ITNs. Information such as age, educational level, marital status, awareness or otherwise of the existence of malaria, and factors influencing rate of ownership and utilization of ITNs were obtained. FGDs were used to obtain qualitative information on rate of utilization of ITNs not captured in the questionnaires. Data obtained was analysed using Epi Info 6 statistical software. Results: Among the respondents interviewed, 97.0%(2 013/2 075) were aware of existence of malaria and 87.0%of these (1 751/2 013) would associate it with mosquitoes. The rate of ownership of any bed net, ITNs and untreated bed nets (UTNs) was 25.1%, 17.0%and 8.3%, respectively. Utilization of ITNs among children was 30.0%(112/373) and UTNs 12.9%(48/373). Positive contributors to ITNs utilization were literacy, enhanced economy, experience of marriage, and being gainfully employed (P<0.05);while negative contributors were ignorance, poverty and some cultural beliefs and values. Conclusions: A more synchronized advocacy should be carried out on the potential benefits of ITNs utilization and sustained. Also ITNs should be made available to the people of the community at minimal or no cost.

  6. Assessing insecticide hazard to bumble bees foraging on flowering weeds in treated lawns.

    Science.gov (United States)

    Larson, Jonathan L; Redmond, Carl T; Potter, Daniel A

    2013-01-01

    Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees.

  7. Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis to experimental chicken sheds treated with insecticide

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    Brazil Reginaldo P

    2010-03-01

    Full Text Available Abstract Background Current strategies for controlling American visceral leishmaniasis (AVL have been unable to prevent the spread of the disease across Brazil. With no effective vaccine and culling of infected dogs an unpopular and unsuccessful alternative, new tools are urgently needed to manage populations of the sand fly vector, Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae. Here, we test two potential strategies for improving L. longipalpis control using the synthetic sand fly pheromone (±-9-methylgermacrene-B: the first in conjunction with spraying of animal houses with insecticide, the second using coloured sticky traps. Results Addition of synthetic pheromone resulted in greater numbers of male and female sand flies being caught and killed at experimental chicken sheds sprayed with insecticide, compared to pheromone-less controls. Furthermore, a ten-fold increase in the amount of sex pheromone released from test sheds increased the number of females attracted and subsequently killed. Treating sheds with insecticide alone resulted in a significant decrease in numbers of males attracted to sheds (compared to pre-spraying levels, and a near significant decrease in numbers of females. However, this effect was reversed through addition of synthetic pheromone at the time of insecticide spraying, leading to an increase in number of flies attracted post-treatment. In field trials of commercially available different coloured sticky traps, yellow traps caught more males than blue traps when placed in chicken sheds. In addition, yellow traps fitted with 10 pheromone lures caught significantly more males than pheromone-less controls. However, while female sand flies showed a preference for both blue and yellow pheromone traps sticky traps over white traps in the laboratory, neither colour caught significant numbers of females in chicken sheds, either with or without pheromone. Conclusions We conclude that synthetic pheromone could

  8. Effectiveness of mist-blower applications of malathion and permethrin to foliage as barrier sprays for salt marsh mosquitoes.

    Science.gov (United States)

    Anderson, A L; Apperson, C S; Knake, R

    1991-03-01

    Permethrin and malathion were applied as salt marsh mosquito barrier sprays by mist-blower to the shrub border of a park. At one and 24 h after treatment, mosquito landing counts in both insecticide treated areas declined by 80-90% relative to counts in an untreated control area. After 48 h, in the malathion-treated area, mosquito activity returned to levels observed in the control area. From 2 to 8 days post-treatment, mosquito landing counts in the permethrin-treated area remained depressed and significantly (P less than 0.01) different from the malathion-treated and control areas. On days 9 and 10 post-treatment, mosquito landing rates returned to high levels in the insecticide-treated and control areas.

  9. Family biosocial variables influencing the use of insecticide treated nets for children in Eastern Nigeria

    Directory of Open Access Journals (Sweden)

    Gabriel U. P. Iloh

    2013-01-01

    Full Text Available Background: Effective reduction of malaria morbidity and mortality in Nigerian children under the age of five depends to a large extent on family biosocial factors. Although, the awareness of insecticide treated bed nets (ITNs is reportedly high and increasing in Nigeria there remain large gaps between awareness, possession and use by families with children under the age of five in Nigeria. Aim: To determine the family biosocial variables that influence the use of insecticide treated nets for children in Eastern Nigeria. Materials and Methods: A descriptive hospital-based study was carried out from June 2008-June 2011 on a cross-section of 415 mothers with children under the age of five, who were treated for confirmed malaria, and met the selection criteria were interviewed using a pretested, structured researcher-administered questionnaire. The questionnaire tool elicited information on family socio-demographic variables, inter-spousal discussion, communication, concurrence and participation in the use of insecticide treated bed nets; and reasons for non-utilization. The period of usage in the previous 6 months was assessed and graded using a scoring system of 0-4. Scores of 1-4 indicated usage while score of 0 meant non use. Results: The rate of ITNs use was 53.0%. The family variables that significantly influenced utilization were secondary education and above of parents (mother: P0 = 0.009; father: P = 0.001, monogamy (P value = 0.024, family size of 1-4 (P value = 0.016 and parents living together ( P = 0.001; others included parents′ occupation (mother: P = 0.003; father: P = 0.04 and inter-spousal discussion (P value = 0.001, communication (P value = 0.001, concurrence ( P = 0.000 and participation ( P = 0.000. The commonest reason for non- use was inconvenience during sleep ( P = 0.04. Conclusion: This study shows that the rate of ITN use was marginally good. Specifically, this rate was significantly influenced by some family variables

  10. Mosquito control insecticides: a probabilistic ecological risk assessment on drift exposures of naled, dichlorvos (naled metabolite) and permethrin to adult butterflies.

    Science.gov (United States)

    Hoang, T C; Rand, G M

    2015-01-01

    A comprehensive probabilistic terrestrial ecological risk assessment (ERA) was conducted to characterize the potential risk of mosquito control insecticide (i.e., naled, it's metabolite dichlorvos, and permethrin) usage to adult butterflies in south Florida by comparing the probability distributions of environmental exposure concentrations following actual mosquito control applications at labeled rates from ten field monitoring studies with the probability distributions of butterfly species response (effects) data from our laboratory acute toxicity studies. The overlap of these distributions was used as a measure of risk to butterflies. The long-term viability (survival) of adult butterflies, following topical (thorax/wings) exposures was the environmental value we wanted to protect. Laboratory acute toxicity studies (24-h LD50) included topical exposures (thorax and wings) to five adult butterfly species and preparation of species sensitivity distributions (SSDs). The ERA indicated that the assessment endpoint of protection, of at least 90% of the species, 90% of the time (or the 10th percentile from the acute SSDs) from acute naled and permethrin exposures, is most likely not occurring when considering topical exposures to adults. Although the surface areas for adulticide exposures are greater for the wings, exposures to the thorax provide the highest potential for risk (i.e., SSD 10th percentile is lowest) for adult butterflies. Dichlorvos appeared to present no risk. The results of this ERA can be applied to other areas of the world, where these insecticides are used and where butterflies may be exposed. Since there are other sources (e.g., agriculture) of pesticides in the environment, where butterfly exposures will occur, the ERA may under-estimate the potential risks under real-world conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Increased proportions of outdoor feeding among residual malaria vector populations following increased use of insecticide-treated nets in rural Tanzania

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    Azizi Salum

    2011-04-01

    Full Text Available Abstract Background Insecticide-treated nets (ITNs and indoor residual spraying (IRS represent the front-line tools for malaria vector control globally, but are optimally effective where the majority of baseline transmission occurs indoors. In the surveyed area of rural southern Tanzania, bed net use steadily increased over the last decade, reducing malaria transmission intensity by 94%. Methods Starting before bed nets were introduced (1997, and then after two milestones of net use had been reached-75% community-wide use of untreated nets (2004 and then 47% use of ITNs (2009-hourly biting rates of malaria vectors from the Anopheles gambiae complex and Anopheles funestus group were surveyed. Results In 1997, An. gambiae s.l. and An. funestus mosquitoes exhibited a tendency to bite humans inside houses late at night. For An. gambiae s.l., by 2009, nocturnal activity was less (p = 0.0018. At this time, the sibling species composition of the complex had shifted from predominantly An. gambiae s.s. to predominantly An. arabiensis. For An. funestus, by 2009, nocturnal activity was less (p = 0.0054 as well as the proportion biting indoors (p An. funestus s.s. remained the predominant species within this group. As a consequence of these altered feeding patterns, the proportion (mean ± standard error of human contact with mosquitoes (bites per person per night occurring indoors dropped from 0.99 ± 0.002 in 1997 to 0.82 ± 0.008 in 2009 for the An. gambiae complex (p = 0.0143 and from 1.00 ± An. funestus complex (p = 0.0004 over the same time period. Conclusions High usage of ITNs can dramatically alter African vector populations so that intense, predominantly indoor transmission is replaced by greatly lowered residual transmission, a greater proportion of which occurs outdoors. Regardless of the underlying mechanism, the residual, self-sustaining transmission will respond poorly to further insecticidal measures within houses. Additional vector control

  12. Insecticide-Treated Net Campaign and Malaria Transmission in Western Kenya: 2003–2015

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    Guofa Zhou

    2016-08-01

    Full Text Available Insecticide-treated nets (ITNs are among the three major intervention measures that have reduced malaria transmission in the past decade. However, increased insecticide resistance in vectors, together with outdoor transmission, has been suggested as a limit to the efficacy of the ITN scaling-up efforts. Observations on longitudinal changes in ITN coverage and its impact on malaria transmission allow policy makers to make informed adjustments to control strategies. We analyzed field surveys on ITN ownership, malaria parasite prevalence, and malaria vector population dynamics in seven sentinel sites in western Kenya from 2003 to 2015. We found that ITN ownership has increased from an average of 18% in 2003 to 85% in 2015. Malaria parasite prevalence in school children decreased by about 70% from 2003 to 2008 (the first mass distribution of free ITNs was in 2006 but has resurged by >50% since then. At the community level, use of ITNs reduced infections by 23% in 2008 and 43% in 2010, although the reduction was down to 25% in 2011. The indoor-resting density of the predominant vector, An. gambiae, has been suppressed since 2007; however, An. funestus populations have resurged and have increased 20-fold in some places since 2007. In conclusion, there is limited room for further increase in ITN coverage in western Kenya. The rebounding in malaria transmission highlights the urgent need of new or improved malaria control interventions so as to further reduce malaria transmission.

  13. Pilot study on the combination of an organophosphate-based insecticide paint and pyrethroid-treated long lasting nets against pyrethroid resistant malaria vectors in Burkina Faso.

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    Mosqueira, Beatriz; Soma, Dieudonné D; Namountougou, Moussa; Poda, Serge; Diabaté, Abdoulaye; Ali, Ouari; Fournet, Florence; Baldet, Thierry; Carnevale, Pierre; Dabiré, Roch K; Mas-Coma, Santiago

    2015-08-01

    A pilot study to test the efficacy of combining an organophosphate-based insecticide paint and pyrethroid-treated Long Lasting Insecticide Treated Nets (LLINs) against pyrethroid-resistant malaria vector mosquitoes was performed in a real village setting in Burkina Faso. Paint Inesfly 5A IGR™, comprised of two organophosphates (OPs) and an Insect Growth Regulator (IGR), was tested in combination with pyrethroid-treated LLINs. Efficacy was assessed in terms of mortality for 12 months using Early Morning Collections of malaria vectors and 30-minute WHO bioassays. Resistance to pyrethroids and OPs was assessed by detecting the frequency of L1014F and L1014S kdr mutations and Ace-1(R)G119S mutation, respectively. Blood meal origin was identified using a direct enzyme-linked immunosorbent assay (ELISA). The combination of Inesfly 5A IGR™ and LLINs was effective in killing 99.9-100% of malaria vector populations for 6 months regardless of the dose and volume treated. After 12 months, mortality rates decreased to 69.5-82.2%. The highest mortality rates observed in houses treated with 2 layers of insecticide paint and a larger volume. WHO bioassays supported these results: mortalities were 98.8-100% for 6 months and decreased after 12 months to 81.7-97.0%. Mortality rates in control houses with LLINs were low. Collected malaria vectors consisted exclusively of Anopheles coluzzii and were resistant to pyrethroids, with a L1014 kdr mutation frequency ranging from 60 to 98% through the study. About 58% of An. coluzzii collected inside houses had bloodfed on non-human animals. Combining Inesfly 5A IGR™ and LLINs yielded a one year killing efficacy against An. coluzzii highly resistant to pyrethroids but susceptible to OPs that exhibited an anthropo-zoophilic behaviour in the study area. The results obtained in a real setting supported previous work performed in experimental huts and underscore the need to study the impact that this novel strategy may have on clinical

  14. Utilization of insecticide-treated nets by under-five children in Nigeria: Assessing progress towards the Abuja targets

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    Sofola Olayemi T

    2008-07-01

    Full Text Available Abstract Background The Abuja target of increasing the proportion of people sleeping under insecticide-treated nets (ITNs to 60% by the year 2005, as one of the measures for malaria control in Africa, has generated an influx of resources for malaria control in several countries in the region. A national household survey conducted in 2005 by the Malaria Control Programme in Nigeria assessed the progress made with respect to ITN ownership and use among pregnant women and children under five years of age since 2000. The survey was the first nationally representative study of ITN use assessing progress towards the Abuja target amongst vulnerable groups. Population and Method A cross-sectional survey of a sample of 7,200 households, selected by a multistage stratified sampling technique from 12 randomly selected states from the six geopolitical zones of the country. Data collection was done during the malarious rainy season (October 2005 using a modified WHO Malaria Indicator Survey structured questionnaire about household ownership and utilization of mosquito nets (treated or untreated from household heads. Results Household ownership of any net was 23.9% (95% CI, 22.8%–25.1% and 10.1% for ITNs (95% CI, 9.2%–10.9%. Education, wealth index, presence of an under-five child in the household, family size, residence, and region by residence were predictive of ownership of any net. The presence of an under-five child in the household, family size, education, presence of health facility in the community, gender of household head, region by residence and wealth index by education predicted ITN ownership. Utilization of any net by children under-five was 11.5% (95% CI, 10.4%–12.6% and 1.7% (95% CI, 1.3%–2.2% for ITN. Predictors of use of any net among under-five children were fever in the previous two weeks, presence of health facility in the community, caregiver's education, residence, and wealth index by caregiver's education; while religion

  15. [Comparative behaviour studies in horses infested with flying insects treated with insecticide or repellent substances].

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    Sünder, Ulrich; Moors, Eva; Hagemann, Kristina; Gauly, Matthias

    2011-01-01

    The aim of this study was to estimate the effects of flying insects (Order Diptera) on the behaviour of grazing horses in relation to the use of insecticide and repellent substances. The investigations were done between June and August in 2008 in 3 periods of 7 days each. As insecticide and repellent two substances were used: "Well-care emulsion" (Co. Essex Tierarznei, München, GER) containing Permethrin and "Bremsen-Frei-Plus" (Co. Dr. Schaette AG, Bad Waldsee, GER) based on etheric oils. Both groups were compared with a non treated control group in a crossover-design. Each group (n = 3-5) was used alternately as control and treatment group. Several climate parameters were taken during the study. Furthermore, the number of insects per animal was estimated at certain times. Once per observation period insects were caught using Malaise traps and differentiated by species. The proportion of horse relevant species of the genera Diptera, especially Culex pipiens and Musca autumnalis, caught was 9% on an average. There was no correlation between the number of Tabanidae caught in the Malaise traps and the number observed near by the horses. Behaviour parameters like tailswishing, headshaking, stamping, skintwitching, snapping at the body, and moving were observed more frequently with increasing insect infestation. When horses were infested with a high number of flying insects, feeding activity was significant lower, whereas locomotion activity was significant higher. Both substances had positive effects for about 50 hours after application with no apparent difference between the substances. However, a lower frequency of headshaking and tailswishing could be observed in the Permethrin treated horses.

  16. Synthesis, Polymorphism, and Insecticidal Activity of Methyl 4-(4-chlorophenyl)-8-iodo-2-methyl-6-oxo-1,6-dihydro-4H-pyrimido[2,1-b]quinazoline-3-Carboxylate Against Anopheles arabiensis Mosquito.

    Science.gov (United States)

    Venugopala, Katharigatta N; Nayak, Susanta K; Gleiser, Raquel M; Sanchez-Borzone, Mariela E; Garcia, Daniel A; Odhav, Bharti

    2016-07-01

    Mosquitoes are the major vectors of pathogens and parasites including those causing malaria, the most deadly vector-borne disease. The negative environmental effects of most synthetic compounds combined with widespread development of insecticide resistance encourage an interest in finding and developing alternative products against mosquitoes. In this study, pyrimido[2,1-b]quinazoline derivative DHPM3 has been synthesized by three-step chemical reaction and screened for larvicide, adulticide, and repellent properties against Anopheles arabiensis, one of the dominant vectors of malaria in Africa. The title compound emerged as potential larvicide agent for further research and development, because it exerted 100% mortality, while adulticide activity was considered moderate.

  17. Benefit of insecticide-treated nets, curtains and screening on vector borne diseases, excluding malaria: a systematic review and meta-analysis

    NARCIS (Netherlands)

    Wilson, A.L.; Dhiman, R.C.; Kitron, U.; Scott, T.W.; Berg, van den H.; Lindsay, S.W.

    2014-01-01

    Introduction Insecticide-treated nets (ITNs) are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs). We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated curt

  18. Benefit of insecticide-treated nets, curtains and screening on vector borne diseases, excluding malaria: a systematic review and meta-analysis

    NARCIS (Netherlands)

    Wilson, A.L.; Dhiman, R.C.; Kitron, U.; Scott, T.W.; Berg, van den H.; Lindsay, S.W.

    2014-01-01

    Introduction Insecticide-treated nets (ITNs) are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs). We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated curt

  19. Benefit of insecticide-treated nets, curtains and screening on vector borne diseases, excluding malaria: a systematic review and meta-analysis

    NARCIS (Netherlands)

    Wilson, A.L.; Dhiman, R.C.; Kitron, U.; Scott, T.W.; Berg, van den H.; Lindsay, S.W.

    2014-01-01

    Introduction Insecticide-treated nets (ITNs) are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs). We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated

  20. Impact of three years of large scale Indoor Residual Spraying (IRS and Insecticide Treated Nets (ITNs interventions on insecticide resistance in Anopheles gambiae s.l. in Benin

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    Padonou Gil

    2012-04-01

    Full Text Available Abstract Background In Benin, Indoor Residual Spraying (IRS and long-lasting insecticidal nets (LLINs are the cornerstones of malaria prevention. In the context of high resistance of Anopheles gambiae to pyrethroids, The National Malaria Control Program (NMCP has undertaken a full coverage of IRS in a no-flood zone in the Oueme region, coupled with the distribution of LLINs in a flood zone. We assessed the impact of this campaign on phenotypic resistance, kdr (knock-down resistance and ace-1R (insensitive acetylcholinesterase mutations. Methods Insecticides used for malaria vector control interventions were bendiocarb WP (0.4 g/m2 and deltamethrin (55 mg/m2, respectively for IRS and LLINs. Susceptibility status of An. gambiae was assessed using World Health Organization bioassay tests to DDT, permethrin, deltamethrin and bendiocarb in the Oueme region before intervention (2007 and after interventions in 2008 and 2010. An. gambiae specimens were screened for identification of species, molecular M and S forms and for the detection of the West African kdr (L1014F as well as ace-1R mutations using PCR techniques. Results The univariate logistic regression performed showed that kdr frequency has increased significantly during the three years in the intervention area and in the control area. Several factors (LLINs, IRS, mosquito coils, aerosols, use of pesticides for crop protection could explain the selection of individual resistant An. gambiae. The Kdr resistance gene could not be the only mechanism of resistance observed in the Oueme region. The high susceptibility to bendiocarb is in agreement with a previous study conducted in Benin. However, the occurrence of ace-1R heterozygous individuals even on sites far from IRS areas, suggests other factors may contribute to the selection of resistance other than those exerted by the vector control program. Conclusion The results of this study have confirmed that An.gambiae have maintained and developed

  1. Degradability of Treated Ethion Insecticide by TiO2 Photocatalysis.

    Science.gov (United States)

    Hassarangsee, Siriporn; Uthaibutra, Jamnong; Nomura, Nakao; Whangchai, Kanda

    2015-01-01

    Ethion, an insecticide, is widely used with fruit and vegetable crops. This research studied the reduction and oxidative degradation of standard ethion by TiO2 photocatalysis. A standard ethion solution (1 mg L(-1)) was treated with different concentrations of TiO2 powder (5, 10, 20, 40 and 60 mg mL(-1)) for 0, 15, 30, 45 and 60 min. The amount of ethion residue was detected by gas chromatography with flame photometric detection (GC-FPD) and the concentration of anions produced as major degradation products was determined by Ion Chromatography (IC). The TiO2 photocatalysis efficiently reduced ethion concentrations, with the highest degradation rate occurring within the first 15 min of reaction. The reaction produced sulphate and phosphate anions. The TiO2photocatalysis reduced 1 mg L(-1) ethion to 0.18 mg L(-1) when treated with 60 mg mL(-1) TiO2 powder for 60 min. The lethal concentration (LC50) of standard ethion was also estimated and compared to the treated ethion. All treatments, especially 60 mg mL(-1) TiO2 powder, markedly detoxified ethion, as tested with brine shrimp (Artemia salina L.), with an LC50 value of 765.8 mg mL(-1), compared to the control of 1.01 mg mL(-1).

  2. Method of analysis and quality-assurance practices by the U. S. Geological Survey Organic Geochemistry Research Group; determination of four selected mosquito insecticides and a synergist in water using liquid-liquid extraction and gas chrom

    Science.gov (United States)

    Zimmerman, L.R.; Strahan, A.P.; Thurman, E.M.

    2001-01-01

    A method of analysis and quality-assurance practices were developed for the determination of four mosquito insecticides (malathion, metho-prene, phenothrin, and resmethrin) and one synergist (piperonyl butoxide) in water. The analytical method uses liquid-liquid extraction (LLE) and gas chromatography/mass spectrometry (GC/MS). Good precision and accuracy were demonstrated in reagent water, urban surface water, and ground water. The mean accuracies as percentages of the true compound concentrations from water samples spiked at 10 and 50 nanograms per liter ranged from 68 to 171 percent, with standard deviations in concentrations of 27 nanograms per liter or less. The method detection limit for all compounds was 5.9 nanograms per liter or less for 247-milliliter samples. This method is valuable for acquiring information about the fate and transport of these mosquito insecticides and one synergist in water.

  3. Insecticidal activity of isobutylamides derived from Piper nigrum against adult of two mosquito species, Culex pipiens pallens and Aedes aegypti.

    Science.gov (United States)

    Park, Il-Kwon

    2012-01-01

    The insecticidal activity of Piper nigrum fruit-derived piperidine alkaloid (piperine) and N-isobutylamide alkaloids (pellitorine, guineensine, pipercide and retrofractamide A) against female adults of Culex pipiens pallens and Aedes aegypti was examined. On the basis of 24-h LD(50) values, the compound most toxic to female C. pipiens pallens was pellitorine (0.4 µg/♀) followed by guineensine (1.9 µg/♀), retrofractamide A (2.4 µg/♀) and pipercide (3.2 µg/♀). LD(50) value of chlorpyrifos was 0.03 µg/♀. Against female A. aegypti, the insecticidal activity was more pronounced in pellitorine (0.17 µg/♀) than in retrofractamide A (1.5 µg/♀), guineensine (1.7 µg/♀), and pipercide (2.0 µg/♀). LD(50) value of chlorpyrifos was 0.0014 µg/♀.

  4. The costs and effects of a nationwide insecticide-treated net programme: the case of Malawi

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    Ortiz Juan

    2005-05-01

    Full Text Available Abstract Background Insecticide-treated nets (ITNs are a proven intervention to reduce the burden of malaria, yet there remains a debate as to the best method of ensuring they are universally utilized. This study is a cost-effectiveness analysis of an intervention in Malawi that started in 1998, in Blantyre district, before expanding nationwide. Over the 5-year period, 1.5 million ITNs were sold. Methods The costs were calculated retrospectively through analysis of expenditure data. Costs and effects were measured as cost per treated-net year (cost/TNY and cost per net distributed. Results The mean cost/TNY was calculated at $4.41, and the mean cost/ITN distributed at $2.63. It also shows evidence of economies of scale, with the cost/TNY falling from $7.69 in year one (72,196 ITN to $3.44 in year five (720,577 ITN. Cost/ITN distributed dropped from $5.04 to $1.92. Conclusion Combining targeting and social marketing has the potential of being both cost-effective and capable of achieving high levels of coverage, and it is possible that increasing returns to scale can be achieved.

  5. No Effect of Insecticide Treated Curtain Deployment on Aedes Infestation in a Cluster Randomized Trial in a Setting of Low Dengue Transmission in Guantanamo, Cuba

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    Lambert, Isora; Montada, Domingo; Baly, Alberto; Van der Stuyft, Patrick

    2015-01-01

    Objective & Methodology The current study evaluated the effectiveness and cost-effectiveness of Insecticide Treated Curtain (ITC) deployment for reducing dengue vector infestation levels in the Cuban context with intensive routine control activities. A cluster randomized controlled trial took place in Guantanamo city, east Cuba. Twelve neighborhoods (about 500 households each) were selected among the ones with the highest Aedes infestation levels in the previous two years, and were randomly allocated to the intervention and control arms. Long lasting ITC (PermaNet) were distributed in the intervention clusters in March 2009. Routine control activities were continued in the whole study area. In both study arms, we monitored monthly pre- and post-intervention House Index (HI, number of houses with at least 1 container with Aedes immature stages/100 houses inspected), during 12 and 18 months respectively. We evaluated the effect of ITC deployment on HI by fitting a generalized linear regression model with a negative binomial link function to these data. Principal Findings At distribution, the ITC coverage (% of households using ≥1 ITC) reached 98.4%, with a median of 3 ITC distributed/household. After 18 months, the coverage remained 97.4%. The local Aedes species was susceptible to deltamethrin (mosquito mortality rate of 99.7%) and the residual deltamethrin activity in the ITC was within acceptable levels (mosquito mortality rate of 73.1%) after one year of curtain use. Over the 18 month observation period after ITC distribution, the adjusted HI rate ratio, intervention versus control clusters, was 1.15 (95% CI 0.57 to 2.34). The annualized cost per household of ITC implementation was 3.8 USD, against 16.8 USD for all routine ACP activities. Conclusion Deployment of ITC in a setting with already intensive routine Aedes control actions does not lead to reductions in Aedes infestation levels. PMID:25794192

  6. Evaluation of the effectiveness of insecticide treated materials for household level dengue vector control.

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    Veerle Vanlerberghe

    Full Text Available OBJECTIVE: To assess the operational effectiveness of long-lasting insecticide treated materials (ITMs, when used at household level, for the control of Aedes aegypti in moderately infested urban and suburban areas. METHODS: In an intervention study, ITMs consisting of curtains and water jar-covers (made from PermaNet were distributed under routine field conditions in 10 clusters (5 urban and 5 suburban, with over 4000 houses, in Trujillo, Venezuela. Impact of the interventions were determined by comparing pre-and post-intervention measures of the Breteau index (BI, number of positive containers/100 houses and pupae per person index (PPI, and by comparison with indices from untreated areas of the same municipalities. The effect of ITM coverage was modeled. RESULTS: At distribution, the proportion of households with ≥1 ITM curtain was 79.7% in urban and 75.2% in suburban clusters, but decreased to 32.3% and 39.0%, respectively, after 18 months. The corresponding figures for the proportion of jars using ITM covers were 34.0% and 50.8% at distribution and 17.0% and 21.0% after 18 months, respectively. Prior to intervention, the BI was 8.5 in urban clusters and 42.4 in suburban clusters, and the PPI was 0.2 and 0.9, respectively. In both urban and suburban clusters, the BI showed a sustained 55% decrease, while no discernable pattern was observed at the municipal level. After controlling for confounding factors, the percentage ITM curtain coverage, but not ITM jar-cover coverage, was significantly associated with both entomological indices (Incidence Rate Ratio = 0.98; 95%CI 0.97-0.99. The IRR implied that ITM curtain coverage of at least 50% was necessary to reduce A. aegypti infestation levels by 50%. CONCLUSION: Deployment of insecticide treated window curtains in households can result in significant reductions in A. aegypti levels when dengue vector infestations are moderate, but the magnitude of the effect depends on the coverage attained

  7. Africa's largest long-lasting insecticide-treated net producer: lessons from A to Z Textiles

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    Daar Abdallah S

    2010-12-01

    Full Text Available Abstract Background Field trials have demonstrated the efficacy of insecticide-treated nets, and the WHO has recently endorsed a shift toward Long-Lasting Insecticide Treated nets (LLINs due to factors such as reduced distribution costs. However, the need for LLINs poses several challenges. Is it possible to manufacture LLINs in large quantities in the African continent, where malaria is most endemic? When production is located in low-income countries, what role is played by local funding and employment, scaling up manufacturing, and partnerships? What factors influence availability and pricing? Discussion A case study of A to Z Textiles was undertaken to answer the question of how large-scale production of LLINs can occur in a low income setting. One of the largest sources of bed nets for Africa, A to Z Textiles is Africa-based, and its Tanzanian operations have a production capacity of 30 million LLINs per year, along with full WHO recommendation for its nets. Our analysis is based on semi-structured interviews with key informants familiar with A to Z, site visits in Tanzania, and literature reviews. This paper discusses the history and current status of A to Z Textiles, identifies the factors that led to its success, and suggests policy considerations that could support similar initiatives in the future. Local funding, scaling up manufacturing, technology transfer, and partnerships all played important roles in A to Z’s ascent, as did perceived benefits of local employment and capacity-building. Regulatory issues and procurement rules acted as barriers. A to Z cost-effectively manufactures high-quality LLINs where malaria is most endemic. Summary With a production capacity of 30 million LLINs per year, and full WHOPES (WHO Pesticide Evaluation Scheme certification, A to Z Textiles demonstrates how key health goods can be successfully produced in the low-income countries that use them. Its example may be instructive and of high interest to

  8. Africa's largest long-lasting insecticide-treated net producer: lessons from A to Z Textiles.

    Science.gov (United States)

    Masum, Hassan; Shah, Ronak; Schroeder, Karl; Daar, Abdallah S; Singer, Peter A

    2010-12-13

    Field trials have demonstrated the efficacy of insecticide-treated nets, and the WHO has recently endorsed a shift toward Long-Lasting Insecticide Treated nets (LLINs) due to factors such as reduced distribution costs. However, the need for LLINs poses several challenges. Is it possible to manufacture LLINs in large quantities in the African continent, where malaria is most endemic? When production is located in low-income countries, what role is played by local funding and employment, scaling up manufacturing, and partnerships? What factors influence availability and pricing? A case study of A to Z Textiles was undertaken to answer the question of how large-scale production of LLINs can occur in a low income setting. One of the largest sources of bed nets for Africa, A to Z Textiles is Africa-based, and its Tanzanian operations have a production capacity of 30 million LLINs per year, along with full WHO recommendation for its nets. Our analysis is based on semi-structured interviews with key informants familiar with A to Z, site visits in Tanzania, and literature reviews.This paper discusses the history and current status of A to Z Textiles, identifies the factors that led to its success, and suggests policy considerations that could support similar initiatives in the future. Local funding, scaling up manufacturing, technology transfer, and partnerships all played important roles in A to Z's ascent, as did perceived benefits of local employment and capacity-building. Regulatory issues and procurement rules acted as barriers. A to Z cost-effectively manufactures high-quality LLINs where malaria is most endemic. With a production capacity of 30 million LLINs per year, and full WHOPES (WHO Pesticide Evaluation Scheme) certification, A to Z Textiles demonstrates how key health goods can be successfully produced in the low-income countries that use them. Its example may be instructive and of high interest to readers in the malaria community, especially in developing

  9. Screening effective insecticides for controlling mosquito, fly and cockroach%对蚊蝇和蟑螂有效防治药剂的筛选研究

    Institute of Scientific and Technical Information of China (English)

    庄静; 靳增军; 王志强; 王建蕊; 王向文; 李现亮

    2012-01-01

    Objective The effect of four kinds of insecticides against Culex pipiens pallens,Musca domestica and Blattella germanica were determined, in order to provide scientific data for vector control. Methods Under laboratory conditions, using soaking, topical application and residual smearing methods. Results The LC50 of delta-methrin to mosquito was 0. 009 1 mg/L, and the toxicity was the highest. The toxicity of lambda-cyhalothrin was the second and its LC50 to mosquito was 0. 012 6 mg/L. The toxicity of tetramethrin was the lowest. The LD50 of lambda-cyhalothrin was 0.008 3 礸/ ? to fly. Propoxur was the lowest toxicity. For cockroach, the KT50 of lambda-cyhalothrin, delta-methrin and fenobucarb were 10. 24,10. 85 and 12. 96 min respectively. Conclusion For fly and cockroach, the toxicity of lambda-cyhalothrin was the highest. The toxicity of delta-methrin to mosquito was the strongest. The control effect of beta-cyfluthrin was the best of them.%目的 掌握多种药剂对淡色库蚊、家蝇和德国小蠊的杀灭效果,为有效控制媒介生物提供依据.方法 在室内条件下分别采用幼虫浸渍法、微量点滴法、三角烧瓶药膜法.结果 溴氰菊酯对淡色库蚊幼虫敏感性最高,毒力最大,LC50为0.009 1 mg/L;高效氯氟氰菊酯次之,LC50为0.0126 mg/L;胺菊酯毒力较弱.家蝇对高效氯氟氰菊酯敏感性同样最高,LD50为0.008 3μg/♀,残杀威毒力最弱.高效氯氟氰菊酯、溴氰菊酯和仲丁威对德国小蠊的KT50分别为10.24、10.85和12.96 min,毒力较强.结论 家蝇、德国小蠊对高效氯氟氰菊酯的敏感性最高,淡色库蚊幼虫对溴氰菊酯的敏感性最高,但高效氯氰菊酯的杀灭效果强于其他.

  10. Collapse of Anopheles darlingi populations in Suriname after introduction of insecticide-treated nets (ITNs); malaria down to near elimination level.

    Science.gov (United States)

    Hiwat, Hélène; Mitro, Sutrisno; Samjhawan, Ashok; Sardjoe, Prem; Soekhoe, Treyanti; Takken, Willem

    2012-04-01

    A longitudinal study of malaria vectors was carried out in three villages in Suriname between 2006 and 2010. During 13,392 man hours of collections, 3,180 mosquitoes were collected, of which 33.7% were anophelines. Of these, Anopheles darlingi accounted for 88.1%, and An. nuneztovari accounted for 11.1%. The highest mean An. darlingi human biting rate (HBR) observed per survey was 1.43 bites/man per hour outdoor and 1.09 bites/man per hour indoor; 2 An. darlingi of the 683 tested were infected with Plasmodium falciparum. The anopheline HBR decreased to zero after the onset of malaria intervention activities, including insecticide-treated net (ITN) distribution, in 2006. Malaria transmission decreased to pre-elimination levels. It is concluded that the combination of ITN and climatic events has led to the collapse of malaria vector populations in the study sites in the interior of the country. The results are discussed in relation to the stability of malaria transmission in areas with low-density human populations.

  11. Green synthesis of selenium nanoparticles conjugated Clausena dentata plant leaf extract and their insecticidal potential against mosquito vectors.

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    Sowndarya, P; Ramkumar, G; Shivakumar, M S

    2016-11-10

    Mosquitoes are major vectors for the transmission of many diseases like chikungunya, malaria, dengue, zika, etc. worldwide. In the present study, selenium nanoparticles (SeNPs) were synthesized from Clausena dentata and were tested for their larvicidal efficacy against the fourth-instar larvae of Anopheles stephensi, Aedes Aegypti, and Culex quinquefasciatus. The synthesized nanoparticles were characterized using UV-Vis spectroscopy, Fourier Transform Infrared Radiation (FTIR) spectroscopy, EDaX, and SEM. The results recorded from UV-Vis spectroscopy show the peak absorption spectrum at 420 nm. In FTIR, the maximum peak value is 2922.25 cm(-1) assigned to N-H group (amide group). In EDaX analysis shows peak around 72.64 which confirm the binding intensity of selenium. In SEM analysis, the synthesized SeNPs sizes were ranging from 46.32 nm to 78.88 nm. The synthesized SeNPs produced high mortality with very low concentration (LC50) were 240.714 mg/L; 104.13 mg/L, and 99.602 mg/L for A. stephensi, A. Aegypti, and C. quinquefasciatus, respectively. These results suggest that the C. dentata leaf extract-mediated biosynthesis of SeNPs has the potential to be used as an ideal ecofriendly approach toward the control of mosquito vectors at early stages.

  12. Untangling the debate surrounding strategies for achieving sustainable high coverage of insecticide-treated nets.

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    Stevens, Warren

    2005-01-01

    On the question of how to achieve the goal of long-term high utilisation of insecticide-treated nets (ITNs), most protagonists fall into one of two camps: free distribution or market development. The 'free distribution' camp argue that given the health benefit to be gained and lives saved, not to mention the relative cost effectiveness of ITNs, such an intervention should be provided free and paid for by governments or donors. In addition, they argue that it is unrealistic to ask the poorest of the population, who are often the ones at most risk, to pay for an ITN, and this risks producing greater inequalities in health. The market advocates counter that free distribution compromises sustainability, both in terms of demand and supply. Firstly they argue that, without a price, people will be less inclined to value ITNs. In turn this could mean lower utilisation, and a lower inclination to replace such an asset at the end of its useful life. In addition, on the supply side, without a price there is little chance of a local market developing for ITNs, although this would be the surest way to ensure a sustainable supply. It is hard to argue with either viewpoint, as both have merit. This article considers three major issues in the debate, and attempts to draw policy conclusions.

  13. Strategies for delivering insecticide-treated nets at scale for malaria control: a systematic review

    Science.gov (United States)

    Paintain, Lucy Smith; Mangham, Lindsay; Car, Josip; Schellenberg, Joanna Armstrong

    2012-01-01

    Abstract Objective To synthesize findings from recent studies of strategies to deliver insecticide-treated nets (ITNs) at scale in malaria-endemic areas. Methods Databases were searched for studies published between January 2000 and December 2010 in which: subjects resided in areas with endemicity for Plasmodium falciparum and Plasmodium vivax malaria; ITN delivery at scale was evaluated; ITN ownership among households, receipt by pregnant women and/or use among children aged cost-effectiveness studies linked to an eligible paper were also included. Study quality was assessed using the Cochrane risk of bias checklist and GRADE criteria. Important influences on scaling up were identified and assessed across delivery strategies. Findings A total of 32 papers describing 20 African studies were reviewed. Many delivery strategies involved health sectors and retail outlets (partial subsidy), antenatal care clinics (full subsidy) and campaigns (full subsidy). Strategies achieving high ownership among households and use among children Costs were largely comparable across strategies; ITNs were the main cost. Cost-effectiveness estimates were most sensitive to the assumed net lifespan and leakage. Common barriers to delivery included cost, stock-outs and poor logistics. Common facilitators were staff training and supervision, cooperation across departments or ministries and stakeholder involvement. Conclusion There is a broad taxonomy of strategies for delivering ITNs at scale. PMID:22984312

  14. Household demand for insecticide-treated bednets in Tanzania and policy options for increasing uptake.

    Science.gov (United States)

    Gingrich, Chris D; Hanson, Kara G; Marchant, Tanya J; Mulligan, Jo-Ann; Mponda, Hadji

    2011-03-01

    There has been considerable controversy about the most appropriate means of delivering insecticide-treated nets (ITNs) to prevent malaria. Household demand for ITNs is a key factor influencing the choice of delivery strategy, but evidence to date about price and income elasticities comes either from studies of hypothetical willingness to pay or small-scale policy experiments. This study estimates the price and income elasticities of demand for ITNs using nationally representative household survey data and actual consumer choices, in the context of a national scheme to provide vouchers for subsidized nets to pregnant women in Tanzania. Under this distribution system, the estimated price elasticity of demand for subsidized ITNs equals -0.12 and the income elasticity estimates range from zero to 0.47, depending on household socio-economic status. The model also shows a substantial decline in short-term ITN purchases for women whose household received a free ITN. These findings suggest that if the Tanzanian government continues to use a mixed public-private model to distribute ITNs, increasing the consumer subsidy alone will not dramatically improve ITN coverage. A concerted effort is required including an increase in the subsidy amount, attention to income growth for poor households, increases in women's and girls' education levels, and expansion of the retail ITN distribution network. Use of a catch-up campaign to distribute free ITNs would increase coverage but raises questions about the effect of households' long-term purchase decisions for ITNs.

  15. Comparative analysis of mosquito (Diptera: Culicidae: Aedes aegypti Liston) responses to the insecticide Temephos and plant derived essential oil derived from Piper betle L.

    Science.gov (United States)

    Vasantha-Srinivasan, Prabhakaran; Senthil-Nathan, Sengottayan; Ponsankar, Athirstam; Thanigaivel, Annamalai; Edwin, Edward-Sam; Selin-Rani, Selvaraj; Chellappandian, Muthiah; Pradeepa, Venkatraman; Lija-Escaline, Jalasteen; Kalaivani, Kandaswamy; Hunter, Wayne B; Duraipandiyan, Veeramuthu; Al-Dhabi, Naif Abdullah

    2017-05-01

    Resistance to treatments with Temephos or plant derived oil, Pb-CVO, between a field collected Wild Strain (WS) and a susceptible Laboratory Strain (LS) of Ae. aegypti were measured. The Temephos (0.1mg/L) showed the greatest percentage of mosquito mortality compared to Pb-CVO (1.5mg/L) in LS Ae. aegypti. However, WS Ae. aegypti was not significantly affected by Temephos (0.1mg/L) treatment compare to the Pb-CVO (1.5mg/L). However, both strains (LS and WS) when treated with Pb-CVO (1.5mg/L) displayed steady larval mortality rate across all instars. The LC50 of Temephos was 0.027mg in LS, but increased in WS to 0.081mg/L. The LC50 of Pb-CVO treatment was observed at concentrations of 0.72 and 0.64mg/L for LS and WS strains respectively. The enzyme level of α- and β-carboxylesterase was reduced significantly in both mosquito strains treated with Pb-CVO. Whereas, there was a prominent deviation in the enzyme ratio observed between LS and WS treated with Temephos. The GST and CYP450 levels were upregulated in the LS, but decreased in WS, after treatment with Temephos. However, treatment with Pb-CVO caused both enzyme levels to increase significantly in both the strains. Visual observations of the midgut revealed cytotoxicity from sub-lethal concentrations of Temephos (0.04mg/L) and Pb-CVO (1.0mg/L) in both strains of Ae. aegypti compared to the control. The damage caused by Temephos was slightly less in WS compared to LS mosquito strains. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Determinants of use of insecticide-treated nets among pregnant women in Nigeria

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    Ezire O

    2015-06-01

    Full Text Available Onoriode Ezire,1 Samson B Adebayo,2 Omokhudu Idogho,3 Elijah A Bamgboye,4 Ernest Nwokolo5 1Research and Evaluation Division, Society for Family Health, Abuja, 2National Agency for Food and Drug Administration and Control, Abuja, 3Enhancing Nigeria’s Response to HIV & AIDS, Abuja, 4Medical Statistics, University of Ibadan, Ibadan, 5Society for Family Health, Abuja, Nigeria Background: Malaria in pregnancy is still a major health issue in Nigeria, accounting for about 33% of cause of maternal death. Despite massive efforts to make insecticide-treated net (ITN available to pregnant women in Nigeria, the use is still low. This study was conducted to identify facilitators and inhibitors for the use of ITN/long-lasting insecticidal net (LLIN among pregnant women in Nigeria.Methods: Data were obtained from the 2011 State-Specific HIV & AIDS, Reproductive and Child Health Survey conducted in 18 states of Nigeria. The survey was a population-based study among men and women of reproductive age living in households in rural and urban areas of Nigeria. Multistage cluster sampling technique was used to select eligible respondents. The sample size per state was 960 respondents. Data were collected between October and November 2011. The analysis was done using Statistical Package for Social Sciences (SPSS version 20.Results: A total of 11.5% of the respondents were pregnant at the time of the survey of which 73.2% lived in rural location and approximately 70% were either not educated or attained at most a primary school education. A total of 93.2% of respondents have heard of net, 82.6% were confident that they can hang or use a net, and 64.6% owned an ITN/LLIN in their household while the actual use was just 19.2%. We found education, location (urban–rural, confidence to use a net, and knowledge that the use of a net can protect a pregnant woman from malaria to be significant at 5% level. The number of nets owned per household, the length of time the net

  17. What Is Threatening the Effectiveness of Insecticide-Treated Bednets? A Case-Control Study of Environmental, Behavioral, and Physical Factors Associated with Prevention Failure.

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    Andrew A Obala

    Full Text Available Insecticide-treated nets are the cornerstone of global malaria control and have been shown to reduce malaria morbidity by 50-60%. However, some areas are experiencing a resurgence in malaria following successful control. We describe an efficacy decay framework to understand why high malaria burden persists even under high ITN coverage in a community in western Kenya.We enrolled 442 children hospitalized with malaria and paired them with age, time, village and gender-matched controls. We completed comprehensive household and neighborhood assessments including entomological surveillance. The indicators are grouped into five domains in an efficacy decay framework: ITN ownership, compliance, physical integrity, vector susceptibility and facilitating factors. After variable selection, case-control data were analyzed using conditional logistic regression models and mosquito data were analyzed using negative binomial regression. Predictive margins were calculated from logistic regression models.Measures of ITN coverage and physical integrity were not correlated with hospitalized malaria in our study. However, consistent ITN use (Adjusted Odds Ratio (AOR = 0.23, 95%CI: 0.12-0.43, presence of nearby larval sites (AOR = 1.137, 95%CI: 1.02-1.27, and specific types of crops (AOR (grains = 0.446, 95%CI: 0.24-0.82 were significantly correlated with malaria amongst children who owned an ITN. The odds of hospitalization for febrile malaria nearly tripled when one other household member had symptomatic malaria infection (AOR-2.76, 95%CI:1.83-4.18. Overall, perfect household adherence could reduce the probability of hospitalization for malaria to less than 30% (95%CI:0.12-0.46 and adjusting environmental factors such as elimination of larval sites and growing grains nearby could reduce the probability of hospitalization for malaria to less than 20% (95%CI:0.04-0.31.Availability of ITNs is not the bottleneck for malaria prevention in this community. Behavior

  18. Costs and effects of the Tanzanian national voucher scheme for insecticide-treated nets

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    Hanson Kara

    2008-02-01

    Full Text Available Abstract Background The cost-effectiveness of insecticide-treated nets (ITNs in reducing morbidity and mortality is well established. International focus has now moved on to how best to scale up coverage and what financing mechanisms might be used to achieve this. The approach in Tanzania has been to deliver a targeted subsidy for those most vulnerable to the effects of malaria while at the same time providing support to the development of the commercial ITN distribution system. In October 2004, with funds from the Global Fund to Fight AIDS Tuberculosis and Malaria, the government launched the Tanzania National Voucher Scheme (TNVS, a nationwide discounted voucher scheme for ITNs for pregnant women and their infants. This paper analyses the costs and effects of the scheme and compares it with other approaches to distribution. Methods Economic costs were estimated using the ingredients approach whereby all resources required in the delivery of the intervention (including the user contribution are quantified and valued. Effects were measured in terms of number of vouchers used (and therefore nets delivered and treated nets years. Estimates were also made for the cost per malaria case and death averted. Results and Conclusion The total financial cost of the programme represents around 5% of the Ministry of Health's total budget. The average economic cost of delivering an ITN using the voucher scheme, including the user contribution, was $7.57. The cost-effectiveness results are within the benchmarks set by other malaria prevention studies. The Government of Tanzania's approach to scaling up ITNs uses both the public and private sectors in order to achieve and sustain the level of coverage required to meet the Abuja targets. The results presented here suggest that the TNVS is a cost-effective strategy for delivering subsidized ITNs to targeted vulnerable groups.

  19. Anopheline and culicine mosquitoes are not repelled by surfaces treated with the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana

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    Mnyone Ladslaus L

    2010-08-01

    Full Text Available Abstract Background Entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, are promising bio-pesticides for application against adult malaria mosquito vectors. An understanding of the behavioural responses of mosquitoes towards these fungi is necessary to guide development of fungi beyond the 'proof of concept' stage and to design suitable intervention tools. Methods Here we tested whether oil-formulations of the two fungi could be detected and avoided by adult Anopheles gambiae s.s., Anopheles arabiensis and Culex quinquefasciatus. The bioassays used a glass chamber divided into three compartments (each 250 × 250 × 250 mm: release, middle and stimulus compartments. Netting with or without fungus was fitted in front of the stimulus compartment. Mosquitoes were released and the proportion that entered the stimulus compartment was determined and compared between treatments. Treatments were untreated netting (control 1, netting with mineral oil (control 2 and fungal conidia formulated in mineral oil evaluated at three different dosages (2 × 1010, 4 × 1010 and 8 × 1010 conidia m-2. Results Neither fungal strain was repellent as the mean proportion of mosquitoes collected in the stimulus compartment did not differ between experiments with surfaces treated with and without fungus regardless of the fungal isolate and mosquito species tested. Conclusion Our results indicate that mineral-oil formulations of M. anisopliae and B. bassiana were not repellent against the mosquito species tested. Therefore, both fungi are suitable candidates for the further development of tools that aim to control host-seeking or resting mosquitoes using entomopathogenic fungi.

  20. Outcome of Patients with Cholinergic Insecticide Poisoning Treated with Gastric Lavage: A Prospective Observational Cohort Study

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    Mekkattukunnel Andrews

    2014-12-01

    Conclusion: Number or timing of GL does not show any association with mortality while multiple GL had protective effect against development of late RF and IMS. Hence, GL might be beneficial in cholinergic insecticide poisoning.

  1. Evaluating the efficacy of biological and conventional insecticides with the new 'MCD bottle' bioassay.

    Science.gov (United States)

    Sternberg, Eleanore D; Waite, Jessica L; Thomas, Matthew B

    2014-12-16

    Control of mosquitoes requires the ability to evaluate new insecticides and to monitor resistance to existing insecticides. Monitoring tools should be flexible and low cost so that they can be deployed in remote, resource poor areas. Ideally, a bioassay should be able to simulate transient contact between mosquitoes and insecticides, and it should allow for excito-repellency and avoidance behaviour in mosquitoes. Presented here is a new bioassay, which has been designed to meet these criteria. This bioassay was developed as part of the Mosquito Contamination Device (MCD) project and, therefore, is referred to as the MCD bottle bioassay. Presented here are two experiments that serve as a proof-of-concept for the MCD bottle bioassay. The experiments used four insecticide products, ranging from fast-acting, permethrin-treated, long-lasting insecticide nets (LLINs) that are already widely used for malaria vector control, to the slower acting entomopathogenic fungus, Beauveria bassiana, that is currently being evaluated as a prospective biological insecticide. The first experiment used the MCD bottle to test the effect of four different insecticides on Anopheles stephensi with a range of exposure times (1 minute, 3 minutes, 1 hour). The second experiment is a direct comparison of the MCD bottle and World Health Organization (WHO) cone bioassay that tests a subset of the insecticides (a piece of LLIN and a piece of netting coated with B. bassiana spores) and a further reduced exposure time (5 seconds) against both An. stephensi and Anopheles gambiae. Immediate knockdown and mortality after 24 hours were assessed using logistic regression and daily survival was assessed using Cox proportional hazards models. Across both experiments, fungus performed much more consistently than the chemical insecticides but measuring the effect of fungus required monitoring of mosquito mortality over several days to a week. Qualitatively, the MCD bottle and WHO cone performed comparably

  2. Insecticide - treated bednet ownership and utilization in Rivers State, Nigeria before a state-wide net distribution campaign.

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    Tobin-West, C I; Alex-Hart, B A

    2011-09-01

    Malaria presents a huge health and economic burden to families living in malaria endemic areas. The use of insecticide-treated nets (ITNs) is one of the global strategies in decreasing the malaria burden on vulnerable populations. The use of ITNs reduces clinical malaria by over 50% and all cause mortality in children by 15-30% when the overall population coverage is >70%. This study was aimed at establishing the level of household insecticide -treated bednet ownership and utilization in Rivers State, Nigeria before a statewide scale -up distribution campaign. A descriptive, cross - sectional study was carried out in the Rivers State in November 2008 among household heads or their proxies to serve as a pre -intervention baseline for the scale -up distribution of insecticide treated bednets in the state. The households were selected by a multi -staged sampling technique: first stage being the selection of Local Government Areas (LGAs) from Senatorial districts, second stage the selection of communities from LGAs and final stage the selection of households. Data were collected using a questionnaire adapted from the WHO/FMoH and analyzed using the Epi -Info version 6.04d statistical software package. Hypothesis tests were conducted to compare summary statistics at 95% significance level. A total of 811 household heads or their proxies were interviewed. Their age ranged between 20 and 70 yr, with a mean of 47.96 ± 4.39 yr. The study showed that although 552 (68.1%) of the households owned bednets, only 245 (30.2%, 95% CI=27.1-33.5) of them owned long -lasting insecticidal nets (LLINs). Similarly, only 37.2% of those who owned ITNs slept under them the night preceding the survey. Household ITN ownership and utilization were low in the state. Incorporating behavour change communication package as part of the ITN distribution intervention is advocated to increase ITNs utilization in the state.

  3. Determinants of use of insecticide treated nets for the prevention of malaria in pregnancy: Jinja, Uganda.

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    Laura R Sangaré

    Full Text Available BACKGROUND: One established means of preventing the adverse consequences of malaria during pregnancy is sleeping under an insecticide treated net (ITN throughout pregnancy. Despite increased access to this intervention over time, consistent ITN use during pregnancy remains relatively uncommon in sub-Saharan Africa. METHODOLOGY/PRINCIPAL FINDINGS: We sought to identify determinants of ITN use during pregnancy. Utilizing a population-based random sample, we interviewed 500 women living in Jinja, Uganda, who had been pregnant in the past year. ITN ownership at the start of pregnancy was reported by 359 women (72% and 28 women (20% acquired an ITN after the first trimester of pregnancy. Among 387 ITN owners, 73% reported either always sleeping under the ITN during all trimesters of pregnancy, or after acquiring their net. Owning more than 1 net was slightly associated with always sleeping under an ITN during pregnancy (RR: 1.13; 95% CI: 1.00, 1.28. Women who always slept under an ITN during pregnancy were more likely to be influenced by an advertisement on the radio/poster than being given an ITN free of charge (RR: 1.48; 95% CI: 1.24, 1.76. No differences were found between other socio-demographic factors, pregnancy history, ANC use or socio-cultural factors. CONCLUSIONS/SIGNIFICANCE: While self-reported ITN ownership and use was common throughout pregnancy, we were unable to pinpoint why a sizable fraction of Ugandan women did not always adhere to recommendations for use of an ITN during pregnancy. More data are needed on the capacity of individual households to support the installation of ITNs which may provide insight into interventions targeted at improving the convenience and adherence of daily ITN use.

  4. Community cooperatives and insecticide-treated materials for malaria control: a new experience in Latin America

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    Ordoñnez-Gonzalez José

    2002-11-01

    Full Text Available Abstract Background and objectives Insecticide-treated materials (ITMs are effective in substantially reducing the burden of malaria and other vector-borne diseases; but how can high coverage rates of ITMs be achieved and maintained? In south Mexico and on the Pacific and Atlantic coasts of Colombia 14 community-based cooperatives offering three different kinds of ITM services (sale of impregnation services; sale of impregnated nets; production of nets and sale of impregnated nets were formed and supervised by a national health service (IMSS-SOLIDARIDAD, Mexico and by an academic institution (the Colombian Institute of Tropical Medicine along with local district health services. The objectives of this research were to analyse the processes and results of this approach and to identify the favourable and limiting factors. Methods The methods used for data collection and analysis were group discussions, individual and semi-structured interviews with users and non-users of ITMs, individual in-depth interviews with cooperative members and supervisors, checks of sales book and observation of impregnation services. Results Coverage with unimpregnated nets was above 50% in all study areas. The fastest increase of ITM coverage was achieved through the exclusive sale of impregnation services. Low-cost social marketing techniques were used to increase demand. The large-scale production of nets in two cooperatives was only possible with the aid of an international NGO which ordered impregnated bednets for their target group. A number of favourable and limiting factors relating to the success of ITM cooperatives were identified. Of particular importance for the more successful Mexican cooperatives were: a support by health services, b smaller size, c lesser desire for quick returns and d lower ITM unit costs. Conclusions ITM community cooperatives supported and supervised by the health services have good potential in the Latin American context for achieving

  5. Determinants of insecticide-treated net ownership and utilization among pregnant women in Nigeria

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    Ankomah Augustine

    2012-02-01

    Full Text Available Abstract Background Malaria during pregnancy is a major public health problem in Nigeria leading to increase in the risk of maternal mortality, low birth weight and infant mortality. This paper is aimed at highlighting key predictors of the ownership of insecticide treated nets (ITNs and its use among pregnant women in Nigeria. Methods A total of 2348 pregnant women were selected by a multi-stage probability sampling technique. Structured interview schedule was used to elicit information on socio-demographic characteristics, ITN ownership, use, knowledge, behaviour and practices. Logistic regression was used to detect predictors of two indicators: ITN ownership, and ITN use in pregnancy among those who owned ITNs. Results ITN ownership was low; only 28.8% owned ITNs. Key predictors of ITN ownership included women who knew that ITNs prevent malaria (OR = 3.85; p p = 0.003. The use of ITNs was equally low with only 7.5% of all pregnant women, and 25.7% of all pregnant women who owned ITNs sleeping under a net. The predictors of ITN use in pregnancy among women who owned ITNs (N = 677 identified by logistic regression were: urban residence (OR = 1.87; p = 0.001; knowledge that ITNs prevent malaria (OR = 2.93; p p = 0.036. Educational level was not significantly related to any of the two outcome variables. Although registration at ANC is significantly associated with ownership of a bednet (perhaps through free ITN distribution this does not translate to significant use of ITNs. Conclusions ITN use lagged well behind ITN ownership. This seems to suggest that the current mass distribution of ITNs at antenatal facilities and community levels may not necessarily lead to use unless it is accompanied by behaviour change interventions that address the community level perceptions, misconceptions and positively position ITN as an effective prevention device to prevent malaria

  6. Community cooperatives and insecticide-treated materials for malaria control: a new experience in Latin America.

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    Kroeger, Axel; Aviñna, Ana; Ordoñnez-Gonzalez, José; Escandon, Celia

    2002-11-15

    Insecticide-treated materials (ITMs) are effective in substantially reducing the burden of malaria and other vector-borne diseases; but how can high coverage rates of ITMs be achieved and maintained? In south Mexico and on the Pacific and Atlantic coasts of Colombia 14 community-based cooperatives offering three different kinds of ITM services (sale of impregnation services; sale of impregnated nets; production of nets and sale of impregnated nets) were formed and supervised by a national health service (IMSS-SOLIDARIDAD, Mexico) and by an academic institution (the Colombian Institute of Tropical Medicine) along with local district health services. The objectives of this research were to analyse the processes and results of this approach and to identify the favourable and limiting factors. The methods used for data collection and analysis were group discussions, individual and semi-structured interviews with users and non-users of ITMs, individual in-depth interviews with cooperative members and supervisors, checks of sales book and observation of impregnation services. Coverage with unimpregnated nets was above 50% in all study areas. The fastest increase of ITM coverage was achieved through the exclusive sale of impregnation services. Low-cost social marketing techniques were used to increase demand. The large-scale production of nets in two cooperatives was only possible with the aid of an international NGO which ordered impregnated bednets for their target group. A number of favourable and limiting factors relating to the success of ITM cooperatives were identified. Of particular importance for the more successful Mexican cooperatives were: a) support by health services, b) smaller size, c) lesser desire for quick returns and d) lower ITM unit costs. ITM community cooperatives supported and supervised by the health services have good potential in the Latin American context for achieving and maintaining high impregnation rates.

  7. 植物源杀虫剂和驱避剂在蚊虫防制中的研究进展%Plant origin insecticides and repellents in mosquito control

    Institute of Scientific and Technical Information of China (English)

    杨频; 盛慧锋

    2010-01-01

    With more and more attentions being paid to environmental protection, greater and greater pressure has been faced to use the traditional chemical insecticides. It is a research hot spot in mosquito control to exploit some plant origin insecticides/repellents with high effectiveness, low toxicity and less easiness to e-merge resistance. This paper summarized the research progress on plant origin insecticides/repellents in mos-quito control.%随着人们环保意识的提高,使用化学杀虫剂面临的压力越来越大,开发高效、低毒或无毒、不易产生抗性的植物源杀虫剂和驱避剂已成为蚊虫化学防制的热点.该文综述了近5年植物源杀虫剂和驱避剂在蚊虫防制中的研究进展.

  8. The impact of mass drug administration and long-lasting insecticidal net distribution on Wuchereria bancrofti infection in humans and mosquitoes: an observational study in northern Uganda

    Science.gov (United States)

    2011-01-01

    Background Lymphatic filariasis (LF) in Uganda is caused by Wuchereria bancrofti and transmitted by anopheline mosquitoes. The mainstay of elimination has been annual mass drug administration (MDA) with ivermectin and albendazole, targeted to endemic districts, but has been sporadic and incomplete in coverage. Vector control could potentially contribute to reducing W. bancrofti transmission, speeding up progress towards elimination. To establish whether the use of long-lasting insecticidal nets (LLINs) can contribute towards reducing transmission of W. bancrofti in a setting with ongoing MDA, a study was conducted in an area of Uganda highly endemic for both LF and malaria. Baseline parasitological and entomological assessments were conducted in 2007, followed by high-coverage LLIN distribution. Net use and entomological surveys were carried out after one year, and final parasitological and entomological evaluations were conducted in 2010. Three rounds of MDA had taken place before the study commenced, with a further three rounds completed during the course of the study. Results In 2007, rapid mapping indicated 22.3% of schoolchildren were W. bancrofti antigen positive, and a baseline survey during the same year found age-adjusted microfilaraemia prevalence was 3.7% (95% confidence interval (CI): 2.6-5.3%). In 2010, age-adjusted microfilaraemia prevalence had fallen to 0.4%, while antigenaemia rates were 0.2% in children against W. bancrofti antigen (odds ratio = 0.44, 95% CI: 0.22-0.89). Prevalence of W. bancrofti larvae in anopheline mosquitoes had decreased significantly between the 2007 and 2010 surveys, but there was an apparent increase in vector densities. Conclusion A marked reduction in W. bancrofti infection and infectivity in humans was observed in the study area, where both MDA and LLINs were used to reduce transmission. The extent to which LLINs contributed to this decline is equivocal, however. Further work investigating the impact of vector control

  9. The infectivity of the entomopathogenic fungus Beauveria bassiana to insecticide-resistant and susceptible Anopheles arabiensis mosquitoes at two different temperatures

    NARCIS (Netherlands)

    Kikankie, C.K.; Brooke, B.D.; Knols, B.G.J.; Koekemoer, L.L.; Farenhorst, M.; Hunt, R.H.; Thomas, M.B.; Coetzee, M.

    2010-01-01

    BACKGROUND: Control of the major African malaria vector species continues to rely extensively on the application of residual insecticides through indoor house spraying or bed net impregnation. Insecticide resistance is undermining the sustainability of these control strategies. Alternatives to the

  10. Determinants of use of insecticide-treated nets among pregnant women in Nigeria

    Science.gov (United States)

    Ezire, Onoriode; Adebayo, Samson B; Idogho, Omokhudu; Bamgboye, Elijah A; Nwokolo, Ernest

    2015-01-01

    Background Malaria in pregnancy is still a major health issue in Nigeria, accounting for about 33% of cause of maternal death. Despite massive efforts to make insecticide-treated net (ITN) available to pregnant women in Nigeria, the use is still low. This study was conducted to identify facilitators and inhibitors for the use of ITN/long-lasting insecticidal net (LLIN) among pregnant women in Nigeria. Methods Data were obtained from the 2011 State-Specific HIV & AIDS, Reproductive and Child Health Survey conducted in 18 states of Nigeria. The survey was a population-based study among men and women of reproductive age living in households in rural and urban areas of Nigeria. Multistage cluster sampling technique was used to select eligible respondents. The sample size per state was 960 respondents. Data were collected between October and November 2011. The analysis was done using Statistical Package for Social Sciences (SPSS) version 20. Results A total of 11.5% of the respondents were pregnant at the time of the survey of which 73.2% lived in rural location and approximately 70% were either not educated or attained at most a primary school education. A total of 93.2% of respondents have heard of net, 82.6% were confident that they can hang or use a net, and 64.6% owned an ITN/LLIN in their household while the actual use was just 19.2%. We found education, location (urban–rural), confidence to use a net, and knowledge that the use of a net can protect a pregnant woman from malaria to be significant at 5% level. The number of nets owned per household, the length of time the net is owned, age, and marital status were not significant. Multiple logistics regression shows that pregnant women who are confident to hang or use a net were almost ten times more likely to use a net than those who do not know, while those who know that the use of an ITN/LLIN can protect a pregnant woman from malaria were almost two times more likely to use a net than those who do not know

  11. Synergism between permethrin and propoxur against Culex quinquefasciatus mosquito larvae.

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    Corbel, V; Chandre, F; Darriet, F; Lardeux, F; Hougard, J-M

    2003-06-01

    To see if synergism occurs between carbamate and pyrethroid insecticides, we tested permethrin and propoxur as representatives of these two classes of compounds used for mosquito control. Larvicidal activity of both insecticides was assessed separately and together on a susceptible strain of the mosquito Culex quinquefasciatus (Diptera: Culicidae) by two methods. When mixed at a constant ratio (permethrin : propoxur 1 : 60 based on LC50) and tested at serial concentrations to plot dose/mortality regression, significant synergy occurred between them (co-toxicity coefficient = 2.2), not just an additive effect. For example, when the mixture gave 50% mortality, the same concentrations of permethrin and propoxur alone would have given merely 2 x 1% mortality. When a sublethal dose (LC0) of permethrin or propoxur was added to the other (range LC10-LC95), synergism occurred up to the LC80 level. Synergistic effects were attributed to the complementary modes of action by these two insecticide classes acting on different components of nerve impulse transmission. Apart from raising new possibilities for Culex control, it seems appropriate to consider using such mixtures or combinations for insecticide-treated mosquito nets in situations with insecticide-resistant Anopheles malaria vectors.

  12. Increasing coverage and decreasing inequity in insecticide-treated bed net use among rural Kenyan children.

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    Abdisalan M Noor

    2007-08-01

    Full Text Available BACKGROUND: Inexpensive and efficacious interventions that avert childhood deaths in sub-Saharan Africa have failed to reach effective coverage, especially among the poorest rural sectors. One particular example is insecticide-treated bed nets (ITNs. In this study, we present repeat observations of ITN coverage among rural Kenyan homesteads exposed at different times to a range of delivery models, and assess changes in coverage across socioeconomic groups. METHODS AND FINDINGS: We undertook a study of annual changes in ITN coverage among a cohort of 3,700 children aged 0-4 y in four districts of Kenya (Bondo, Greater Kisii, Kwale, and Makueni annually between 2004 and 2006. Cross-sectional surveys of ITN coverage were undertaken coincidentally with the incremental availability of commercial sector nets (2004, the introduction of heavily subsidized nets through clinics (2005, and the introduction of free mass distributed ITNs (2006. The changing prevalence of ITN coverage was examined with special reference to the degree of equity in each delivery approach. ITN coverage was only 7.1% in 2004 when the predominant source of nets was the commercial retail sector. By the end of 2005, following the expansion of heavily subsidized clinic distribution system, ITN coverage rose to 23.5%. In 2006 a large-scale mass distribution of ITNs was mounted providing nets free of charge to children, resulting in a dramatic increase in ITN coverage to 67.3%. With each subsequent survey socioeconomic inequity in net coverage sequentially decreased: 2004 (most poor [2.9%] versus least poor [15.6%]; concentration index 0.281; 2005 (most poor [17.5%] versus least poor [37.9%]; concentration index 0.131, and 2006 with near-perfect equality (most poor [66.3%] versus least poor [66.6%]; concentration index 0.000. The free mass distribution method achieved highest coverage among the poorest children, the highly subsidised clinic nets programme was marginally in favour of

  13. Public-private delivery of insecticide-treated nets: a voucher scheme in Volta Region, Ghana

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    Taylor Ian

    2007-02-01

    Full Text Available Abstract Background Coverage of vulnerable groups with insecticide-treated nets (ITNs in Ghana, as in the majority of countries of sub-Saharan Africa is currently low. A voucher scheme was introduced in Volta Region as a possible sustainable delivery system for increasing this coverage through scale-up to other regions. Successful scale-up of public health interventions depends upon optimal delivery processes but operational research for delivery processes in large-scale implementation has been inadequate. Methods A simple tool was developed to monitor numbers of vouchers given to each health facility, numbers issued to pregnant women by the health staff, and numbers redeemed by the distributors back to the management agent. Three rounds of interviews were undertaken with health facility staff, retailers and pregnant women who had attended antenatal clinic (ANC. Results During the one year pilot 25,926 vouchers were issued to eligible women from clinics, which equates to 50.7% of the 51,658 ANC registrants during this time period. Of the vouchers issued 66.7% were redeemed by distributors back to the management agent. Initially, non-issuing of vouchers to pregnant women was mainly due to eligibility criteria imposed by the midwives; later in the year it was due to decisions of the pregnant women, and supply constraints. These in turn were heavily influenced by factors external to the programme: current household ownership of nets, competing ITN delivery strategies, and competition for the limited number of ITNs available in the country from major urban areas of other regions. Conclusion Both issuing and redemption of vouchers should be monitored as factors assumed to influence voucher redemption had an influence on issuing, and vice versa. More evidence is needed on how specific contextual factors influence the success of voucher schemes and other models of delivery of ITNs. Such an evidence base will facilitate optimal strategic decision making

  14. Malaria transmission pattern resilience to climatic variability is mediated by insecticide-treated nets

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    Taleo George

    2008-06-01

    Full Text Available Abstract Background Malaria is an important public-health problem in the archipelago of Vanuatu and climate has been hypothesized as important influence on transmission risk. Beginning in 1988, a major intervention using insecticide-treated bed nets (ITNs was implemented in the country in an attempt to reduce Plasmodium transmission. To date, no study has addressed the impact of ITN intervention in Vanuatu, how it may have modified the burden of disease, and whether there were any changes in malaria incidence that might be related to climatic drivers. Methods and findings Monthly time series (January 1983 through December 1999 of confirmed Plasmodium falciparum and Plasmodium vivax infections in the archipelago were analysed. During this 17 year period, malaria dynamics underwent a major regime shift around May 1991, following the introduction of bed nets as a control strategy in the country. By February of 1994 disease incidence from both parasites was reduced by at least 50%, when at most 20% of the population at risk was covered by ITNs. Seasonal cycles, as expected, were strongly correlated with temperature patterns, while inter-annual cycles were associated with changes in precipitation. Following the bed net intervention, the influence of environmental drivers of malaria dynamics was reduced by 30–80% for climatic forces, and 33–54% for other factors. A time lag of about five months was observed for the qualitative change ("regime shift" between the two parasites, the change occurring first for P. falciparum. The latter might be explained by interspecific interactions between the two parasites within the human hosts and their distinct biology, since P. vivax can relapse after a primary infection. Conclusion The Vanuatu ITN programme represents an excellent example of implementing an infectious disease control programme. The distribution was undertaken to cover a large, local proportion (~80% of people in villages where malaria was

  15. Combining Synthetic Human Odours and Low-Cost Electrocuting Grids to Attract and Kill Outdoor-Biting Mosquitoes: Field and Semi-Field Evaluation of an Improved Mosquito Landing Box.

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    Nancy S Matowo

    Full Text Available On-going malaria transmission is increasingly mediated by outdoor-biting vectors, especially where indoor insecticidal interventions such as long-lasting insecticide treated nets (LLINs are widespread. Often, the vectors are also physiologically resistant to insecticides, presenting major obstacles for elimination. We tested a combination of electrocuting grids with synthetic odours as an alternative killing mechanism against outdoor-biting mosquitoes.An odour-baited device, the Mosquito Landing Box (MLB, was improved by fitting it with low-cost electrocuting grids to instantly kill mosquitoes attracted to the odour lure, and automated photo switch to activate attractant-dispensing and mosquito-killing systems between dusk and dawn. MLBs fitted with one, two or three electrocuting grids were compared outdoors in a malaria endemic village in Tanzania, where vectors had lost susceptibility to pyrethroids. MLBs with three grids were also tested in a large semi-field cage (9.6 × 9.6 × 4.5m, to assess effects on biting-densities of laboratory-reared Anopheles arabiensis on volunteers sitting near MLBs.Significantly more mosquitoes were killed when MLBs had two or three grids, than one grid in wet and dry seasons (P<0.05. The MLBs were highly efficient against Mansonia species and malaria vector, An. arabiensis. Of all mosquitoes, 99% were non-blood fed, suggesting host-seeking status. In the semi-field, the MLBs reduced mean number of malaria mosquitoes attempting to bite humans fourfold.The improved odour-baited MLBs effectively kill outdoor-biting malaria vector mosquitoes that are behaviourally and physiologically resistant to insecticidal interventions e.g. LLINs. The MLBs reduce human-biting vector densities even when used close to humans, and are insecticide-free, hence potentially antiresistance. The devices could either be used as surveillance tools or complementary mosquito control interventions to accelerate malaria elimination where

  16. Push-pull tactics to disrupt the host-seeking behaviour of malaria mosquitoes

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    Menger, D.J.

    2015-01-01

    Malaria remains a major health burden, especially in sub-Saharan Africa. The efficacy of the main vector control tools, insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS), is compromised by the development of physiological and behavioural resistance in the target mosquito species

  17. Push-pull tactics to disrupt the host-seeking behaviour of malaria mosquitoes

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    Menger, D.J.

    2015-01-01

    Malaria remains a major health burden, especially in sub-Saharan Africa. The efficacy of the main vector control tools, insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS), is compromised by the development of physiological and behavioural resistance in the target mosquito species

  18. Decreased proportions of indoor feeding and endophily in Anopheles gambiae s.l. populations following the indoor residual spraying and insecticide-treated net interventions in Benin (West Africa

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    Padonou Gil

    2012-11-01

    Full Text Available Abstract Background In many parts of Africa as in Benin, the main strategies of vector control are based on the scaling-up of Long Lasting Insecticide Treated Nets (LLITNs and indoor residual spraying (IRS. The need to understand the biological implications of IRS in large scale and full coverage of LLITNs is paramount. It is in this context that the present study was conducted. It aims to evaluate the effect of a large scale IRS using a non-pyrethroid insecticide and full coverage of deltamethrin treated nets on the behavior of An. gambiae s.l. in the intervention areas compared to untreated areas used as controls. Methods Mosquitoes were collected using human landing catches, pyrethrum spray catches and window exit traps to assess reduction of entry rate, endophily rate, endophagy rate and overall mortality rate in natural populations of An. gambiae s.l. before IRS and LLITNs intervention (2007 and after in 2008 and 2010. Results In the IRS arm, endophily rate was 67.13% before intervention and 4.5% after intervention, whereas in the control arm it was stable at 51.67% (P > 0 .05. In the LLITN arm endophily rates also decreased after intervention. After the IRS, no gravid mosquitoes were collected from all treated localities, but LLITN performance was not that spectacular. The proportion of mosquitoes biting indoors in the IRS arm decreased from 67.09% before intervention to 42.85% after intervention, compared to a low but significant decrease (71.31% to 57. 46% in the LLITN arm. The use of vector control tools and behavior of the host would be the main factors that modify the behavior of taking a human blood meal observed on An. gambiae s.l. inside human dwellings. Conclusion The impact on the behavior of An. gambiae s.l. observed with the bendiocarb used in IRS was highly effective compared with the free distribution of LLITNs in terms of mortality and the decrease of proportions of indoor feeding. Despite this efficacy, there is a need

  19. Implementation of an insecticide-treated net subsidy scheme under a public-private partnership for malaria control in Tanzania – challenges in implementation

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    Gilson Lucy

    2009-08-01

    Full Text Available Abstract Background In the past decade there has been increasing visibility of malaria control efforts at the national and international levels. The factors that have enhanced this scenario are the availability of proven interventions such as artemisinin-based combination therapy, the wide scale use of insecticide-treated nets (ITNs and a renewed emphasis in indoor residual house-spraying. Concurrently, there has been a window of opportunity of financial commitments from organizations such as the Global Fund for HIV/AIDS, Tuberculosis and Malaria (GFATM, the President's Malaria Initiative and the World Bank Booster programme. Methods The case study uses the health policy analysis framework to analyse the implementation of a public-private partnership approach embarked upon by the government of Tanzania in malaria control – 'The Tanzania National Voucher Scheme'- and in this synthesis, emphasis is on the challenges faced by the scheme during the pre-implementation (2001 – 2004 and implementation phases (2004 – 2005. Qualitative research tools used include: document review, interview with key informants, stakeholder's analysis, force-field analysis, time line of events, policy characteristic analysis and focus group discussions. The study is also complemented by a cross-sectional survey, which was conducted at the Rufiji Health Demographic Surveillance Site, where a cohort of women of child-bearing age were followed up regarding access and use of ITNs. Results The major challenges observed include: the re-introduction of taxes on mosquito nets and related products, procurement and tendering procedures in the implementation of the GFATM, and organizational arrangements and free delivery of mosquito nets through a Presidential initiative. Conclusion The lessons gleaned from this synthesis include: (a the consistency of the stakeholders with a common vision, was an important strength in overcoming obstacles, (b senior politicians often steered

  20. Implementation of an insecticide-treated net subsidy scheme under a public-private partnership for malaria control in Tanzania--challenges in implementation.

    Science.gov (United States)

    Njau, Ritha J A; de Savigny, Don; Gilson, Lucy; Mwageni, Eleuther; Mosha, Franklin W

    2009-08-21

    In the past decade there has been increasing visibility of malaria control efforts at the national and international levels. The factors that have enhanced this scenario are the availability of proven interventions such as artemisinin-based combination therapy, the wide scale use of insecticide-treated nets (ITNs) and a renewed emphasis in indoor residual house-spraying. Concurrently, there has been a window of opportunity of financial commitments from organizations such as the Global Fund for HIV/AIDS, Tuberculosis and Malaria (GFATM), the President's Malaria Initiative and the World Bank Booster programme. The case study uses the health policy analysis framework to analyse the implementation of a public-private partnership approach embarked upon by the government of Tanzania in malaria control - 'The Tanzania National Voucher Scheme'- and in this synthesis, emphasis is on the challenges faced by the scheme during the pre-implementation (2001 - 2004) and implementation phases (2004 - 2005). Qualitative research tools used include: document review, interview with key informants, stakeholder's analysis, force-field analysis, time line of events, policy characteristic analysis and focus group discussions. The study is also complemented by a cross-sectional survey, which was conducted at the Rufiji Health Demographic Surveillance Site, where a cohort of women of child-bearing age were followed up regarding access and use of ITNs. The major challenges observed include: the re-introduction of taxes on mosquito nets and related products, procurement and tendering procedures in the implementation of the GFATM, and organizational arrangements and free delivery of mosquito nets through a Presidential initiative. The lessons gleaned from this synthesis include: (a) the consistency of the stakeholders with a common vision, was an important strength in overcoming obstacles, (b) senior politicians often steered the policy agenda when the policy in question was a 'crisis event

  1. Evaluation of different insecticides and fabric types for development of treated targets for stable fly (Diptera: Muscidae) control.

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    Hogsette, Jerome A; Nalli, Alyce; Foil, Lane D

    2008-06-01

    Stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), once only a pest of pastured cattle, has become a serious pest of range cattle in the United States. Because of the difficulties associated with stable fly management under range conditions, a pesticide-impregnated cloth target is being developed as a management tool. We conducted studies to determine the influence of weather, time, fabric type, insecticide type, and insecticide concentration on the mortality of stable flies from a susceptible laboratory colony exposed for 30 s to treated cloth targets. We found that 100% of the flies exposed to trigger (Trigger-Royal Box, 65% polyester and 35% cotton) fabric targets that were treated with 0.1% h-cyhalothrin or 0.1% zeta-cypermethrin and weathered outdoors in Gainesville, FL., for up to 3 mo, were dead within 20 min after a 30-s exposure. The results of this study support the concept that treated targets can be developed for integration into stable fly control programs.

  2. Bioactivity and laundering resistance of five commercially available, factory-treated permethrin-impregnated fabrics for the prevention of mosquito-borne diseases: the need for a standardized testing and licensing procedure.

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    Faulde, Michael K; Pages, Frederic; Uedelhoven, Waltraud

    2016-04-01

    Personal protective measures against hematophagous vectors constitute the first line of defense against arthropod-borne diseases. In this regard, a major advance has been the development of residual insecticides that can be impregnated into clothing. Currently, however, information on specific treatment procedures, initial insecticide concentrations, arthropod toxicity, residual activity, and laundering resistance is either fragmentary or non-existent, and no World Health Organization Pesticides Evaluation Scheme or other guidelines exist for the standardized testing and licensing of insecticide-treated clothing. The aim of this study was to analyze the insecticide content, contact toxicity, laundering resistance, and residual activity of five commercially available and commonly used permethrin-treated fabrics-Insect Shield, ExOfficio, Sol's Monarch T-shirts, battle dress uniforms (BDUs), and Labonal socks-against vector-competent Aedes aegypti, Anopheles stephensi, and Culex pipiens mosquitoes under laboratory conditions. Prior to laundering, permethrin concentrations ranged from 4300 to 870 mg/m(2) whereas, after 100 defined machine launderings, the remaining permethrin content fell to between 1800 and 20 mg/m(2), a percentage permethrin loss of 58.1 to 98.5 %. The highest 99 % knockdown (KD99) efficacy of permethrin was detected in Ae. aegypti, followed by An. stephensi and Cx. pipiens demonstrating that Ae. aegypti is the most sensitive species and Cx. pipiens the least sensitive. After 100 launderings, the remaining biocidal efficacy differed markedly among the five brands, with KD99 times varying from 38.8 ± 2.9 to >360 min for Ae. aegypti, from 44 ± 3.5 to >360 min for An. stephensi, and from 98 ± 10.6 to >360 min for Cx. pipiens. Overall, the ranking of the residual biocidal efficacies within the five brands tested was as follows: BDU ≈ Labonal > Sol's Monarch > ExOfficio > Insect Shield. When applying German Armed Forces

  3. Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala

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    Rizzo Nidia

    2012-10-01

    Full Text Available Abstract Background In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. Methods The study was conducted as a cluster randomized community trial using “reduction of the vector population” as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.. The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. Results At baseline (during the dry season a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae. After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed in 970 study

  4. Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala.

    Science.gov (United States)

    Rizzo, Nidia; Gramajo, Rodrigo; Escobar, Maria Cabrera; Arana, Byron; Kroeger, Axel; Manrique-Saide, Pablo; Petzold, Max

    2012-10-30

    In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs) alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. The study was conducted as a cluster randomized community trial using "reduction of the vector population" as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods) and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices) at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material) and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.). The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. At baseline (during the dry season) a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae). After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed) in 970 study households, tropical rains occurred in the area and

  5. An examination of the effect of aerosolized permanone insecticide on zebra finch susceptibility to West Nile virus

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    Jankowski, Mark D.; Murray, E. Moore; Hofmeister, Erik K.

    2017-01-01

    West Nile virus is primarily maintained cryptically primarily in avian (Passerine) populations where it is transmitted by Culex spp. mosquitoes. Mosquito control measures currently include physical activities to reduce mosquito breeding sites, the application of mosquito larvicides, or aerosolized insecticides to kill adults (adulticides) when arboviral diseases such as West Nile virus (WNV) or Zika virus are detected in mosquito populations. Organochlorine, organohosphorus, carbamate and pyrethroid insecticides are often used. Previous work suggests an effect of pyrethroids on the immune system in a variety of vertebrates. We examined the effects of exposure to aerosolized Permanone® 30:30 insecticide (permethrin and piperonyl butoxide in soy oil vehicle) at ∼103−106x potential environmental concentrations on the response of captive zebra finches (Taeniopygia guttata) to experimental challenge with WNV. Compared to vehicle control birds, WNV outcome was unchanged (65% of birds produced a viremia) in the ‘low’ exposure (9.52 mg/m3±3.13 SD permethrin) group, but reduced in the ‘high’ exposure (mean 376.5 mg/m3±27.9 SD permethrin) group (30% were viremic) (p < 0.05). After clearing WNV infection, birds treated with Permanone regained less body mass than vehicle treated birds (p < 0.001). Our study suggests that exposure to aerosolized Permanone insecticide at levels exceeding typical application rates has the potential to not change or mildly enhance a bird's resistance to WNV.

  6. "Before we used to get sick all the time": perceptions of malaria and use of long-lasting insecticide-treated bed nets (LLINs in a rural Kenyan community

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    Smith Jacqueline

    2010-11-01

    Full Text Available Abstract Background Malaria is a leading global cause of preventable morbidity and mortality, especially in sub-Saharan Africa, despite recent advances in treatment and prevention technologies. Scale-up and wide distribution of long-lasting insecticide-treated nets (LLINs could rapidly decrease malarial disease in endemic areas, if used properly and continuously. Studies have shown that effective use of LLINs depends, in part, upon understanding causal factors associated with malaria. This study examined malaria beliefs, attitudes, and practices toward LLINs assessed during a large-scale integrated prevention campaign (IPC in rural Kenya. Methods Qualitative interviews were conducted with 34 IPC participants who received LLINs as part of a comprehensive prevention package of goods and services. One month after distribution, interviewers asked these individuals about their attitudes and beliefs regarding malaria, and about their use of LLINs. Results Virtually all participants noted that mosquitoes were involved in causing malaria, though a substantial proportion of participants (47 percent also mentioned an incorrect cause in addition to mosquitoes. For example, participants commonly noted that the weather (rain, cold or consumption of bad food and water caused malaria. Regardless, most participants used the LLINs they were given and most mentioned positive benefits from their use, namely reductions in malarial illness and in the costs associated with its diagnosis and treatment. Conclusions Attitudes toward LLINs were positive in this rural community in Western Kenya, and respondents noted benefits with LLIN use. With improved understanding and clarification of the direct (mosquitoes and indirect (e.g., standing water causes of malaria, it is likely that LLIN use can be sustained, offering effective household-level protection against malaria.

  7. Use of intermittent presumptive treatment and insecticide treated bed nets by pregnant women in four Kenyan districts.

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    Guyatt, H L; Noor, A M; Ochola, S A; Snow, R W

    2004-02-01

    The roll back malaria (RBM) movement promotes the use of insecticide-treated bednets (ITNs) and intermittent presumptive treatment (IPT) of malaria infection as preventive measures against the adverse effects of malaria among pregnant women in Africa. To determine the use of these preventive measures we undertook a community-based survey of recently pregnant women randomly selected from communities in four districts of Kenya in December 2001. Of the 1814 women surveyed, only 5% had slept under an ITN. More than half of the 13% of women using a bednet (treated or untreated) had bought their nets from shops or markets. Women from rural areas used bednets less than urban women (11% vs. 27%; P commodity supply and service costs to clients will be the greatest impediments to reaching RBM targets.

  8. Combining Synthetic Human Odours and Low-Cost Electrocuting Grids to Attract and Kill Outdoor-Biting Mosquitoes: Field and Semi-Field Evaluation of an Improved Mosquito Landing Box.

    Science.gov (United States)

    Matowo, Nancy S; Koekemoer, Lizette L; Moore, Sarah J; Mmbando, Arnold S; Mapua, Salum A; Coetzee, Maureen; Okumu, Fredros O

    2016-01-01

    On-going malaria transmission is increasingly mediated by outdoor-biting vectors, especially where indoor insecticidal interventions such as long-lasting insecticide treated nets (LLINs) are widespread. Often, the vectors are also physiologically resistant to insecticides, presenting major obstacles for elimination. We tested a combination of electrocuting grids with synthetic odours as an alternative killing mechanism against outdoor-biting mosquitoes. An odour-baited device, the Mosquito Landing Box (MLB), was improved by fitting it with low-cost electrocuting grids to instantly kill mosquitoes attracted to the odour lure, and automated photo switch to activate attractant-dispensing and mosquito-killing systems between dusk and dawn. MLBs fitted with one, two or three electrocuting grids were compared outdoors in a malaria endemic village in Tanzania, where vectors had lost susceptibility to pyrethroids. MLBs with three grids were also tested in a large semi-field cage (9.6 × 9.6 × 4.5m), to assess effects on biting-densities of laboratory-reared Anopheles arabiensis on volunteers sitting near MLBs. Significantly more mosquitoes were killed when MLBs had two or three grids, than one grid in wet and dry seasons (Pmosquitoes, 99% were non-blood fed, suggesting host-seeking status. In the semi-field, the MLBs reduced mean number of malaria mosquitoes attempting to bite humans fourfold. The improved odour-baited MLBs effectively kill outdoor-biting malaria vector mosquitoes that are behaviourally and physiologically resistant to insecticidal interventions e.g. LLINs. The MLBs reduce human-biting vector densities even when used close to humans, and are insecticide-free, hence potentially antiresistance. The devices could either be used as surveillance tools or complementary mosquito control interventions to accelerate malaria elimination where outdoor transmission is significant.

  9. The infectivity of the entomopathogenic fungus Beauveria bassiana to insecticide-resistant and susceptible Anopheles arabiensis mosquitoes at two different temperatures

    NARCIS (Netherlands)

    Kikankie, C.K.; Brooke, B.D.; Knols, B.G.J.; Koekemoer, L.L.; Farenhorst, M.; Hunt, R.H.; Thomas, M.B.; Coetzee, M.

    2010-01-01

    BACKGROUND: Control of the major African malaria vector species continues to rely extensively on the application of residual insecticides through indoor house spraying or bed net impregnation. Insecticide resistance is undermining the sustainability of these control strategies. Alternatives to the c

  10. Multiple insecticide resistance: an impediment to insecticide-based malaria vector control program.

    Directory of Open Access Journals (Sweden)

    Delenasaw Yewhalaw

    Full Text Available BACKGROUND: Indoor Residual Spraying (IRS, insecticide-treated nets (ITNs and long-lasting insecticidal nets (LLINs are key components in malaria prevention and control strategy. However, the development of resistance by mosquitoes to insecticides recommended for IRS and/or ITNs/LLINs would affect insecticide-based malaria vector control. We assessed the susceptibility levels of Anopheles arabiensis to insecticides used in malaria control, characterized basic mechanisms underlying resistance, and evaluated the role of public health use of insecticides in resistance selection. METHODOLOGY/PRINCIPAL FINDINGS: Susceptibility status of An. arabiensis was assessed using WHO bioassay tests to DDT, permethrin, deltamethrin, malathion and propoxur in Ethiopia from August to September 2009. Mosquito specimens were screened for knockdown resistance (kdr and insensitive acetylcholinesterase (ace-1(R mutations using AS-PCR and PCR-RFLP, respectively. DDT residues level in soil from human dwellings and the surrounding environment were determined by Gas Chromatography with Electron Capture Detector. An. arabiensis was resistant to DDT, permethrin, deltamethrin and malathion, but susceptible to propoxur. The West African kdr allele was found in 280 specimens out of 284 with a frequency ranged from 95% to 100%. Ace-1(R mutation was not detected in all specimens scored for the allele. Moreover, DDT residues were found in soil samples from human dwellings but not in the surrounding environment. CONCLUSION: The observed multiple-resistance coupled with the occurrence of high kdr frequency in populations of An. arabiensis could profoundly affect the malaria vector control programme in Ethiopia. This needs an urgent call for implementing rational resistance management strategies and integrated vector control intervention.

  11. Mosquito Nets Treated with a Mixture of Chlorfenapyr and Alphacypermethrin Control Pyrethroid Resistant Anopheles gambiae and Culex quinquefasciatus Mosquitoes in West Africa: e87710

    National Research Council Canada - National Science Library

    Corine Ngufor; Andreas A Kudom; Pelagie Boko; Abibathou Odjo; David Malone; Mark Rowland

    2014-01-01

    .... Methods The pyrrole chlorfenapyr and the pyrethroid alphacypermethrin were tested individually and as a mixture on mosquito nets in an experimental hut trial in southern Benin against pyrethroid...

  12. Novel AChE inhibitors for sustainable insecticide resistance management.

    Directory of Open Access Journals (Sweden)

    Haoues Alout

    Full Text Available Resistance to insecticides has become a critical issue in pest management and it is particularly chronic in the control of human disease vectors. The gravity of this situation is being exacerbated since there has not been a new insecticide class produced for over twenty years. Reasoned strategies have been developed to limit resistance spread but have proven difficult to implement in the field. Here we propose a new conceptual strategy based on inhibitors that preferentially target mosquitoes already resistant to a currently used insecticide. Application of such inhibitors in rotation with the insecticide against which resistance has been selected initially is expected to restore vector control efficacy and reduce the odds of neo-resistance. We validated this strategy by screening for inhibitors of the G119S mutated acetylcholinesterase-1 (AChE1, which mediates insensitivity to the widely used organophosphates (OP and carbamates (CX insecticides. PyrimidineTrione Furan-substituted (PTF compounds came out as best hits, acting biochemically as reversible and competitive inhibitors of mosquito AChE1 and preferentially inhibiting the mutated form, insensitive to OP and CX. PTF application in bioassays preferentially killed OP-resistant Culex pipiens and Anopheles gambiae larvae as a consequence of AChE1 inhibition. Modeling the evolution of frequencies of wild type and OP-insensitive AChE1 alleles in PTF-treated populations using the selectivity parameters estimated from bioassays predicts a rapid rise in the wild type allele frequency. This study identifies the first compound class that preferentially targets OP-resistant mosquitoes, thus restoring OP-susceptibility, which validates a new prospect of sustainable insecticide resistance management.

  13. Sodium channel gene expression in mosquitoes, Aedes albopictus (S.)

    Institute of Scientific and Technical Information of China (English)

    NANNAN LIU; QIANG XU; LEE ZHANG

    2006-01-01

    A mosquito strain of Aerdes albopictus,HAmAalG0,from Huntsville,Alabama,USA,showed a normal susceptibility and low tolerance to permethrin and resmethrin (pyrethroid insecticides) compared to a susceptible Ikaken strain,even though these pyrethroid insecticides have been used in the field for a long period of time in Alabama.Recently,we treated HAmAalG0 in the laboratory with permethrin for five generations and detected no significant change in the level of resistance to permethrin in the selected mosquitoes,HAmAalG5,compared with the parental strain HAmAalG0. We then examined the allelic expression at the L-to-F kdr site of the sodium channel gene in the Aedes mosquitoes to address our hypothesis that the L-to-F kdr mutation was not present in HAmAalG0 and HAmAalG5 mosquitoes. We found that every tested individual in Ikaken,HAmAalG0,and HAmAalG5 populations expressed a codon of CTA at the L-to-F kdr site encoding Leu,strongly corresponding to their susceptibility to insecticides.

  14. Metabolomic profiling of permethrin-treated Drosophila melanogaster identifies a role for tryptophan catabolism in insecticide survival.

    Science.gov (United States)

    Brinzer, Robert A; Henderson, Louise; Marchiondo, Alan A; Woods, Debra J; Davies, Shireen A; Dow, Julian A T

    2015-12-01

    Insecticides and associated synergists are rapidly losing efficacy in target insect pest populations making the discovery of alternatives a priority. To discover novel targets for permethrin synergists, metabolomics was performed on permethrin-treated Drosophila melanogaster. Changes were observed in several metabolic pathways including those for amino acids, glycogen, glycolysis, energy, nitrogen, NAD(+), purine, pyrimidine, lipids and carnitine. Markers for acidosis, ammonia stress, oxidative stress and detoxification responses were also observed. Many of these changes had not been previously characterized after permethrin exposure. From the altered pathways, tryptophan catabolism was selected for further investigation. The knockdown of some tryptophan catabolism genes (vermilion, cinnabar and CG6950) in the whole fly and in specific tissues including fat body, midgut and Malpighian tubules using targeted RNAi resulted in altered survival phenotypes against acute topical permethrin exposure. The knockdown of vermilion, cinnabar and CG6950 in the whole fly also altered survival phenotypes against chronic oral permethrin, fenvalerate, DDT, chlorpyriphos and hydramethylnon exposure. Thus tryptophan catabolism has a previously uncharacterized role in defence against insecticides, and shows that metabolomics is a powerful tool for target identification in pesticide research.

  15. Community Structure of Ammonia-Oxidizing Archaea and Ammonia-Oxidizing Bacteria in Soil Treated with the Insecticide Imidacloprid

    Directory of Open Access Journals (Sweden)

    Mariusz Cycoń

    2015-01-01

    Full Text Available The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA and ammonia-oxidizing bacteria (AOB in soil using the denaturing gradient gel electrophoresis (DGGE approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S and the Shannon-Wiener index (H values for soil treated with the field rate (FR dosage of imidacloprid (1 mg/kg soil showed no changes in measured indices for the AOA and AOB community members. In turn, the 10*FR dosage of insecticide (10 mg/kg soil negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4+, known as the most important factor which determines the contribution of these microorganisms to soil nitrification.

  16. Equity and coverage of insecticide-treated bed nets in an area of intense transmission of Plasmodium falciparum in Tanzania

    Directory of Open Access Journals (Sweden)

    Mtei Frank

    2009-04-01

    Full Text Available Abstract Background There is no clear consensus on the most sustainable and effective distribution strategy for insecticide treated bed nets (ITNs. Tanzania has been a leader in social marketing but it is still not clear if this can result in high and equitable levels of coverage. Methods A cluster-randomized survey of ITN and bed net ownership and use was conducted in a rural area exposed to intense Plasmodium falciparum transmission in NE Tanzania where ITN distribution had been subject to routine delivery of national strategies and episodic free distribution through local clinics. Data were collected on household assets to assess equity of ITN coverage and a rapid diagnostic test for malaria (RDT was performed in all ages. Results Among 598 households in four villages the use of any or insecticidal bed nets in children less than five years of age was 71% and 54% respectively. However there was a 19.8% increase in the number of bed nets per person (p Conclusion Marked inequity persists with the poorest households still experiencing the highest risk of malaria and the lowest ITN coverage. Abolition of this inequity within the foreseeable future is likely to require mass or targeted free distribution, but risks damaging what is otherwise an effective commercial market.

  17. Mosquito-Disseminated Insecticide for Citywide Vector Control and Its Potential to Block Arbovirus Epidemics: Entomological Observations and Modeling Results from Amazonian Brazil.

    Science.gov (United States)

    Abad-Franch, Fernando; Zamora-Perea, Elvira; Luz, Sérgio L B

    2017-01-01

    Mosquito-borne viruses threaten public health worldwide. When the ratio of competent vectors to susceptible humans is low enough, the virus's basic reproductive number (R0) falls below 1.0 (each case generating, on average, <1.0 additional case) and the infection fades out from the population. Conventional mosquito control tactics, however, seldom yield R0 < 1.0. A promising alternative uses mosquitoes to disseminate a potent growth-regulator larvicide, pyriproxyfen (PPF), to aquatic larval habitats; this kills most mosquito juveniles and substantially reduces adult mosquito emergence. We tested mosquito-disseminated PPF in Manacapuru, a 60,000-inhabitant city (~650 ha) in Amazonian Brazil. We sampled juvenile mosquitoes monthly in 100 dwellings over four periods in February 2014-January 2016: 12 baseline months, 5 mo of citywide PPF dissemination, 3 mo of focal PPF dissemination around Aedes-infested dwellings, and 3 mo after dissemination ended. We caught 19,434 juvenile mosquitoes (66% Aedes albopictus, 28% Ae. aegypti) in 8,271 trap-months. Using generalized linear mixed models, we estimated intervention effects on juvenile catch and adult emergence while adjusting for dwelling-level clustering, unequal sampling effort, and weather-related confounders. Following PPF dissemination, Aedes juvenile catch decreased by 79%-92% and juvenile mortality increased from 2%-7% to 80%-90%. Mean adult Aedes emergence fell from 1,077 per month (range 653-1,635) at baseline to 50.4 per month during PPF dissemination (range 2-117). Female Aedes emergence dropped by 96%-98%, such that the number of females emerging per person decreased to 0.06 females per person-month (range 0.002-0.129). Deterministic models predict, under plausible biological-epidemiological scenarios, that the R0 of typical Aedes-borne viruses would fall from 3-45 at baseline to 0.004-0.06 during PPF dissemination. The main limitations of our study were that it was a before-after trial lacking truly

  18. Mosquito-Disseminated Insecticide for Citywide Vector Control and Its Potential to Block Arbovirus Epidemics: Entomological Observations and Modeling Results from Amazonian Brazil

    Science.gov (United States)

    Abad-Franch, Fernando; Luz, Sérgio L. B.

    2017-01-01

    Background Mosquito-borne viruses threaten public health worldwide. When the ratio of competent vectors to susceptible humans is low enough, the virus’s basic reproductive number (R0) falls below 1.0 (each case generating, on average, <1.0 additional case) and the infection fades out from the population. Conventional mosquito control tactics, however, seldom yield R0 < 1.0. A promising alternative uses mosquitoes to disseminate a potent growth-regulator larvicide, pyriproxyfen (PPF), to aquatic larval habitats; this kills most mosquito juveniles and substantially reduces adult mosquito emergence. We tested mosquito-disseminated PPF in Manacapuru, a 60,000-inhabitant city (~650 ha) in Amazonian Brazil. Methods and Findings We sampled juvenile mosquitoes monthly in 100 dwellings over four periods in February 2014–January 2016: 12 baseline months, 5 mo of citywide PPF dissemination, 3 mo of focal PPF dissemination around Aedes-infested dwellings, and 3 mo after dissemination ended. We caught 19,434 juvenile mosquitoes (66% Aedes albopictus, 28% Ae. aegypti) in 8,271 trap-months. Using generalized linear mixed models, we estimated intervention effects on juvenile catch and adult emergence while adjusting for dwelling-level clustering, unequal sampling effort, and weather-related confounders. Following PPF dissemination, Aedes juvenile catch decreased by 79%–92% and juvenile mortality increased from 2%–7% to 80%–90%. Mean adult Aedes emergence fell from 1,077 per month (range 653–1,635) at baseline to 50.4 per month during PPF dissemination (range 2–117). Female Aedes emergence dropped by 96%–98%, such that the number of females emerging per person decreased to 0.06 females per person-month (range 0.002–0.129). Deterministic models predict, under plausible biological-epidemiological scenarios, that the R0 of typical Aedes-borne viruses would fall from 3–45 at baseline to 0.004–0.06 during PPF dissemination. The main limitations of our study were

  19. Mosquito-Disseminated Insecticide for Citywide Vector Control and Its Potential to Block Arbovirus Epidemics: Entomological Observations and Modeling Results from Amazonian Brazil.

    Directory of Open Access Journals (Sweden)

    Fernando Abad-Franch

    2017-01-01

    Full Text Available Mosquito-borne viruses threaten public health worldwide. When the ratio of competent vectors to susceptible humans is low enough, the virus's basic reproductive number (R0 falls below 1.0 (each case generating, on average, <1.0 additional case and the infection fades out from the population. Conventional mosquito control tactics, however, seldom yield R0 < 1.0. A promising alternative uses mosquitoes to disseminate a potent growth-regulator larvicide, pyriproxyfen (PPF, to aquatic larval habitats; this kills most mosquito juveniles and substantially reduces adult mosquito emergence. We tested mosquito-disseminated PPF in Manacapuru, a 60,000-inhabitant city (~650 ha in Amazonian Brazil.We sampled juvenile mosquitoes monthly in 100 dwellings over four periods in February 2014-January 2016: 12 baseline months, 5 mo of citywide PPF dissemination, 3 mo of focal PPF dissemination around Aedes-infested dwellings, and 3 mo after dissemination ended. We caught 19,434 juvenile mosquitoes (66% Aedes albopictus, 28% Ae. aegypti in 8,271 trap-months. Using generalized linear mixed models, we estimated intervention effects on juvenile catch and adult emergence while adjusting for dwelling-level clustering, unequal sampling effort, and weather-related confounders. Following PPF dissemination, Aedes juvenile catch decreased by 79%-92% and juvenile mortality increased from 2%-7% to 80%-90%. Mean adult Aedes emergence fell from 1,077 per month (range 653-1,635 at baseline to 50.4 per month during PPF dissemination (range 2-117. Female Aedes emergence dropped by 96%-98%, such that the number of females emerging per person decreased to 0.06 females per person-month (range 0.002-0.129. Deterministic models predict, under plausible biological-epidemiological scenarios, that the R0 of typical Aedes-borne viruses would fall from 3-45 at baseline to 0.004-0.06 during PPF dissemination. The main limitations of our study were that it was a before-after trial lacking

  20. Household possession, use and non-use of treated or untreated mosquito nets in two ecologically diverse regions of Nigeria – Niger Delta and Sahel Savannah

    Directory of Open Access Journals (Sweden)

    Otsemobor Peju

    2009-02-01

    Full Text Available Abstract Background Current use of treated mosquito nets for the prevention of malaria falls short of what is expected in sub-Saharan Africa (SSA, though research within the continent has indicated that the use of these commodities can reduce malaria morbidity by 50% and malaria mortality by 20%. Governments in sub-Sahara Africa are investing substantially in scaling-up treated mosquito net coverage for impact. However, certain significant factors still prevent the use of the treated mosquito nets, even among those who possess them. This survey examines household ownership as well as use and non-use of treated mosquito nets in Sahel Savannah and Niger Delta regions of Nigeria. Methodology This survey employed cross-sectional survey to collect data from households on coverage and use of mosquito nets, whether treated or not. Fever episodes in previous two weeks among children under the age of five were also recorded. The study took place in August 1 – 14 2007, just five months after the March distribution of treated mosquito nets, coinciding with the second raining period of the year and a time of high malaria transmission during the wet season. EPI INFO version 2003 was used in data analysis. Results The survey covered 439 households with 2,521 persons including 739 under-fives, 585 women in reproductive age and 78 pregnant women in Niger Delta Region and Sahel Savannah Region. Of the 439 HHs, 232 had any mosquito nets. Significantly higher proportion of households in the Niger Delta Region had any treated or untreated mosquito nets than those in the Sahel Savannah Region. In the Niger Delta Region, the proportion of under-fives that had slept under treated nets the night before the survey exceeded those that slept under treated nets in the Sahel Savannah Region. Children under the age of five years in the Niger Delta Region were four times more likely to sleep under treated nets than those in the Sahel Savannah Region. Conclusion This study

  1. Bioassay evaluation on the efficacy of α-cypermethrin impregnated into long lasting insecticide treated nets using Anopheles stephensi

    Institute of Scientific and Technical Information of China (English)

    Vatandoost Hassan; Mamivand Poor Hossein; Shayeghi Mansoreh; Abai Mohamad Reza; Raeisi Ahmad; Nikpoor Fatemeh

    2012-01-01

    Objective: To evaluate the bioefficacy of α-cypermethrin impregnated into long lasting insecticide treated nets (LLITNs- INTERCEPTOR®) against main malaria vector, Anopheles stephensi (An. stephensi). Methods: The effectiveness of bed net impregnated withα-cypermethrin (INTERCEPTOR®) with washing was evaluated. The washing procedure and bioassay tests were carried out according to the WHO-recommended methods. Malaria vector, An. stephensi was exposed to impregnated bed net for three minutes and then mortality measured after 24 h recovery period. Knockdown was also measured according to the logarithmic times. Results:Result of cone bioassay method showed that bioefficacy ofα-cypermethrin decreased from 100%in unwashed to 15%in 20 washes. KT50 was measure as one minute in one wash and increased to 40 min in 20 washes. Discussion: Findings of this study provide guideline for malaria vector control authorities and people using pyrethroid-impregnated bed nets.

  2. Utilization of insecticide treated nets (ITNs among male students of a tertiary institution in Lagos State, Nigeria

    Directory of Open Access Journals (Sweden)

    Abdul-Hakeem Olatunji Abiola

    2014-01-01

    Full Text Available Background: Malaria is an eminently preventable, treatable and curable disease. Proven effective options to reduce morbidity and mortality include early diagnosis, combined with prompt effective therapy and malaria prevention through reduction of human-vector contact, emphasizing the use of insecticide-treated nets (ITNs. The aim of this study was to determine the knowledge, attitude and utilization of malaria preventive methods among the students residing in Mariere Hostel of the University of Lagos, Akoka. Materials and Methods: The study design was a cross-sectional descriptive study. Simple random sampling method was used to select the respondents. Pre-tested, structured, open and close-ended self administered questionnaires were used for data collection. Data analysis was done using Epi info version 3.5.1 statistical software package. The study was carried out in February 2012. Results: A total of 221 out of the administered 250 questionnaires were retrieved and analyzed giving a response rate of 88.4%. All the respondents were males with a mean age of 20 ± 2.8 years. The mean knowledge score (% of the respondents was 76.5 ± 3.19. Although, 91.0% of the respondents recommended the use of ITNs to all students, only 31.6% use ITNs. The major reason given for non-usage of ITNs being that it is uncomfortable (45.3%. There was no statistically significant relationship between socio-demographic characteristics and utilization of ITN. Conclusion: This study has demonstrated high level of knowledge of malaria and positive attitude towards malaria prevention but poor malaria prevention practice as evidenced by poor usage of insecticide-treated nets. There is therefore need for more enlightenment campaigns to improve and sustain the knowledge and attitude towards malaria prevention as well as improve utilization of ITNs.

  3. Larvicidal activity of the leaf extracts of Spondias mombin Linn. (Anacardiaceae) from various solvents against malarial, dengue and filarial vector mosquitoes (Diptera: Culicidae)

    OpenAIRE

    Elijah Ajaegbu Eze; Simon Pierre Yinyang Danga; Festus Basden Chiedu Okoye

    2015-01-01

    Background & objectives: Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus are vector mosquitoes of dengue, malaria, and filariasis, respectively. Since no vaccine is available to treat these diseases, the control of the main mosquito vectors is essential. As conventional insecticides have limited success, plants may be alternative larvicidal agents, since they contain a rich source of bioactive chemicals. The aim of this study was to evaluate the larvicidal activity of methanol cru...

  4. Insecticide-treated plastic sheeting for emergency malaria prevention and shelter among displaced populations: an observational cohort study in a refugee setting in Sierra Leone

    NARCIS (Netherlands)

    Burns, M.R.; Rowland, M.; N'Guessan, R.; Carneiro, I.; Beeche, A.; Sesler Ruiz, S.; Kamara, S.; Takken, W.; Carnevale, P.; Allan, R.

    2012-01-01

    A double-blind phase III malaria prevention trial was conducted in two refugee camps using pre-manufactured insecticide-treated plastic sheeting (ITPS) or untreated polyethylene sheeting (UPS) randomly deployed to defined sectors of each camp. In Largo camp the ITPS or UPS was attached to inner wall

  5. Determination of the predictive factors of long-lasting insecticide-treated net ownership and utilisation in the Bamenda Health District of Cameroon.

    Science.gov (United States)

    Fokam, Eric B; Kindzeka, Germaine F; Ngimuh, Leonard; Dzi, Kevin T J; Wanji, Samuel

    2017-03-16

    Malaria is a serious health concern in Africa. In Cameroon, an endemic country where malaria remains a major public health problem, several control measures have been put in place among which the use of insecticide-treated bednets (LLINs/ITNs) is considered one of the core vector control strategies. However, the greatest challenges include ownership and utilisation by individuals and households. Factors such as age, marital status, gender, education and occupation of the household head, household size, knowledge of bednets, socioeconomic status, and environmental factors have been suggested to have an impact on bednet ownership and utilisation in different settings. The present study sought to determine bednet ownership and utilisation rates and to assess the impact of predictive factors on bednet ownership and use in the Bamenda Health District (BHD) of Cameroon. A cross-sectional study involving 384 households was conducted in six health areas in the BHD. A structured and semi-structured questionnaire was used to collect data on demographic and household characteristics as well as information on their bednet ownership and utilisation. Descriptive statistics, bivariate and multivariate logistic regression analysis were performed. Frequency of bednet ownership was relatively high (63.5%) with LLINs being most abundant (91.9%); the majority of households (87.7%) obtained their bednets during the 2011 free distribution campaign. Utilisation was relatively high (69.3%), with negligence (29.3%) and heat discomfort (26.7%) accounting most for non-usage of bednets. Children less than 5 years (63%) and pregnant women (60%) most often used these nets. Households headed by a married couple, those with older household heads, household with smaller size (5-12 persons), and knowledge of bednets (good knowledge) had positive impacts on bednet ownership (p gender of the household head (males), their educational level, environmental conditions (presence of suitable mosquito

  6. Anopheline and culicine mosquitoes are not repelled by surfaces treated with the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana

    NARCIS (Netherlands)

    Mnyone, L.L.; Koenraadt, C.J.M.; Lyimo, I.N.; Mpingwa, M.W.; Takken, W.; Russell, T.L.

    2010-01-01

    Background - Entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, are promising bio-pesticides for application against adult malaria mosquito vectors. An understanding of the behavioural responses of mosquitoes towards these fungi is necessary to guide development of fungi beyond t

  7. High-Throughput Mosquito and Fly Bioassay System for Natural and Artificial Substrates Treated with Residual Insecticides

    Science.gov (United States)

    2013-03-01

    ventilation throughout the tube that prevents condensation and limits mold growth, while allowing insects to easily reach the nutrient source. Completed...Doyle MA, Kline DL, Allan SA, Kaufman PE. 2009. Efficacy of residual bifenthrin applied to landscape vegetation against Aedes albopictus. J Am Mosq

  8. The effects of zooprophylaxis and other mosquito control measures against malaria in Nouna, Burkina Faso

    Directory of Open Access Journals (Sweden)

    Sié Ali

    2009-12-01

    Full Text Available Abstract Background In the absence of large scale, organized vector control programmes, individual protective measures against mosquitoes are essential for reducing the transmission of diseases like malaria. Knowledge of the types and effectiveness of mosquito control methods used by households can aid in the development and promotion of preventive measures. Methods A matched, population-based case control study was carried out in the semi-urban region of Nouna, Burkina Faso. Surveys and mosquito captures were conducted for each participating household. Data were analysed using conditional logistic regression and Pearson's product-moment correlations. Results In Nouna, Burkina Faso, the main types of reported mosquito control measures used included sleeping under bed nets (insecticide-treated and untreated and burning mosquito coils. Most of the study households kept animals within the compound or house at night. Insecticide house sprays, donkeys, rabbits and pigs were significantly associated with a reduced risk of malaria only in univariate analyses. Conclusion Given the conflicting results of the effects of zooprophylaxis from previous studies, other community-based preventive measures, such as bed nets, coils and insecticide house-spraying, may be of more benefit.

  9. Insecticide poisoning

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002832.htm Insecticide poisoning To use the sharing features on this page, please enable JavaScript. Insecticide is a chemical that kills bugs. Insecticide poisoning ...

  10. Analysis of population structure and insecticide resistance in mosquitoes of the genus Culex, Anopheles and Aedes from different environments of Greece with a history of mosquito borne disease transmission

    Science.gov (United States)

    Greece has been recently affected by several mosquito borne diseases, with the West Nile Virus (WNV) outbreak in 2010 being one of the largest reported in Europe. Currently at the epicenter of an economic and refugee crisis, and as a country which is visited by over 16 million tourists a year, the i...

  11. Mosquito Control

    Science.gov (United States)

    ... Share Facebook Twitter Google+ Pinterest Contact Us Mosquito Control About Mosquitoes General Information Life Cycle Information from ... Repellent that is Right for You DEET Mosquito Control Methods Success in mosquito control: an integrated approach ...

  12. Impact of decreasing ratios of insecticide-treated seed on flea beetle (Coleoptera: Chrysomelidae, Phyllotreta spp.) feeding levels and canola seed yields.

    Science.gov (United States)

    Soroka, Juliana J; Grenkow, Larry F; Irvine, R Byron

    2008-12-01

    Field studies were conducted at two locations on the Canadian prairies to investigate use of reduced ratios of insecticide-treated seed in controlling flea beetle (Coleoptera: Chrysomelidae, Phyllotreta spp.) damage to canola (Brassica napus L. and Brassica rapa L.). Five treatments were evaluated: bare seed control, fungicide-only (0X), and three ratios of insecticide plus fungicide in proportions of all (1X), two thirds (0.67X), or one third (0.33X) of the seeds coated with insecticide. Decreasing treated seed ratios by one third had no consistent deleterious effects on flea beetle damage, seedling growth, plant density, seed yield, or net cash return. Flea beetle injury to seedlings in the 1X treatment was similar to that of seedlings in the 0.67X treatment, with only two exceptions, and it was almost always lower than that of seedlings without insecticide. The 0.33X treatment generally had flea beetle feeding levels between those of the two high and the two noninsecticide treatments. Plant stand and seedling growth rates with 1X and 0.67X treatments were similar and higher than with bare seed or fungicide-alone treatments. Seed yields were inversely proportional to flea beetle feeding levels. Under very heavy flea beetle feeding, seed yields and net cash returns were highest in 1X plots, but when flea beetle feeding pressure was less extreme and canola growing conditions were favorable, 0.67X seed yields and profits from them were comparable to those in 1X treatments. On an economic basis, currently there is no advantage to decreasing the level of insecticide treated canola seed, but other considerations may affect this assessment.

  13. Insecticide Resistance Reducing Effectiveness of Malaria Control

    Centers for Disease Control (CDC) Podcasts

    2007-01-24

    Malaria prevention is increasingly insecticide based. Dr. John Gimnig, an entomologist with the Division of Parasitic Diseases, CDC, discusses evidence that mosquito resistance to insecticides, which is measured in the laboratory, could compromise malaria prevention in the field.  Created: 1/24/2007 by Emerging Infectious Diseases.   Date Released: 3/13/2007.

  14. Insecticide resistance status in Anopheles gambiae in southern Benin

    Directory of Open Access Journals (Sweden)

    Corbel Vincent

    2010-03-01

    Full Text Available Abstract Background The emergence of pyrethroid resistance in Anopheles gambiae has become a serious concern to the future success of malaria control. In Benin, the National Malaria Control Programme has recently planned to scaling up long-lasting insecticidal nets (LLINs and indoor residual spraying (IRS for malaria prevention. It is, therefore, crucial to monitor the level and type of insecticide resistance in An. gambiae, particularly in southern Benin where reduced efficacy of insecticide-treated nets (ITNs and IRS has previously been reported. Methods The protocol was based on mosquito collection during both dry and rainy seasons across forty districts selected in southern Benin. Bioassay were performed on adults collected from the field to assess the susceptibility of malaria vectors to insecticide-impregnated papers (permethrin 0.75%, delthamethrin 0.05%, DDT 4%, and bendiocarb 0.1% following WHOPES guidelines. The species within An. gambiae complex, molecular form and presence of kdr and ace-1 mutations were determined by PCR. Results Strong resistance to permethrin and DDT was found in An. gambiae populations from southern Benin, except in Aglangandan where mosquitoes were fully susceptible (mortality 100% to all insecticides tested. PCR showed the presence of two sub-species of An. gambiae, namely An. gambiae s.s, and Anopheles melas, with a predominance for An. gambiae s.s (98%. The molecular M form of An. gambiae was predominant in southern Benin (97%. The kdr mutation was detected in all districts at various frequency (1% to 95% whereas the Ace-1 mutation was found at a very low frequency (≤ 5%. Conclusion This study showed a widespread resistance to permethrin in An. gambiae populations from southern Benin, with a significant increase of kdr frequency compared to what was observed previously in Benin. The low frequency of Ace-1 recorded in all populations is encouraging for the use of bendiocarb as an alternative insecticide to

  15. Community trial of insecticide-treated bed net use promotion in southern Ghana: the Net Use Intervention study.

    Science.gov (United States)

    Elder, John P; Botwe, Augustine Aboagye; Selby, Richmond Ato; Franklin, Nadra; Shaw, Willard D

    2011-06-01

    Insecticide-treated nets (ITNs) reduce malaria transmission and related morbidity and child mortality; however, incorrect and inconsistent use limits their protective factors. This community trial titled the Net Use Intervention study sought to bridge the gap between ITN ownership and use in southern (coastal) Ghana and to determine the best mix of communication tools to affect behavior of ITN owners to consistent use while maintaining optimal internal and external validity. This two-group, non-randomized experiment evaluated a multichannel, multisector intervention process over the course of 8 weeks. A longitudinal cohort was scientifically sampled from six intervention and six control communities for both baseline and posttest surveys. The posttest survey showed no change in knowledge of ITNs in the intervention or control. In terms of use the previous night, there was a strong and statistically significant intervention effect (OR = 1.67; p promotion efforts succeeded well beyond the planners' expectations, not only promoting usage but also dramatically increasing demand for new ITNs.

  16. Insecticide-treated nets for the prevention of malaria in pregnancy: a systematic review of randomised controlled trials.

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    Carol Gamble

    2007-03-01

    Full Text Available BACKGROUND: Protection from malaria with insecticide-treated bednets (ITNs during pregnancy is widely advocated, but evidence of benefit has been inconsistent. We undertook a systematic review of randomised trials. METHODS AND FINDINGS: Three cluster-randomised and two individually randomised trials met the inclusion criteria; four from Africa (n = 6,418 and one from Thailand (n = 223. In Africa, ITNs compared to no nets increased mean birth weight by 55 g (95% confidence interval [CI] 21-88, reduced low birth weight by 23% (relative risk [RR] 0.77, 95% CI 0.61-0.98, and reduced miscarriages/stillbirths by 33% (RR 0.67, 0.47-0.97 in the first few pregnancies. Placental parasitaemia was reduced by 23% in all gravidae (RR 0.77, 0.66-0.90. The effects were apparent in the cluster-randomised trials and the one individually randomised trial in Africa. The trial in Thailand, which randomised individuals to ITNs or untreated nets, showed reductions in anaemia and fetal loss in all gravidae, but not reductions in clinical malaria or low birth weight. CONCLUSIONS: ITNs used throughout pregnancy or from mid-pregnancy onwards have a beneficial impact on pregnancy outcome in malaria-endemic Africa in the first few pregnancies. The potential impact of ITNs in pregnant women and their newborns in malaria regions outside Africa requires further research.

  17. A modified experimental hut design for studying responses of disease-transmitting mosquitoes to indoor interventions: the Ifakara experimental huts.

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    Fredros O Okumu

    Full Text Available Differences between individual human houses can confound results of studies aimed at evaluating indoor vector control interventions such as insecticide treated nets (ITNs and indoor residual insecticide spraying (IRS. Specially designed and standardised experimental huts have historically provided a solution to this challenge, with an added advantage that they can be fitted with special interception traps to sample entering or exiting mosquitoes. However, many of these experimental hut designs have a number of limitations, for example: 1 inability to sample mosquitoes on all sides of huts, 2 increased likelihood of live mosquitoes flying out of the huts, leaving mainly dead ones, 3 difficulties of cleaning the huts when a new insecticide is to be tested, and 4 the generally small size of the experimental huts, which can misrepresent actual local house sizes or airflow dynamics in the local houses. Here, we describe a modified experimental hut design - The Ifakara Experimental Huts- and explain how these huts can be used to more realistically monitor behavioural and physiological responses of wild, free-flying disease-transmitting mosquitoes, including the African malaria vectors of the species complexes Anopheles gambiae and Anopheles funestus, to indoor vector control-technologies including ITNs and IRS. Important characteristics of the Ifakara experimental huts include: 1 interception traps fitted onto eave spaces and windows, 2 use of eave baffles (panels that direct mosquito movement to control exit of live mosquitoes through the eave spaces, 3 use of replaceable wall panels and ceilings, which allow safe insecticide disposal and reuse of the huts to test different insecticides in successive periods, 4 the kit format of the huts allowing portability and 5 an improved suite of entomological procedures to maximise data quality.

  18. Gains in awareness, ownership and use of insecticide-treated nets in Nigeria, Senegal, Uganda and Zambia

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    Marin M Celeste

    2008-08-01

    Full Text Available Abstract Background In April 2000, the Roll Back Malaria (RBM "Abuja Summit" set a target of having at least 60% of pregnant women and children under five use insecticide-treated nets (ITNs. Thereafter, programmes were implemented to create demand, reduce taxes and tariffs, spur the commercial market, and reach vulnerable populations with subsidized ITNs. Using national ITN monitoring data from the USAID-sponsored AED/NetMark project, this article examines the extent to which these activities were successful in increasing awareness, ownership, and use of nets and ITNs. Methods A series of surveys with standardized sampling and measurement methods was used to compare four countries at two points in time. Surveys were conducted in 2000 and again in 2004 (Nigeria, Senegal, Zambia or 2006 (Uganda. They contained questions permitting classification of each net as untreated, ever-treated or currently-treated (an ITN. Household members as well as nets owned were enumerated so that households, household members, and nets could be used as units of analysis. Several measures of net/ITN ownership, plus RBM ITN use indicators, were calculated. The results show the impact of ITN activities before the launch of massive free net distribution programmes. Results In 2000, treated nets were just being introduced to the public, but four to six years later the awareness of ITNs was nearly universal in all countries but Nigeria, where awareness increased from 7% to 60%. By any measure, there were large increases in ownership of nets, especially treated nets, in all countries. All countries but Nigeria made commensurate gains in the proportion of under-fives sleeping under a net/ITN, and in all countries the proportion of pregnant women sleeping under a net/ITN increased greatly. Conclusion A mix of demand creation, a strengthened commercial sector, reduced taxes and tariffs, and programmes making ITNs available at reduced prices resulted in impressive gains in

  19. PMI Activity TZ-1,2: IRS and LLIN: Integration of Methods and Insecticide Mode of Actions for Control of African Malaria Vector Mosquitoes

    OpenAIRE

    Fredros O Okumu; Moore, Sarah J.

    2012-01-01

    Long lasting Insecticidal nets (LLINs) and indoor residual spraying (IRS) are the preferred techniques for malaria vector control in Africa, where their application has a proven contribution to the recent significant reductions in the burden of the disease. Even though both methods are commonly used together in the same households, evidence of improved malaria control due to the use of combinations as opposed to use of either method alone has been minimal and inconclusive.To measure the mode ...

  20. Theoretical impact of insecticide-impregnated school uniforms on dengue incidence in Thai children

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    Eduardo Massad

    2013-03-01

    Full Text Available Background: Children carry the main burden of morbidity and mortality caused by dengue. Children spend a considerable amount of their day at school; hence strategies that reduce human–mosquito contact to protect against the day-biting habits of Aedes mosquitoes at schools, such as insecticide-impregnated uniforms, could be an effective prevention strategy. Methodology: We used mathematical models to calculate the risk of dengue infection based on force of infection taking into account the estimated proportion of mosquito bites that occur in school and the proportion of school time that children wear the impregnated uniforms. Principal findings: The use of insecticide-impregnated uniforms has efficacy varying from around 6% in the most pessimistic estimations, to 55% in the most optimistic scenarios simulated. Conclusions: Reducing contact between mosquito bites and human hosts via insecticide-treated uniforms during school time is theoretically effective in reducing dengue incidence and may be a valuable additional tool for dengue control in school-aged children. The efficacy of this strategy, however, is dependent on the compliance of the target population in terms of proper and consistent wearing of uniforms and, perhaps more importantly, the proportion of bites inflicted by the Aedes population during school time.

  1. Benefit of insecticide-treated nets, curtains and screening on vector borne diseases, excluding malaria: a systematic review and meta-analysis.

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    Anne L Wilson

    2014-10-01

    Full Text Available Insecticide-treated nets (ITNs are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs. We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated curtains (ITCs and insecticide-treated house screening (ITS against Chagas disease, cutaneous and visceral leishmaniasis, dengue, human African trypanosomiasis, Japanese encephalitis, lymphatic filariasis and onchocerciasis.MEDLINE, EMBASE, LILACS and Tropical Disease Bulletin databases were searched using intervention, vector- and disease-specific search terms. Cluster or individually randomised controlled trials, non-randomised trials with pre- and post-intervention data and rotational design studies were included. Analysis assessed the efficacy of ITNs, ITCs or ITS versus no intervention. Meta-analysis of clinical data was performed and percentage reduction in vector density calculated.Twenty-one studies were identified which met the inclusion criteria. Meta-analysis of clinical data could only be performed for four cutaneous leishmaniasis studies which together showed a protective efficacy of ITNs of 77% (95%CI: 39%-91%. Studies of ITC and ITS against cutaneous leishmaniasis also reported significant reductions in disease incidence. Single studies reported a high protective efficacy of ITS against dengue and ITNs against Japanese encephalitis. No studies of Chagas disease, human African trypanosomiasis or onchocerciasis were identified.There are likely to be considerable collateral benefits of ITN roll out on cutaneous leishmaniasis where this disease is co-endemic with malaria. Due to the low number of studies identified, issues with reporting of entomological outcomes, and few studies reporting clinical outcomes, it is difficult to make strong conclusions on the effect of ITNs, ITCs or ITS on other VBDs and therefore further studies be conducted. Nonetheless, it

  2. What Is Threatening the Effectiveness of Insecticide-Treated Bednets? A Case-Control Study of Environmental, Behavioral, and Physical Factors Associated with Prevention Failure

    OpenAIRE

    Obala, Andrew A.; Judith Nekesa Mangeni; Alyssa Platt; Daniel Aswa; Lucy Abel; Jane Namae; Wendy Prudhomme O'Meara

    2015-01-01

    Background Insecticide-treated nets are the cornerstone of global malaria control and have been shown to reduce malaria morbidity by 50–60%. However, some areas are experiencing a resurgence in malaria following successful control. We describe an efficacy decay framework to understand why high malaria burden persists even under high ITN coverage in a community in western Kenya. Methods We enrolled 442 children hospitalized with malaria and paired them with age, time, village and gender-matche...

  3. Status of carbohydrate, protein and lipid profile in the mosquito larvae treated with certain phytoextracts

    Institute of Scientific and Technical Information of China (English)

    Preeti Sharma; Lalit Mohan; Kamal Kumar Dua; Chand Narayan Srivastava

    2011-01-01

    Objective:To investigate the impact of the most potent petroleum ether extract ofArtemisia annua (A. annua) andAzadirachta indica (Az. indica) on total carbohydrate, lipid and protein level ofAnopheles stephensi andCulex quinquefasciatuslarvae.Methods: Mosquito larvae were exposed to the extracts selected as per standardWHO procedure. Carbohydrate (glucose), total lipid and protein were estimated by the methods as Nelson, Bragdon and Lowry described, respectively.Results: The glucose levels were increased to27.87% and46.8%, respectively in anopheline larval tissues after treatment with petroleum ether extract ofA. annua and methanolic extract ofAz. indica. In culicine larvae, glucose levels were reduced to58.96% and24.65%, respectively. After treatment withA. annua extract, lipid contents in anopheline and culicine larvae decreased by28.57% and25.0%, respectively and increased by14.29% and50.00% in theAnopheles andCulex larvae, respectively after treatment with methanolic extract ofAz. indica. Total protein levels were reduced to63.13% and92.62% in anopheline and to32.39% and 48.12% in culicine larvae after treatment withA. annua andAz. Indica extracts, respectively. Conclusions: Two extracts produce significant alterations in the biochemical profiles of anopheline and culicine larvae. Further, the impacting factors of extracts on carbohydrate, lipid and protein contents of larvae are species and specific extraction. It indicates the disturbed metabolic activity of the larvae.

  4. Combination of Insecticide Treated Nets and Indoor Residual Spraying in Northern Tanzania Provides Additional Reduction in Vector Population Density and Malaria Transmission Rates Compared to Insecticide Treated Nets Alone: A Randomised Control Trial.

    Science.gov (United States)

    Protopopoff, Natacha; Wright, Alexandra; West, Philippa A; Tigererwa, Robinson; Mosha, Franklin W; Kisinza, William; Kleinschmidt, Immo; Rowland, Mark

    2015-01-01

    Indoor residual spraying (IRS) combined with insecticide treated nets (ITN) has been implemented together in several sub-Saharan countries with inconclusive evidence that the combined intervention provides added benefit. The impact on malaria transmission was evaluated in a cluster randomised trial comparing two rounds of IRS with bendiocarb plus universal coverage ITNs, with ITNs alone in northern Tanzania. From April 2011 to December 2012, eight houses in 20 clusters per study arm were sampled monthly for one night with CDC light trap collections. Anopheles gambiae s.l. were identified to species using real time PCR Taq Man and tested for the presence of Plasmodium falciparum circumsporozoite protein. ITN and IRS coverage was estimated from household surveys. IRS coverage was more than 85% in two rounds of spraying in January and April 2012. Household coverage with at least one ITN per house was 94.7% after the universal coverage net campaign in the baseline year and the proportion of household with all sleeping places covered by LLIN was 50.1% decreasing to 39.1% by the end of the intervention year. An.gambiae s.s. comprised 80% and An.arabiensis 18.3% of the anopheline collection in the baseline year. Mean An.gambiae s.l. density in the ITN+IRS arm was reduced by 84% (95%CI: 56%-94%, p = 0.001) relative to the ITN arm. In the stratum of clusters categorised as high anopheline density at baseline EIR was lower in the ITN+IRS arm compared to the ITN arm (0.5 versus 5.4 per house per month, Incidence Rate Ratio: 0.10, 95%CI: 0.01-0.66, p-value for interaction rate compared to ITN alone in an area of moderate coverage of LLIN and high pyrethroid resistance in An.gambiae s.s.

  5. A systematic review of mosquito coils and passive emanators: defining recommendations for spatial repellency testing methodologies

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    Ogoma Sheila B

    2012-12-01

    Full Text Available Abstract Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS, long lasting insecticide treated nets (LLINs and insecticide treated materials (ITMs. PubMed, (National Centre for Biotechnology Information (NCBI, U.S. National Library of Medicine, NIH, MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words “Mosquito coils” “Mosquito emanators” and “Spatial repellents”. It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose–response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP, which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control.

  6. Pyrethroid Resistance Alters the Blood-Feeding Behavior in Puerto Rican Aedes aegypti Mosquitoes Exposed to Treated Fabric

    Science.gov (United States)

    Emerging insecticide resistance is a major issue for vector control; it decreases effectiveness of insecticides, thereby requiring greater quantities for comparable control with a net increase in risk of disease resurgence, product cost, and damage risk to the ecosystem. Pyrethroid resistance has b...

  7. Effect of transmission reduction by insecticide-treated bednets (ITNs on antimalarial drug resistance in western Kenya.

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    Monica Shah

    Full Text Available Despite the clear public health benefit of insecticide-treated bednets (ITNs, the impact of malaria transmission-reduction by vector control on the spread of drug resistance is not well understood. In the present study, the effect of sustained transmission reduction by ITNs on the prevalence of Plasmodium falciparum gene mutations associated with resistance to the antimalarial drugs sulfadoxine-pyrimethamine (SP and chloroquine (CQ in children under the age of five years was investigated during an ITN trial in Asembo area, western Kenya. During the ITN trial, the national first line antimalarial treatment changed from CQ to SP. Smear-positive samples collected from cross sectional surveys prior to ITN introduction (baseline, n = 250 and five years post-ITN intervention (year 5 survey, n = 242 were genotyped for single nucleotide polymorphisms (SNPs at dhfr-51, 59, 108, 164 and dhps-437, 540 (SP resistance, and pfcrt-76 and pfmdr1-86 (CQ resistance. The association between the drug resistance mutations and epidemiological variables was evaluated. There were significant increases in the prevalence of SP dhps mutations and the dhfr/dhps quintuple mutant, and a significant reduction in the proportion of mixed infections detected at dhfr-51, 59 and dhps-437, 540 SNPs from baseline to the year 5 survey. There was no change in the high prevalence of pfcrt-76 and pfmdr1-86 mutations. Multivariable regression analysis further showed that current antifolate use and year of survey were significantly associated with more SP drug resistance mutations. These results suggest that increased antifolate drug use due to drug policy change likely led to the high prevalence of SP mutations 5 years post-ITN intervention and reduced transmission had no apparent effect on the existing high prevalence of CQ mutations. There is no evidence from the current study that sustained transmission reduction by ITNs reduces the prevalence of genes associated with malaria

  8. Novel Methods for Mosquito Control using RNAi.

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    The discovery and development of novel insecticides for vector control is a primary focus of toxicology research conducted at the Mosquito and Fly Research Unit, Gainesville, FL. Targeting critical genes/proteins in mosquitoes using RNA interference (RNAi) is being investigated as a method to devel...

  9. Spinosad: a biorational mosquito larvicide for use in car tires in southern Mexico

    OpenAIRE

    Marina Carlos F; Bond J; Muñoz José; Valle Javier; Chirino Nelva; Williams Trevor

    2012-01-01

    Abstract Background Car tires are important habitats for mosquito development because of the high density populations they can harbor and their presence in urban settings. Water in experimental tires was treated with one of three insecticides or an untreated control. Aquatic invertebrates were sampled at weekly intervals. Eggs, larval and pupal samples were laboratory-reared to estimate seasonal fluctuations in Aedes aegypti and Ae. albopictus abundance. Results Spinosad treatments at 1 or 5 ...

  10. Combination of Insecticide Treated Nets and Indoor Residual Spraying in Northern Tanzania Provides Additional Reduction in Vector Population Density and Malaria Transmission Rates Compared to Insecticide Treated Nets Alone: A Randomised Control Trial.

    Directory of Open Access Journals (Sweden)

    Natacha Protopopoff

    Full Text Available Indoor residual spraying (IRS combined with insecticide treated nets (ITN has been implemented together in several sub-Saharan countries with inconclusive evidence that the combined intervention provides added benefit. The impact on malaria transmission was evaluated in a cluster randomised trial comparing two rounds of IRS with bendiocarb plus universal coverage ITNs, with ITNs alone in northern Tanzania. From April 2011 to December 2012, eight houses in 20 clusters per study arm were sampled monthly for one night with CDC light trap collections. Anopheles gambiae s.l. were identified to species using real time PCR Taq Man and tested for the presence of Plasmodium falciparum circumsporozoite protein. ITN and IRS coverage was estimated from household surveys. IRS coverage was more than 85% in two rounds of spraying in January and April 2012. Household coverage with at least one ITN per house was 94.7% after the universal coverage net campaign in the baseline year and the proportion of household with all sleeping places covered by LLIN was 50.1% decreasing to 39.1% by the end of the intervention year. An.gambiae s.s. comprised 80% and An.arabiensis 18.3% of the anopheline collection in the baseline year. Mean An.gambiae s.l. density in the ITN+IRS arm was reduced by 84% (95%CI: 56%-94%, p = 0.001 relative to the ITN arm. In the stratum of clusters categorised as high anopheline density at baseline EIR was lower in the ITN+IRS arm compared to the ITN arm (0.5 versus 5.4 per house per month, Incidence Rate Ratio: 0.10, 95%CI: 0.01-0.66, p-value for interaction <0.001. This trial provides conclusive evidence that combining carbamate IRS and ITNs produces major reduction in Anopheles density and entomological inoculation rate compared to ITN alone in an area of moderate coverage of LLIN and high pyrethroid resistance in An.gambiae s.s.

  11. Mosquito Bites

    Science.gov (United States)

    ... larvae, then pupae, and then they become adult mosquitos. The males live for about a week to ... can live for months. What health problems can mosquito bites cause? Most mosquito bites are harmless, but ...

  12. The development of insecticide-treated durable wall lining for malaria control: insights from rural and urban populations in Angola and Nigeria

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    Messenger Louisa A

    2012-09-01

    Full Text Available Abstract Background Durable lining (DL is a deltamethrin-impregnated polyethylene material, which is designed to cover domestic walls that would normally be sprayed with residual insecticide. The operational success of DL as a long-lasting insecticidal substrate will be dependent on a high level of user acceptability as households must maintain correctly installed linings on their walls for several years. Preliminary trials were undertaken to identify a material to develop into a marketable wall lining and to assess its level of acceptability among rural and urban populations. Methods In Angola (n=60, prototype DL and insecticide-treated plastic sheeting (ITPS were installed on urban house walls and ceilings, respectively, and acceptability was compared to indoor residual spraying (IRS (n=20 using a knowledge, attitude and practice (KAP questionnaire. In Nigeria (n=178, three materials (prototype DL, ITPS and insecticide-treated wall netting were distributed among rural and urban households. User opinions were gathered from focus group discussions, in-depth interviews and KAP questionnaires. Results In Angola, after two weeks, the majority of participants (98% expressed satisfaction with the products and identified the killing of insects as the materials’ principal benefits (73%. After one year, despite a loss of almost 50% of households to refugee repatriation, all 32 remaining households still asserted that they had liked the DL/ITPS in their homes and given the choice of intervention preferred DL/ITPS to IRS (94% or insecticide-treated nets (78%. In Nigeria, a dichotomy between rural and urban respondents emerged. Rural participants favoured wall adornments and accepted wall linings because of their perceived decorative value and entomological efficacy. By contrast, urban households preferred minimal wall decoration and rejected the materials based upon objections to their aesthetics and installation feasibility. Conclusions The high level

  13. Objective monitoring of Insecticide-treated bednet use to improve malaria prevention: SmartNet development and validation.

    Science.gov (United States)

    Krezanoski, Paul J; Campbell, Jeffrey I; Santorino, Data; Bangsberg, David R

    2017-01-01

    Malaria is a serious health concern for three billion people worldwide, killing nearly 600,000 people a year. Insecticide-treated bednets (ITNs) are an effective and valuable tool for preventing malaria and hundreds of millions of ITNs have been distributed throughout sub-Saharan Africa. Nevertheless, our current methods for measuring ITN use are inadequate to inform malaria prevention programs. The most common method, self-reported ITN use, is limited by 1) social desirability, 2) recall and 3) sampling bias. An acceptable objective and longitudinal method of assessing adherence to ITN use would improve our ability to better understand the determinants of ITN use and design more effective malaria prevention interventions. We describe the development and initial proof-of-concept validity testing of an ITN adherence monitoring tool called SmartNet. SmartNet uses conductive thread interwoven into an ITN and a microcontroller to detect the state of the ITN. We tested SmartNet among five volunteers using the device over their beds in Boston, USA for two weeks with the goal of evaluating device reliability, accuracy and acceptability to inform future device improvements. The device recorded data for 63.1% (35172/55711) of installed two-minute time intervals, with 97.3% (19990/20539) of the recording errors relating to battery failures. Overall, the device was 71.7% (25204/35172) accurate in determining the state of the ITN (whether it was folded up or unfurled) and performed significantly better at detecting an unfurled ITN than a folded ITN, 77.3% versus 68.4% (p<0.001). Participants noted no significant acceptability concerns and all participants felt SmartNet was easy or very easy to use. SmartNet is a novel approach to objectively measure ITN adherence over time. Our results suggest a variety of device improvements to both extend reliability and improve performance of SmartNet prior to deployment in a malaria-endemic setting.

  14. Impact of health facility-based insecticide treated bednet distribution in Malawi: progress and challenges towards achieving universal coverage.

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    Jacek Skarbinski

    Full Text Available BACKGROUND: High levels of insecticide treated bednet (ITN use reduce malaria burden in countries with intense transmission such as Malawi. Since 2007 Malawi has implemented free health facility-based ITN distribution for pregnant women and children <5 years old (under-5s. We evaluated the progress of this targeted approach toward achieving universal ITN coverage. METHODS: We conducted a cross-sectional household survey in eight districts in April 2009. We assessed household ITN possession, ITN use by all household members, and P. falciparum asexual parasitemia and anemia (hemoglobin <11 grams/deciliter in under-5s. RESULTS: We surveyed 7,407 households containing 29,806 persons. Fifty-nine percent of all households (95% confidence interval [95% CI]: 56-62, 67% (95% CI: 64-70 of eligible households (i.e., households with pregnant women or under-5s, and 40% (95% CI: 36-45 of ineligible households owned an ITN. In households with at least one ITN, 76% (95% CI: 74-78 of all household members, 88% (95% CI: 87-90 of under-5s and 90% (95% CI: 85-94 of pregnant women used an ITN the previous night. Of 6,677 ITNs, 92% (95% CI: 90-94 were used the previous night with a mean of 2.4 persons sleeping under each ITN. In multivariable models adjusting for district, socioeconomic status and indoor residual spraying use, ITN use by under-5s was associated with a significant reduction in asexual parasitemia (adjusted odds ratio (aOR 0.79; 95% CI: 0.64-0.98; p-value 0.03 and anemia (aOR 0.79; 95% CI 0.62-0.99; p-value 0.04. Of potential targeted and non-targeted mass distribution strategies, a campaign distributing 1 ITN per household might increase coverage to 2.1 household members per ITN, and thus achieve near universal coverage often defined as 2 household members per ITN. CONCLUSIONS: Malawi has substantially increased ITN coverage using health facility-based distribution targeting pregnant women and under-5s, but needs to supplement these activities with

  15. Insecticide-treated nets and treatment service: a trial using public and private sector channels in rural United Republic of Tanzania.

    Science.gov (United States)

    Fraser-Hurt, N; Lyimo, E O

    1998-01-01

    The Rotary Net Initiative, implemented in Kilombero District, southern United Republic of Tanzania, allowed us to explore different sales channels for the distribution of insecticide-treated nets (ITNs) and the insecticide treatment service in a rural area of very high malaria transmission. Several types of ITNs were promoted and sold through different channels in the public and private sector, i.e. hospital pharmacy, mother and child health (MCH) clinic, net committee, village health workers and retail shops. The ITNs were sold for US$ 5.0-9.2, with profit margins of 9-16%. Net treatment cost US$ 0.33, with commission fees of 75%. Net transport and treatment were partially subsidized. Some outlets established their own fund by ITN sales. Sales of nets and treatments were seasonal, and certain net types were preferred. Demand for insecticide treatment was generally low. Changes in net coverage were assessed in two villages. A range of outlet features were compared qualitatively. Our experience supports suggestions that ITN technology should be delivered through MCH care services and demonstrates that specific promotion and innovation are necessary to achieve substantial net treatment levels. A large-scale ITN project in the same area and other ITN studies should lead to better understanding of ITN implementation at the population level.

  16. International forum for surveillance and control of mosquitoes and mosquito-borne diseases

    Science.gov (United States)

    This manuscript provides highlights of presentations given at the 1st International Forum for Surveillance and Control of Mosquitoes and Mosquito-borne Disease in Beijing, China. Topics covered in this 4-day forum included: diseases, surveillance, insecticides, physiology and ecology, behavior, inv...

  17. Comparison of the Insecticidal Characteristics of Commercially Available Plant Essential Oils Against Aedes aegypti and Anopheles gambiae (Diptera: Culicidae).

    Science.gov (United States)

    Norris, Edmund J; Gross, Aaron D; Dunphy, Brendan M; Bessette, Steven; Bartholomay, Lyric; Coats, Joel R

    2015-09-01

    Aedes aegypti and Anopheles gambiae are two mosquito species that represent significant threats to global public health as vectors of Dengue virus and malaria parasites, respectively. Although mosquito populations have been effectively controlled through the use of synthetic insecticides, the emergence of widespread insecticide-resistance in wild mosquito populations is a strong motivation to explore new insecticidal chemistries. For these studies, Ae. aegypti and An. gambiae were treated with commercially available plant essential oils via topical application. The relative toxicity of each essential oil was determined, as measured by the 24-h LD(50) and percentage knockdown at 1 h, as compared with a variety of synthetic pyrethroids. For Ae. aegypti, the most toxic essential oil (patchouli oil) was ∼1,700-times less toxic than the least toxic synthetic pyrethroid, bifenthrin. For An. gambiae, the most toxic essential oil (patchouli oil) was ∼685-times less toxic than the least toxic synthetic pyrethroid. A wide variety of toxicities were observed among the essential oils screened. Also, plant essential oils were analyzed via gas chromatography/mass spectrometry (GC/MS) to identify the major components in each of the samples screened in this study. While the toxicities of these plant essential oils were demonstrated to be lower than those of the synthetic pyrethroids tested, the large amount of GC/MS data and bioactivity data for each essential oil presented in this study will serve as a valuable resource for future studies exploring the insecticidal quality of plant essential oils.

  18. Biochemical mechanisms of insecticide resistance in field population of Dengue vector Aedes aegypti (Diptera: Culicidae.

    Directory of Open Access Journals (Sweden)

    R. Muthusamy

    2014-03-01

    Full Text Available Insecticide resistance has been known to be prevalent in several insect species including mosquito. It has become a major problem in vector control programme due to pesticide resistance through detoxification enzymes. The present study investigated the toxicity of Ae. aegypti to organophosphates and pyrethroid insecticide and biochemical mechanisms involved in insecticide resistance in larval population. Larval bioassay revealed an LC50 value of 0.734 ppm for dichlorvos and 1.140 ppm for λ-cyhalothrin exposure. Biochemical assay revealed increased activity of AChE (0.3 µmole/mg protein and GST in dichlorvos (1-1.5 µmole/mg protein treatment and esterase activity in λ-cyhalothrin treated compared to control activity. These studies suggest that AChE and GST is associated with organophosphate and esterase associated with pyrethroid resistance in Ae. aegypti.

  19. Impact of insecticide-treated bed nets on malaria transmission indices on the south coast of Kenya

    Directory of Open Access Journals (Sweden)

    Mutuku Francis M

    2011-12-01

    Full Text Available Abstract Background Besides significantly reducing malaria vector densities, prolonged usage of bed nets has been linked to decline of Anopheles gambiae s.s. relative to Anopheles arabiensis, changes in host feeding preference of malaria vectors, and behavioural shifts to exophagy (outdoor biting for the two important malaria vectors in Africa, An. gambiae s.l. and Anopheles funestus. In southern coastal Kenya, bed net use was negligible in 1997-1998 when Anopheles funestus and An. gambiae s.s. were the primary malaria vectors, with An. arabiensis and Anopheles merus playing a secondary role. Since 2001, bed net use has increased progressively and reached high levels by 2009-2010 with corresponding decline in malaria transmission. Methods To evaluate the impact of the substantial increase in household bed net use within this area on vector density, vector composition, and human-vector contact, indoor and outdoor resting mosquitoes were collected in the same region during 2009-2010 using pyrethrum spray catches and clay pots for indoor and outdoor collections respectively. Information on bed net use per sleeping spaces and factors influencing mosquito density were determined in the same houses using Poisson regression analysis. Species distribution was determined, and number of mosquitoes per house, human-biting rates (HBR, and entomological inoculation rate (EIR were compared to those reported for the same area during 1997-1998, when bed net coverage had been minimal. Results Compared to 1997-1998, a significant decline in the relative proportion of An. gambiae s.s. among collected mosquitoes was noted, coupled with a proportionate increase of An. arabiensis. Following > 5 years of 60-86% coverage with bed nets, the density, human biting rate and EIR of indoor resting mosquitoes were reduced by more than 92% for An. funestus and by 75% for An. gambiae s.l. In addition, the host feeding choice of both vectors shifted more toward non

  20. Impact of insecticide-treated bed nets on malaria transmission indices on the south coast of Kenya.

    Science.gov (United States)

    Mutuku, Francis M; King, Charles H; Mungai, Peter; Mbogo, Charles; Mwangangi, Joseph; Muchiri, Eric M; Walker, Edward D; Kitron, Uriel

    2011-12-13

    Besides significantly reducing malaria vector densities, prolonged usage of bed nets has been linked to decline of Anopheles gambiae s.s. relative to Anopheles arabiensis, changes in host feeding preference of malaria vectors, and behavioural shifts to exophagy (outdoor biting) for the two important malaria vectors in Africa, An. gambiae s.l. and Anopheles funestus. In southern coastal Kenya, bed net use was negligible in 1997-1998 when Anopheles funestus and An. gambiae s.s. were the primary malaria vectors, with An. arabiensis and Anopheles merus playing a secondary role. Since 2001, bed net use has increased progressively and reached high levels by 2009-2010 with corresponding decline in malaria transmission. To evaluate the impact of the substantial increase in household bed net use within this area on vector density, vector composition, and human-vector contact, indoor and outdoor resting mosquitoes were collected in the same region during 2009-2010 using pyrethrum spray catches and clay pots for indoor and outdoor collections respectively. Information on bed net use per sleeping spaces and factors influencing mosquito density were determined in the same houses using Poisson regression analysis. Species distribution was determined, and number of mosquitoes per house, human-biting rates (HBR), and entomological inoculation rate (EIR) were compared to those reported for the same area during 1997-1998, when bed net coverage had been minimal. Compared to 1997-1998, a significant decline in the relative proportion of An. gambiae s.s. among collected mosquitoes was noted, coupled with a proportionate increase of An. arabiensis. Following > 5 years of 60-86% coverage with bed nets, the density, human biting rate and EIR of indoor resting mosquitoes were reduced by more than 92% for An. funestus and by 75% for An. gambiae s.l. In addition, the host feeding choice of both vectors shifted more toward non-human vertebrates. Besides bed net use, malaria vector abundance

  1. Evidence that mutant PfCRT facilitates the transmission to mosquitoes of chloroquine-treated Plasmodium gametocytes.

    Science.gov (United States)

    Ecker, Andrea; Lakshmanan, Viswanathan; Sinnis, Photini; Coppens, Isabelle; Fidock, David A

    2011-01-15

    Resistance of the human malarial parasite Plasmodium falciparum to the antimalarial drug chloroquine has rapidly spread from several independent origins and is now widely prevalent throughout the majority of malaria-endemic areas. Field studies have suggested that chloroquine-resistant strains might be more infective to mosquito vectors. To test the hypothesis that the primary chloroquine resistance determinant, mutations in PfCRT, facilitates parasite transmission under drug pressure, we have introduced a mutant or wild-type pfcrt allele into the rodent model malarial parasite Plasmodium berghei. Our results show that mutant PfCRT from the chloroquine-resistant 7G8 strain has no effect on asexual blood stage chloroquine susceptibility in vivo or ex vivo but confers a significant selective advantage in competitive mosquito infections in the presence of this drug, by protecting immature gametocytes from its lethal action. Enhanced infectivity to mosquitoes may have been a key factor driving the worldwide spread of mutant pfcrt.

  2. Social marketing and the fight against malaria in Africa: population services international (PSI) and insecticide treated nets (ITNS).

    Science.gov (United States)

    Omona, Julius

    2009-12-01

    This textual analyses on Social marketing, Insecticide Treated Nets (ITNs) and Population Services International (PSI) were undertaken to achieve two objectives: (a) to contribute to the continuing debate and search for a better strategy for combating malaria in sub-Saharan Africa; and (b) to contribute to theory building on social marketing. The analyses revealed that Malaria has reached an epidemic proportion and despite major inroads by PSI in combating malaria on the principles of social marketing, the strategies of pricing and segmentation of the clients are not appropriate for Sub-Saharan African countries that are mired in absolute poverty where majority of the rural communities eke a living on less than a dollar per day and the health sector does not receive priority attention from policy makers and politicians. The descriptive statistics and a one sample t test for the sampled countries suggest that sub-Saharan countries have not even met the hypothesized 5% investment of their GDP on health, compared to their counterparts, the developed countries, who are all above this figure. The null hypothesis that there is no significant different between the population and the sample means of both developed and a developing country in their investments in the health sector was also tested and rejected. Though the elements in some of the existent models and theories of social marketing such as Health Belief Model, Theory of Reasoned Action, Social Cognitive Theory and Trans-theoretical Models all attempt to advocate for elimination of constraints and barriers to effective access to a service or product, PSI is adamant to these and try to generalize these principles in all contexts, including in Sub-Saharan Africa. The African scenario, where about 90% of Malaria related deaths cases in the world occur, demands more than what these theories present. Accordingly, it was concluded that however good intentioned social marketing is, in the case of ITNs in this region, it

  3. Modeling Mosquito Distribution. Impact of the Landscape

    Science.gov (United States)

    Dumont, Y.

    2011-09-01

    In order to use efficiently vector control tools, like insecticides, and mechanical control, it is necessary to provide mosquito density estimate and mosquito distribution, taking into account the environment and entomological knowledges. Mosquito dispersal modeling, together with a compartmental approach, leads to a quasilinear parabolic system. Using the time splitting approach and appropriate numerical methods for each operator, we construct a reliable numerical scheme. Considering various landscapes, we show that the environment can have a strong influence on mosquito distribution and, thus, in the efficiency or not of vector control.

  4. Spatio-temporal Modeling of Mosquito Distribution

    Science.gov (United States)

    Dumont, Y.; Dufourd, C.

    2011-11-01

    We consider a quasilinear parabolic system to model mosquito displacement. In order to use efficiently vector control tools, like insecticides, and mechanical control, it is necessary to provide density estimates of mosquito populations, taking into account the environment and entomological knowledges. After a brief introduction to mosquito dispersal modeling, we present some theoretical results. Then, considering a compartmental approach, we get a quasilinear system of PDEs. Using the time splitting approach and appropriate numerical methods for each operator, we construct a reliable numerical scheme. Considering vector control scenarii, we show that the environment can have a strong influence on mosquito distribution and in the efficiency of vector control tools.

  5. Evolution de la résistance au bactério-insecticide Bti chez les moustiques

    OpenAIRE

    Paris, Margot

    2010-01-01

    Mosquito control represents a major public health concern, as mosquitoes transmit many severe human diseases. After the massive use of chemical insecticides since the fifties, the bacterio-insecticide Bacillus thuringiensis subsp. israelensis (Bti) represents a safe alternative and is now widely used to control mosquito populations. High toxicity due to commercial Bti proliferation and persistence was found in decaying leaf litter collected in mosquito breeding sites. In order to evaluate the...

  6. The impact of insecticide-treated school uniforms on dengue infections in school-aged children: study protocol for a randomised controlled trial in Thailand

    Directory of Open Access Journals (Sweden)

    Wilder-Smith Annelies

    2012-11-01

    Full Text Available Abstract Background There is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence. Methods A randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7–18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons. Discussion Practical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed. Trial registration clinicaltrial.gov. Registration number: NCT01563640

  7. Octachlorodipropyl ether (s-2) mosquito coils are inadequately studied for residential use in Asia and illegal in the United States.

    OpenAIRE

    Krieger, Robert I; Dinoff, Travis M; Zhang, Xiaofei

    2003-01-01

    Children and their parents in residences are often protected by insecticides from nuisance and disease-bearing mosquitoes. The annual worldwide consumption of the four major types of residential insecticide products--aerosols, mosquito coils, liquid vaporizers, and vaporizing mats--is in the billions of units. Mosquito coils are burned indoors and outdoors in East Asia and to a limited extent in other parts of the world, including the United States. Coils consist of an insecticide/repellant, ...

  8. Evaluation of efficacy of Interceptor(®) G2, a long-lasting insecticide net coated with a mixture of chlorfenapyr and alpha-cypermethrin, against pyrethroid resistant Anopheles gambiae s.l. in Burkina Faso.

    Science.gov (United States)

    Bayili, Koama; N'do, Severin; Namountougou, Moussa; Sanou, Roger; Ouattara, Abdoulaye; Dabiré, Roch K; Ouédraogo, Anicet G; Malone, David; Diabaté, Abdoulaye

    2017-05-08

    Malaria vectors have acquired widespread resistance throughout sub-Saharan Africa to many of the currently used insecticides. Hence, there is an urgent need to develop alternative strategies including the development of new insecticides for effective management of insecticide resistance. To maintain progress against malaria, it is necessary to identify other residual insecticides for mosquito nets. In the present WHOPES phase II analogue study, the utility of chlorfenapyr, a pyrrole class insecticide mixed with alpha-cypermethrin on a long-lasting mosquito bed net was evaluated against Anopheles gambiae s.l. Bed nets treated with chlorfenapyr and alpha-cypermethrin and mixture of both compounds were tested for their efficacy on mosquitoes. Washed (20 times) and unwashed of each type of treated nets and were tested according to WHOPES guidelines. Efficacy of nets were expressed in terms of blood-feeding inhibition rate, deterrence, induced exophily and mortality rate. The evaluation was conducted in experimental huts of Vallée du Kou seven (VK7) in Burkina Faso (West Africa) following WHOPES phase II guidelines. In addition, a WHOPES phase I evaluation was also performed. Mixture treated nets killed significantly (P  0.05) different from nets treated with chlorfenapyr 200 mg/m(2) unwashed (86%). The washed and unwashed nets treated with the mixtures resulted in personal protection against An. gambiae s.l. biting 34 and 44%. In contrast the personal protection observed for washed and unwashed alpha-cypermethrin treated nets generated (14 and 24%), and chlorfenapyr solo treated net was rather low (22%). Among all nets trialled, the combination of chlorfenapyr and alpha-cypermethrin on bed nets provided better mortality in phase II after 20 washes. Results suggest that this combination could be a potential insecticide resistance management tool for preventing malaria transmission in areas compromised by the spread of pyrethroid resistance.

  9. The combination of the entomopathogenic fungus Metarhizium anisopliae with the insecticide Imidacloprid increases virulence against the dengue vector Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Paula, Adriano R; Carolino, Aline T; Paula, Cátia O; Samuels, Richard I

    2011-01-25

    Dengue fever transmitted by the mosquito Aedes aegypti, is one of the most rapidly spreading insect borne diseases, stimulating the search for alternatives to current control measures. The dengue vector A. aegypti has received less attention than anophelene species, although more than 2.5 billion people are at risk of infection worldwide. Entomopathogenic fungi are emerging as potential candidates for the control of mosquitoes. Here we continue our studies on the pathogenicity of the entomopathogenic fungus Metarhizium anisopliae against adult A. aegypti females. With the aim of further reducing mean survival times of A. aegypti exposed to fungus impregnated surfaces, a sub-lethal concentration of the neonicotinoid insecticide Imidacloprid (IMI) was added to fungal suspensions. A sub-lethal concentration of IMI that did not significantly alter the daily survival rates or mean survival percentages of mosquitoes was identified to be 0.1 ppm. This sub-lethal concentration was combined with M. anisopliae conidia (1 × 10(9) conidia mL(-1)). Both the combined treatment and the conidia alone were able to reduce the survival of A. aegypti compared with untreated or IMI treated mosquitoes. Importantly, mosquito survival following exposure to the combined treatment for 6 and 12 hrs was significantly reduced when compared with mosquitoes exposed to conidia alone. This is the first time that a combination of an insecticide and an entomopathogenic fungus has been tested against A. aegypti. Firstly, the study showed the potential of IMI as an alternative to the currently employed pyrethroid adulticides. Secondly, as an alternative to applications of high concentrations of chemical insecticides, we suggest that adult A. aegypti could be controlled by surface application of entomopathogenic fungi and that the efficiency of these fungi could be increased by combining the fungi with ultra-low concentrations of insecticides, resulting in higher mortality following relatively short

  10. The combination of the entomopathogenic fungus Metarhizium anisopliae with the insecticide Imidacloprid increases virulence against the dengue vector Aedes aegypti (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Samuels Richard I

    2011-01-01

    Full Text Available Abstract Background Dengue fever transmitted by the mosquito Aedes aegypti, is one of the most rapidly spreading insect borne diseases, stimulating the search for alternatives to current control measures. The dengue vector A. aegypti has received less attention than anophelene species, although more than 2.5 billion people are at risk of infection worldwide. Entomopathogenic fungi are emerging as potential candidates for the control of mosquitoes. Here we continue our studies on the pathogenicity of the entomopathogenic fungus Metarhizium anisopliae against adult A. aegypti females. With the aim of further reducing mean survival times of A. aegypti exposed to fungus impregnated surfaces, a sub-lethal concentration of the neonicotinoid insecticide Imidacloprid (IMI was added to fungal suspensions. Results A sub-lethal concentration of IMI that did not significantly alter the daily survival rates or mean survival percentages of mosquitoes was identified to be 0.1 ppm. This sub-lethal concentration was combined with M. anisopliae conidia (1 × 109 conidia mL-1. Both the combined treatment and the conidia alone were able to reduce the survival of A. aegypti compared with untreated or IMI treated mosquitoes. Importantly, mosquito survival following exposure to the combined treatment for 6 and 12 hrs was significantly reduced when compared with mosquitoes exposed to conidia alone. Conclusions This is the first time that a combination of an insecticide and an entomopathogenic fungus has been tested against A. aegypti. Firstly, the study showed the potential of IMI as an alternative to the currently employed pyrethroid adulticides. Secondly, as an alternative to applications of high concentrations of chemical insecticides, we suggest that adult A. aegypti could be controlled by surface application of entomopathogenic fungi and that the efficiency of these fungi could be increased by combining the fungi with ultra-low concentrations of insecticides

  11. Insecticide control in a Dengue epidemics model

    CERN Document Server

    Rodrigues, Helena Sofia; Torres, Delfim F M

    2010-01-01

    A model for the transmission of dengue disease is presented. It consists of eight mutually-exclusive compartments representing the human and vector dynamics. It also includes a control parameter (insecticide) in order to fight the mosquitoes. The main goal of this work is to investigate the best way to apply the control in order to effectively reduce the number of infected humans and mosquitoes. A case study, using data of the outbreak that occurred in 2009 in Cape Verde, is presented.

  12. Tools for delivering entomopathogenic fungi to malaria mosquitoes: effects of delivery surfaces on fungal efficacy and persistence

    Directory of Open Access Journals (Sweden)

    Mnyone Ladslaus L

    2010-08-01

    Full Text Available Abstract Background Entomopathogenic fungi infection on malaria vectors increases daily mortality rates and thus represents a control measure that could be used in integrated programmes alongside insecticide-treated bed nets (ITNs and indoor residual spraying (IRS. Before entomopathogenic fungi can be integrated into control programmes, an effective delivery system must be developed. Methods The efficacy of Metarhizium anisopliae ICIPE-30 and Beauveria bassiana I93-825 (IMI 391510 (2 × 1010 conidia m-2 applied on mud panels (simulating walls of traditional Tanzanian houses, black cotton cloth and polyester netting was evaluated against adult Anopheles gambiae sensu stricto. Mosquitoes were exposed to the treated surfaces 2, 14 and 28 d after conidia were applied. Survival of mosquitoes was monitored daily. Results All fungal treatments caused a significantly increased mortality in the exposed mosquitoes, descending with time since fungal application. Mosquitoes exposed to M. anisopliae conidia on mud panels had a greater daily risk of dying compared to those exposed to conidia on either netting or cotton cloth (p B. bassiana conidia on mud panels or cotton cloth had similar daily risk of death (p = 0.14, and a higher risk than those exposed to treated polyester netting (p Conclusion Both fungal isolates reduced mosquito survival on immediate exposure and up to 28 d after application. Conidia were more effective when applied on mud panels and cotton cloth compared with polyester netting. Cotton cloth and mud, therefore, represent potential substrates for delivering fungi to mosquitoes in the field.

  13. Wolbachia-a foe for mosquitoes

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    Nadipinayakanahalli Munikrishnappa Guruprasad

    2014-02-01

    Full Text Available Mosquitoes act as vectors for a wide range of viral and parasitic infectious diseases such as malaria, dengue, Chickungunya, lymphatic filariasis, Japanese encephalitis and West Nile virus in humans as well as in animals. Although a wide range of insecticides are used to control mosquitoes, it has only resulted in development of resistance to such insecticides. The evolution of insecticide resistance and lack of vaccines for many mosquito-borne diseases have made these arthropods highly harmful vectors. Recently, a novel approach to control mosquitoes by transinfection of life shortening maternally transmitted endo-symbiont Wolbachia wMelPop strain from fruitfly Drosophila into mosquito population has been developed by researchers. The wMelPop strain up-regulated the immune gene expression in mosquitoes thereby reducing the dengue and Chickungunya viral replication in Aedes aegypti, and also it significantly reduced the Plasmodium level in Anopheles gambiae. Here, we discuss the strategy of using Wolbachia in control of vector-borne diseases of mosquitoes.

  14. Comparative assessment of diverse strategies for malaria vector population control based on measured rates at which mosquitoes utilize targeted resource subsets.

    Science.gov (United States)

    Killeen, Gerry F; Kiware, Samson S; Seyoum, Aklilu; Gimnig, John E; Corliss, George F; Stevenson, Jennifer; Drakeley, Christopher J; Chitnis, Nakul

    2014-08-28

    Eliminating malaria requires vector control interventions that dramatically reduce adult mosquito population densities and survival rates. Indoor applications of insecticidal nets and sprays are effective against an important minority of mosquito species that rely heavily upon human blood and habitations for survival. However, complementary approaches are needed to tackle a broader diversity of less human-specialized vectors by killing them at other resource targets. Impacts of strategies that target insecticides to humans or animals can be rationalized in terms of biological coverage of blood resources, quantified as proportional coverage of all blood resources mosquito vectors utilize. Here, this concept is adapted to enable impact prediction for diverse vector control strategies based on measurements of utilization rates for any definable, targetable resource subset, even if that overall resource is not quantifiable. The usefulness of this approach is illustrated by deriving utilization rate estimates for various blood, resting site, and sugar resource subsets from existing entomological survey data. Reported impacts of insecticidal nets upon human-feeding vectors, and insecticide-treated livestock upon animal-feeding vectors, are approximately consistent with model predictions based on measured utilization rates for those human and animal blood resource subsets. Utilization rates for artificial sugar baits compare well with blood resources, and are consistent with observed impact when insecticide is added. While existing data was used to indirectly measure utilization rates for a variety of resting site subsets, by comparison with measured rates of blood resource utilization in the same settings, current techniques for capturing resting mosquitoes underestimate this quantity, and reliance upon complex models with numerous input parameters may limit the applicability of this approach. While blood and sugar consumption can be readily quantified using existing

  15. Biological Control of Mosquito Vectors: Past, Present, and Future

    Science.gov (United States)

    Benelli, Giovanni; Jeffries, Claire L.; Walker, Thomas

    2016-01-01

    Mosquitoes represent the major arthropod vectors of human disease worldwide transmitting malaria, lymphatic filariasis, and arboviruses such as dengue virus and Zika virus. Unfortunately, no treatment (in the form of vaccines or drugs) is available for most of these diseases and vector control is still the main form of prevention. The limitations of traditional insecticide-based strategies, particularly the development of insecticide resistance, have resulted in significant efforts to develop alternative eco-friendly methods. Biocontrol strategies aim to be sustainable and target a range of different mosquito species to reduce the current reliance on insecticide-based mosquito control. In this review, we outline non-insecticide based strategies that have been implemented or are currently being tested. We also highlight the use of mosquito behavioural knowledge that can be exploited for control strategies. PMID:27706105

  16. Repellent and mosquitocidal effects of leaf extracts of Clausena anisata against the Aedes aegypti mosquito (Diptera: Culicidae).

    Science.gov (United States)

    Mukandiwa, Lillian; Eloff, Jacobus Nicolaas; Naidoo, Vinny

    2016-06-01

    Mosquitoes are rapidly developing resistance to insecticides that millions of people relied on to protect themselves from the diseases they carry, thereby creating a need to develop new insecticides. Clausena anisata is used traditionally as an insect repellent by various communities in Africa and Asia. For this study, the repellency and adulticidal activities of leaf extracts and compounds isolated from this plant species were evaluated against the yellow fever mosquito, Aedes aegypti. In the topical application assays, using total bites as an indicator, repellency was dose dependent, with the acetone crude extract (15 %) having 93 % repellence and the hexane fraction (7.5 %) 67 % repellence after 3 h. Fractionation resulted in a loss of total repellence. As mosquito-net treating agents, the acetone and hexane extracts of C. anisata, both at 15 %, had average repellences of 46.89 ± 2.95 and 50.13 ± 2.02 %, respectively, 3 h after exposure. The C. anisata acetone extract and its hexane fraction caused mosquito knockdown and eventually death when nebulised into the testing chamber, with an EC50 of 78.9 mg/ml (7.89 %) and 71.6 mg/ml (7.16 %) in the first 15 min after spraying. C. anisata leaf extracts have potential to be included in protection products against mosquitoes due to the repellent and cidal compounds contained therein.

  17. Plant-borne ovicides in the fight against mosquito vectors of medical and veterinary importance: a systematic review.

    Science.gov (United States)

    Benelli, Giovanni

    2015-09-01

    Mosquitoes (Diptera: Culicidae) are a huge threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. Culicidae control is of crucial importance. Mosquito eggs, larvae, and pupae are usually targeted using organophosphates, insect growth regulators, and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment, and induce resistance in a number of species. Eco-friendly tools have been recently implemented against mosquito vectors, including botanical insecticides. The majority of researches focused on larvicides (745 SCOPUS results, July 2015) and adult repellents (434 SCOPUS results), while limited efforts were conducted to identify effective ovicides of botanical origin (59 SCOPUS results). Here, I review current knowledge on the effectiveness of plant-borne ovicides against major mosquito vectors of medical and veterinary importance. The majority of researches focused on the toxicity of crude extracts, their fractions, or essential oils against three important mosquito vectors, Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. As a general trend, C. quinquefasciatus eggs were the most resistant to botanical ovicides. Five studies proposed selected compounds from plant extracts and essential oils as ovicides effective at few parts per million. However, no efforts were conducted to shed light on possible mechanisms underlying the toxicity of plant-borne ovicides. In the final section, a number of hot issues needing further research and cooperation among parasitologists, entomologists, and researchers working in natural product chemistry are outlined.

  18. Evidence That Mutant PfCRT Facilitates the Transmission to Mosquitoes of Chloroquine-Treated Plasmodium Gametocytes

    OpenAIRE

    Ecker, Andrea; Lakshmanan, Viswanathan; Sinnis, Photini; Coppens, Isabelle; Fidock, David A

    2011-01-01

    Resistance of the human malarial parasite Plasmodium falciparum to the antimalarial drug chloroquine has rapidly spread from several independent origins and is now widely prevalent throughout the majority of malaria-endemic areas. Field studies have suggested that chloroquine-resistant strains might be more infective to mosquito vectors. To test the hypothesis that the primary chloroquine resistance determinant, mutations in PfCRT, facilitates parasite transmission under drug pressure, we hav...

  19. Success of Senegal's first nationwide distribution of long-lasting insecticide-treated nets to children under five - contribution toward universal coverage

    Directory of Open Access Journals (Sweden)

    Diouf Mame

    2011-04-01

    Full Text Available Abstract Background In 2009, the first national long-lasting insecticide-treated net (LLIN distribution campaign in Senegal resulted in the distribution of 2.2 million LLINs in two phases to children aged 6-59 months. Door-to-door teams visited all households to administer vitamin A and mebendazole, and to give a coupon to redeem later for an LLIN. Methods A nationwide community-based two-stage cluster survey was conducted, with clusters selected within regions by probability proportional to size sampling, followed by GPS-assisted mapping, simple random selection of households in each cluster, and administration of a questionnaire using personal digital assistants (PDAs. The questionnaire followed the Malaria Indicator Survey format, with rosters of household members and bed nets, and questions on campaign participation. Results There were 3,280 households in 112 clusters representing 33,993 people. Most (92.1% guardians of eligible children had heard about the campaign, the primary sources being health workers (33.7%, neighbours (26.2%, and radio (22.0%. Of eligible children, 82.4% received mebendazole, 83.8% received vitamin A, and 75.4% received LLINs. Almost all (91.4% LLINs received during the campaign remained in the household; of those not remaining, 74.4% had been given away and none were reported sold. At least one insecticide-treated net (ITN was present in 82.3% of all households, 89.2% of households with a child Conclusions The nationwide integrated LLIN distribution campaign allowed household ITN ownership of one or more ITNs to surpass the RBM target of 80% set for 2010, though additional distribution strategies are needed to reach populations missed by the targeted campaign and to reach the universal coverage targets of one ITN per sleeping space and 80% of the population using an ITN.

  20. Costing the distribution of insecticide-treated nets: a review of cost and cost-effectiveness studies to provide guidance on standardization of costing methodology

    Directory of Open Access Journals (Sweden)

    Hanson Kara

    2006-05-01

    Full Text Available Abstract Background Insecticide-treated nets (ITNs are an effective and cost-effective means of malaria control. Scaling-up coverage of ITNs is challenging. It requires substantial resources and there are a number of strategies to choose from. Information on the cost of different strategies is still scarce. To guide the choice of a delivery strategy (or combination of strategies, reliable and standardized cost information for the different options is required. Methods The electronic online database PubMed was used for a systematic search of the published English literature on costing and economic evaluations of ITN distribution programmes. The keywords used were: net, bednet, insecticide, treated, ITN, cost, effectiveness, economic and evaluation. Identified papers were analysed to determine and evaluate the costing methods used. Methods were judged against existing standards of cost analysis to arrive at proposed standards for undertaking and presenting cost analyses. Results Cost estimates were often not readily comparable or could not be adjusted to a different context. This resulted from the wide range of methods applied and measures of output chosen. Most common shortcomings were the omission of certain costs and failure to adjust financial costs to generate economic costs. Generalisability was hampered by authors not reporting quantities and prices of resources separately and not examining the sensitivity of their results to variations in underlying assumptions. Conclusion The observed shortcomings have arisen despite the abundance of literature and guidelines on costing of health care interventions. This paper provides ITN specific recommendations in the hope that these will help to standardize future cost estimates.

  1. Insecticide resistance in Anopheles gambiae from south-western Chad, Central Africa

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    Etang Josiane

    2008-09-01

    Full Text Available Abstract Background Indoor residual spraying and insecticide-treated nets (ITN are essential components of malaria vector control in Africa. Pyrethroids are the only recommended compounds for nets treatment because they are fast-acting insecticides with low mammalian toxicity. However, there is growing concern that pyrethroid resistance may threaten the sustainability of ITN scaling-up programmes. Here, insecticide susceptibility was investigated in Anopheles gambiae sensu lato from an area of large scale ITN distribution programme in south-western Chad. Methods Susceptibility to 4% DDT, 0.05% deltamethrin, 0.75% permethrin, 0.1% bendiocarb and 5% malathion was assessed using the WHO standard procedures for adult mosquitoes. Tests were carried out with two to four days-old, non-engorged female mosquitoes. The An. gambiae Kisumu strain was used as a reference. Knockdown effect was recorded every 5 min and mortality scored 24 h after exposure. Mosquitoes were identified to species and molecular form by PCR-RFLP and genotypes at the kdr locus were determined in surviving specimens by Hot Oligonucleotide Ligation Assay (HOLA. Results During this survey, full susceptibility to malathion was recorded in all samples. Reduced susceptibility to bendiocarb (mortality rate of 96.1% was found in one sample out of nine assayed. Increased tolerance to pyrethroids was detected in most samples (8/9 with mortality rates ranging from 70.2 to 96.6% for deltamethrin and from 26.7 to 96.3% for permethrin. Pyrethroid tolerance was not associated with a significant increase of knock-down times. Anopheles arabiensis was the predominant species of the An. gambiae complex in the study area, representing 75 to 100% of the samples. Screening for kdr mutations detected the L1014F mutation in 88.6% (N = 35 of surviving An. gambiae sensu stricto S form mosquitoes. All surviving An. arabiensis (N = 49 and M form An. gambiae s.s. (N = 1 carried the susceptible allele

  2. Vorticella sp: Prospective Mosquito Biocontrol agent

    OpenAIRE

    Chandrashekhar Devidas Patil; Chandrakant Prakash Narkhede; Rahul Khushal Suryawanshi; Satish Vitthal Patil

    2016-01-01

    Background: Considering the disadvantages of chemical insecticides, we aimed to evaluate Vorticella parasites for control of mosquito larvae of Anopheles stephensi and Aedes aegypti at different larval stages.Methods: Vorticella sp infected mosquito larvae were crushed in the 0.85% saline and homogenized well to get Vorti­cella in suspension. The effects of Vorticella sp infections on larval development were investigated by inoculat­ing protozoan on different larval instars of An. stephensi a...

  3. Vorticella sp: Prospective Mosquito Biocontrol Agent

    OpenAIRE

    Patil, Chandrashekhar Devidas; Narkhede, Chandrakant Prakash; Suryawanshi, Rahul Khushal; Patil, Satish Vitthal

    2016-01-01

    Background: Considering the disadvantages of chemical insecticides, we aimed to evaluate Vorticella parasites for control of mosquito larvae of Anopheles stephensi and Aedes aegypti at different larval stages. Methods: Vorticella sp infected mosquito larvae were crushed in the 0.85% saline and homogenized well to get Vorticella in suspension. The effects of Vorticella sp infections on larval development were investigated by inoculating protozoan on different larval instars of An. stephensi an...

  4. RNA Interference for Mosquito and Mosquito-Borne Disease Control

    Directory of Open Access Journals (Sweden)

    Paul M. Airs

    2017-01-01

    Full Text Available RNA interference (RNAi is a powerful tool to silence endogenous mosquito and mosquito-borne pathogen genes in vivo. As the number of studies utilizing RNAi in basic research grows, so too does the arsenal of physiological targets that can be developed into products that interrupt mosquito life cycles and behaviors and, thereby, relieve the burden of mosquitoes on human health and well-being. As this technology becomes more viable for use in beneficial and pest insect management in agricultural settings, it is exciting to consider its role in public health entomology. Existing and burgeoning strategies for insecticide delivery could be adapted to function as RNAi trigger delivery systems and thereby expedite transformation of RNAi from the lab to the field for mosquito control. Taken together, development of RNAi-based vector and pathogen management techniques & strategies are within reach. That said, tools for successful RNAi design, studies exploring RNAi in the context of vector control, and studies demonstrating field efficacy of RNAi trigger delivery have yet to be honed and/or developed for mosquito control.

  5. Averting a malaria disaster: will insecticide resistance derail malaria control?

    Science.gov (United States)

    Hemingway, Janet; Ranson, Hilary; Magill, Alan; Kolaczinski, Jan; Fornadel, Christen; Gimnig, John; Coetzee, Maureen; Simard, Frederic; Roch, Dabiré K; Hinzoumbe, Clément Kerah; Pickett, John; Schellenberg, David; Gething, Peter; Hoppé, Mark; Hamon, Nicholas

    2016-04-23

    World Malaria Day 2015 highlighted the progress made in the development of new methods of prevention (vaccines and insecticides) and treatment (single dose drugs) of the disease. However, increasing drug and insecticide resistance threatens the successes made with existing methods. Insecticide resistance has decreased the efficacy of the most commonly used insecticide class of pyrethroids. This decreased efficacy has increased mosquito survival, which is a prelude to rising incidence of malaria and fatalities. Despite intensive research efforts, new insecticides will not reach the market for at least 5 years. Elimination of malaria is not possible without effective mosquito control. Therefore, to combat the threat of resistance, key stakeholders need to rapidly embrace a multifaceted approach including a reduction in the cost of bringing new resistance management methods to market and the streamlining of associated development, policy, and implementation pathways to counter this looming public health catastrophe.

  6. Acceptability and perceived side effects of insecticide indoor residual spraying under different resistance management strategies

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    Rodríguez Américo David

    2006-01-01

    Full Text Available OBJECTIVE: To assess household acceptability and perceived side effects of residual indoor pyrethroid (PYR, carbamate and organophosphate insecticides sprayed by annual rotation (ROT, spatial mosaic (MOS, and a single insecticide (DDT or PYR in communities of the coastal plain of Chiapas, Mexico. MATERIAL AND METHODS: A questionnaire to assess the acceptability and perceived side effects of indoor insecticides was administered to one member of 30% of the families in eight villages of Chiapas. The association of different insecticide treatments with their responses was evaluated (Chi-square. The intensity of side effects indicated under different treatments was compared in an ordered logistic model, using a severity index as the response variable. RESULTS: Insecticide spraying as a probable cause of symptoms was identified by 2.1% of interviewees. A significantly high percentage of persons with blurred vision, dizziness, sneezing, coughing, numbness, watery eyes, and itching lived in villages under MOS and ROT and a high severity index was significantly associated with ROT treatment. Reduction of mosquito bites and cockroaches were the perceived main benefits, and most villagers that perceived no benefits lived in DDT treated villages. Most of the interviewees welcomed spraying (83.7%, but the smell and having to remove furniture from houses were the main arguments against it. CONCLUSIONS: Acceptability correlated with insecticide spray coverage, although the most frequent suggestion for improvement was to increase the understanding of the objectives of spraying in the communities. The frequency of side effects was low, but higher in localities where a combination of insecticides was applied. This is a limitation for the use of this type of resistance management strategy in public health.

  7. Insecticide-driven patterns of genetic variation in the dengue vector Aedes aegypti in Martinique Island.

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    Sébastien Marcombe

    Full Text Available Effective vector control is currently challenged worldwide by the evolution of resistance to all classes of chemical insecticides in mosquitoes. In Martinique, populations of the dengue vector Aedes aegypti have been intensively treated with temephos and deltamethrin insecticides over the last fifty years, resulting in heterogeneous levels of resistance across the island. Resistance spreading depends on standing genetic variation, selection intensity and gene flow among populations. To determine gene flow intensity, we first investigated neutral patterns of genetic variability in sixteen populations representative of the many environments found in Martinique and experiencing various levels of insecticide pressure, using 6 microsatellites. Allelic richness was lower in populations resistant to deltamethrin, and consanguinity was higher in populations resistant to temephos, consistent with a negative effect of insecticide pressure on neutral genetic diversity. The global genetic differentiation was low, suggesting high gene flow among populations, but significant structure was found, with a pattern of isolation-by-distance at the global scale. Then, we investigated adaptive patterns of divergence in six out of the 16 populations using 319 single nucleotide polymorphisms (SNPs. Five SNP outliers displaying levels of genetic differentiation out of neutral expectations were detected, including the kdr-V1016I mutation in the voltage-gated sodium channel gene. Association tests revealed a total of seven SNPs associated with deltamethrin resistance. Six other SNPs were associated with temephos resistance, including two non-synonymous substitutions in an alkaline phosphatase and in a sulfotransferase respectively. Altogether, both neutral and adaptive patterns of genetic variation in mosquito populations appear to be largely driven by insecticide pressure in Martinique.

  8. Quantifying the mosquito's sweet tooth: modelling the effectiveness of attractive toxic sugar baits (ATSB) for malaria vector control.

    Science.gov (United States)

    Marshall, John M; White, Michael T; Ghani, Azra C; Schlein, Yosef; Muller, Gunter C; Beier, John C

    2013-08-23

    Current vector control strategies focus largely on indoor measures, such as long-lasting insecticide treated nets (LLINs) and indoor residual spraying (IRS); however mosquitoes frequently feed on sugar sources outdoors, inviting the possibility of novel control strategies. Attractive toxic sugar baits (ATSB), either sprayed on vegetation or provided in outdoor bait stations, have been shown to significantly reduce mosquito densities in these settings. Simple models of mosquito sugar-feeding behaviour were fitted to data from an ATSB field trial in Mali and used to estimate sugar-feeding rates and the potential of ATSB to control mosquito populations. The model and fitted parameters were then incorporated into a larger integrated vector management (IVM) model to assess the potential contribution of ATSB to future IVM programmes. In the Mali experimental setting, the model suggests that about half of female mosquitoes fed on ATSB solution per day, dying within several hours of ingesting the toxin. Using a model incorporating the number of gonotrophic cycles completed by female mosquitoes, a higher sugar-feeding rate was estimated for younger mosquitoes than for older mosquitoes. Extending this model to incorporate other vector control interventions suggests that an IVM programme based on both ATSB and LLINs may substantially reduce mosquito density and survival rates in this setting, thereby substantially reducing parasite transmission. This is predicted to exceed the impact of LLINs in combination with IRS provided ATSB feeding rates are 50% or more of Mali experimental levels. In addition, ATSB is predicted to be particularly effective against Anopheles arabiensis, which is relatively exophilic and therefore less affected by IRS and LLINs. These results suggest that high coverage with a combination of LLINs and ATSB could result in substantial reductions in malaria transmission in this setting. Further field studies of ATSB in other settings are needed to assess

  9. Persistent oscillations and backward bifurcation in a malaria model with varying human and mosquito populations: implications for control.

    Science.gov (United States)

    Ngonghala, Calistus N; Teboh-Ewungkem, Miranda I; Ngwa, Gideon A

    2015-06-01

    We derive and study a deterministic compartmental model for malaria transmission with varying human and mosquito populations. Our model considers disease-related deaths, asymptomatic immune humans who are also infectious, as well as mosquito demography, reproduction and feeding habits. Analysis of the model reveals the existence of a backward bifurcation and persistent limit cycles whose period and size is determined by two threshold parameters: the vectorial basic reproduction number Rm, and the disease basic reproduction number R0, whose size can be reduced by reducing Rm. We conclude that malaria dynamics are indeed oscillatory when the methodology of explicitly incorporating the mosquito's demography, feeding and reproductive patterns is considered in modeling the mosquito population dynamics. A sensitivity analysis reveals important control parameters that can affect the magnitudes of Rm and R0, threshold quantities to be taken into consideration when designing control strategies. Both Rm and the intrinsic period of oscillation are shown to be highly sensitive to the mosquito's birth constant λm and the mosquito's feeding success probability pw. Control of λm can be achieved by spraying, eliminating breeding sites or moving them away from human habitats, while pw can be controlled via the use of mosquito repellant and insecticide-treated bed-nets. The disease threshold parameter R0 is shown to be highly sensitive to pw, and the intrinsic period of oscillation is also sensitive to the rate at which reproducing mosquitoes return to breeding sites. A global sensitivity and uncertainty analysis reveals that the ability of the mosquito to reproduce and uncertainties in the estimations of the rates at which exposed humans become infectious and infectious humans recover from malaria are critical in generating uncertainties in the disease classes.

  10. Comparison of Insecticide-Treated Nets and Indoor Residual Spraying to Control the Vector of Visceral Leishmaniasis in Mymensingh District, Bangladesh

    Science.gov (United States)

    Chowdhury, Rajib; Dotson, Ellen; Blackstock, Anna J.; McClintock, Shannon; Maheswary, Narayan P.; Faria, Shyla; Islam, Saiful; Akter, Tangin; Kroeger, Axel; Akhter, Shireen; Bern, Caryn

    2011-01-01

    Integrated vector management is a pillar of the South Asian visceral leishmaniasis (VL) elimination program, but the best approach remains a matter of debate. Sand fly seasonality was determined in 40 houses sampled monthly. The impact of interventions on Phlebotomus argentipes density was tested from 2006–2007 in a cluster-randomized trial with four arms: indoor residual spraying (IRS), insecticide-treated nets (ITNs), environmental management (EVM), and no intervention. Phlebotomus argentipes density peaked in March with the highest proportion of gravid females in May. The EVM (mud plastering of wall and floor cracks) showed no impact. The IRS and ITNs were associated with a 70–80% decrease in male and female P. argentipes density up to 5 months post intervention. Vector density rebounded by 11 months post-IRS, whereas ITN-treated households continued to show significantly lower density compared with households without intervention. Our data suggest that both IRS and ITNs may help to improve VL control in Bangladesh. PMID:21540372

  11. Impact of artemisinin-based combination therapy and insecticide-treated nets on malaria burden in Zanzibar.

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    Achuyt Bhattarai

    2007-11-01

    Full Text Available BACKGROUND: The Roll Back Malaria strategy recommends a combination of interventions for malaria control. Zanzibar implemented artemisinin-based combination therapy (ACT for uncomplicated malaria in late 2003 and long-lasting insecticidal nets (LLINs from early 2006. ACT is provided free of charge to all malaria patients, while LLINs are distributed free to children under age 5 y ("under five" and pregnant women. We investigated temporal trends in Plasmodium falciparum prevalence and malaria-related health parameters following the implementation of these two malaria control interventions in Zanzibar. METHODS AND FINDINGS: Cross-sectional clinical and parasitological surveys in children under the age of 14 y were conducted in North A District in May 2003, 2005, and 2006. Survey data were analyzed in a logistic regression model and adjusted for complex sampling design and potential confounders. Records from all 13 public health facilities in North A District were analyzed for malaria-related outpatient visits and admissions. Mortality and demographic data were obtained from District Commissioner's Office. P. falciparum prevalence decreased in children under five between 2003 and 2006; using 2003 as the reference year, odds ratios (ORs and 95% confidence intervals (CIs were, for 2005, 0.55 (0.28-1.08, and for 2006, 0.03 (0.00-0.27; p for trend < 0.001. Between 2002 and 2005 crude under-five, infant (under age 1 y, and child (aged 1-4 y mortality decreased by 52%, 33%, and 71%, respectively. Similarly, malaria-related admissions, blood transfusions, and malaria-attributed mortality decreased significantly by 77%, 67% and 75%, respectively, between 2002 and 2005 in children under five. Climatic conditions favorable for malaria transmission persisted throughout the observational period. CONCLUSIONS: Following deployment of ACT in Zanzibar 2003, malaria-associated morbidity and mortality decreased dramatically within two years. Additional distribution

  12. Dissecting the organ specificity of insecticide resistance candidate genes in Anopheles gambiae: known and novel candidate genes

    OpenAIRE

    2014-01-01

    Background The elevated expression of enzymes with insecticide metabolism activity can lead to high levels of insecticide resistance in the malaria vector, Anopheles gambiae. In this study, adult female mosquitoes from an insecticide susceptible and resistant strain were dissected into four different body parts. RNA from each of these samples was used in microarray analysis to determine the enrichment patterns of the key detoxification gene families within the mosquito and to identify additio...

  13. Biological Control of Mosquito Vectors: Past, Present, and Future

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    Giovanni Benelli

    2016-10-01

    Full Text Available Mosquitoes represent the major arthropod vectors of human disease worldwide transmitting malaria, lymphatic filariasis, and arboviruses such as dengue virus and Zika virus. Unfortunately, no treatment (in the form of vaccines or drugs is available for most of these diseases andvectorcontrolisstillthemainformofprevention. Thelimitationsoftraditionalinsecticide-based strategies, particularly the development of insecticide resistance, have resulted in significant efforts to develop alternative eco-friendly methods. Biocontrol strategies aim to be sustainable and target a range of different mosquito species to reduce the current reliance on insecticide-based mosquito control. In thisreview, weoutline non-insecticide basedstrategiesthat havebeenimplemented orare currently being tested. We also highlight the use of mosquito behavioural knowledge that can be exploited for control strategies.

  14. Inhibition of the growth and development of mosquito larvae ofCulex quinquefasciatus (Diptera:Culicidae) treated with extract from leaves of Pseudocalymma alliaceum (Bignonaceae)

    Institute of Scientific and Technical Information of China (English)

    Carlos Granados-Echegoyen; Rafael Prez-Pacheco; Marcos Soto-Hernndez; Jaime Ruiz-Vega; Luicita Lagunez-Rivera; Nancy Alonso-Hernandez; Rene Gato-Armas

    2014-01-01

    Objective:To determine larvicidal activity of the essential oil, hydrolat and botanical extracts derived from leaves ofPseudocalymma alliaceum on mosquito larvae ofCulex quinquefasciatus. Methods:Groups of twenty larvae were used in the larvicidal assays.The mortality, relative growth rate, the larval and pupal duration and viability was estimated.The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to massspectrometry. Results:Essential oil at800 ppm showed larvicidal activity at24 h with lethal values ofLC50 and LC90of267.33 and493.63 ppm.The hydrolat at20% and10% on2nd stage larvae showed100% effectiveness after24 h.The aqueous extract at10% had a relative growth index of0.58, while the ethanolic and methanolic extract obtained values of0.76 and0.70 and control reached0.99. Larvae treated with10% of methanol, ethanol and aqueous extract showed a reduction in larval duration of5.00,2.20 and4.35 days; ethanol extract at1% provoke decrease of2.40 days in the development and exhibited an increment of3.30 days when treated with0.01%.Aqueous, ethanol and methanol extracts at10% reduced in6.15,3.42 and5.57 days pupal development.The main compounds were diallyl disulfide(50.05%), diallyl sulfide(11.77%) and trisulfide di-2-propenyl (10.37%).Conclusions:The study demonstrated for the first time, the larvicidal activity of the essential oil and hydrolat ofPseudocalymma alliaceum; aqueous, ethanol and methanol extracts inhibited the normal growth and development of mosquito larvae, prolonging and delaying larval and pupal duration.

  15. Inhibition of the growth and development of mosquito larvae of Culex quinquefasciatus (Diptera: Culicidae) treated with extract from leaves of Pseudocalymma alliaceum (Bignonaceae).

    Science.gov (United States)

    Granados-Echegoyen, Carlos; Pérez-Pacheco, Rafael; Soto-Hernández, Marcos; Ruiz-Vega, Jaime; Lagunez-Rivera, Luicita; Alonso-Hernandez, Nancy; Gato-Armas, Rene

    2014-08-01

    To determine larvicidal activity of the essential oil, hydrolat and botanical extracts derived from leaves of Pseudocalymma alliaceum on mosquito larvae of Culex quinquefasciatus. Groups of twenty larvae were used in the larvicidal assays. The mortality, relative growth rate, the larval and pupal duration and viability was estimated. The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to mass spectrometry. Essential oil at 800 ppm showed larvicidal activity at 24 h with lethal values of LC50 and LC90 of 267.33 and 493.63 ppm. The hydrolat at 20% and 10% on 2nd stage larvae showed 100% effectiveness after 24 h. The aqueous extract at 10% had a relative growth index of 0.58, while the ethanolic and methanolic extract obtained values of 0.76 and 0.70 and control reached 0.99. Larvae treated with 10% of methanol, ethanol and aqueous extract showed a reduction in larval duration of 5.00, 2.20 and 4.35 days; ethanol extract at 1% provoke decrease of 2.40 days in the development and exhibited an increment of 3.30 days when treated with 0.01%. Aqueous, ethanol and methanol extracts at 10% reduced in 6.15, 3.42 and 5.57 days pupal development. The main compounds were diallyl disulfide (50.05%), diallyl sulfide (11.77%) and trisulfide di-2-propenyl (10.37%). The study demonstrated for the first time, the larvicidal activity of the essential oil and hydrolat of Pseudocalymma alliaceum; aqueous, ethanol and methanol extracts inhibited the normal growth and development of mosquito larvae, prolonging and delaying larval and pupal duration. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  16. Insecticide susceptibility tests conducted in Kamhororo, Masakadza and Chilonga villages in Zimbabwe during the 2011 malaria period

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    N. Lukwa

    2012-12-01

    Full Text Available Insecticide susceptibility tests using World Health Organization papers treated with 4% dichloro-diphenyl-trichloro-ethane (DDT, 0.05% deltamethrin, 0.05% lambda-cyhalothrin, 0.5% etofenprox, 0.15% cyfluthrin and 0.75% permethrin were conducted in Kamhororo, Masakadza and Chilonga villages, Zimbabwe. Three to 5-day old female Anopheles gambiae sensu lato adult mosquitoes were used. Deltamethrin knocked down 100% of the mosquitoes from Kamhororo, Masakadza and Chilonga at 35 min exposure. DDT did not knock down 100% of the mosquitoes from Kamhororo and Masakadza but did so in Chilonga. One hundred percent knockdown was achieved for cyfluthrin when exposed to mosquitoes from Kamhororo (60 min, Masakadza (25 min and Chilonga (25 min. Etofenprox knocked down 100% of the mosquitoes collected from Kamhororo (30 min, Masakadza (30 min and Chilonga (55 min. Knockdown of mosquitoes due to deltamethrin, DDT, cyfluthrin, permethrin; lambda-cyhalothrin and etofenprox were different at different observation times. One hundred percent mortality due to deltamethrin, DDT, etofenprox, lambdacyhalothrin and cyfluthrin was recorded for mosquitoes collected from all the 3 sites. One hundred percent mortality due to pemethrin was recorded for mosquitoes collected from Kamhororo and Chilonga but mortality was 98.5% for those collected from Masakadza. No knockdown or mortality occurred in the controls from each locality. The kd50 (knockdown of 50% of the mosquitoes values were 24.4-73.7 min (DDT, 8-13 min (pemethrin, 9.4-16.3 min (cyfluthrin, 9.4-14.4 min (etofenprox, 8.7-13 min (lambda-cyhalothrin and 12.1-15.9 min (deltamethrin. The kd90 (knockdown of 90% of the mosquitoes values were 45.6-199.5 min (DDT, 14.7-26.5 min (pemethrin, 16.5-34.9 min (cyfluthrin, 21.8-24.4 min (etofenprox, 16.3-31.6 min (lambdacyhalothrin and 21-25.3 min (deltamethrin. No insecticide resistance was recorded from the 3 sites.

  17. Multiple mutations and mutation combinations in the sodium channel of permethrin resistant mosquitoes, Culex quinquefasciatus

    Science.gov (United States)

    Li, Ting; Zhang, Lee; Reid, William R.; Xu, Qiang; Dong, Ke; Liu, Nannan

    2012-10-01

    A previous study identified 3 nonsynonymous and 6 synonymous mutations in the entire mosquito sodium channel of Culex quinquefasciatus, the prevalence of which were strongly correlated with levels of resistance and increased dramatically following insecticide selection. However, it is unclear whether this is unique to this specific resistant population or is a common mechanism in field mosquito populations in response to insecticide pressure. The current study therefore further characterized these mutations and their combinations in other field and permethrin selected Culex mosquitoes, finding that the co-existence of all 9 mutations was indeed correlated with the high levels of permethrin resistance in mosquitoes. Comparison of mutation combinations revealed several common mutation combinations presented across different field and permethrin selected populations in response to high levels of insecticide resistance, demonstrating that the co-existence of multiple mutations is a common event in response to insecticide resistance across different Cx. quinquefasciatus mosquito populations.

  18. Mosquito repellency of novel Trifluoromethylphenyl amides

    Science.gov (United States)

    Human diseases caused by mosquito-transmitted pathogens include malaria, dengue and yellow fever and are responsible for several million human deaths every year, according to the World Health Organization (WHO). Our current research projects focus on the development of new insecticides and repellent...

  19. Plant-based strategies for mosquito control

    Science.gov (United States)

    Mosquitoes transmit some of the most devastating emerging infectious diseases of humans, domestic animals, and wildlife. Although vector control by use of chemical insecticides has played an important role in prevention and management of these diseases, their sustained use remains questionable due t...

  20. Insecticide-treated net ownership and utilization and factors that influence their use in Itang, Gambella region, Ethiopia: cross-sectional study

    Directory of Open Access Journals (Sweden)

    Watiro AH

    2016-05-01

    Full Text Available Aklilu Habte Watiro,1 Worku Awoke,2 1Médecins Sans Frontières OCA (MSF Holland Ethiopia Mission, Addis Ababa, 2Department of Epidemiology, School of Public Health, College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia Background: Malaria remains a major public health problem in Ethiopia. Consequently, Ethiopia designed the 2011–2015, Malaria Prevention and Control Strategic Plan to fight the vector. It was discovered that most of the studies conducted on the use of insecticide-treated nets (ITNs were not in line with the strategic plan of the country. This study aimed to assess ITN ownership and utilization, and includes barriers related to its use among the target-area population at household (HH level. Materials and methods: A cross-sectional design was employed in Itang for this study. Data were collected by trained nurses through face-to-face interview and observation. A total of 845 participants were selected through multistage sampling, and the size was determined by using a single-population proportion formula. EPI Info and SPSS was used for analysis, and all necessary statistical association was computed in order to explain the outcome variable through explanatory variables of this study. Results: Among 845 HHs interviewed, 81.7% (690 had at least one ITN, while 52.3% (361 had used the ITN the night preceding the data-collection day. HH awareness of malaria prevention, number of ITNs, family size, number of family members sharing sleeping area/beds, sleeping patterns of adolescents, HH-head age, and inconvenience of using ITNs were found to be barriers to the use of ITNs in this study. Conclusion and recommendation: The study concluded that very few HHs owned ITNs and there was very low usage of ITNs. In recommendation, the regional health bureau and district health office should consider bigger nets that can accommodate family members who share the same sleeping area/bed in the area. Keywords: consistent

  1. Repellent, irritant and toxic effects of 20 plant extracts on adults of the malaria vector Anopheles gambiae mosquito.

    Science.gov (United States)

    Deletre, Emilie; Martin, Thibaud; Campagne, Pascal; Bourguet, Denis; Cadin, Andy; Menut, Chantal; Bonafos, Romain; Chandre, Fabrice

    2013-01-01

    Pyrethroid insecticides induce an excito-repellent effect that reduces contact between humans and mosquitoes. Insecticide use is expected to lower the risk of pathogen transmission, particularly when impregnated on long-lasting treated bednets. When applied at low doses, pyrethroids have a toxic effect, however the development of pyrethroid resistance in several mosquito species may jeopardize these beneficial effects. The need to find additional compounds, either to kill disease-carrying mosquitoes or to prevent mosquito contact with humans, therefore arises. In laboratory conditions, the effects (i.e., repellent, irritant and toxic) of 20 plant extracts, mainly essential oils, were assessed on adults of Anopheles gambiae, a primary vector of malaria. Their effects were compared to those of DEET and permethrin, used as positive controls. Most plant extracts had irritant, repellent and/or toxic effects on An. gambiae adults. The most promising extracts, i.e. those combining the three types of effects, were from Cymbopogon winterianus, Cinnamomum zeylanicum and Thymus vulgaris. The irritant, repellent and toxic effects occurred apparently independently of each other, and the behavioural response of adult An. gambiae was significantly influenced by the concentration of the plant extracts. Mechanisms underlying repellency might, therefore, differ from those underlying irritancy and toxicity. The utility of the efficient plant extracts for vector control as an alternative to pyrethroids may thus be envisaged.

  2. Entomopathogenic fungi for mosquito control: A review

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    Ernst-Jan Scholte

    2004-06-01

    Full Text Available Fungal diseases in insects are common and widespread and can decimate their populations in spectacular epizootics. Virtually all insect orders are susceptible to fungal diseases, including Dipterans. Fungal pathogens such as Lagenidium, Coelomomyces and Culicinomyces are known to affect mosquito populations, and have been studied extensively. There are, however, many other fungi that infect and kill mosquitoes at the larval and/or adult stage. The discovery, in 1977, of the selective mosquito-pathogenic bacterium Bacillus thuringiensis Berliner israelensis (Bti curtailed widespread interest in the search for other suitable biological control agents. In recent years interest in mosquito-killing fungi is reviving, mainly due to continuous and increasing levels of insecticide resistance and increasing global risk of mosquito-borne diseases. This review presents an update of published data on mosquito-pathogenic fungi and mosquito-pathogen interactions, covering 13 different fungal genera. Notwithstanding the potential of many fungi as mosquito control agents, only a handful have been commercialized and are marketed for use in abatement programs. We argue that entomopathogenic fungi, both new and existing ones with renewed/improved efficacies may contribute to an expansion of the limited arsenal of effective mosquito control tools, and that they may contribute in a significant and sustainable manner to the control of vector-borne diseases such as malaria, dengue and filariasis.

  3. Entomopathogenic fungi for mosquito control: a review.

    Science.gov (United States)

    Scholte, Ernst-Jan; Knols, Bart G J; Samson, Robert A; Takken, Willem

    2004-01-01

    Fungal diseases in insects are common and widespread and can decimate their populations in spectacular epizootics. Virtually all insect orders are susceptible to fungal diseases, including Dipterans. Fungal pathogens such as Lagenidium, Coelomomyces and Culicinomyces are known to affect mosquito populations, and have been studied extensively. There are, however, many other fungi that infect and kill mosquitoes at the larval and/or adult stage. The discovery, in 1977, of the selective mosquito-pathogenic bacterium Bacillus thuringiensis Berliner israelensis (Bti) curtailed widespread interest in the search for other suitable biological control agents. In recent years interest in mosquito-killing fungi is reviving, mainly due to continuous and increasing levels of insecticide resistance and increasing global risk of mosquito-borne diseases. This review presents an update of published data on mosquito-pathogenic fungi and mosquito-pathogen interactions, covering 13 different fungal genera. Notwithstanding the potential of many fungi as mosquito control agents, only a handful have been commercialized and are marketed for use in abatement programs. We argue that entomopathogenic fungi, both new and existing ones with renewed/improved efficacies may contribute to an expansion of the limited arsenal of effective mosquito control tools, and that they may contribute in a significant and sustainable manner to the control of vector-borne diseases such as malaria, dengue and filariasis.

  4. UV light and urban pollution: bad cocktail for mosquitoes?

    Science.gov (United States)

    Tetreau, Guillaume; Chandor-Proust, Alexia; Faucon, Frédéric; Stalinski, Renaud; Akhouayri, Idir; Prud'homme, Sophie M; Régent-Kloeckner, Myriam; Raveton, Muriel; Reynaud, Stéphane

    2014-01-01

    Mosquito breeding sites consist of water pools, which can either be large open areas or highly covered ponds with vegetation, thus with different light exposures combined with the presence in water of xenobiotics including polycyclic aromatic hydrocarbons (PAHs) generated by urban pollution. UV light and PAHs are abiotic factors known to both affect the mosquito insecticide resistance status. Nonetheless, their potential combined effects on the mosquito physiology have never been investigated. The present article aims at describing the effects of UV exposure alongside water contamination with two major PAH pollutants (fluoranthene and benzo[a]pyrene) on a laboratory population of the yellow fever mosquito Aedes aegypti. To evaluate the effects of PAH exposure and low energetic UV (UV-A) irradiation on mosquitoes, different parameters were measured including: (1) The PAH localization and its impact on cell mortality by fluorescent microscopy; (2) The detoxification capacities (cytochrome P450, glutathione-S-transferase, esterase); (3) The responses to oxidative stress (Reactive Oxygen Species-ROS) and (4) The tolerance of mosquito larvae to a bioinsecticide (Bacillus thuringiensis subsp. israelensis-Bti) and to five chemical insecticides (DDT, imidacloprid, permethrin, propoxur and temephos). Contrasting effects regarding mosquito cell mortality, detoxification and oxidative stress were observed as being dependent on the pollutant considered, despite the fact that the two PAHs belong to the same family. Moreover, UV is able to modify pollutant effects on mosquitoes, including tolerance to three insecticides (imidacloprid, propoxur and temephos), cell damage and response to oxidative stress. Taken together, our results suggest that UV and pollution, individually or in combination, are abiotic parameters that can affect the physiology and insecticide tolerance of mosquitoes; but the complexity of their direct effect and of their interaction will require further

  5. DESCRIPTIVE ANALYSIS OF HOUSEHOLD INSECTICIDE IN COMMUNITY

    Directory of Open Access Journals (Sweden)

    Aram Sih Joharina

    2014-06-01

    Full Text Available The most popular and effective vector control is the use of insecticides. Surveywas done in the houses and some supermarket to know many kind of insecticides usedby people. The formulation, active ingredients, and concentration were recorded andanalyzed. Based on the results of the survey, household insecticides formulated invarious formulations such as liquid, mosquito coils, aerosol, mat and liquid vaporizer,chalk and paper burn. In addition to formulation, active ingredients and concentrationalso vary. Almost all household insecticide products on the market using the syntheticpyrethroid. Selection of household insecticides should be adapted to the type of insectpests because each type of active ingredients and formulations have advantages anddisadvantages. Efficacy of various active ingredients in various formulations has beenstudied and the results vary widely. Insecticide efficacy is influenced by the type ofactive ingredient, dosage, concentration, formulation, and the susceptibility of insectspecies, temperature, sunlight, wind, and application method.Key word: household insecticide, insecticides formulation, active ingredientsABSTRAKPengendalian serangga vektor penyakit yang paling efektif dan populer adalahpenggunaan insektisida. Survei dilakukan di masyarakat dan supermarket untuk mengetahuijcnis-jenis insektisida yang digunakan oleh masyarakat. Berdasarkan hasil survei, insektisidarumah tangga terkemas dalam berbagai formulasi antara lain liquid, mosquito coil, aerosol, mat& liquid vaporizer, kapur serangga dan kertas bakar. Disamping formulasi, bahan aktif dankonsentrasi yang digunakan juga bermacam-macam. Hampir semua produk insektisida rumahtangga di pasaran menggunakan bahan aktif golongan piretroid sintetik. Pemilihan insektisidarumah tangga hendaknya disesuaikan dengan jenis serangga sasaran karena tiap jenis bahan aktifdan formulasi memiliki kelcbihan dan kekurangan. Efikasi berbagai bahan aktif dalam berbagaiformulasi telah

  6. Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial

    Science.gov (United States)

    Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

    2015-01-01

    Background Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. Methods A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4–6 weeks after the second intervention (March to April 2014). Results Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Conclusions Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. PMID:25604762

  7. Reduction of childhood malaria by social marketing of insecticide-treated nets: a case-control study of effectiveness in Malawi.

    Science.gov (United States)

    Mathanga, Don P; Campbell, Carl H; Taylor, Terrie E; Barlow, Robin; Wilson, Mark L

    2005-09-01

    Use of an insecticide-treated net (ITN) is now the central focus for the Roll Back Malaria campaign, and disease-endemic countries have embarked on large-scale ITN distribution programs. We assessed the impact of an ITN social marketing program on clinical malaria in children less than five years of age. A case-control study was undertaken at Ndirande Health Center in the peri-urban area of the city of Blantyre, Malawi. Cases were defined by an axillary temperature > or = 37.5 degrees C or a history of fever within the last 48 hours and a positive blood smear for Plasmodium falciparum. The individual effectiveness of ITN use was 40% (95% confidence interval [CI] = 10-60%) when cases were compared with clinic controls and 50% (95% CI = 0-60%) in comparison with community controls. With ITN coverage of 42%, the community effectiveness of this program was estimated to range from 17% to 21%. This represents 1,480 malaria cases averted by the intervention in a population of 15,000 children. Our results show that the benefits of ITN social marketing programs in reducing malaria are enormous. Targeting the poor could increase those benefits.

  8. Insecticide-treated plastic sheeting for emergency malaria prevention and shelter among displaced populations: an observational cohort study in a refugee setting in Sierra Leone.

    Science.gov (United States)

    Burns, Matthew; Rowland, Mark; N'guessan, Raphael; Carneiro, Ilona; Beeche, Arlyne; Ruiz, Stefani Sesler; Kamara, Sarian; Takken, Willem; Carnevale, Pierre; Allan, Richard

    2012-08-01

    A double-blind phase III malaria prevention trial was conducted in two refugee camps using pre-manufactured insecticide-treated plastic sheeting (ITPS) or untreated polyethylene sheeting (UPS) randomly deployed to defined sectors of each camp. In Largo camp the ITPS or UPS was attached to inner walls and ceilings of shelters, whereas in Tobanda the ITPS or UPS was used to line only the ceiling and roof. In Largo the Plasmodium falciparum incidence rate in children up to 3 years of age who were cleared of parasites and monitored for 8 months was 163/100 person-years under UPS and 63 under ITPS (adjusted odds ratio [AOR] = 0.40, 95% confidence interval [CI] = 0.33-0.47). In Tobanda incidence was 157/100 person-years under UPS and 134 under ITPS (AOR = 0.85, 95% CI = 0.75-0.95). Protective efficacy was 61% under fully lined ITPS and 15% under roof lined ITPS. Anemia rates improved under ITPS in both camps. This novel tool proved to be a convenient, safe, and long-lasting method of malaria control when used as a full shelter lining in an emergency setting.

  9. Mosquito Traps: An Innovative, Environmentally Friendly Technique to Control Mosquitoes.

    Science.gov (United States)

    Poulin, Brigitte; Lefebvre, Gaëtan; Muranyi-Kovacs, Camille; Hilaire, Samuel

    2017-03-18

    We tested the use of mosquito traps as an alternative to spraying insecticide in Camargue (France) following the significant impacts observed on the non-target fauna through Bti persistence and trophic perturbations. In a village of 600 inhabitants, 16 Techno Bam traps emitting CO₂ and using octenol lures were set from April to November 2016. Trap performance was estimated at 70% overall based on mosquitoes landing on human bait in areas with and without traps. The reduction of Ochlerotatus caspius and Oc. detritus, the two species targeted by Bti spraying, was, respectively, 74% and 98%. Traps were less efficient against Anopheles hyrcanus (46%), which was more attracted by lactic acid than octenol lures based on previous tests. Nearly 300,000 mosquitoes from nine species were captured, with large variations among traps, emphasizing that trap performance is also influenced by surrounding factors. Environmental impact, based on the proportion of non-target insects captured, was mostly limited to small chironomids attracted by street lights. The breeding success of a house martin colony was not significantly affected by trap use, in contrast to Bti spraying. Our experiment confirms that the deployment of mosquito traps can offer a cost-effective alternative to Bti spraying for protecting local populations from mosquito nuisance in sensitive natural areas.

  10. Mosquito Traps: An Innovative, Environmentally Friendly Technique to Control Mosquitoes

    Directory of Open Access Journals (Sweden)

    Brigitte Poulin

    2017-03-01

    Full Text Available We tested the use of mosquito traps as an alternative to spraying insecticide in Camargue (France following the significant impacts observed on the non-target fauna through Bti persistence and trophic perturbations. In a village of 600 inhabitants, 16 Techno Bam traps emitting CO2 and using octenol lures were set from April to November 2016. Trap performance was estimated at 70% overall based on mosquitoes landing on human bait in areas with and without traps. The reduction of Ochlerotatus caspius and Oc. detritus, the two species targeted by Bti spraying, was, respectively, 74% and 98%. Traps were less efficient against Anopheles hyrcanus (46%, which was more attracted by lactic acid than octenol lures based on previous tests. Nearly 300,000 mosquitoes from nine species were captured, with large variations among traps, emphasizing that trap performance is also influenced by surrounding factors. Environmental impact, based on the proportion of non-target insects captured, was mostly limited to small chironomids attracted by street lights. The breeding success of a house martin colony was not significantly affected by trap use, in contrast to Bti spraying. Our experiment confirms that the deployment of mosquito traps can offer a cost-effective alternative to Bti spraying for protecting local populations from mosquito nuisance in sensitive natural areas.

  11. Natural plant sugar sources of Anopheles mosquitoes strongly impact malaria transmission potential.

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    Weidong Gu

    Full Text Available An improved knowledge of mosquito life history could strengthen malaria vector control efforts that primarily focus on killing mosquitoes indoors using insecticide treated nets and indoor residual spraying. Natural sugar sources, usually floral nectars of plants, are a primary energy resource for adult mosquitoes but their role in regulating the dynamics of mosquito populations is unclear. To determine how the sugar availability impacts Anopheles sergentii populations, mark-release-recapture studies were conducted in two oases in Israel with either absence or presence of the local primary sugar source, flowering Acacia raddiana trees. Compared with population estimates from the sugar-rich oasis, An. sergentii in the sugar-poor oasis showed smaller population size (37,494 vs. 85,595, lower survival rates (0.72 vs. 0.93, and prolonged gonotrophic cycles (3.33 vs. 2.36 days. The estimated number of females older than the extrinsic incubation period of malaria (10 days in the sugar rich site was 4 times greater than in the sugar poor site. Sugar feeding detected in mosquito guts in the sugar-rich site was significantly higher (73% than in the sugar-poor site (48%. In contrast, plant tissue feeding (poor quality sugar source in the sugar-rich habitat was much less (0.3% than in the sugar-poor site (30%. More important, the estimated vectorial capacity, a standard measure of malaria transmission potential, was more than 250-fold higher in the sugar-rich oasis than that in the sugar-poor site. Our results convincingly show that the availability of sugar sources in the local environment is a major determinant regulating the dynamics of mosquito populations and their vector potential, suggesting that control interventions targeting sugar-feeding mosquitoes pose a promising tactic for combating transmission of malaria parasites and other pathogens.

  12. Enhanced protection against malaria by indoor residual spraying in addition to insecticide treated nets: is it dependent on transmission intensity or net usage?

    Directory of Open Access Journals (Sweden)

    Philippa A West

    Full Text Available Insecticide treated nets (ITNs and indoor residual spraying (IRS are effective vector control tools that protect against malaria. There is conflicting evidence regarding whether using ITNs and IRS in combination provides additional benefit over using either of these methods alone. This study investigated factors that may modify the effect of the combined use of IRS and ITNs compared to using ITNs alone on malaria infection prevalence.Secondary analysis was carried out on data from a cluster randomised trial in north-west Tanzania. 50 clusters received ITNs from a universal coverage campaign; of these 25 were randomly allocated to additionally receive two rounds of IRS in 2012. In cross-sectional household surveys children 0.5-14 years old were tested for Plasmodium falciparum infections (PfPR two, six and ten months after the first IRS round.IRS protected those sleeping under nets (OR = 0.38, 95%CI 0.26-0.57 and those who did not (OR = 0.43, 95%CI 0.29-0.63. The protective effect of IRS was not modified by community level ITN use (ITN use = 50%, OR = 0.46, 95%CI 0.28-0.74. The additional protection from IRS was similar in low (<10% PfPR, OR = 0.38, 95%CI 0.19-0.75 and high transmission areas (≥10% PfPR, OR = 0.34, 95%CI 0.18-0.67. ITN use was protective at the individual-level regardless of whether the village had been sprayed (OR = 0.83, 95%CI 0.70-0.98. Living in a sprayed village was protective regardless of whether the individual slept under an ITN last night (OR = 0.41, 95%CI 0.29-0.58.Implementing IRS in addition to ITNs was beneficial for individuals from villages with a wide range of transmission intensities and net utilisation levels. Net users received additional protection from IRS. ITNs were providing some individual protection, even in this area with high levels of pyrethroid insecticide resistance. These results demonstrate that there is a supplementary benefit of IRS even when ITNs are effective.ClinicalTrials.gov NCT01697852.

  13. Mitigating Diseases Transmitted by Aedes Mosquitoes: A Cluster-Randomised Trial of Permethrin-Impregnated School Uniforms

    Science.gov (United States)

    Kittayapong, Pattamaporn; Olanratmanee, Phanthip; Maskhao, Pongsri; Byass, Peter; Logan, James; Tozan, Yesim; Louis, Valérie; Gubler, Duane J.; Wilder-Smith, Annelies

    2017-01-01

    the number of Aedes mosquitoes inside treatment schools immediately after impregnation and before insecticidal activity declined. However, there was no serological evidence of protection against dengue infections over the five months school term, best explained by the rapid washing-out of permethrin after 4 washes. If rapid washing-out of permethrin could be overcome by novel technological approaches, insecticide-treated clothes might become a potentially cost-effective and scalable intervention to protect against diseases transmitted by Aedes mosquitoes such as dengue, Zika, and chikungunya. Trial Registration ClinicalTrials.gov NCT01563640 PMID:28103255

  14. Mitigating Diseases Transmitted by Aedes Mosquitoes: A Cluster-Randomised Trial of Permethrin-Impregnated School Uniforms.

    Directory of Open Access Journals (Sweden)

    Pattamaporn Kittayapong

    2017-01-01

    mosquitoes inside treatment schools immediately after impregnation and before insecticidal activity declined. However, there was no serological evidence of protection against dengue infections over the five months school term, best explained by the rapid washing-out of permethrin after 4 washes. If rapid washing-out of permethrin could be overcome by novel technological approaches, insecticide-treated clothes might become a potentially cost-effective and scalable intervention to protect against diseases transmitted by Aedes mosquitoes such as dengue, Zika, and chikungunya.ClinicalTrials.gov NCT01563640.

  15. Using a near-infrared spectrometer to estimate the age of anopheles mosquitoes exposed to pyrethroids.

    Science.gov (United States)

    Sikulu, Maggy T; Majambere, Silas; Khatib, Bakar O; Ali, Abdullah S; Hugo, Leon E; Dowell, Floyd E

    2014-01-01

    We report on the accuracy of using near-infrared spectroscopy (NIRS) to predict the age of Anopheles mosquitoes reared from wild larvae and a mixed age-wild adult population collected from pit traps after exposure to pyrethroids. The mosquitoes reared from wild larvae were estimated as 8 d for both susceptible and resistant groups. The age structure of wild-collected mosquitoes was not significantly different for the pyrethroid-susceptible and pyrethroid-resistant mosquitoes (P = 0.210). Based on these findings, NIRS chronological age estimation technique for Anopheles mosquitoes may be independent of insecticide exposure and the environmental conditions to which the mosquitoes are exposed.

  16. Heterologous expression in transgenic mosquitoes

    Institute of Scientific and Technical Information of China (English)

    Santhosh P K; Yu hua Deng; Weidong Gu; Xiaoguang Chen

    2010-01-01

    Arthropod-borne diseases such as malaria and dengue virus afflict billions of people worldwide imposing major economic and social burdens. Control of such pathogens is mainly performed by vector management and treatment of affected individuals with drugs. The failure of these conventional approaches due to emergence of insecticide-resistant insects and drug-resistant parasites demonstrate the need of novel and efficacious control strategies to combat these diseases. Genetic modification(GM) of mosquito vectors to impair their ability to be infected and transmit pathogens has emerged as a new strategy to reduce transmission of many vector-borne diseases and deliver public health gains. Several advances in developing transgenic mosquitoes unable to transmit pathogens have gained support, some of them attempt to manipulate the naturally occurring endogenous refractory mechanisms, while others initiate the identification of an exogenous foreign gene which disrupt the pathogen development in insect vectors. Heterologous expression of transgenes under a native or heterologous promoter is important for the screening and effecting of the transgenic mosquitoes. The effect of the transgene on mosquito fitness is a crucial parameter influencing the success of this transgenic approach. This review examines these two aspects and describes the basic research work that has been accomplished towards understanding the complex relation between the parasite and its vector and focuses on recent advances and perspectives towards construction of transgenic mosquitoes refractory to vector-borne disease transmission.

  17. Wash resistance and repellent properties of Africa University mosquito blankets against mosquitoes

    Directory of Open Access Journals (Sweden)

    N. Lukwa

    2013-04-01

    Full Text Available The effect of permethrin-treated Africa University (AU mosquito blankets on susceptible female Anopheles gambiae sensu lato mosquitoes was studied under laboratory conditions at Africa University Campus in Mutare, Zimbabwe. Wash resistance (ability to retain an effective dose that kills ≥80% of mosquitoes after a number of washes and repellence (ability to prevent ≥80% of mosquito bites properties were studied. The AU blankets were wash resistant when 100% mortality was recorded up to 20 washes, declining to 90% after 25 washes. Untreated AU blankets did not cause any mortality on mosquitoes. However, mosquito repellence was 96%, 94%, 97.9%, 87%, 85% and 80.7% for treated AU blankets washed 0, 5, 10, 15, 20 and 25 times, respectively. Mosquito repellence was consistently above 80% from 0-25 washes. In conclusion, AU blankets washed 25 times were effective in repelling and killing An. gambiae sl mosquitoes under laboratory conditions.

  18. Insecticide Resistance and Management Strategies in Urban Ecosystems

    Directory of Open Access Journals (Sweden)

    Fang Zhu

    2016-01-01

    Full Text Available The increased urbanization of a growing global population makes imperative the development of sustainable integrated pest management (IPM strategies for urban pest control. This emphasizes pests that are closely associated with the health and wellbeing of humans and domesticated animals. Concurrently there are regulatory requirements enforced to minimize inadvertent exposures to insecticides in the urban environment. Development of insecticide resistance management (IRM strategies in urban ecosystems involves understanding the status and mechanisms of insecticide resistance and reducing insecticide selection pressure by combining multiple chemical and non-chemical approaches. In this review, we will focus on the commonly used insecticides and molecular and physiological mechanisms underlying insecticide resistance in six major urban insect pests: house fly, German cockroach, mosquitoes, red flour beetle, bed bugs and head louse. We will also discuss several strategies that may prove promising for future urban IPM programs.

  19. UV light and urban pollution: Bad cocktail for mosquitoes?

    Energy Technology Data Exchange (ETDEWEB)

    Tetreau, Guillaume, E-mail: guillaume.tetreau@gmail.com [Laboratoire d’Ecologie Alpine, LECA-UMR 5553, Université de Grenoble 1, BP 53, 38041 Grenoble cedex 09 (France); Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456 (United States); Chandor-Proust, Alexia; Faucon, Frédéric; Stalinski, Renaud; Akhouayri, Idir; Prud’homme, Sophie M.; Régent-Kloeckner, Myriam; Raveton, Muriel; Reynaud, Stéphane [Laboratoire d’Ecologie Alpine, LECA-UMR 5553, Université de Grenoble 1, BP 53, 38041 Grenoble cedex 09 (France)

    2014-01-15

    Highlights: •Mosquito tolerance to temephos is induced by PAHs and UV exposure. •Toxicity of fluoranthene for mosquito Malpighian tubules cells is induced by UV. •Fluoranthene crystallizes in mosquito Malpighian tubules upon UV exposure. •Mixture of two PAHs is less toxic for mosquitoes than each PAHs separately. •Combination of abiotic parameters (PAHs and UV) affect mosquito physiology. -- Abstract: Mosquito breeding sites consist of water pools, which can either be large open areas or highly covered ponds with vegetation, thus with different light exposures combined with the presence in water of xenobiotics including polycyclic aromatic hydrocarbons (PAHs) generated by urban pollution. UV light and PAHs are abiotic factors known to both affect the mosquito insecticide resistance status. Nonetheless, their potential combined effects on the mosquito physiology have never been investigated. The present article aims at describing the effects of UV exposure alongside water contamination with two major PAH pollutants (fluoranthene and benzo[a]pyrene) on a laboratory population of the yellow fever mosquito Aedes aegypti. To evaluate the effects of PAH exposure and low energetic UV (UV-A) irradiation on mosquitoes, different parameters were measured including: (1) The PAH localization and its impact on cell mortality by fluorescent microscopy; (2) The detoxification capacities (cytochrome P450, glutathione-S-transferase, esterase); (3) The responses to oxidative stress (Reactive Oxygen Species–ROS) and (4) The tolerance of mosquito larvae to a bioinsecticide (Bacillus thuringiensis subsp. israelensis–Bti) and to five chemical insecticides (DDT, imidacloprid, permethrin, propoxur and temephos). Contrasting effects regarding mosquito cell mortality, detoxification and oxidative stress were observed as being dependent on the pollutant considered, despite the fact that the two PAHs belong to the same family. Moreover, UV is able to modify pollutant effects on

  20. Wash resistance and repellent properties of Africa University mosquito blankets against mosquitoes

    OpenAIRE

    N. Lukwa; A. Makuwaza; T. Chiwade; Mutambu, S L; M. Zimba; P. Munosiyei

    2013-01-01

    The effect of permethrin-treated Africa University (AU) mosquito blankets on susceptible female Anopheles gambiae sensu lato mosquitoes was studied under laboratory conditions at Africa University Campus in Mutare, Zimbabwe. Wash resistance (ability to retain an effective dose that kills ≥80% of mosquitoes after a number of washes) and repellence (ability to prevent ≥80% of mosquito bites) properties were studied. The AU blankets were wash resistant when 100% mortality was recorded up t...

  1. Engineered mosquitoes to fight mosquito borne diseases: not a merely technical issue.

    Science.gov (United States)

    Favia, Guido

    2015-01-01

    Malaria, dengue and other mosquito-borne diseases pose dramatic problems of public health, particularly in tropical and sub-tropical countries. Historically, vector control has been one of the most successfully strategies to eradicate some mosquito-borne diseases, as witnessed by malaria eradication in Mediterranean regions such as Italy and Greece. Vector control through insecticides has been used worldwide; unfortunately, it is losing effectiveness due to spread of resistances. Control of mosquito-borne diseases through field-releases of genetically engineered mosquitoes is an innovative and now feasible approach. Genetically modified mosquitoes have already been released into the wild in some regions, and protocols for this release are on hand in others. Local authorities are vigilant that transgenic insects in the field are safe for human and animal populations, and the public engagement in every control program is assuming a central role.

  2. Mosquito Management on National Wildlife Refuges, Ecosystem Effects Study. Phase II, Part 1 - Effects of Ultra Low Volume Applications of Pyrethrin, Malathion and Permethrin on Macro-Invertebrates in the Sacramento National Wildlife Refuge, California

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Mosquito control districts often use ultra-low volume (ULV) applications of insecticides to control adult mosquitoes. Few field studies have tested the effects of...

  3. Indoor application of attractive toxic sugar bait (ATSB) in combination with mosquito nets for control of pyrethroid-resistant mosquitoes.

    Science.gov (United States)

    Stewart, Zachary P; Oxborough, Richard M; Tungu, Patrick K; Kirby, Matthew J; Rowland, Mark W; Irish, Seth R

    2013-01-01

    Attractive toxic sugar bait (ATSB) sprayed onto vegetation has been successful in controlling Anopheles mosquitoes outdoors. Indoor application of ATSB has yet to be explored. The purpose of this study was to determine whether ATSB stations positioned indoors have the potential to kill host-seeking mosquitoes and constitute a new approach to control of mosquito-borne diseases. Insecticides were mixed with dyed sugar solution and tested as toxic baits against Anopheles arabiensis, An. Gambiae s.s. and Culex quinquefasciatus in feeding bioassay tests to identify suitable attractant-insecticide combinations. The most promising ATSB candidates were then trialed in experimental huts in Moshi, Tanzania. ATSB stations were hung in huts next to untreated mosquito nets occupied by human volunteers. The proportions of mosquitoes killed in huts with ATSB treatments relative to huts with non-insecticide control treatments huts were recorded, noting evidence of dye in mosquito abdomens. In feeding bioassays, chlorfenapyr 0.5% v/v, boric acid 2% w/v, and tolfenpyrad 1% v/v, mixed in a guava juice-based bait, each killed more than 90% of pyrethroid-susceptible An. Gambiae s.s. and pyrethroid-resistant An. arabiensis and Cx. quinquefasciatus. In the hut trial, mortality rates of the three ATSB treatments ranged from 41-48% against An. arabiensis and 36-43% against Cx. quinquefasciatus and all were significantly greater than the control mortalities: 18% for An. arabiensis, 7% for Cx. quinquefasciatus (pmosquito nets for controlling mosquitoes. Indoor ATSB constitute a novel application method for insecticide classes that act as stomach poisons and have not hitherto been exploited for mosquito control. Combined with LLIN, indoor use of ATSB has the potential to serve as a strategy for managing insecticide resistance.

  4. Integrating Household Water Treatment, Hand Washing, and Insecticide-Treated Bed Nets into Pediatric HIV Care in Mombasa, Kenya: Impact on Diarrhea and Malaria Risk.

    Science.gov (United States)

    Sugar, Naomi R; Schilling, Katharine A; Kim, Sunkyung; Ahmed, Aabid; Muyanga, Dennis Ngui; Sivapalasingam, Sumathi; Quick, Robert

    2017-08-04

    In developing countries, HIV-infected children are at higher risk for morbidity and mortality from opportunistic infections than HIV-uninfected children. To address this problem, the Healthy Living Initiative (HLI) in Mombasa, Kenya distributed basic care packages (BCPs) containing improved water storage vessels, water treatment solution, soap, and insecticide-treated bednets (ITNs) to prevent diarrhea and malaria in children, and had community health workers (CHWs) make bimonthly home visits to encourage adherence with HLI interventions and antiretroviral medicine use. To evaluate HLI, we enrolled 500 HIV-infected children from Bomu Hospital. In the implementation phase, from February-August 2011, we conducted surveys of caregivers, then provided free BCPs. In the evaluation phase, from September 2011-August 2012, CHWs recorded observations of BCP use during home visits. We abstracted hospital data to compare diarrhea and malaria episodes, and pharmacy data on antiretrovirals (ARVs) dispensed, between the 12-month pre-implementation baseline phase (February 2010-January 2011) and the evaluation phase. The retention rate of children in HLI was 78.4%. In a multivariable logistic regression model adjusting for demographic characteristics, number of CHW home visits, distance to clinic, orphan status, and number of ARVs dispensed, children in HLI had 71 % lower risk of diarrhea (relative risk [RR] 0.29, pdiarrhea and malaria during the evaluation phase than the baseline phase.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

  5. Socio-economic inequity in demand for insecticide-treated nets, in-door residual house spraying, larviciding and fogging in Sudan

    Directory of Open Access Journals (Sweden)

    Mustafa Sara

    2005-12-01

    Full Text Available Abstract Background In order to optimally prioritize and use public and private budgets for equitable malaria vector control, there is a need to determine the level and determinants of consumer demand for different vector control tools. Objectives To determine the demand from people of different socio-economic groups for indoor residual house-spraying (IRHS, insecticide-treated nets (ITNs, larviciding with chemicals (LWC, and space spraying/fogging (SS and the disease control implications of the result. Methods Ratings and levels of willingness-to-pay (WTP for the vector control tools were determined using a random cross-sectional sample of 720 householdes drawn from two states. WTP was elicited using the bidding game. An asset-based socio-economic status (SES index was used to explore whether WTP was related to SES of the respondents. Results IRHS received the highest proportion of highest preferred rating (41.0% followed by ITNs (23.1%. However, ITNs had the highest mean WTP followed by IRHS, while LWC had the least. The regression analysis showed that SES was positively and statistically significantly related to WTP across the four vector control tools and that the respondents' rating of IRHS and ITNs significantly explained their levels of WTP for the two tools. Conclusion People were willing to pay for all the vector-control tools, but the demand for the vector control tools was related to the SES of the respondents. Hence, it is vital that there are public policies and financing mechanisms to ensure equitable provision and utilisation of vector control tools, as well as protecting the poor from cost-sharing arrangements.

  6. Comparative cost analysis of insecticide-treated net delivery strategies: sales supported by social marketing and free distribution through antenatal care.

    Science.gov (United States)

    De Allegri, Manuela; Marschall, Paul; Flessa, Steffen; Tiendrebéogo, Justin; Kouyaté, Bocar; Jahn, Albrecht; Müller, Olaf

    2010-01-01

    Insecticide-treated nets (ITNs) are effective in substantially reducing malaria transmission. Still, ITN coverage in sub-Saharan Africa (SSA) remains extremely low. Policy makers are concerned with identifying the most suitable delivery mechanism to achieve rapid yet sustainable increases in ITN coverage. Little is known, however, on the comparative costs of alternative ITN distribution strategies. This paper aimed to fill this gap in knowledge by developing such a comparative cost analysis, looking at the cost per ITN distributed for two alternative interventions: subsidized sales supported by social marketing and free distribution to pregnant women through antenatal care (ANC). The study was conducted in rural Burkina Faso, where the two interventions were carried out alongside one another in 2006/07. Cost information was collected prospectively to derive both a financial analysis adopting a provider's perspective and an economic analysis adopting a societal perspective. The average financial cost per ITN distributed was US$8.08 and US$7.21 for sales supported by social marketing and free distribution through ANC, respectively. The average economic cost per ITN distributed was US$4.81 for both interventions. Contrary to common belief, costs did not differ substantially between the two interventions. Due to the district's ability to rely fully on the use of existing resources, financial costs associated with free ITN distribution through ANC were in fact even lower than those associated with the social marketing campaign. This represents an encouraging finding for SSA governments and points to the possibility to invest in programmes to favour free ITN distribution through existing health facilities. Given restricted budgets, however, free distribution programmes are unlikely to be feasible.

  7. Subsidized sales of insecticide-treated nets in Afghan refugee camps demonstrate the feasibility of a transition from humanitarian aid towards sustainability

    Directory of Open Access Journals (Sweden)

    Kolaczinski Jan H

    2004-06-01

    Full Text Available Abstract Background Introducing sustainability and self-reliance is essential in chronic humanitarian emergencies before financial assistance is phased out. In Pakistan-based Afghan refugee camps, this was attempted through shifting from indoor residual spraying (IRS to the subsidized sale of insecticide-treated nets (ITNs for prevention of malaria and anthroponotic cutaneous leishmaniasis (ACL. Here we outline the strategy and document the progress to provide guidance for replication of similar approaches in other chronic refugee situations. Methods The operational monitoring data presented were collected through: (i two surveys of knowledge, attitude and practice (KAP; (ii routine sales reporting of health-care providers; (iii records completed during field visits; and (iv registers used during annual re-treatment campaigns. Results From 2000 until 2003, subsidized ITN sales expanded from 17 to 44 camps. Based on 2003 sales records, maximum coverage from subsidized sales exceeded 50% in 13 camps and 20% in an additional 14 camps. Free annual treatment campaigns showed that many refugees were in possession of non-programme nets, which were either locally-made or had leaked from an ITN programme in Afghanistan. Estimated re-treatment coverage of sold and existing nets through annual campaigns exceeded 43% in all camps and was above 70% in the majority. Conclusion Subsidized sales of ITNs have effectively introduced the components of sustainability and self-reliance to the prevention of malaria and ACL in Afghan refugee camps. Similar approaches should be investigated in other chronic refugee situations to discourage expectations of continuing humanitarian donations that cannot be fulfilled.

  8. Use of antenatal care, maternity services, intermittent presumptive treatment and insecticide treated bed nets by pregnant women in Luwero district, Uganda

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    Mufubenga Patrobas

    2008-03-01

    Full Text Available Abstract Background To reduce the intolerable burden of malaria in pregnancy, the Ministry of Health in Uganda improved the antenatal care package by including a strong commitment to increase distribution of insecticide-treated nets (ITNs and introduction of intermittent preventive treatment with sulphadoxine-pyrimethamine for pregnant women (IPTp-SP as a national policy in 2000. This study assessed uptake of both ITNs and IPTp-SP by pregnant women as well as antenatal and maternity care use with the aim of optimizing their delivery. Methods 769 post-partum women were recruited from a rural area of central Uganda with perennial malaria transmission through a cross-sectional, community-based household survey in May 2005. Results Of the 769 women interviewed, antenatal clinic (ANC attendance was high (94.4%; 417 (57.7% visiting initially during the 2nd trimester, 242 (33.5% during the 3rd trimester and 266 (37.1% reporting ≥ 4 ANC visits. About 537 (71% and 272 (35.8% received one or ≥ 2 IPTp-SP doses respectively. Only 85 (15.8% received the first dose of IPTp-SP in the 3rd trimester. ITNs were used by 239 (31.3% of women during pregnancy and 314 (40.8% delivered their most recent pregnancy outside a health facility. Post-partum women who lacked post-primary education were more likely not to have attended four or more ANC visits (odds ratio [OR] 3.3, 95% confidence interval [CI] 1.2–9.3. Conclusion These findings illustrate the need to strengthen capacity of the district to further improve antenatal care and maternity services utilization and IPTp-SP uptake. More specific and effective community health strategies to improve effective ANC, maternity services utilization and IPTp-SP uptake in rural communities should be undertaken.

  9. Vouchers for scaling up insecticide-treated nets in Tanzania: Methods for monitoring and evaluation of a national health system intervention

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    Bruce Jane

    2008-06-01

    Full Text Available Abstract Background The Tanzania National Voucher Scheme (TNVS uses the public health system and the commercial sector to deliver subsidised insecticide-treated nets (ITNs to pregnant women. The system began operation in October 2004 and by May 2006 was operating in all districts in the country. Evaluating complex public health interventions which operate at national level requires a multidisciplinary approach, novel methods, and collaboration with implementers to support the timely translation of findings into programme changes. This paper describes this novel approach to delivering ITNs and the design of the monitoring and evaluation (M&E. Methods A comprehensive and multidisciplinary M&E design was developed collaboratively between researchers and the National Malaria Control Programme. Five main domains of investigation were identified: (1 ITN coverage among target groups, (2 provision and use of reproductive and child health services, (3 "leakage" of vouchers, (4 the commercial ITN market, and (5 cost and cost-effectiveness of the scheme. Results The evaluation plan combined quantitative (household and facility surveys, voucher tracking, retail census and cost analysis and qualitative (focus groups and in-depth interviews methods. This plan was defined in collaboration with implementing partners but undertaken independently. Findings were reported regularly to the national malaria control programme and partners, and used to modify the implementation strategy over time. Conclusion The M&E of the TNVS is a potential model for generating information to guide national and international programmers about options for delivering priority interventions. It is independent, comprehensive, provides timely results, includes information on intermediate processes to allow implementation to be modified, measures leakage as well as coverage, and measures progress over time.

  10. High retention and appropriate use of insecticide-treated nets distributed to HIV-affected households in Rakai, Uganda: results from interviews and home visits

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    Ludigo James

    2009-04-01

    Full Text Available Abstract Background Distribution of insecticide-treated nets (ITNs has recently been incorporated into comprehensive care strategies for HIV-positive people in malaria-endemic areas. WHO now recommends free or low-cost distribution of ITNs to all persons in malaria-endemic areas, regardless of age, pregnancy and HIV status. Knowledge about and appropriate use of ITNs among HIV-positive ITN recipients and their household members has not been well characterized. Methods 142 randomly selected adults were interviewed in July–August 2006 to assess knowledge, retention, and appropriate use of ITNs they had received through a PEPFAR-funded comprehensive HIV care programme in rural Uganda. Results Among all participants, 102 (72%, CI: 65%–79% reported they had no ITNs except those provided by the programme. Of 131 participants who stated they were given ≥ 1 ITN, 128 (98%, CI: 96%–100% stated they still possessed at least one programme-provided ITN. Reported programme-ITN (pITN use by participants was high: 119 participants (91%, CI: 86%–96% reported having slept under pITN the night prior to the survey and 115 (88%, CI: 82%–94% reported sleeping under pITN seven days per week. Being away from home and heat were the most common reasons given for not sleeping under an ITN. A sub-study of thirteen random home visits demonstrated concordance between participants' survey reports and actual use of ITNs in homes. Conclusion There was excellent self-reported retention and appropriate use of ITNs distributed as a part of a community-based outpatient HIV care programme. Participants perceived ITNs as useful and were unlikely to have received ITNs from other sources.

  11. Biolarvicidal and pupicidal activity of Acalypha alnifolia Klein ex Willd.(Family:Euphorbiaceae) leaf extract and microbial insecticide, Metarhizium anisopliae(Metsch.)against malaria fever mosquito Anopheles stephensi Liston

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    This study was made to determine the biological activity of Acalypha alnifolia leaf extract and the microbial insecticide Metarizhium anisopliae against larvae and pupae of the malaria vector Anopheles stephensi. Ethanolic A. alnifolia leaf extract tested against 1st through 4th instars and pupae o...

  12. Plasmodium infection decreases fecundity and increases survival of mosquitoes.

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    Vézilier, J; Nicot, A; Gandon, S; Rivero, A

    2012-10-07

    Long-lived mosquitoes maximize the chances of Plasmodium transmission. Yet, in spite of decades of research, the effect of Plasmodium parasites on mosquito longevity remains highly controversial. On the one hand, many studies report shorter lifespans in infected mosquitoes. On the other hand, parallel (but separate) studies show that Plasmodium reduces fecundity and imply that this is an adaptive strategy of the parasite aimed at redirecting resources towards longevity. No study till date has, however, investigated fecundity and longevity in the same individuals to see whether this prediction holds. In this study, we follow for both fecundity and longevity in Plasmodium-infected and uninfected mosquitoes using a novel, albeit natural, experimental system. We also explore whether the genetic variations that arise through the evolution of insecticide resistance modulate the effect of Plasmodium on these two life-history traits. We show that (i) a reduction in fecundity in Plasmodium-infected mosquitoes is accompanied by an increase in longevity; (ii) this increase in longevity arises through a trade-off between reproduction and survival; and (iii) in insecticide-resistant mosquitoes, the slope of this trade-off is steeper when the mosquito is infected by Plasmodium (cost of insecticide resistance).

  13. Travelers' Health: Protection against Mosquitoes, Ticks, and Other Arthropods

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    ... of these products appear to have repellent or insecticidal activity under particular conditions, they have not yet been ... clothing treatments. Permethrin-treated materials retain repellency or insecticidal activity after repeated laundering but should be retreated, as ...

  14. INFRAVEC: research capacity for the implementation of genetic control of mosquitoes.

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    Crisanti, Andrea

    2013-12-01

    Mosquitoes represent a major and global cause of human suffering due to the diseases they transmit. These include parasitic diseases, i.e. malaria and filariasis, and viral infections such as dengue, encephalitis, and yellow fever. The threat of mosquito-borne diseases is not limited to tropical and subtropical regions of the world. Trade and climate changes have opened new niches to tropical vectors in temperate areas of the world, thus putting previously unaffected regions at risk of disease transmission. The most notable example is the spread of Aedes species, particularly the Asian tiger mosquito Aedes albopictus to southern Europe (reviewed in Ref. 1). Endogenous cases of vector-borne diseases including West Nile fever, chikungunya, and dengue are frequently being reported, highlighting the increased risk of tropical diseases for the European population. Typically, vector control measures targetting mosquitoes are in most cases carried with the use of insecticides. This approach has a number of limitations that constrain their effectiveness. Lack of resources, inadequate logistics, and the insurgence of insecticide resistance are some of the problems encountered in disease-endemic countries (DECs). More recently in Africa, the widespread use of insecticide-treated bed nets has caused a dramatic reduction in malaria mortality and morbidity. Bed nets however are a temporary solution, a testimony of the failure to implement area-wide control measures aimed at eradicating malaria. US and Europe, with well-developed economies, have also failed to control the spread of mosquito vectors, particularly Aedes species. This alarming situation clearly speaks for the need to expand the knowledge on mosquito vectors and for the urgency of developing and validating novel biological and genetic control measures that overcome the limitations of current insecticide-based approaches. During the last 10 years, significant advances have been made in understanding the biology, the

  15. Synthesis of the insecticide prothrin and its analogues from biomass-derived 5-(chloromethyl)furfural.

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    Chang, Fei; Dutta, Saikat; Becnel, James J; Estep, Alden S; Mascal, Mark

    2014-01-15

    Prothrin, a synthetic pyrethroid insecticide, was synthesized from the biomass-derived platform chemical 5-(chloromethyl)furfural in six steps and overall 65% yield. Two structural analogues of prothrin were also prepared following the same synthetic approach. Preliminary testing of these furan-based pyrethroids against the yellow fever mosquito Aedes aegypti indicates promising insecticidal activities.

  16. Modified mosquito landing boxes dispensing transfluthrin provide effective protection against Anopheles arabiensis mosquitoes under simulated outdoor conditions in a semi-field system.

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    Andrés, Marta; Lorenz, Lena M; Mbeleya, Edgar; Moore, Sarah J

    2015-06-24

    Efforts to control malaria vectors have primarily focused on scaling-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying. Although highly efficient against indoor-biting and indoor-resting vectors, these interventions have lower impact on outdoor-biting mosquitoes. Innovative vector control tools are required to prevent outdoor human-mosquito contacts. In this work, the potential of spatial repellents, delivered in an active system that requires minimal user compliance, to provide personal protection against exophagic mosquitoes active in the early evening was explored. A device previously used as an odour-baited lure and kill apparatus, the mosquito landing box (MLB), was modified to dispense the volatile synthetic pyrethroid, transfluthrin, as a spatial repellent. The MLB has an active odour-dispensing mechanism that uses a solar-powered fan and switches on at dusk to provide long duration dispensing of volatile compounds without the need for the user to remember to employ it. Two MLBs were located 5 m from a human volunteer to investigate the repellent effects of a transfluthrin 'bubble' created between the MLBs. Transfluthrin was emanated from polyester strips, hanging inside the MLB odour-dispensing unit. A fully randomized cross-over design was performed in a large, semi-field, screened cage to assess the effect of the repellent against laboratory-reared Anopheles arabiensis mosquitoes under ambient outdoor conditions. The knock-down capacity of the transfluthrin-treated strips was also evaluated at different time points up to 3 weeks after being impregnated to measure duration of efficacy. The protective transfluthrin bubble provided 68.9% protection against An. arabiensis bites under these simulated outdoor conditions. Volatile transfluthrin caused low mortality among mosquitoes in the semi-field system. Transfluthrin-treated strips continued to knock down mosquitoes in laboratory tests, 3 weeks after impregnation, although this effect

  17. Synthesis, crystal structure, and insecticidal activity of novel N-alkyloxyoxalyl derivatives of 2-arylpyrrole.

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    Zhao, Yu; Mao, Chunhui; Li, Yongqiang; Zhang, Pengxiang; Huang, Zhiqiang; Bi, Fuchun; Huang, Runqiu; Wang, Qingmin

    2008-08-27

    Two series of novel N-alkyloxyoxalyl derivatives of 2-arylpyrrole were synthesized, and their structures were characterized by (1)H NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. The insecticidal activities of the new compounds were evaluated. The results of bioassays indicated that some of these title compounds exhibited excellent insecticidal activities, and their insecticidal activities against oriental armyworm, mosquito, and spider mite are comparable to those of the commercialized Chlorfenapyr.

  18. Plant extracts as potential mosquito larvicides

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    Ghosh, Anupam; Chowdhury, Nandita; Chandra, Goutam

    2012-01-01

    Mosquitoes act as a vector for most of the life threatening diseases like malaria, yellow fever, dengue fever, chikungunya ferver, filariasis, encephalitis, West Nile Virus infection, etc. Under the Integrated Mosquito Management (IMM), emphasis was given on the application of alternative strategies in mosquito control. The continuous application of synthetic insecticides causes development of resistance in vector species, biological magnification of toxic substances through the food chain and adverse effects on environmental quality and non target organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are non-toxic, easily available at affordable prices, biodegradable and show broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on phytochemical sources and mosquitocidal activity, their mechanism of action on target population, variation of their larvicidal activity according to mosquito species, instar specificity, polarity of solvents used during extraction, nature of active ingredient and promising advances made in biological control of mosquitoes by plant derived secondary metabolites have been reviewed. PMID:22771587

  19. An insecticide resistance-breaking mosquitocide targeting inward rectifier potassium channels in vectors of Zika virus and malaria.

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    Swale, Daniel R; Engers, Darren W; Bollinger, Sean R; Gross, Aaron; Inocente, Edna Alfaro; Days, Emily; Kanga, Fariba; Johnson, Reed M; Yang, Liu; Bloomquist, Jeffrey R; Hopkins, Corey R; Piermarini, Peter M; Denton, Jerod S

    2016-11-16

    Insecticide resistance is a growing threat to mosquito control programs around the world, thus creating the need to discover novel target sites and target-specific compounds for insecticide development. Emerging evidence suggests that mosquito inward rectifier potassium (Kir) channels represent viable molecular targets for developing insecticides with new mechanisms of action. Here we describe the discovery and characterization of VU041, a submicromolar-affinity inhibitor of Anopheles (An.) gambiae and Aedes (Ae.) aegypti Kir1 channels that incapacitates adult female mosquitoes from representative insecticide-susceptible and -resistant strains of An. gambiae (G3 and Akron, respectively) and Ae. aegypti (Liverpool and Puerto Rico, respectively) following topical application. VU041 is selective for mosquito Kir channels over several mammalian orthologs, with the exception of Kir2.1, and is not lethal to honey bees. Medicinal chemistry was used to develop an analog, termed VU730, which retains activity toward mosquito Kir1 but is not active against Kir2.1 or other mammalian Kir channels. Thus, VU041 and VU730 are promising chemical scaffolds for developing new classes of insecticides to combat insecticide-resistant mosquitoes and the transmission of mosquito-borne diseases, such as Zika virus, without harmful effects on humans and beneficial insects.

  20. Comparative susceptibility to permethrin of two Anopheles gambiae s.l. populations from Southern Benin, regarding mosquito sex, physiological status, and mosquito age

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    Nazaire Aïzoun

    2014-04-01

    Conclusions: The resistance is a hereditary and dynamic phenomenon which can be due to metabolic mechanisms like overproduction of detoxifying enzymes activity. Many factors influence vector susceptibility to insecticide. Among these factors, there are mosquito sex, mosquito age, its physiological status. Therefore, it is useful to respect the World Health Organization criteria in the assessment of insecticide susceptibility tests in malaria vectors. Otherwise, susceptibility testing is conducted using unfed female mosquitoes aged 3-5 days old. Tests should also be carried out at (25±2 °C and (80±10% relative humidity.

  1. A note on the insecticide susceptibility status of principal malaria vector Anopheles culicifacies in four states of India

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    Kamaraju Raghavendra

    2014-08-01

    Full Text Available Background & objectives: The major malaria vector, Anopheles culicifacies Giles is reported to contribute ~ 65% of the malaria cases in India. This species developed resistance to DDT and later to HCH, malathion and also to pyrethroids in some states due to their use in the national malaria control programme. In the present study, insecticide susceptibility of this species was monitored in four states of India. Methods: To determine insecticide susceptibility status of the major malaria vector An. culicifacies, adult mosquitoes were collected from different localities of 32 tribal districts in the states of Andhra Pradesh, Odisha, Jharkhand and West Bengal during October/November 2009-10. Mosquitoes were collected from stratified ecotypes comprising a group of districts in West Bengal and individual districts in three other states. Mosquitoes were exposed to papers treated with WHO diagnostic dose: 4% DDT, 5% malathion and 0.05% deltamethrin following the WHO tube method. Results: Results provided the susceptibility status of An. culicifacies to different insecticides used in the public health programme in 32 districts in four states. An. culicifacies was found resistant to DDT (mortality range 0-36% in all the 32 districts; to malathion it was resistant in 14 districts, verification required in 10 districts and susceptible in eight districts (mortality range 32.2-100%. It was resistant to deltamethrin in four districts, verification required in 11 districts and susceptible in 17 districts (mortality range 43.3-100%. Interpretation & conclusion: Development of widespread resistance to insecticides used in public health sprays for vector control including to pyrethroids in An. culicifacies in the surveyed districts is of great concern for the malaria control programme as the major interventions for vector control are heavily reliant on chemical insecticides, mainly synthetic pyrethroids used both for indoor residual spraying and for long

  2. Towards achieving Abuja targets: identifying and addressing barriers to access and use of insecticides treated nets among the poorest populations in Kenya.

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    Chuma, Jane; Okungu, Vincent; Ntwiga, Janet; Molyneux, Catherine

    2010-03-16

    Ensuring that the poor and vulnerable population benefit from malaria control interventions remains a challenge for malaria endemic countries. Until recently, ownership and use of insecticides treated nets (ITNs) in most countries was low and inequitable, although coverage has increased in countries where free ITN distribution is integrated into mass vaccination campaigns. In Kenya, free ITNs were distributed to children aged below five years in 2006 through two mass campaigns. High and equitable coverage were reported after the campaigns in some districts, although national level coverage remained low, suggesting that understanding barriers to access remains important. This study was conducted to explore barriers to ownership and use of ITNs among the poorest populations before and after the mass campaigns, to identify strategies for improving coverage, and to make recommendations on how increased coverage levels can be sustained. The study was conducted in the poorest areas of four malaria endemic districts in Kenya. Multiple data collection methods were applied including: cross-sectional surveys (n = 708 households), 24 focus group discussions and semi-structured interviews with 70 ITN suppliers. Affordability was reported as a major barrier to access but non-financial barriers were also shown to be important determinants. On the demand side key barriers to access included: mismatch between the types of ITNs supplied through interventions and community preferences; perceptions and beliefs on illness causes; physical location of suppliers and; distrust in free delivery and in the distribution agencies. Key barriers on the supply side included: distance from manufacturers; limited acceptability of ITNs provided through interventions; crowding out of the commercial sector and the price. Infrastructure, information and communication played a central role in promoting or hindering access. Significant resources have been directed towards addressing affordability

  3. Towards achieving Abuja targets: identifying and addressing barriers to access and use of insecticides treated nets among the poorest populations in Kenya

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    Okungu Vincent

    2010-03-01

    Full Text Available Abstract Background Ensuring that the poor and vulnerable population benefit from malaria control interventions remains a challenge for malaria endemic countries. Until recently, ownership and use of insecticides treated nets (ITNs in most countries was low and inequitable, although coverage has increased in countries where free ITN distribution is integrated into mass vaccination campaigns. In Kenya, free ITNs were distributed to children aged below five years in 2006 through two mass campaigns. High and equitable coverage were reported after the campaigns in some districts, although national level coverage remained low, suggesting that understanding barriers to access remains important. This study was conducted to explore barriers to ownership and use of ITNs among the poorest populations before and after the mass campaigns, to identify strategies for improving coverage, and to make recommendations on how increased coverage levels can be sustained. Methods The study was conducted in the poorest areas of four malaria endemic districts in Kenya. Multiple data collection methods were applied including: cross-sectional surveys (n = 708 households, 24 focus group discussions and semi-structured interviews with 70 ITN suppliers. Results Affordability was reported as a major barrier to access but non-financial barriers were also shown to be important determinants. On the demand side key barriers to access included: mismatch between the types of ITNs supplied through interventions and community preferences; perceptions and beliefs on illness causes; physical location of suppliers and; distrust in free delivery and in the distribution agencies. Key barriers on the supply side included: distance from manufacturers; limited acceptability of ITNs provided through interventions; crowding out of the commercial sector and the price. Infrastructure, information and communication played a central role in promoting or hindering access. Conclusions Significant

  4. Universal coverage with insecticide-treated nets - applying the revised indicators for ownership and use to the Nigeria 2010 malaria indicator survey data.

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    Kilian, Albert; Koenker, Hannah; Baba, Ebenezer; Onyefunafoa, Emmanuel O; Selby, Richmond A; Lokko, Kojo; Lynch, Matthew

    2013-09-10

    Until recently only two indicators were used to evaluate malaria prevention with insecticide-treated nets (ITN): "proportion of households with any ITN" and "proportion of the population using an ITN last night". This study explores the potential of the expanded set of indicators recommended by the Roll Back Malaria Monitoring and Evaluation Reference Group (MERG) for comprehensive analysis of universal coverage with ITN by applying them to the Nigeria 2010 Malaria Indicator Survey data. The two additional indicators of "proportion of households with at least one ITN for every two people" and "proportion of population with access to an ITN within the household" were calculated as recommended by MERG. Based on the estimates for each of the four ITN indicators three gaps were calculated: i) households with no ITN, ii) households with any but not enough ITN, iii) population with access to ITN not using it. In addition, coverage with at least one ITN at community level was explored by applying Lot Quality Assurance Sampling (LQAS) decision rules to the cluster level of the data. All outcomes were analysed by household background characteristics and whether an ITN campaign had recently been done. While the proportion of households with any ITN was only 42% overall, it was 75% in areas with a recent mass campaign and in these areas 66% of communities had coverage of 80% or better. However, the campaigns left a considerable intra-household ownership gap with 66% of households with any ITN not having enough for every family member. In contrast, the analysis comparing actual against potential use showed that ITN utilization was good overall with only 19% of people with access not using the ITN, but with a significant difference between the North, where use was excellent (use gap 11%), and the South (use gap 36%) indicating the need for enhanced behaviour change communication. The expanded ITN indicators to assess universal coverage provide strong tools for a comprehensive

  5. Assessing healthcare providers' knowledge and practices relating to insecticide-treated nets and the prevention of malaria in Ghana, Laos, Senegal and Tanzania

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    Hoffman Steven J

    2011-12-01

    Full Text Available Abstract Background Research evidence is not always being disseminated to healthcare providers who need it to inform their clinical practice. This can result in the provision of ineffective services and an inefficient use of resources, the implications of which might be felt particularly acutely in low- and middle-income countries. Malaria prevention is a particularly compelling domain to study evidence/practice gaps given the proven efficacy, cost-effectiveness and disappointing utilization of insecticide-treated nets (ITNs. Methods This study compares what is known about ITNs to the related knowledge and practices of healthcare providers in four low- and middle-income countries. A new questionnaire was developed, pilot tested, translated and administered to 497 healthcare providers in Ghana (140, Laos (136, Senegal (100 and Tanzania (121. Ten questions tested participants' knowledge and clinical practice related to malaria prevention. Additional questions addressed their individual characteristics, working context and research-related activities. Ordinal logistic regressions with knowledge and practices as the dependent variable were conducted in addition to descriptive statistics. Results The survey achieved a 75% response rate (372/497 across Ghana (107/140, Laos (136/136, Senegal (51/100 and Tanzania (78/121. Few participating healthcare providers correctly answered all five knowledge questions about ITNs (13% or self-reported performing all five clinical practices according to established evidence (2%. Statistically significant factors associated with higher knowledge within each country included: 1 training in acquiring systematic reviews through the Cochrane Library (OR 2.48, 95% CI 1.30-4.73; and 2 ability to read and write English well or very well (OR 1.69, 95% CI 1.05-2.70. Statistically significant factors associated with better clinical practices within each country include: 1 reading scientific journals from their own country (OR

  6. The effect of household heads training on long-lasting insecticide-treated bed nets utilization: a cluster randomized controlled trial in Ethiopia

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    Deribew Amare

    2012-03-01

    Full Text Available Abstract Background Long-lasting insecticide-treated bed nets (LLITN have demonstrated significant impact in reducing malaria-related childhood morbidity and mortality. However, utilization of LLITN by under-five children is not satisfactory in many sub-Saharan African countries due to behavioural barriers. Previous studies had focused on the coverage and ownership of LLITN. The effect of skill-based training for household heads on LLITN utilization had not yet been investigated. A cluster-randomized trial on the effect of training of household heads on the use of LLITN was done in Ethiopia to fill this knowledge gap. Methods The study included 22 (11 intervention and 11 control villages in southwest Ethiopia. The intervention consisted of tailored training of household heads about the proper use of LLITN and community network system. All households in each group received free LLITN. Data were collected at baseline, six and 12 months of the follow up periods. Utilization of LLITN in the control and intervention villages was compared at baseline and follow up periods. Results A total of 21,673; 14,735 and 13,758 individuals were included at baseline, sixth and twelfth months of the project period. At the baseline survey, 47.9% of individuals in the intervention villages and 68.4% in the control villages reported that they had utilized LLITN the night before the survey. At the six month, 81.0% of individuals in the intervention villages and 79.3% in the control villages had utilized LLITN. The utilization of LLITN in all age groups in the intervention villages was increased by 17.7 percentage point (95% CI 9.7-25.6 at sixth month and by 31.0 percentage point (95% CI 16.9-45.1 at the twelfth month. Among under-five children, the LLITN utilization increased by 31.6 percentage point (95% CI 17.3-45.8 at the sixth month and 38.4 percentage point (95% CI 12.1-64.7 at the twelfth months of the project period. Conclusion Household level skill

  7. Collapse of Anopheles darlingi populations in Suriname after introduction of insecticide-treated nets (ITNs); malaria down to near elimination level

    NARCIS (Netherlands)

    Hiwat, H.; Mitro, S.; Samjhawan, A.; Sardjoe, P.; Soekhoe, T.; Takken, W.

    2012-01-01

    A longitudinal study of malaria vectors was carried out in three villages in Suriname between 2006 and 2010. During 13,392 man hours of collections, 3,180 mosquitoes were collected, of which 33.7% were anophelines. Of these, Anopheles darlingi accounted for 88.1%, and An. nuneztovari accounted for 1

  8. An Operational Framework for Insecticide Resistance Management Planning.

    Science.gov (United States)

    Chanda, Emmanuel; Thomsen, Edward K; Musapa, Mulenga; Kamuliwo, Mulakwa; Brogdon, William G; Norris, Douglas E; Masaninga, Freddie; Wirtz, Robert; Sikaala, Chadwick H; Muleba, Mbanga; Craig, Allen; Govere, John M; Ranson, Hilary; Hemingway, Janet; Seyoum, Aklilu; Macdonald, Michael B; Coleman, Michael

    2016-05-01

    Arthropod vectors transmit organisms that cause many emerging and reemerging diseases, and their control is reliant mainly on the use of chemical insecticides. Only a few classes of insecticides are available for public health use, and the increased spread of insecticide resistance is a major threat to sustainable disease control. The primary strategy for mitigating the detrimental effects of insecticide resistance is the development of an insecticide resistance management plan. However, few examples exist to show how to implement such plans programmatically. We describe the formulation and implementation of a resistance management plan for mosquito vectors of human disease in Zambia. We also discuss challenges, steps taken to address the challenges, and directions for the future.

  9. Contact Bioassays with Phenoxybenzyl and Tetrafluorobenzyl Pyrethroids against Target-Site and Metabolic Resistant Mosquitoes.

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    Sebastian Horstmann

    Full Text Available Mosquito strains that exhibit increased tolerance to the chemical class of compounds with a sodium channel modulator mode of action (pyrethroids and pyrethrins are typically described as "pyrethroid resistant". Resistance to pyrethroids is an increasingly important challenge in the control of mosquito-borne diseases, such as malaria or dengue, because one of the main interventions (the distribution of large numbers of long-lasting insecticide-treated bed nets currently relies entirely on long-lasting pyrethroids. Increasing tolerance of target insects against this class of insecticides lowers their impact in vector control. The current study suggests that the level of metabolic resistance depends on the structure of the molecule and that structurally different compounds may still be effective because detoxifying enzymes are unable to bind to these uncommon structures.Treated surface contact bioassays were performed on susceptible Aedes aegypti, East African knockdown resistance (kdr Anopheles gambiae (strain RSP-H and metabolically resistant Anopheles funestus (strain FUMOZ-R with different pyrethroids, such as cypermethrin, ß-cyfluthrin, deltamethrin, permethrin and transfluthrin (alone and in combination with the synergist piperonyl butoxide. The nonfluorinated form of transfluthrin was also assessed as a single agent and in combination with piperonyl butoxide.Although the dosages for pyrethroids containing a phenoxybenzyl moiety have exhibited differences in terms of effectiveness among the three tested mosquito species, the structurally different transfluthrin with a polyfluorobenzyl moiety remained active in mosquitoes with upregulated P450 levels. In trials with transfluthrin mixed with piperonyl butoxide, the added synergist exhibited no efficacy-enhancing effect.The results of this study suggest that transfluthrin has the potential to control P450-mediated metabolically resistant mosquitoes because the structural formula of

  10. Armazenamento de sementes de braquiária peletizadas e tratadas com fungicida e inseticida Brachiaria coated seed storage treated with fungicide and insecticide

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    Carlos Eduardo Pereira

    2011-12-01

    Full Text Available A qualidade de sementes é fundamental para o sucesso da formação de pastagem, de forma que é importante viabilizar tecnologias para elas. Assim, objetivou-se com este trabalho avaliar o desempenho de sementes de Brachiaria decumbens peletizadas e tratadas com fungicida e inseticida, durante o armazenamento. As sementes foram tratadas com thiabendazol na dosagem de 200mL 100kg-1 de sementes, com fipronil na dosagem de 500mL 100kg-1 de sementes e com a mistura de ambos (nas mesmas dosagens e parte não foi submetida a esses tratamentos (testemunha. Posteriormente, as sementes foram peletizadas utilizando-se uma mistura de areia + microcelulose e cola Cascorex - PVA (20%, as quais em seguida foram armazenadas em condições ambientais em armazém convencional (temperatura e umidade relativa do ar média de 21,9°C e 68%, respectivamente, durante 12 meses. As sementes foram avaliadas inicialmente e a cada quatro meses com as seguintes avaliações: teor de água, teste de germinação, índice de velocidade de germinação, teste de emergência e índice de velocidade de emergência. A peletização das sementes de Brachiaria decumbens com areia e microcelulose prejudica a porcentagem e velocidade de germinação, bem como a emergência de plântulas durante o armazenamento. Sementes de Brachiaria decumbens cv. 'Basilisk' tratadas com fipronil, thiabendazol, ou com ambos, não devem ser armazenadas por mais de oito meses.The quality of seed is crucial to the success of pasture formation. Thus the aim of this research was to evaluate the performance of Brachiaria decumbens seeds pelleted and treated with fungicides and insecticides during storage. The seeds were treated with thiabendazole at a dosage of 200mL 100kg-1 of seeds, with fipronil at a dosage of 500mL 100kg-1 of seeds and a mixture of both (in the same dosages and some was not subjected to such treatment (control. Subsequently the seeds were coated using a mixture of sand

  11. The biological activity of a-mangostin, a larvicidal botanic mosquito sterol carrier protein-2 inhibitor

    Science.gov (United States)

    Alpha-mangostin derived from mangosteen was identified as a mosquito sterol carrier protein-2 inhibitor via high throughput insecticide screening. Alpha-mangostin was tested for its larvicidal activity against 3rd instar larvae of six mosquito species and the LC50 values range from 0.84 to 2.90 ppm....

  12. Discovering and Designing New Insecticides and their Development Vector Control.

    Science.gov (United States)

    The discovery and development of novel insecticides for vector control is a primary focus of toxicology research conducted at the Mosquito and Fly Research Unit, Gainesville, FL. To identify new active ingredients, the screening of large numbers of experimental compounds is conducted using a primary...

  13. Metofluthrin: a potent new synthetic pyrethroid with high vapor activity against mosquitoes.

    Science.gov (United States)

    Ujihara, Kazuya; Mori, Tatsuya; Iwasaki, Tomonori; Sugano, Masayo; Shono, Yoshinori; Matsuo, Noritada

    2004-01-01

    (1R)-trans-Norchrysanthemic acid fluorobenzyl esters are synthesized and their structure-activity relationships are discussed. These esters show outstanding insecticidal activity against mosquitoes. In particular, the 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl analog (metofluthrin) exhibits the highest potency, being approximately forty times as potent as d-allethrin in a mosquito coil formulation when tested against southern house mosquitoes (Culex quinquefasciatus). Metofluthrin also exhibits a significant vapor action at room temperature.

  14. Synthesis of insecticidal sucrose esters

    Institute of Scientific and Technical Information of China (English)

    Song Zi-juan; Li Shu-jun; Chen Xi; Liu Li-mei; Song Zhan-qian

    2006-01-01

    Some synthetic sucrose esters (SE) are a relatively new class of insecticidal compounds produced by reacting sugars with fatty acids, which are safe for the environment. Especially, sucrose esters composed of C6-C12 fatty acids have desirable insecticidal properties against many soft-bodied arthropod pests. In our study, sucrose octanoate which has the highest activity against a range of arthropod species was synthesized by a trans-esterification method and proved its insecticidal property. Under the condition of a homogeneous liquid, sucrose octanoate was prepared by reacting ethyl octanoate with sucrose at reduced pressure; the yield was 79.11%. Sucrose octanoate synthesized was identified and its property analyzed by IR, TLC and spectrophotometric analysis. It was shown that the ratio of monoester to polyester in sucrose octanoate was 1.48:1. The insecticidal activity of the synthetic sucrose octanoate was evaluated at a concentration of 4 and 8 mg·mL-1. The mortality of first-instar larvae ofLymantria dispar from its contact toxicity was 72.5% after 36 hours, the revision insect reduced rate of Aphis glycines reached above 80% at 4 and 8 mg·mL-1 after being treated for 5 days. Since the SE products are nontoxic to humans and higher animals, fully biodegradable and hydrolyzed to readily metabolizable sucrose and fatty acid, they are not harmful to crops and appear to be good insecticide candidates.

  15. To assess whether indoor residual spraying can provide additional protection against clinical malaria over current best practice of long-lasting insecticidal mosquito nets in The Gambia: study protocol for a two-armed cluster-randomised trial

    Directory of Open Access Journals (Sweden)

    Parker David

    2011-06-01

    Full Text Available Abstract Background Recently, there has been mounting interest in scaling-up vector control against malaria in Africa. It needs to be determined if indoor residual spraying (IRS with DDT will provide significant marginal protection against malaria over current best practice of long-lasting insecticidal nets (LLINs and prompt treatment in a controlled trial, given that DDT is currently the most persistent insecticide for IRS. Methods A 2 armed cluster-randomised controlled trial will be conducted to assess whether DDT IRS and LLINs combined provide better protection against clinical malaria in children than LLINs alone in rural Gambia. Each cluster will be a village, or a group of small adjacent villages; all clusters will receive LLINs and half will receive IRS in addition. Study children, aged 6 months to 13 years, will be enrolled from all clusters and followed for clinical malaria using passive case detection to estimate malaria incidence for 2 malaria transmission seasons in 2010 and 2011. This will be the primary endpoint. Exposure to malaria parasites will be assessed using light and exit traps followed by detection of Anopheles gambiae species and sporozoite infection. Study children will be surveyed at the end of each transmission season to estimate the prevalence of Plasmodium falciparum infection and the prevalence of anaemia. Discussion Practical issues concerning intervention implementation, as well as the potential benefits and risks of the study, are discussed. Trial Registration ISRCTN01738840 - Spraying And Nets Towards malaria Elimination (SANTE

  16. Avoid Mosquito Bites

    Science.gov (United States)

    ... Submit What's this? Submit Button Past Emails Avoid Mosquito Bites Language: English (US) Español (Spanish) Recommend on ... finding a travel medicine clinic near you. Prevent Mosquito Bites While Traveling Mosquito bites are bothersome enough, ...

  17. Indoor Application of Attractive Toxic Sugar Bait (ATSB) in Combination with Mosquito Nets for Control of Pyrethroid-Resistant Mosquitoes

    Science.gov (United States)

    Stewart, Zachary P.; Oxborough, Richard M.; Tungu, Patrick K.; Kirby, Matthew J.; Rowland, Mark W.; Irish, Seth R.

    2013-01-01

    Background Attractive toxic sugar bait (ATSB) sprayed onto vegetation has been successful in controlling Anopheles mosquitoes outdoors. Indoor application of ATSB has yet to be explored. The purpose of this study was to determine whether ATSB stations positioned indoors have the potential to kill host-seeking mosquitoes and constitute a new approach to control of mosquito-borne diseases. Methods Insecticides were mixed with dyed sugar solution and tested as toxic baits against Anopheles arabiensis, An. Gambiae s.s. and Culex quinquefasciatus in feeding bioassay tests to identify suitable attractant-insecticide combinations. The most promising ATSB candidates were then trialed in experimental huts in Moshi, Tanzania. ATSB stations were hung in huts next to untreated mosquito nets occupied by human volunteers. The proportions of mosquitoes killed in huts with ATSB treatments relative to huts with non-insecticide control treatments huts were recorded, noting evidence of dye in mosquito abdomens. Results In feeding bioassays, chlorfenapyr 0.5% v/v, boric acid 2% w/v, and tolfenpyrad 1% v/v, mixed in a guava juice-based bait, each killed more than 90% of pyrethroid-susceptible An. Gambiae s.s. and pyrethroid-resistant An. arabiensis and Cx. quinquefasciatus. In the hut trial, mortality rates of the three ATSB treatments ranged from 41-48% against An. arabiensis and 36-43% against Cx. quinquefasciatus and all were significantly greater than the control mortalities: 18% for An. arabiensis, 7% for Cx. quinquefasciatus (p<0.05). Mortality rates with ATSB were comparable to those with long lasting insecticidal nets previously tested against the same species in this area. Conclusions Indoor ATSB shows promise as a supplement to mosquito nets for controlling mosquitoes. Indoor ATSB constitute a novel application method for insecticide classes that act as stomach poisons and have not hitherto been exploited for mosquito control. Combined with LLIN, indoor use of ATSB has the

  18. Indoor application of attractive toxic sugar bait (ATSB in combination with mosquito nets for control of pyrethroid-resistant mosquitoes.

    Directory of Open Access Journals (Sweden)

    Zachary P Stewart

    Full Text Available BACKGROUND: Attractive toxic sugar bait (ATSB sprayed onto vegetation has been successful in controlling Anopheles mosquitoes outdoors. Indoor application of ATSB has yet to be explored. The purpose of this study was to determine whether ATSB stations positioned indoors have the potential to kill host-seeking mosquitoes and constitute a new approach to control of mosquito-borne diseases. METHODS: Insecticides were mixed with dyed sugar solution and tested as toxic baits against Anopheles arabiensis, An. Gambiae s.s. and Culex quinquefasciatus in feeding bioassay tests to identify suitable attractant-insecticide combinations. The most promising ATSB candidates were then trialed in experimental huts in Moshi, Tanzania. ATSB stations were hung in huts next to untreated mosquito nets occupied by human volunteers. The proportions of mosquitoes killed in huts with ATSB treatments relative to huts with non-insecticide control treatments huts were recorded, noting evidence of dye in mosquito abdomens. RESULTS: In feeding bioassays, chlorfenapyr 0.5% v/v, boric acid 2% w/v, and tolfenpyrad 1% v/v, mixed in a guava juice-based bait, each killed more than 90% of pyrethroid-susceptible An. Gambiae s.s. and pyrethroid-resistant An. arabiensis and Cx. quinquefasciatus. In the hut trial, mortality rates of the three ATSB treatments ranged from 41-48% against An. arabiensis and 36-43% against Cx. quinquefasciatus and all were significantly greater than the control mortalities: 18% for An. arabiensis, 7% for Cx. quinquefasciatus (p<0.05. Mortality rates with ATSB were comparable to those with long lasting insecticidal nets previously tested against the same species in this area. CONCLUSIONS: Indoor ATSB shows promise as a supplement to mosquito nets for controlling mosquitoes. Indoor ATSB constitute a novel application method for insecticide classes that act as stomach poisons and have not hitherto been exploited for mosquito control. Combined with LLIN, indoor

  19. Mosquito Control in Poland: Pro- and Anti-Environmental Activities

    Directory of Open Access Journals (Sweden)

    Gliniewicz Aleksandra

    2014-12-01

    Full Text Available Mosquito control in Poland is still dominated by the use of chemicals. Although it has been 13 years since the flood of the century, only in few cities and towns (Wroclaw, Gorzow Wielkopolski and Torun various methods of mosquito control such as mapping of larvae development and setting time limits for the imagines occur-rence were developed. The problem of mosquito control is not only limited to adult insects, it is also much more a complex issue due to the use of insecticides in the environment that we would rather like to keep unchanged, with a diversity of co-existing species of plants and animals. In addition to eradication of larvae and adult insects, we should also: carry out actions modifying environment so that it becomes less friendly to mosquitoes (e.g. drying wet mead-ows as a result of land reclamation, protect places where people reside - with the use of insecticide lamps and spatial repellents, as well as catchers for aggressive female mosquitoes. Increasing the share of environmental management methods and public education on preventing to form and eliminating existing places of mosquito larvae development in urban green areas (parks, river overflow areas and drainage ditches are still an undervalued element of integrated mosquito control in Poland.

  20. Old ingredients for a new recipe? Neem cake, a low-cost botanical by-product in the fight against mosquito-borne diseases.

    Science.gov (United States)

    Benelli, Giovanni; Murugan, Kadarkarai; Panneerselvam, Chellasamy; Madhiyazhagan, Pari; Conti, Barbara; Nicoletti, Marcello

    2015-02-01

    Mosquitoes (Diptera: Culicidae) represent an important threat to millions of people worldwide, since they act as vectors for important pathogens, such as malaria, yellow fever, dengue and West Nile. Control programmes mainly rely on chemical treatments against larvae, indoor residual spraying and insecticide-treated bed nets. In recent years, huge efforts have been carried out to propose new eco-friendly alternatives, with a special focus on the evaluation of plant-borne mosquitocidal compounds. Major examples are neem-based products (Azadirachta indica A. Juss, Meliaceae) that have been proven as really effective against a huge range of pests of medical and veterinary importance, including mosquitoes. Recent research highlighted that neem cake, a cheap by-product from neem oil extraction, is an important source of mosquitocidal metabolites. In this review, we examined (i) the latest achievements about neem cake metabolomics with special reference to nor-terpenoid and related content; (ii) the neem cake ovicidal, larvicidal and pupicidal toxicity against Aedes, Anopheles and Culex mosquito vectors; (iii) its non-target effects against vertebrates; and (iv) its oviposition deterrence effects on mosquito females. Overall, neem cake can be proposed as an eco-friendly and low-cost source of chemicals to build newer and safer control tools against mosquito vectors.

  1. Multiple activities of insect repellents on odorant receptors in mosquitoes

    Science.gov (United States)

    Several lines of evidence suggest that insect repellent molecules reduce mosquito-host contacts by interacting with odorants and odorant receptors (ORs) ultimately affecting olfactory-driven behaviors. We describe the molecular effects of ten insect repellents and a pyrethroid insecticide with known...

  2. A Chlorfenapyr Mixture Net Interceptor® G2 Shows High Efficacy and Wash Durability against Resistant Mosquitoes in West Africa.

    OpenAIRE

    N'Guessan, R.; Odjo, A; Ngufor, C; Malone, D.; Rowland, M

    2016-01-01

    Background Malaria control through use of long-lasting insecticidal nets (LN) is threatened by the selection of anopheline mosquitoes strongly resistant to pyrethroid insecticides. To sustain future effectiveness it is essential to identify and evaluate novel insecticides suitable for nets. Mixtures of two insecticides with contrasting mode of action have the potential to kill resistant vectors and restore transmission control provided the formulation can withstand regular washing over the ne...

  3. Efficacy of the vegetative cells of Lysinibacillus sphaericus for biological control of insecticide-resistant Aedes aegypti

    National Research Council Canada - National Science Library

    Paula Andrea Rojas-Pinzon; Jenny Dussan

    2017-01-01

    ... such as Culex spp., Anopheles spp. and Aedes spp., and thus, an endemic country for the diseases transmitted by these mosquitoes [2]. Since the re-invasion of Ae. aegypti in the 1960s, prevention against the diseases transmitted by this mosquito is based on the use of chemical insecticides [5]. Although biological control of Ae. aeg...

  4. Plant-mediated biosynthesis of nanoparticles as an emerging tool against mosquitoes of medical and veterinary importance: a review.

    Science.gov (United States)

    Benelli, Giovanni

    2016-01-01

    Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. Mosquito young instars are usually targeted with organophosphates, insect growth regulators and microbial control agents. Indoors residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have strong negative effects on human health and the environment. Newer and safer tools have been recently implemented to enhance control of mosquitoes. In this review, I focus on characterization, effectiveness, and non-target effects of mosquitocidal nanoparticles synthesized using botanical products (mosquitocidal nanoparticles, MNP). The majority of plant-fabricated MNP are silver ones. The synthesis of MNP is usually confirmed by UV-visualization spectroscopy, followed by scanning electron microscopy or transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction studies. Interestingly, plant-synthesized metal nanoparticles have been reported as effective ovicides, larvicides, pupicides, adulticides, and oviposition deterrents against different mosquito species of medical and veterinary importance. Few parts per million of different MNP are highly toxic against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti, and the filariasis mosquito Culex quiquefasciatus. However, despite the growing number of evidences about the effectiveness of MNP, moderate efforts have been carried out to shed light on their possible non-target effects against mosquito's natural enemies and other aquatic organisms. In the final section, particular attention was dedicated to this issue. A number of hot areas that need further research and cooperation among parasitologists and entomologists are highlighted.

  5. Potential benefits, limitations and target product-profiles of odor-baited mosquito traps for malaria control in Africa.

    Directory of Open Access Journals (Sweden)

    Fredros O Okumu

    Full Text Available BACKGROUND: Traps baited with synthetic human odors have been proposed as suitable technologies for controlling malaria and other mosquito-borne diseases. We investigated the potential benefits of such traps for preventing malaria transmission in Africa and the essential characteristics that they should possess so as to be effective. METHODS AND PRINCIPAL FINDINGS: An existing mathematical model was reformulated to distinguish availability of hosts for attack by mosquitoes from availability of blood per se. This adaptation allowed the effects of pseudo-hosts such as odor-baited mosquito traps, which do not yield blood but which can nonetheless be attacked by the mosquitoes, to be simulated considering communities consisting of users and non-users of insecticide-treated nets (ITNs, currently the primary malaria prevention method. We determined that malaria transmission declines as trap coverage (proportion of total availability of all hosts and pseudo hosts that traps constitute increases. If the traps are more attractive than humans and are located in areas where mosquitoes are most abundant, 20-130 traps per 1000 people would be sufficient to match the impact of 50% community-wide ITN coverage. If such traps are used to complement ITNs, malaria transmission can be reduced by 99% or more in most scenarios representative of Africa. However, to match cost-effectiveness of ITNs, the traps delivery, operation and maintenance would have to cost a maximum of US$4.25 to 27.61 per unit per year. CONCLUSIONS AND SIGNIFICANCE: Odor-baited mosquito traps might potentially be effective and affordable tools for malaria control in Africa, particularly if they are used to complement, rather than replace, existing methods. We recommend that developers should focus on super-attractive baits and cheaper traps to enhance cost-effectiveness, and that the most appropriate way to deploy such technologies is through vertical delivery mechanisms.

  6. Evaluation of novel insecticides for control of dengue vector Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Paul, Ayesa; Harrington, Laura C; Scott, Jeffrey G

    2006-01-01

    Insecticides are one of the major tools for controlling vector populations and for reducing the transmission of human pathogens. However, there are few new insecticides being developed and marketed for vector control. Herein, we report on the toxicity of six novel insecticides to both adult and larval Aedes aegypti (L). and the toxicity of three novel insect growth regulators (IGRs) to larvae. Four insecticides were highly or moderately toxic to larvae with LC50 values of 16 (chlorfenapyr), 70 (hydramethylnon), 79 (indoxacarb), and 84 ng/ml (imidacloprid). Diafenthiuron and chlorfenapyr were moderately toxic to adult mosquitoes with LC50 values of 13 and 92 ng/cm2, respectively. Imidacloprid was strongly synergized by piperonyl butoxide (PBO) in Ae. aegypti adults, suggesting that neonicotinoids are intrinsically very toxic to adult mosquitoes (in the absence of detoxification). The effect of PBO on the toxicity in adults and larvae was considerably different, both in terms of the insecticides that were synergized (or antagonized for chlorfenapyr versus adults) and in terms of the degree of synergism. This result implies that the cytochrome P450s involved in metabolism of these insecticides are different between adults and larvae. Pyriproxyfen was confirmed as a potent IGR (EC50 of 0.0017 ng/ml) for mosquitoes, although tebufenozide lacked activity. The potential for use of these materials in mosquito control is discussed.

  7. Chlorfenapyr (A Pyrrole Insecticide) Applied Alone or as a Mixture with Alpha-Cypermethrin for Indoor Residual Spraying against Pyrethroid Resistant Anopheles gambiae sl: An Experimental Hut Study in Cove, Benin.

    Science.gov (United States)

    Ngufor, Corine; Critchley, Jessica; Fagbohoun, Josias; N'Guessan, Raphael; Todjinou, Damien; Rowland, Mark

    2016-01-01

    Indoor spraying of walls and ceilings with residual insecticide remains a primary method of malaria control. Insecticide resistance in malaria vectors is a growing problem. Novel insecticides for indoor residual spraying (IRS) which can improve the control of pyrethroid resistant malaria vectors are urgently needed. Insecticide mixtures have the potential to improve efficacy or even to manage resistance in some situations but this possibility remains underexplored experimentally. Chlorfenapyr is a novel pyrrole insecticide which has shown potential to improve the control of mosquitoes which are resistant to current WHO-approved insecticides. The efficacy of IRS with chlorfenapyr applied alone or as a mixture with alpha-cypermeththrin (a pyrethroid) was evaluated in experimental huts in Cove, Southern Benin against wild free flying pyrethroid resistant Anopheles gambiae sl. Comparison was made with IRS with alpha-cypermethrin alone. Fortnightly 30-minute in situ cone bioassays were performed to assess the residual efficacy of the insecticides on the treated hut walls. Survival rates of wild An gambiae from the Cove hut site in WHO resistance bioassays performed during the trial were >90% with permethrin and deltamethrin treated papers. Mortality of free-flying mosquitoes entering the experimental huts was 4% in the control hut. Mortality with alpha-cypermethrin IRS did not differ from the control (5%, P>0.656). The highest mortality was achieved with chlorfenapyr alone (63%). The alpha-cypermethrin + chlorfenapyr mixture killed fewer mosquitoes than chlorfenapyr alone (43% vs. 63%, P<0.001). While the cone bioassays showed a more rapid decline in residual mortality with chlorfenapyr IRS to <30% after only 2 weeks, fortnightly mortality rates of wild free-flying An gambiae entering the chlorfenapyr IRS huts were consistently high (50-70%) and prolonged, lasting over 4 months. IRS with chlorfenapyr shows potential to significantly improve the control of malaria

  8. Transfer of toxin genes to alternate bacterial hosts for mosquito control

    Directory of Open Access Journals (Sweden)

    Sergio Orduz

    1995-02-01

    Full Text Available Mosquitoes are vector of serious human and animal diseases, such as malaria, dengue, yellow fever, among others. The use of biological control agents has provide an environmentally safe and highly specific alternative to the use of chemical insecticides in the control of vector borne diseases. Bacillus thuringiensis and B. sphaericus produce toxic proteins to mosquito larvae. Great progress has been made on the biochemical and molecular characterization of such proteins and the genes encoding them. Nevertheless, the low residuality of these biological insecticides is one of the major drawbacks. This article present some interesting aspects of the mosquito larvae feeding habits and review the attempts that have been made to genetically engineer microorganisms that while are used by mosquito larvae as a food source should express the Bacillus toxin genes in order to improve the residuality and stability in the mosquito breeding ponds.

  9. Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania

    OpenAIRE

    Malima Robert; Maxwell Caroline; Magesa Stephen; Tungu Patrick; Masue Dennis; Sudi Wema; Myamba Joseph; Pigeon Olivier; Rowland Mark

    2010-01-01

    Abstract Background Combination mosquito nets incorporating two unrelated insecticides or insecticide plus synergist are designed to control insecticide resistant mosquitoes. PermaNet 3.0 is a long-lasting combination net incorporating deltamethrin on the side panels and a mixture of deltamethrin and synergist piperonyl butoxide (PBO) on the top panel. PBO is an inhibitor of mixed function oxidases implicated in pyrethroid resistance. Method An experimental hut trial comparing PermaNet 3.0, P...

  10. Spinosad: a biorational mosquito larvicide for use in car tires in southern Mexico

    Directory of Open Access Journals (Sweden)

    Marina Carlos F

    2012-05-01

    Full Text Available Abstract Background Car tires are important habitats for mosquito development because of the high density populations they can harbor and their presence in urban settings. Water in experimental tires was treated with one of three insecticides or an untreated control. Aquatic invertebrates were sampled at weekly intervals. Eggs, larval and pupal samples were laboratory-reared to estimate seasonal fluctuations in Aedes aegypti and Ae. albopictus abundance. Results Spinosad treatments at 1 or 5 ppm (mg a.i./liter provided 6–8 weeks of effective control of Ae. aegypti, Ae. albopictus, Culex quinquefasiatus and Cx. coronator larvae, both in the dry season and the rainy season when mosquito populations increased markedly in southern Mexico. Spinosad continued to provide partial control of larvae for several weeks after initial recolonization of treated tires. The larvicidal performance of VectoBac 12AS (Bacillus thuringiensis var. israelensis was relatively poor with one week of complete control of Aedes spp. larvae and no discernible control of Culex spp., whereas the duration of larvicidal activity of 1% temephos mineral-based granules was intermediate between those of VectoBac and spinosad treatments. Populations of chironomids, ostracods and Toxorhynchites theobaldi were generally reduced in spinosad and temephos treatments, but were similar in control and VectoBac treatments. Conclusion The present study is the first to report spinosad as an effective larvicide against Cx. coronator, which is currently invading the southern United States. These results substantiate the use of spinosad as a highly effective mosquito larvicide, even in habitats such as unused car tires that can represent prolific sources of adult mosquitoes.

  11. Vorticella sp: Prospective Mosquito Biocontrol agent

    Directory of Open Access Journals (Sweden)

    Chandrashekhar Devidas Patil

    2016-10-01

    Full Text Available Background: Considering the disadvantages of chemical insecticides, we aimed to evaluate Vorticella parasites for control of mosquito larvae of Anopheles stephensi and Aedes aegypti at different larval stages.Methods: Vorticella sp infected mosquito larvae were crushed in the 0.85% saline and homogenized well to get Vorti­cella in suspension. The effects of Vorticella sp infections on larval development were investigated by inoculat­ing protozoan on different larval instars of An. stephensi and Ae. aegypti and observed under light microscope. Le­thal time of the Vorticella infected larvae at different stages was calculated.Results: First and 2nd larval instars of both An. stephensi and Ae. aegypti did not show signs of infection by Vorti­cella sp., whereas 3rd instars of An. stephensi showed more Vorticella infection than those of Ae. aegypti. However, 4th larval instars of both mosquitoes were heavily infected with Vorticella parasite which was responsible for slug­gish movements of larvae and eventually death. Moreover, parasites (Vorticella spp were responsible for more than 90% reduction in adult emergence for both infected An. stephensi and Ae. aegypti.Conclusion: This study provides insights for mosquito larvicidal action of surface parasite Vorticella on different larval stages of An. stephensi and Ae. Aegypti. It could be suggested as a potential candidate in mosquito biocontrol programs.

  12. Neem (Azadirachta indica): towards the ideal insecticide?

    Science.gov (United States)

    Benelli, Giovanni; Canale, Angelo; Toniolo, Chiara; Higuchi, Akon; Murugan, Kadarkarai; Pavela, Roman; Nicoletti, Marcello

    2017-02-01

    Pesticide resistance is going to change rapidly our antibiotics and insecticides arsenal. In this scenario, plant-derived natural products are considered valuable candidates to reverse this negative trend. Growing research attention is focused on neem (Azadirachta indica, Meliaceae), exploring the utility of its products as insecticides and antibiotics. In this review, we summarised the knowledge on neem oil and neem cake by-products in arthropod pest control, with special reference to mosquito vectors of public health importance. To the best of our knowledge, neem-borne products currently showed effective and eco-friendly features, including little non-target effects, multiple mechanisms of action, low cost, easy production in countries with limited industrial facilities. In particular, the potentiality of neem cake as ideal and affordable source of mosquitocidal compounds in anopheline and aedine control programmes is outlined. Overall, we propose the employ of neem-based products as an advantageous alternative to build newer and safer arthropod control tools.

  13. Eliciting renal failure in mosquitoes with a small-molecule inhibitor of inward-rectifying potassium channels.

    Directory of Open Access Journals (Sweden)

    Rene Raphemot

    Full Text Available Mosquito-borne diseases such as malaria and dengue fever take a large toll on global health. The primary chemical agents used for controlling mosquitoes are insecticides that target the nervous system. However, the emergence of resistance in mosquito populations is reducing the efficacy of available insecticides. The development of new insecticides is therefore urgent. Here we show that VU573, a small-molecule inhibitor of mammalian inward-rectifying potassium (Kir channels, inhibits a Kir channel cloned from the renal (Malpighian tubules of Aedes aegypti (AeKir1. Injection of VU573 into the hemolymph of adult female mosquitoes (Ae. aegypti disrupts the production and excretion of urine in a manner consistent with channel block of AeKir1 and renders the mosquitoes incapacitated (flightless or dead within 24 hours. Moreover, the toxicity of VU573 in mosquitoes (Ae. aegypti is exacerbated when hemolymph potassium levels are elevated, suggesting that Kir channels are essential for maintenance of whole-animal potassium homeostasis. Our study demonstrates that renal failure is a promising mechanism of action for killing mosquitoes, and motivates the discovery of selective small-molecule inhibitors of mosquito Kir channels for use as insecticides.

  14. Bioreactor and substrate selection for solid-state cultivation of the malaria mosquito control agent Metarhizium anisopliae

    NARCIS (Netherlands)

    Breukelen, van F.R.; Haemers, S.; Wijffels, R.H.; Rinzema, A.

    2011-01-01

    Metarhizium anisopliae spores are a promising alternative to chemical insecticides against malaria mosquitoes. In-house application resulting in infection of mosquitoes with the fungus can strongly contribute to reducing malaria transmission. For such application, fungal spores need to be produced i

  15. Chlorfenapyr: irritant effect compared to other insecticides and its intrinsic toxicity in multiple-insecticide-susceptible and -resistant Anopheles stephensi (Diptera: Culicidae).

    Science.gov (United States)

    Verma, Vaishali; Elamathi, N; Velamuri, Poonam S; Sreehari, U; Agrawal, O P; Raghavendra, K

    2015-03-01

    For effective management of vector resistance there is a need for new insecticide molecules with novel modes of action. For desired toxic effect of an insecticide, apart from other behavioural aspects, toxicity and chemical nature of the molecule are important that may cause irritability in the mosquito to the insecticide affecting the uptake. In this study, a pyrrole class insecticide, chlorfenapyr (a late acting insecticide) was tested for its irritability against multiple-insecticide-susceptible and -resistant strains of Anopheles stephensi Liston 1901 (Diptera: Culicidae). Studies were conducted to assess the irritability due to chlorfenapyr, DDT, malathion, deltamethrin and permethrin and intrinsic toxicity of chlorfenapyr in multiple-insecticide-susceptible and -resistant laboratory strains of An. stephensi following standard WHO methods. Chlorfenapyr molecule has shown least irritant effect against susceptible and resistant strains among all the insecticides tested allowing more landing time to the vector species on the impregnated surfaces to pick-up lethal dose. Chlorfenapyr could be an ideal insecticide for management of multiple-insecticide-resistance including pyrethroids.

  16. REVIEW ON THE EFFICACY OF INSECTICIDES AND BIO-INSECTICIDES (PATHOGEN AND IGR AGAINST VECTOR DISEASES EVALUATIONS CONDUCTED BY VRCRU (2001-2002

    Directory of Open Access Journals (Sweden)

    Damar Tri Boewono

    2012-11-01

    Full Text Available Vector and Reservoir Control Research Unit (VRCRU Salatiga, as WHO Collaborating Center for Pesticide Evaluation, has evaluate the efficacy of several new insecticides for various purposes especially for the registration in Indonesia Pesticide Commission. This unit has evaluated insecticides inc ollaboration with pesticide companies and WHO. The aim of the studies were to provide the efficacy and residual effect of insecticides against vector disease. Such as malaria, dengue haemorrhagic fever (DHF, filariasis, plague, diarrhea, etc. The studied insecticides in the unit were belong to Organophosphate, Carbamate and Synthetic Phyrethroid compounds and also bio-insecticides (pathogen & Insect Grow Regulator/IGR. Various insecticide applications were performed against the adult, e.g. residual spraying (IRS, thermal fogging, Ultra Low Volume (ULV, bed nets impregnation. The study was also conducted to evaluate the efficacy of insecticides, bio-insecticides (pathogen and IGR against mosquito larvae as well as insecticides against fleas and cockroaches. This paper is an overall review of the related studies which were conducted on 2001-2002. Keywords: efficacy, bio-insecticides, vector disease

  17. No difference in the incidence of malaria in human-landing mosquito catch collectors and non-collectors in a Senegalese village with endemic malaria.

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    Amélé N Wotodjo

    Full Text Available The human landing catches is the gold standard method used to study the vectors of malaria and to estimate their aggressiveness. However, this method has raised safety concerns due to a possible increased risk of malaria or other mosquito-borne diseases among the mosquito collectors. The aim of this study was to evaluate the incidence of malaria attacks among mosquito collectors and to compare these results with those of non-collectors in a Senegalese village.From July 1990 to December 2011, a longitudinal malaria study involving mosquito collectors and non-collectors was performed in Dielmo village, Senegal. During the study period, 4 drugs were successively used to treat clinical malaria, and long-lasting insecticide-treated nets were offered to all villagers in July 2008. No malaria chemoprophylaxis was given to mosquito collectors. Incidence of uncomplicated clinical malaria and asymptomatic malaria infection were analyzed among these two groups while controlling for confounding factors associated with malaria risk in random effects negative binomial and logistic regression models, respectively.A total of 3,812 person-trimester observations of 199 adults at least 15 years of age were analyzed. Clinical malaria attacks accounted for 6.3% both in collectors and non-collectors, and asymptomatic malaria infections accounted for 21% and 20% in collectors and non-collectors, respectively. A non-significant lower risk of malaria was observed in the collector group in comparison with the non-collector group after adjusting for other risk factors of malaria and endemicity level (Clinical malaria: adjusted incidence rate ratio = 0.89; 95% confidence interval = 0.65-1.22; p= 0.47.Being a mosquito collector in Dielmo was not significantly associated with an increased risk of malaria both under holoendemic, mesoendemic and hypoendemic conditions of malaria epidemiology. This result supports the view that HLC, the most accurate method for evaluating

  18. Modeling and biological control of mosquitoes.

    Science.gov (United States)

    Lord, Cynthia C

    2007-01-01

    Models can be useful at many different levels when considering complex issues such as biological control of mosquitoes. At an early stage, exploratory models are valuable in exploring the characteristics of an ideal biological control agent and for guidance in data collection. When more data are available, models can be used to explore alternative control strategies and the likelihood of success. There are few modeling studies that explicitly consider biological control in mosquitoes; however, there have been many theoretical studies of biological control in other insect systems and of mosquitoes and mosquito-borne diseases in general. Examples are used here to illustrate important aspects of designing, using and interpreting models. The stability properties of a model are valuable in assessing the potential of a biological control agent, but may not be relevant to a mosquito population with frequent environmental perturbations. The time scale and goal of proposed control strategies are important considerations when analyzing a model. The underlying biology of the mosquito host and the biological control agent must be carefully considered when deciding what to include in a model. Factors such as density dependent population growth in the host, the searching efficiency and aggregation of a natural enemy, and the resource base of both have been shown to influence the stability and dynamics of the interaction. Including existing mosquito control practices into a model is useful if biological control is proposed for locations with current insecticidal control. The development of Integrated Pest Management (IPM) strategies can be enhanced using modeling techniques, as a wide variety of options can be simulated and examined. Models can also be valuable in comparing alternate routes of disease transmission and to investigate the level of control needed to reduce transmission.

  19. Cytotoxic and Insecticidal Activities of Derivatives of Harmine, a Natural Insecticidal Component Isolated from Peganum harmala

    Directory of Open Access Journals (Sweden)

    Guohua Zhong

    2010-11-01

    Full Text Available In a continuing effort to develop novel β-carbolines endowed with better insecticidal activity, a simple high-yielding method for the synthesis of harmine compounds starting from L-tryptophan has been developed and a series of 1,3-substituted β-carboline derivatives have been synthesized and evaluated for their cytotoxicity against insect cultured Sf9 cell line in vitro and insecticidal activities against 4th instar larvae of mosquitos, Culex pipiens quinquefasciatus and mustard aphid, Lipaphis erysimi. The results demonstrated that 1-phenyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (compound 2 and methyl 1-phenyl-β-carboline-3-carboxylate (compound 13 represented the best potential compounds, with Sf9 cells inhibition rates of 71.55% and 60.21% after 24 h treatment at concentrations of 50–200 mg/L, respectively. Both compounds 2 and 13 also showed strong insecticidal activity towards 4th instar larvae of mosquitos with LC50 values of 20.82 mg/L and 23.98 mg/L, and their LC90 values were 88.29 mg/L and 295.13 mg/L, respectively. Furthermore, the LC50 values of compounds 2 and 13 against mustard aphids were 53.16 mg/L and 68.05 mg/L, and their LC90 values were 240.10 mg/L and 418.63 mg/L after 48 h treatment. The in vitro cytotoxicity of these compounds was consistent with the insecticidal activity in vivo. The results indicated that the 1- and 3-positions of the β-carboline ring deserve further investigation to develop biorational insecticides based on the natural compound harmine as a lead compound.

  20. Proof of concept for a novel insecticide bioassay based on sugar feeding by adult Aedes aegypti (Stegomyia aegypti).

    Science.gov (United States)

    Stell, F M; Roe, R M; Arellano, C; Kennedy, L; Thornton, H; Saavedra-Rodriguez, K; Wesson, D M; Black, W C; Apperson, C S

    2013-09-01

    Aedes aegypti L. (Stegomyia aegypti) (Diptera: Culicidae) is the principal vector of dengue and yellow fever viruses in tropical and subtropical regions of the world. Disease management is largely based on mosquito control achieved by insecticides applied to interior resting surfaces and through space sprays. Population monitoring to detect insecticide resistance is a significant component of integrated disease management programmes. We developed a bioassay method for assessing insecticide susceptibility based on the feeding activity of mosquitoes on plant sugars. Our prototype sugar-insecticide feeding bioassay system was composed of inexpensive, disposable components, contained minimal volumes of insecticide, and was compact and highly transportable. Individual mosquitoes were assayed in a plastic cup that contained a sucrose-permethrin solution. Trypan blue dye was added to create a visual marker in the mosquito's abdomen for ingested sucrose-permethrin solution. Blue faecal spots provided further evidence of solution ingestion. With the sugar-insecticide feeding bioassay, the permethrin susceptibility of Ae. aegypti females from two field-collected strains was characterized by probit analysis of dosage-response data. The field strains were also tested by forced contact of females with permethrin residues on filter paper. Dosage-response patterns were similar, indicating that the sugar-insecticide feeding bioassay had appropriately characterized the permethrin susceptibility of the two strains.

  1. Mosquito population regulation and larval source management in heterogeneous environments.

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    David L Smith

    Full Text Available An important question for mosquito population dynamics, mosquito-borne pathogen transmission and vector control is how mosquito populations are regulated. Here we develop simple models with heterogeneity in egg laying patterns and in the responses of larval populations to crowding in aquatic habitats. We use the models to evaluate how such heterogeneity affects mosquito population regulation and the effects of larval source management (LSM. We revisit the notion of a carrying capacity and show how heterogeneity changes our understanding of density dependence and the outcome of LSM. Crowding in and productivity of aquatic habitats is highly uneven unless egg-laying distributions are fine-tuned to match the distribution of habitats' carrying capacities. LSM reduces mosquito population density linearly with coverage if adult mosquitoes avoid laying eggs in treated habitats, but quadratically if eggs are laid in treated habitats and the effort is therefore wasted (i.e., treating 50% of habitat reduces mosquito density by approximately 75%. Unsurprisingly, targeting (i.e. treating a subset of the most productive pools gives much larger reductions for similar coverage, but with poor targeting, increasing coverage could increase adult mosquito population densities if eggs are laid in higher capacity habitats. Our analysis suggests that, in some contexts, LSM models that accounts for heterogeneity in production of adult mosquitoes provide theoretical support for pursuing mosquito-borne disease prevention through strategic and repeated application of modern larvicides.

  2. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides

    OpenAIRE

    Sayono Sayono; Anggie Puspa Nur Hidayati; Sukmal Fahri; Didik Sumanto; Edi Dharmana; Suharyo Hadisaputro; Puji Budi Setia Asih; Din Syafruddin

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNa V gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide...

  3. An experimental hut evaluation of Olyset® nets against anopheline mosquitoes after seven years use in Tanzanian villages

    Directory of Open Access Journals (Sweden)

    Mosha Frank W

    2008-02-01

    Full Text Available Abstract Background Long-lasting insecticidal nets (LLINs are advocated by WHO for protection against malaria. Of the three brands of LLINs currently approved by WHO, Olyset® is the only one currently granted full recommendation. With this type of LLIN, the insecticide (permethrin is incorporated into the polyethylene fibre during manufacture and diffuses from the core to the surface, thereby maintaining surface concentrations. It has not been determined for how long Olyset nets remain protective against mosquitoes in household use. Methods Examples of Olyset nets, which had been in use in Tanzanian villages for seven years, were tested in experimental huts against naturally entering Anopheles gambiae and Anopheles funestus mosquitoes. Performance was compared with new Olyset nets, conventionally treated ITNs (either newly treated with alphacypermethrin or taken from local villages after 1.5 years of use and untreated nets. All nets were artificially holed except for the seven-year Olyset nets, which had developed holes during prolonged domestic use. Results Anopheles funestus and An. gambiae in NE Tanzania are susceptible to pyrethroids. The new Olyset nets caused high mortality against An. funestus (73.9% and An. gambiae (62.7% in experimental huts. The seven-year Olyset nets caused 58.9% mortality against An. funestus and 40.0% mortality against An. gambiae. The freshly treated alphacypermethrin nets also caused high mortality against An. funestus (70.6% and An. gambiae (72.0%; this decreased to 58.4% and 69.6% respectively after 1.5 years of use. The new Olyset nets inhibited blood-feeding by 40–50%. The 7 year Olyset nets showed no feeding inhibition over that shown by the untreated nets. The alphacypermethrin treated nets failed to inhibit blood-feeding after 1.5 years of use. However iHhhdn laboratory tunnel tests samples of all types of treated net including the 7 year Olyset inhibited blood-feeding by more than 95%. Conclusion After

  4. An experimental hut evaluation of Olyset nets against anopheline mosquitoes after seven years use in Tanzanian villages.

    Science.gov (United States)

    Malima, Robert C; Magesa, Stephen M; Tungu, Patrick K; Mwingira, Victor; Magogo, Frank S; Sudi, Wema; Mosha, Frank W; Curtis, Christopher F; Maxwell, Caroline; Rowland, Mark

    2008-02-28

    Long-lasting insecticidal nets (LLINs) are advocated by WHO for protection against malaria. Of the three brands of LLINs currently approved by WHO, Olyset(R) is the only one currently granted full recommendation. With this type of LLIN, the insecticide (permethrin) is incorporated into the polyethylene fibre during manufacture and diffuses from the core to the surface, thereby maintaining surface concentrations. It has not been determined for how long Olyset nets remain protective against mosquitoes in household use. Examples of Olyset nets, which had been in use in Tanzanian villages for seven years, were tested in experimental huts against naturally entering Anopheles gambiae and Anopheles funestus mosquitoes. Performance was compared with new Olyset nets, conventionally treated ITNs (either newly treated with alphacypermethrin or taken from local villages after 1.5 years of use) and untreated nets. All nets were artificially holed except for the seven-year Olyset nets, which had developed holes during prolonged domestic use. Anopheles funestus and An. gambiae in NE Tanzania are susceptible to pyrethroids. The new Olyset nets caused high mortality against An. funestus (73.9%) and An. gambiae (62.7%) in experimental huts. The seven-year Olyset nets caused 58.9% mortality against An. funestus and 40.0% mortality against An. gambiae. The freshly treated alphacypermethrin nets also caused high mortality against An. funestus (70.6%) and An. gambiae (72.0%); this decreased to 58.4% and 69.6% respectively after 1.5 years of use. The new Olyset nets inhibited blood-feeding by 40-50%. The 7 year Olyset nets showed no feeding inhibition over that shown by the untreated nets. The alphacypermethrin treated nets failed to inhibit blood-feeding after 1.5 years of use. However iHhhdn laboratory tunnel tests samples of all types of treated net including the 7 year Olyset inhibited blood-feeding by more than 95%. After seven years of use Olyset nets were still strongly

  5. Polymer nanoparticles containing essential oils: new options for mosquito control.

    Science.gov (United States)

    Werdin González, Jorge Omar; Jesser, Emiliano Nicolás; Yeguerman, Cristhian Alan; Ferrero, Adriana Alicia; Fernández Band, Beatriz

    2017-07-01

    Mosquitoes (Diptera: Culicidae) are vectors of important parasites and pathogens causing death, poverty and social disability worldwide. The overuse of synthetic insecticides to control mosquito vectors lead to resistance, adverse environmental effects and high operational costs. Therefore, the development of eco-friendly control tools is an important public health challenge. In this study, two different essential oils (EO) (geranium, Geranium maculatum, and bergamot, Citrus bergamia) loaded polymeric nanoparticle (PN) were elaborated using polyethylene glycol (PEG) and chitosan (Qx) as the polymeric matrix/coating. In addition, the mosquito larvicidal acute and residual activity of the PN was evaluated on Culex pipiens pipiens. The physicochemical characterization of PN revealed that PEG-PN had sizes eco-friendly mosquito larvicidal products.

  6. Implications of bio-efficacy and persistence of insecticides when indoor residual spraying and long-lasting insecticide nets are combined for malaria prevention

    Directory of Open Access Journals (Sweden)

    Okumu Fredros O

    2012-11-01

    treated surfaces is assured, LLINs and IRS kill high proportions of susceptible An. arabiensis mosquitoes, though these efficacies decay gradually for LLINs and rapidly for IRS. It is, therefore, important to always add intact nets in sprayed houses, guaranteeing protection even after the IRS decays, and to ensure accurate timing, quality control and regular re-spraying in IRS programmes. By contrast, adding IRS in houses with intact LLINs is unlikely to improve protection relative to LLINs alone, since there is no guarantee that unfed vectors would rest long enough on the sprayed surfaces, and because of the rapid IRS decay. However, there is need to clarify these effects using data from observations of free flying mosquitoes in huts. Physiological susceptibility of An. arabiensis in the area remains 100% against DDT, but is slightly reduced against pyrethroids, necessitating caution over possible spread of resistance. The loss of LLIN toxicity, particularly Olyset® nets suggests that protection offered by these nets against An. arabiensis may be primarily due to physical bite prevention rather than insecticidal efficacy.

  7. Interdependence of domestic malaria prevention measures and mosquito-human interactions in urban Dar es Salaam, Tanzania

    Science.gov (United States)

    Geissbühler, Yvonne; Chaki, Prosper; Emidi, Basiliana; Govella, Nicodemus J; Shirima, Rudolf; Mayagaya, Valeliana; Mtasiwa, Deo; Mshinda, Hassan; Fillinger, Ulrike; Lindsay, Steven W; Kannady, Khadija; de Castro, Marcia Caldas; Tanner, Marcel; Killeen, Gerry F

    2007-01-01

    Background Successful malaria vector control depends on understanding behavioural interactions between mosquitoes and humans, which are highly setting-specific and may have characteristic features in urban environments. Here mosquito biting patterns in Dar es Salaam, Tanzania are examined and the protection against exposure to malaria transmission that is afforded to residents by using an insecticide-treated net (ITN) is estimated. Methods Mosquito biting activity over the course of the night was estimated by human landing catch in 216 houses and 1,064 residents were interviewed to determine usage of protection measures and the proportion of each hour of the night spent sleeping indoors, awake indoors, and outdoors. Results Hourly variations in biting activity by members of the Anopheles gambiae complex were consistent with classical reports but the proportion of these vectors caught outdoors in Dar es Salaam was almost double that of rural Tanzania. Overall, ITNs confer less protection against exophagic vectors in Dar es Salaam than in rural southern Tanzania (59% versus 70%). More alarmingly, a biting activity maximum that precedes 10 pm and much lower levels of ITN protection against exposure (38%) were observed for Anopheles arabiensis, a vector of modest importance locally, but which predominates transmission in large parts of Africa. Conclusion In a situation of changing mosquito and human behaviour, ITNs may confer lower, but still useful, levels of personal protection which can be complemented by communal transmission suppression at high coverage. Mosquito-proofing houses appeared to be the intervention of choice amongst residents and further options for preventing outdoor transmission include larviciding and environmental management. PMID:17880679

  8. Interdependence of domestic malaria prevention measures and mosquito-human interactions in urban Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Mshinda Hassan

    2007-09-01

    Full Text Available Abstract Background Successful malaria vector control depends on understanding behavioural interactions between mosquitoes and humans, which are highly setting-specific and may have characteristic features in urban environments. Here mosquito biting patterns in Dar es Salaam, Tanzania are examined and the protection against exposure to malaria transmission that is afforded to residents by using an insecticide-treated net (ITN is estimated. Methods Mosquito biting activity over the course of the night was estimated by human landing catch in 216 houses and 1,064 residents were interviewed to determine usage of protection measures and the proportion of each hour of the night spent sleeping indoors, awake indoors, and outdoors. Results Hourly variations in biting activity by members of the Anopheles gambiae complex were consistent with classical reports but the proportion of these vectors caught outdoors in Dar es Salaam was almost double that of rural Tanzania. Overall, ITNs confer less protection against exophagic vectors in Dar es Salaam than in rural southern Tanzania (59% versus 70%. More alarmingly, a biting activity maximum that precedes 10 pm and much lower levels of ITN protection against exposure (38% were observed for Anopheles arabiensis, a vector of modest importance locally, but which predominates transmission in large parts of Africa. Conclusion In a situation of changing mosquito and human behaviour, ITNs may confer lower, but still useful, levels of personal protection which can be complemented by communal transmission suppression at high coverage. Mosquito-proofing houses appeared to be the intervention of choice amongst residents and further options for preventing outdoor transmission include larviciding and environmental management.

  9. Evaluation of Imidacloprid-Treated Traps as an Attract and Kill System for Filth Flies During Contingency Settings

    Science.gov (United States)

    2013-04-01

    because water-based insecticides often leave little residue on the surfaces of water- repellent plastics. Also, some com- monly used pyrethroid...insecticides used for impregnation of mosquito nets. B World Health Organ. 2003;81:324-333. Tomizawa M, Casida JE. Neonicotinoid insecticide 11. toxicology...Silver Spring, Maryland. Dr Hogsette: Mosquito and Fly Research Unit, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, Florida.

  10. Mosquito, egg raft (image)

    Science.gov (United States)

    ... that float in still or stagnant water. The mosquito lays the eggs one at a time sticking ... feed on micro-organisms before developing into flying mosquitoes. (Image courtesy of the Centers for Disease Control ...

  11. Mosquito, adult (image)

    Science.gov (United States)

    This illustration shows an adult southern house mosquito. This mosquito feeds on blood and is the carrier of many diseases, such as encephalitis, West Nile, dengue fever, yellow fever, and others. ( ...

  12. Controlling Mosquitoes Outside

    Centers for Disease Control (CDC) Podcasts

    2016-08-09

    Mosquitoes can carry viruses, like West Nile, Zika, dengue, and chikungunya. In this podcast, Mr. Hubbard will teach you and his neighbor, Laura, ways to help reduce the number of mosquitoes outside your home. Tips include eliminating areas of standing water where mosquitoes lay eggs and using larvicides to kill young mosquitoes.  Created: 8/9/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/9/2016.

  13. Eco-friendly larvicides from Indian plants: Effectiveness of lavandulyl acetate and bicyclogermacrene on malaria, dengue and Japanese encephalitis mosquito vectors.

    Science.gov (United States)

    Govindarajan, Marimuthu; Benelli, Giovanni

    2016-11-01

    Mosquitoes (Diptera: Culicidae) are a key threat for millions of people and animals worldwide, since they act as vectors for devastating pathogens and parasites, including malaria, dengue, Japanese encephalitis, filiariasis and Zika virus. Mosquito young instars are usually targeted using organophosphates, insect growth regulators and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment and induce resistance in a number of vectors. In this scenario, newer and safer tools have been recently implemented to enhance mosquito control. The concrete potential of screening plant species as sources of metabolites for entomological and parasitological purposes is worthy of attention, as recently elucidated by the Y. Tu's example. Here we investigated the toxicity of Heracleum sprengelianum (Apiaceae) leaf essential oil and its major compounds toward third instar larvae of the malaria vector Anopheles subpictus, the arbovirus vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. GC-MS analysis showed that EO major components were lavandulyl acetate (17.8%) and bicyclogermacrene (12.9%). The EO was toxic to A. subpictus, A. albopictus, and C. tritaeniorhynchus, with LC50 of 33.4, 37.5 and 40.9µg/ml, respectively. Lavandulyl acetate was more toxic to mosquito larvae if compared to bicyclogermacrene. Their LC50 were 4.17 and 10.3µg/ml for A. subpictus, 4.60 and 11.1µg/ml for A. albopictus, 5.11 and 12.5µg/ml for C. tritaeniorhynchus. Notably, the EO and its major compounds were safer to three non-target mosquito predators, Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 ranging from 206 to 4219µg/ml. Overall, this study highlights that H. sprengelianum EO is a promising source of eco-friendly larvicides against three important mosquito vectors with moderate toxicity against non-target aquatic

  14. Genetic control of mosquitoes: population suppression strategies.

    Science.gov (United States)

    Wilke, André Barretto Bruno; Marrelli, Mauro Toledo

    2012-01-01

    Over the last two decades, morbidity and mortality from malaria and dengue fever among other pathogens are an increasing Public Health problem. The increase in the geographic distribution of vectors is accompanied by the emergence of viruses and diseases in new areas. There are insufficient specific therapeutic drugs available and there are no reliable vaccines for malaria or dengue, although some progress has been achieved, there is still a long way between its development and actual field use. Most mosquito control measures have failed to achieve their goals, mostly because of the mosquito's great reproductive capacity and genomic flexibility. Chemical control is increasingly restricted due to potential human toxicity, mortality in no target organisms, insecticide resistance, and other environmental impacts. Other strategies for mosquito control are desperately needed. The Sterile Insect Technique (SIT) is a species-specific and environmentally benign method for insect population suppression, it is based on mass rearing, radiation mediated sterilization, and release of a large number of male insects. Releasing of Insects carrying a dominant lethal gene (RIDL) offers a solution to many of the drawbacks of traditional SIT that have limited its application in mosquitoes while maintaining its environmentally friendly and species-specific utility. The self-limiting nature of sterile mosquitoes tends to make the issues related to field use of these somewhat less challenging than for self-spreading systems characteristic of population replacement strategies. They also are closer to field use, so might be appropriate to consider first. The prospect of genetic control methods against mosquito vectored human diseases is rapidly becoming a reality, many decisions will need to be made on a national, regional and international level regarding the biosafety, social, cultural and ethical aspects of the use and deployment of these vector control methods.

  15. Genetic Control of Mosquitoes: population suppression strategies

    Directory of Open Access Journals (Sweden)

    André Barretto Bruno Wilke

    2012-10-01

    Full Text Available Over the last two decades, morbidity and mortality from malaria and dengue fever among other pathogens are an increasing Public Health problem. The increase in the geographic distribution of vectors is accompanied by the emergence of viruses and diseases in new areas. There are insufficient specific therapeutic drugs available and there are no reliable vaccines for malaria or dengue, although some progress has been achieved, there is still a long way between its development and actual field use. Most mosquito control measures have failed to achieve their goals, mostly because of the mosquito's great reproductive capacity and genomic flexibility. Chemical control is increasingly restricted due to potential human toxicity, mortality in no target organisms, insecticide resistance, and other environmental impacts. Other strategies for mosquito control are desperately needed. The Sterile Insect Technique (SIT is a species-specific and environmentally benign method for insect population suppression, it is based on mass rearing, radiation mediated sterilization, and release of a large number of male insects. Releasing of Insects carrying a dominant lethal gene (RIDL offers a solution to many of the drawbacks of traditional SIT that have limited its application in mosquitoes while maintaining its environmentally friendly and species-specific utility. The self-limiting nature of sterile mosquitoes tends to make the issues related to field use of these somewhat less challenging than for self-spreading systems characteristic of population replacement strategies. They also are closer to field use, so might be appropriate to consider first. The prospect of genetic control methods against mosquito vectored human diseases is rapidly becoming a reality, many decisions will need to be made on a national, regional and international level regarding the biosafety, social, cultural and ethical aspects of the use and deployment of these vector control methods.

  16. MAN, MOSQUITOES AND MICROBES.

    Science.gov (United States)

    SCHOONOVER, ROBERT A.

    THE CONTROL OF MOSQUITOES IS A MATTER OF INCREASING CONCERN IN THE STATE OF FLORIDA. A BRIEF DESCRIPTION OF THE LIFE CYCLE, VARIOUS SPECIES, CONTROL, AND DESCRIPTION OF DISEASES TRANSMITTED BY THE MOSQUITO WAS PRESENTED. THE ARTICLE CONCLUDED THAT MOSQUITO CONTROL IS NOT ONLY A HEALTH PROBLEM, BUT ALSO A MATTER OF IMPROVED ECONOMICS IN RELATION TO…

  17. [Progress on transgenic mosquitoes].

    Science.gov (United States)

    Yang, Pin

    2011-04-30

    The genetically modified mosquitoes have been developed aiming to control mosquito-borne diseases by either reducing population sizes or replacing existing populations with vectors unable to transmit the disease. introduces some progress on the generation of transgenic mosquitoes and their fitness in wild population. This paper

  18. Mosquito Life Cycle

    Science.gov (United States)

    Knowing the stages of the mosquito's life will help you prevent mosquitoes around your home and help you choose the right pesticides for your needs, if you decide to use them. All mosquito species go through four distinct stages during their live cycle.

  19. Profiles of Amino Acids and Acylcarnitines Related with Insecticide Exposure in Culex quinquefasciatus (Say)

    Science.gov (United States)

    Martin-Park, Abdiel; Gomez-Govea, Mayra A.; Lopez-Monroy, Beatriz; Treviño-Alvarado, Víctor Manuel; Torres-Sepúlveda, María del Rosario; López-Uriarte, Graciela Arelí; Villanueva-Segura, Olga Karina; Ruiz-Herrera, María del Consuelo; Martinez-Fierro, Margarita de la Luz; Delgado-Enciso, Ivan; Flores-Suárez, Adriana E.; White, Gregory S.; Martínez de Villarreal, Laura E.; Ponce-Garcia, Gustavo; Black, William C.; Rodríguez-Sanchez, Irám Pablo

    2017-01-01

    Culex quinquefasciatus Say is a vector of many pathogens of humans, and both domestic and wild animals. Personal protection, reduction of larval habitats, and chemical control are the best ways to reduce mosquito bites and, therefore, the transmission of mosquito-borne pathogens. Currently, to reduce the risk of transmission, the pyrethroids, and other insecticide groups have been extensively used to control both larvae and adult mosquitoes. In this context, amino acids and acylcarnitines have never been associated with insecticide exposure and or insecticide resistance. It has been suggested that changes in acylcarnitines and amino acids profiles could be a powerful diagnostic tool for metabolic alterations. Monitoring these changes could help to better understand the mechanisms involved in insecticide resistance, complementing the strategies for managing this phenomenon in the integrated resistance management. The purpose of the study was to determine the amino acids and acylcarnitines profiles in larvae of Cx. quinquefasciatus after the exposure to different insecticides. Bioassays were performed on Cx. quinquefasciatus larvae exposed to the diagnostic doses (DD) of the insecticides chlorpyrifos (0.001 μg/mL), temephos (0.002 μg/mL) and permethrin (0.01 μg/mL). In each sample, we analyzed the profile of 12 amino acids and 31 acylcarnitines by LC-MS/MS. A t-test was used to determine statistically significant differences between groups and corrections of q-values. Results indicates three changes, the amino acids arginine (ARG), free carnitine (C0) and acetyl-carnitine (C2) that could be involved in energy production and insecticide detoxification. We confirmed that concentrations of amino acids and acylcarnitines in Cx. quinquefasciatus vary with respect to different insecticides. The information generated contributes to understand the possible mechanisms and metabolic changes occurring during insecticide exposure. PMID:28085898

  20. Toxicity and bioaccumulation of fipronil in the nontarget arthropodan fauna associated with subalpine mosquito breeding sites.

    Science.gov (United States)

    Chaton, P F; Ravanel, P; Tissut, M; Meyran, J C

    2002-05-01

    In order to examine ecological impact of fipronil use for larval culicine control in natural hydrosystems, toxicity and bioaccumulation of this new insecticide were analyzed on aquatic species representative of the nontarget arthropodan fauna (nonculicine larval Diptera: Chaoboridae, Chironomidae; planktonic Crustacea: Cladocera, Copepoda, Ostracoda) associated with target larval mosquito populations in the subalpine breeding sites. Standard toxicological bioassays using fipronil aqueous solutions from 1 to 2000 nM indicated different sensitivity levels among species. Insecticide bioaccumulation analyses, using [(14)C]fipronil solutions in simplified laboratory ecosystem, also indicated large differences among species. These differences may come from biological parameters characteristic of each species. Taking into account these nontarget effects of fipronil, a possible strategy of use of this insecticide for integrated mosquito control management was proposed, which is based upon selective dietary absorption of the insecticide by larval Culicidae.

  1. A Chlorfenapyr Mixture Net Interceptor® G2 Shows High Efficacy and Wash Durability against Resistant Mosquitoes in West Africa.

    Science.gov (United States)

    N'Guessan, Raphael; Odjo, Abibatou; Ngufor, Corine; Malone, David; Rowland, Mark

    2016-01-01

    Malaria control through use of long-lasting insecticidal nets (LN) is threatened by the selection of anopheline mosquitoes strongly resistant to pyrethroid insecticides. To sustain future effectiveness it is essential to identify and evaluate novel insecticides suitable for nets. Mixtures of two insecticides with contrasting mode of action have the potential to kill resistant vectors and restore transmission control provided the formulation can withstand regular washing over the net's life span. The efficacy of a novel mixture LN, Interceptor® G2, that combines the pyrrole chlorfenapyr and pyrethroid alpha-cypermethrin was evaluated under controlled household conditions (experimental hut trial) and by laboratory bioassay against pyrethroid resistant An. gambiae in Benin before and after standardized washing. Comparison arms included standard alpha-cypermethrin LN, nets hand-treated with chlorfenapyr-only and untreated nets. The chlorfenapyr-alphacypermethrin LN demonstrated improved efficacy and wash resistance compared to a standard alpha-cypermethrin LN against pyrethroid resistant mosquitoes (resistance ratio 207). In experimental hut trial alpha-cypermethrin LN killed only 20% (95% CI 15-26%) of host-seeking An. gambiae whilst mixture LN killed 71% (95% CI 65-77%). Mixture LN washed 20 times killed 65% (95% CI 58-71%), and thus intensive washing reduced efficacy by only 6% (95% CI 1.3-11%). The chlorfenapyr net killed 76% (95% CI 70-81%). Personal protection and blood feeding inhibition did not differ between mixture and pyrethroid LN; however, the mixture LN was 2.5 (95% CI: 2.1-3.1) times more protective than untreated nets. Standard WHO cone bioassays conducted during day time hours failed to anticipate field efficacy but overnight tunnel tests successfully predicted mixture LN and chlorfenapyr net efficacy in field trials. Interceptor® G2 LN demonstrates the potential to control transmission and provide community protection over the normal lifespan of

  2. Monitoring malaria vector control interventions: effectiveness of five different adult mosquito sampling methods.

    Science.gov (United States)

    Onyango, Shirley A; Kitron, Uriel; Mungai, Peter; Muchiri, Eric M; Kokwaro, Elizabeth; King, Charles H; Mutuku, Francis M

    2013-09-01

    Long-term success of ongoing malaria control efforts based on mosquito bed nets (long-lasting insecticidal net) and indoor residual spraying is dependent on continuous monitoring of mosquito vectors, and thus on effective mosquito sampling tools. The objective of our study was to identify the most efficient mosquito sampling tool(s) for routine vector surveillance for malaria and lymphatic filariasis transmission in coastal Kenya. We evaluated relative efficacy of five collection methods--light traps associated with a person sleeping under a net, pyrethrum spray catches, Prokopack aspirator, clay pots, and urine-baited traps--in four villages representing three ecological settings along the south coast of Kenya. Of the five methods, light traps were the most efficient for collecting female Anopheles gambiae s.l. (Giles) (Diptera: Culicidae) and Anopheles funestus (Giles) (Diptera: Culicidae) mosquitoes, whereas the Prokopack aspirator was most efficient in collecting Culex quinquefasciatus (Say) (Diptera: Culicidae) and other culicines. With the low vector densities here, and across much of sub-Saharan Africa, wherever malaria interventions, long-la