Evolution determines how global warming and pesticide exposure will shape predator-prey interactions with vector mosquitoes.

Science.gov (United States)

Tran, Tam T; Janssens, Lizanne; Dinh, Khuong V; Op de Beeck, Lin; Stoks, Robby

2016-07-01

How evolution may mitigate the effects of global warming and pesticide exposure on predator-prey interactions is directly relevant for vector control. Using a space-for-time substitution approach, we addressed how 4°C warming and exposure to the pesticide endosulfan shape the predation on Culex pipiens mosquitoes by damselfly predators from replicated low- and high-latitude populations. Although warming was only lethal for the mosquitoes, it reduced predation rates on these prey. Possibly, under warming escape speeds of the mosquitoes increased more than the attack efficiency of the predators. Endosulfan imposed mortality and induced behavioral changes (including increased filtering and thrashing and a positional shift away from the bottom) in mosquito larvae. Although the pesticide was only lethal for the mosquitoes, it reduced predation rates by the low-latitude predators. This can be explained by the combination of the evolution of a faster life history and associated higher vulnerabilities to the pesticide (in terms of growth rate and lowered foraging activity) in the low-latitude predators and pesticide-induced survival selection in the mosquitoes. Our results suggest that predation rates on mosquitoes at the high latitude will be reduced under warming unless predators evolve toward the current low-latitude phenotype or low-latitude predators move poleward.

Relationship between exposure to vector bites and antibody responses to mosquito salivary gland extracts.

Science.gov (United States)

Fontaine, Albin; Pascual, Aurélie; Orlandi-Pradines, Eve; Diouf, Ibrahima; Remoué, Franck; Pagès, Frédéric; Fusaï, Thierry; Rogier, Christophe; Almeras, Lionel

2011-01-01

Mosquito-borne diseases are major health problems worldwide. Serological responses to mosquito saliva proteins may be useful in estimating individual exposure to bites from mosquitoes transmitting these diseases. However, the relationships between the levels of these IgG responses and mosquito density as well as IgG response specificity at the genus and/or species level need to be clarified prior to develop new immunological markers to assess human/vector contact. To this end, a kinetic study of antibody levels against several mosquito salivary gland extracts from southeastern French individuals living in three areas with distinct ecological environments and, by implication, distinct Aedes caspius mosquito densities were compared using ELISA. A positive association was observed between the average levels of IgG responses against Ae. caspius salivary gland extracts and spatial Ae. caspius densities. Additionally, the average level of IgG responses increased significantly during the peak exposure to Ae. caspius at each site and returned to baseline four months later, suggesting short-lived IgG responses. The species-specificity of IgG antibody responses was determined by testing antibody responses to salivary gland extracts from Cx. pipiens, a mosquito that is present at these three sites at different density levels, and from two other Aedes species not present in the study area (Ae. aegypti and Ae. albopictus). The IgG responses observed against these mosquito salivary gland extracts contrasted with those observed against Ae. caspius salivary gland extracts, supporting the existence of species-specific serological responses. By considering different populations and densities of mosquitoes linked to environmental factors, this study shows, for the first time, that specific IgG antibody responses against Ae. caspius salivary gland extracts may be related to the seasonal and geographical variations in Ae. caspius density. Characterisation of such immunological

Evolution determines how global warming and pesticide exposure will shape predator‐prey interactions with vector mosquitoes

DEFF Research Database (Denmark)

Tran, Tam H.; Janssens, Lizanne; Dinh, Khuong Van

2016-01-01

How evolution may mitigate the effects of global warming and pesticide exposure on predator–prey interactions is directly relevant for vector control. Using a space-for-time substitution approach, we addressed how 4°C warming and exposure to the pesticide endosulfan shape the predation on Culex...... pipiens mosquitoes by damselfly predators from replicated low- and high-latitude populations. Although warming was only lethal for the mosquitoes, it reduced predation rates on these prey. Possibly, under warming escape speeds of the mosquitoes increased more than the attack efficiency of the predators...... at the high latitude will be reduced under warming unless predators evolve toward the current low-latitude phenotype or low-latitude predators move poleward...

Resistance Level of Mosquito Species (Diptera: Culicidae from Shandong Province, China

Directory of Open Access Journals (Sweden)

Hong-Mei Liu

2015-01-01

Full Text Available This study describes the aquatic habitats, species composition, and the insecticide resistance level of the mosquito Culex pipiens pallens in Shandong Province, China. A cross-sectional survey of mosquito larval habitats was conducted from May to November 2014 to determine the species composition and larval abundance. Larvae were collected using the standard dipping technique, and a total of four habitat types were sampled. The fourth instar larvae of Cx. pipiens pallens collected in each habitat type were tested for resistance to five insecticides according to a WHO bioassay. A total of 7,281 mosquito larvae were collected, of which 399 (5.48% were categorized as Anopheles mosquito larvae ( An. sinensis , 6636 (91.14% as culicine larvae ( Cx. pipiens pallens, Cx. tritaeniorhynchus, Cx. halifaxii, and Cx. bitaeniorhynchus , 213 (2.93% as Armigeres larvae, and 33 (0.45% as Aedes larvae ( Aedes albopictus . In addition, a total of 1,149 mosquito pupae were collected. Culex larvae were distributed in all habitats investigated. Tukeys HSD analysis showed that roadside drainages were the most productive habitat type for Culex larvae. Armigeres species were found only in drains, Aedes only in water tanks, and Anopheles in water that was comparatively clear and rich in emergent plants. Bioassay showed that the maximum resistance level of Cx. pipiens pallens was to deltamethrin, while it was lowest to plifenate. The productivity of various mosquitoes in different habitat types is very heterogeneous. It is particularly important to modify human activity and the environment to achieve effective mosquito vector control. For effective larval control, the type of habitat should be considered, and the most productive habitat type should be given priority in mosquito abatement programs.

Reduced Insecticide Susceptibility in Aedes vexans (Diptera: Culicidae) Where Agricultural Pest Management Overlaps With Mosquito Abatement.

Science.gov (United States)

Dunbar, Mike W; Bachmann, Amanda; Varenhorst, Adam J

2018-05-04

Mosquito abatement programs in Midwestern communities frequently exist within landscapes dominated by agriculture. Although separately managed, both agricultural pests and mosquitoes are targeted by similar classes of insecticides. As a result, there is the potential for unintended insecticide exposure to mosquito populations from agricultural pest management. To determine the impact that agricultural management practices have on mosquito insecticide susceptibility we compared the mortality of Aedes vexans (Meigen; Diptera: Culicidae) between populations sampled from locations with and without mosquito abatement in South Dakota, a region dominated by agricultural production. Collection locations were either within towns with mosquito abatement programs (n = 2; Brookings and Sioux Falls, SD) or located > 16 km from towns with mosquito abatement programs (n = 2; areas near Harrold and Willow Lake, SD). WHO bioassays were used to test susceptibly of adults to differing insecticide classes relative to their respective controls; 1) an organochlorine (dieldrin 4%), 2) an organophosphate (malathion 5%), and 3) a pyrethroid (lambda-cyhalothrin 0.05%). Corrected mortality did not significantly differ between locations with or without abatement; however, when locations were analized by proportion of developed land within the surrounding landscape pyrethroid mortality was significantly lower where crop production dominated the surrounding landscape and mosquito abatement was present. These data suggest that agricultural pest management may incidentally contribute to reduced mosquito susceptibility where overlap between agricultural pest management and mosquito abatement exists. Decoupling insecticide classes used by both agricultural and public health pest management programs may be necessary to ensure continued efficacy of pest management tools.

77 FR 14837 - Bioassay at Uranium Mills

Science.gov (United States)

2012-03-13

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0057] Bioassay at Uranium Mills AGENCY: Nuclear Regulatory..., ``Bioassay at Uranium Mills.'' This guide describes a bioassay program acceptable to the NRC staff for uranium mills and applicable portions of uranium conversion facilities where the possibility of exposure...

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.

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

Mediation of oviposition site selection in the African malaria mosquito Anopheles gambiae (Diptera: Culicidae) by semiochemicals of microbial origin

NARCIS (Netherlands)

Sumba, L.A.; Guda, T.O.; Deng, A.L.; Hassanali, A.; Beier, J.C.; Knols, B.G.J.

2004-01-01

Laboratory studies were carried out to investigate the role of larval habitat-derived microorganisms in the production of semiochemicals for oviposition site selection by Anopheles gambiae Giles sensu stricto mosquitoes. Dual-choice bioassays with gravid females were conducted in standard mosquito

Exposure dose assessment using bioassay

International Nuclear Information System (INIS)

Suga, Shinichi

1994-01-01

Bioassay involves following steps: sampling, pre-treatment, chemical separation and counting of radioactivity. As bioassay samples, urines are usually used, although faecal analysis may be required in some occasions for example to assess intake of non-transferable radioactive materials. Nasal smear is a useful indicator of an inhalation case. Exhalation air is used to estimate the intake of tritiated water. Sample pre-treatment includes evaporation for concentration, wet ashing, dry ashing and co-precipitation. After adding small amount of nitric acid, the sample can be concentrated by 1/10 of initial volume, which may be used to identify γ-emitters. As the pre-treatment of urine, wet ashing is used for example for analysis of Pu, and co-precipitation is used for example for analysis of Sr. Dry ashing by electric furnace is usually adopted for faecal samples. Methods of chemical separation depend on the radionuclide(s) to be analysed. The detection limit depends also on radionuclide, and for example typical detection limits are 0.4Bq / l (volume of urine sample) for 89 Sr or 90 Sr, and 0.01 Bq / l with urine and 0.01 Bq per sample with faeces for 238 Pu, 239 Pu or 241 Am. Simpler methods can be used for some radionuclides: For example, radioactivity concentration of tritium can be determined by liquid scintillation counting of urine or condensed water from exhaled air, and natural uranium in urine can be quantified by using fluorometric method. In some circumstances, gross-α or gross-β analyses are useful for quick estimation. To estimate intakes by inhalation or by ingestion from bioassay results and to assess the committed dose equivalent, commonly available bases are the relevant publications by the ICRP and domestic guides and manuals that conform to the radiation protection regulations. (author)

Concentration of Plasmodium falciparum gametocytes in whole blood samples by magnetic cell sorting enhances parasite infection rates in mosquito feeding assays

NARCIS (Netherlands)

Reuling, I.J.; Stone, W.J.R.; Vegte-Bolmer, M. van de; Gemert, G.J.A. van; Siebelink-Stoter, R.; Graumans, W.; Lanke, K.H.; Bousema, T.; Sauerwein, R.W.

2017-01-01

BACKGROUND: Mosquito-feeding assays are important tools to guide the development and support the evaluation of transmission-blocking interventions. These functional bioassays measure the sporogonic development of gametocytes in blood-fed mosquitoes. Measuring the infectivity of low gametocyte

Bystander Exposure to Ultra-Low-Volume Insecticide Applications Used for Adult Mosquito Management

Directory of Open Access Journals (Sweden)

Robert K.D. Peterson

2011-06-01

Full Text Available A popular and effective management option for adult mosquitoes is the use of insecticides applied by ultra-low-volume (ULV equipment. However, there is a paucity of data on human dermal exposure to insecticides applied by this method. The objective of the current study was to estimate dermal exposures to the insecticide active ingredient permethrin using water- (Aqua-Reslin® and oil-based (Permanone® 30-30 formulations with passive dosimetry. No significant differences in deposition of permethrin were observed between years, distance from the spray source, front or back of the body, or the placement of the patches on the body. However, exposure to Aqua-Reslin was significantly greater than Permanone 30-30 and average concentrations deposited on the body were 4.2 and 2.1 ng/cm2, respectively. The greater deposition of Aqua-Reslin is most likely due to the higher density of the water-based formulation which causes it to settle out faster than the lighter oil-based formulation of Permanone 30-30. The estimated average absorbed dermal exposure for permethrin from Aqua-Reslin and Permanone 30-30 was 0.00009 and 0.00005 mg/kg body weight, respectively. We also found that ground deposition of ULV insecticides can be used as a surrogate for estimating dermal exposure. The estimated exposures support the findings of previous risk assessments that exposure to ULV applications used for mosquito management are below regulatory levels of concern.

Risk of exposure to potential vector mosquitoes for rural workers in Northern Lao PDR.

Directory of Open Access Journals (Sweden)

Julie-Anne A Tangena

2017-07-01

Full Text Available One major consequence of economic development in South-East Asia has been a rapid expansion of rubber plantations, in which outbreaks of dengue and malaria have occurred. Here we explored the difference in risk of exposure to potential dengue, Japanese encephalitis (JE, and malaria vectors between rubber workers and those engaged in traditional forest activities in northern Laos PDR.Adult mosquitoes were collected for nine months in secondary forests, mature and immature rubber plantations, and villages. Human behavior data were collected using rapid participatory rural appraisals and surveys. Exposure risk was assessed by combining vector and human behavior and calculating the basic reproduction number (R0 in different typologies. Compared to those that stayed in the village, the risk of dengue vector exposure was higher for those that visited the secondary forests during the day (odds ratio (OR 36.0, for those living and working in rubber plantations (OR 16.2 and for those that tapped rubber (OR 3.2. Exposure to JE vectors was also higher in the forest (OR 1.4 and, similar when working (OR 1.0 and living in the plantations (OR 0.8. Exposure to malaria vectors was greater in the forest (OR 1.3, similar when working in the plantations (OR 0.9 and lower when living in the plantations (OR 0.6. R0 for dengue was >2.8 for all habitats surveyed, except villages where R0≤0.06. The main malaria vector in all habitats was Anopheles maculatus s.l. in the rainy season and An. minimus s.l. in the dry season.The highest risk of exposure to vector mosquitoes occurred when people visit natural forests. However, since rubber workers spend long periods in the rubber plantations, their risk of exposure is increased greatly compared to those who temporarily enter natural forests or remain in the village. This study highlights the necessity of broadening mosquito control to include rubber plantations.

Evaluation of internal exposure of nuclear medicine staff through in vivo and in vitro bioassay techniques

Energy Technology Data Exchange (ETDEWEB)

Lucena, E.A.; Araujo, F.; Sousa, W.O.; Dantas, A.L.A.; Dantas, B.M. [Instituto de Radioprotecao e Dosimetria, CNEN, Av. Salvador Allende s/n, CEP 22780-160 Rio de Janeiro (Brazil); Rebelo, A.M.O.; Corbo, R. [Hospital Universitario Clementino Fraga Filho, HU-UFRJ, Av. Brigadeiro Trompowsky, s/n, ILHA do Fundao, CEP 21945-560, Rio de Janeiro, RJ (Brazil)

2007-07-01

The manipulation of a wide variety of unsealed sources in Nuclear Medicine results in a significant risk of internal exposure of the workers. {sup 131}I should be highlighted among the most frequently used radionuclides because of its large application for diagnosis and therapy of thyroid diseases. The increasing use of radionuclides for medical purposes creates a demand for feasible methodologies to perform occupational control of internal contamination. Currently in Brazil, there are {approx}300 nuclear medicine centres in operation but individual monitoring is still restricted to the control of external exposure. This work presents the development of in vivo and in vitro bioassay techniques aimed to quantify incorporation of radionuclides used in Nuclear Medicine. It is also presented the results of a preliminary survey of internal exposure of a group of workers involved in the preparation of therapeutic doses of {sup 131}I. Workers were monitored with a gamma camera available in the Nuclear Medicine Service of the University Hospital of Rio de Janeiro and at the Institute of Radiation Protection and Dosimetry Whole-Body Counter (IRDWBC). The in vivo detection systems were calibrated with a neck-thyroid phantom developed in IRD. Urine samples from radiopharmacy workers were collected after preparation and administration of therapeutic doses (10-250 mCi) of {sup 131}I and measured with a HPGe detection system available in the Bioassay Laboratory of IRD. The results show that the bioassay methods developed in this work present enough sensitivity for routine monitoring of nuclear medicine workers. All workers monitored in this survey presented positive results for {sup 131}I in urine samples and two workers presented detectable activities in thyroid when measured at the IRD-WBC. The highest committed effective dose per preparation was estimated to be 17 {mu}Sv. (authors)

Assessment of occupational exposure to malathion and bifenthrin in mosquito control sprayers through dermal contact.

Science.gov (United States)

Kongtip, Pornpimol; Sasrisuk, Somnuek; Preklang, Smart; Yoosook, Witaya; Sujirarat, Dusit

2013-12-01

To assess occupational exposure of malathion and bifenthrin concentrations by dermal contact and urinary 3-(2-chloro-3, 3, 3-trifluoro-1-propenyl)-2, 2-dimethyl-cyclopropanecarboxylic (TFP) acid, health symptoms developed and the relationship between bifenthrin concentrations and TFP acid in urine of the mosquito control sprayers. The aerosols of these two pesticides were collected using 100 cm2 cotton patches attached on the skin of upper legs of 54 volunteer of mosquito control sprayers. Their urine samples were also collected before and after application. These subjects exposed to average malathion and bifenthrin concentrations of 0.18 and 0.32 microg/cm2, respectively After application, the average concentration of urinary TFP acid in the sprayers was 39.22 +/- 0.77 mg/g creatinine ranging from 0.58 to 261.19 mg/g creatinine. A significant difference was found between urinary TFP acid levels before and after application (p bifenthrin concentrations through dermal contact and urinary TFP acid levels were not significantly correlated (p > 0.05). The mosquito control sprayers had dermal contact with smoke of malathion and bifenthrin and some sprayers developed health symptoms after exposure. They should use protective clothing made ofplastic, nylon or polyester to protect sprayers from skin contact.

UV light and urban pollution: Bad cocktail for mosquitoes?

International Nuclear Information System (INIS)

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

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

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

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.

Part 2. Assessment of genotoxicity after exposure to diesel exhaust from U.S. 2007-compliant diesel engines: report on 1- and 3-month exposures in the ACES bioassay.

Science.gov (United States)

Bemis, Jeffrey C; Torous, Dorothea K; Dertinger, Stephen D

2012-09-01

Micronucleus (MN*) formation is a well-established endpoint in genetic toxicology; studies designed to examine MN formation in vivo have been conducted for decades. Conditions that cause double-strand breaks or disrupt the proper segregation of chromosomes during division result in an increase in MN frequency. Thus this endpoint is commonly employed in preclinical studies designed to assess the potential risks of human exposure to a myriad of chemical and physical agents, including inhaled diesel exhaust (DE). As part of the Advanced Collaborative Emissions Study (ACES) this investigation examined the potential of inhaled DE to induce chromosome damage in chronically exposed rodents. The ACES design included exposure of both rats and mice to DE derived from 2007-compliant heavy-duty engines. The exposure conditions consisted of air control and dilutions of DE resulting in three levels of exposure. At specified times, blood samples were collected, fixed, and shipped by the bioassay staff to Litron Laboratories for further processing and analysis. Significant improvements have been made to MN scoring by using objective, automated methods such as flow cytometry, which allows for the detection of micronucleated reticulocytes (MN-RET), micronucleated normochromatic erythrocytes (MN-NCE), and reticulocytes (RETs) in peripheral blood samples from mice and rats. By using a simple staining procedure coupled with rapid and efficient analysis, many more cells were examined in less time than was possible in traditional, microscopy-based MN assays. Thus, for each sample, 20,000 RETs were scored for the presence of MN. In the chronic-exposure bioassay, blood samples were obtained from independent groups of exposed animals at specific time points throughout the course of the entire study. This automated method is supported by numerous regulatory guidelines and meets the requirements for an Organization of Economic Cooperation and Development (OECD)-compliant assay for

Scorpion neurotoxin AaIT-expressing Beauveria bassiana enhances the virulence against Aedes albopictus mosquitoes.

Science.gov (United States)

Deng, Sheng-Qun; Cai, Qun-Di; Deng, Ming-Zhi; Huang, Qiang; Peng, Hong-Juan

2017-12-01

To improve the insecticidal efficacy of this entomopathogen Beauveria bassiana, the fungus was genetically modified to express an insect-specific scorpion neurotoxin AaIT. The virulence of the recombinant B. bassiana strain (Bb-AaIT) against Aedes albopictus adults (which occurs via penetration through the cuticle during spore germination or by conidia ingestion), and the larvae (by conidia ingestion) was measured with bioassays. The median lethal concentration (LC 50 ) of Bb-AaIT against A. albopictus larvae was 313.3-fold lower on day 4 and 11.3-fold lower on day 10 than that of the wild type (WT). Through conidia feeding or body contact, Bb-AaIT killed 50% of adult female mosquitoes at 3.9- or 1.9-fold reduced concentrations on day 4 and at 2.1- or 2.4-fold reduced concentrations on day 10. Compared with the results for the WT, the median lethal time (LT 50 ) of Bb-AaIT was reduced by 28.6% at 1 × 10 7 conidia ml -1 and 34.3% at 1 × 10 6 conidia ml -1 in the larvae bioassay by conidia ingestion, while it decreased 32.3% at 1 × 10 7 conidia ml -1 by conidia ingestion and 24.2% at 1 × 10 8 conidia ml -1 by penetrating through the cuticle in the adult bioassay. All the differences were significant. Our findings indicated that Bb-AaIT had higher virulence and faster action than the WT in killing the larval and adult mosquitoes, and therefore, it is valuable for development as a commercial mosquito pesticide.

Mosquito knock-down and adulticidal activities of essential oils by vaporizer, impregnated filter paper and aerosol methods

Directory of Open Access Journals (Sweden)

M. Ramar

2014-09-01

Full Text Available Essential oils from 12 medicinal plants were evaluated by three different bioassay methods (Vaporizer, Filter paper and Aerosol for Knock-down and adulticidal efficacy on the filarial vector mosquito, Culex quinquefasciatus. Based on screening results the effective plants were selected for investigating Knock-down and adulticidal potential against adult female of the laboratory-reared mosquito species, Cx. quinquefasciatus. In vaporizer bioassay method four different doses (1.25, 2.5, 5 and 10% were used. Four different doses (0.625, 1.25, 2.5 and 10% were used both filter paper (cm2 and aerosol (cm3 bioassay methods. Five essential oils (calamus, camphor, citronella, clove and eucalyptus were identified as potential treatments in vaporizer bioassay. The result showed that the knock down time decreased with increased concentration in clove oil treatment; the Knock-down time (KT 50 = 46.1 ± 0.1, 38.5 ± 0.1, 30.7 ± 0.2, and 20.1 ± 0.1 minutes was recorded at 1.25, 2.5, 5 and 10% /cm3 respectively. In filter paper method nine essential oils were identified as potential treatments. After 1 hr exposure period clove oil recorded the lowest median Knock-down time (KT50 which was calculated as 9.15 ± 0.1min/cm2. Followed by citronella (KT50 =11.4 ± 0.1 min and eucalyptus (KT50 =11.4 ±0.1min oils since they recorded lower median Knock-down time. All the twelve essential oils were identified as potential treatments in aerosol activity. The lethal time decreased when the concentration increased. At 5 % concentration the median lethal time (LT50 for clove oil was calculated as (LT50=3.80 ± 0.1minutes. The Cinnamon oil was effective which recorded (LT50 = 1.99 mins as median lethal time. Camphor (LT50 =19.6± 0.1 min oil were found to be less toxic by aerosol method. These results suggest that clove oil and cinnamon oil have the potential to be used as a eco-friendly approach for the control of the major important filaria vector Cx. quinquefasciatus

Longevity and efficacy of bifenthrin treatment on desert-pattern US military camouflage netting against mosquitoes in a hot-arid environment.

Science.gov (United States)

Britch, Seth C; Linthicum, Kenneth J; Wynn, Willard W; Aldridge, Robert L; Walker, Todd W; Farooq, Muhammad; Dunford, James C; Smith, Vincent L; Robinson, Cathy A; Lothrop, Branka B; Snelling, Melissa; Gutierrez, Arturo; Wittie, Jeremy; White, Gregory

2011-09-01

The current Department of Defense pest management system does not provide adequate protection from arthropod disease vectors to personnel deployed in support of US military operations. We hypothesized that military camouflage netting, ubiquitous around living and working areas in current US military operations in Africa and the Middle East, treated with a residual pesticide such as bifenthrin may reduce the presence of biting insects and improve the military pest management system. In this study, we examined the longevity and efficacy of bifenthrin applied to camouflage netting material at the maximum label rate of 0.03 liter formulation (7.9% AI) per 92.9 m2 against field populations of mosquitoes in southern California in a hot-arid environment similar to regions of Iraq, Afghanistan, and the Horn of Africa. We showed that bifenthrin treatment of camouflage netting was effective at reducing mosquito populations, predominantly Psorophora columbiae and Aedes vexans, by an average of up to 46% for 56 days, and could cause as much as 40% mortality in Culex quinquefasciatus in laboratory bioassays for nearly 2 months postapplication. These population reductions could translate to commensurate reductions in risk of exposure to mosquito-borne pathogens, and could potentially be effective against sand flies and filth flies.

Ethnobotanical study of some of mosquito repellent plants in north-eastern Tanzania

Directory of Open Access Journals (Sweden)

Tenu Filemoni

2008-08-01

Full Text Available Abstract Background The use of plant repellents against nuisance biting insects is common and its potential for malaria vector control requires evaluation in areas with different level of malaria endemicity. The essential oils of Ocimum suave and Ocimum kilimandscharicum were evaluated against malaria vectors in north-eastern Tanzania. Methodology An ethnobotanical study was conducted at Moshi in Kilimanjaro region north-eastern Tanzania, through interviews, to investigate the range of species of plants used as insect repellents. Also, bioassays were used to evaluate the protective potential of selected plants extracts against mosquitoes. Results The plant species mostly used as repellent at night are: fresh or smoke of the leaves of O. suave and O. kilimandscharicum (Lamiaceae, Azadirachta indica (Meliaceae, Eucalyptus globules (Myrtaceae and Lantana camara (Verbenaceae. The most popular repellents were O. kilimandscharicum (OK and O. suave (OS used by 67% out of 120 households interviewed. Bioassay of essential oils of the two Ocimum plants was compared with citronella and DEET to study the repellence and feeding inhibition of untreated and treated arms of volunteers. Using filter papers impregnated with Ocimum extracts, knockdown effects and mortality was investigated on malaria mosquito Anopheles arabiensis and Anopheles gambiae, including a nuisance mosquito, Culex quinquefasciatus. High biting protection (83% to 91% and feeding inhibition (71.2% to 92.5% was observed against three species of mosquitoes. Likewise the extracts of Ocimum plants induced KD90 of longer time in mosquitoes than citronella, a standard botanical repellent. Mortality induced by standard dosage of 30 mg/m2 on filter papers, scored after 24 hours was 47.3% for OK and 57% for OS, compared with 67.7% for citronella. Conclusion The use of whole plants and their products as insect repellents is common among village communities of north-eastern Tanzania and the results

Genetic variation associated with increased insecticide resistance in the malaria mosquito, Anopheles coluzzii.

Science.gov (United States)

Main, Bradley J; Everitt, Amanda; Cornel, Anthony J; Hormozdiari, Fereydoun; Lanzaro, Gregory C

2018-04-04

Malaria mortality rates in sub-Saharan Africa have declined significantly in recent years as a result of increased insecticide-treated bed net (ITN) usage. A major challenge to further progress is the emergence and spread of insecticide resistance alleles in the Anopheles mosquito vectors, like An. coluzzii. A non-synonymous mutation in the para voltage-gated sodium channel gene reduces pyrethroid-binding affinity, resulting in knockdown resistance (kdr). Metabolic mechanisms of insecticide resistance involving detoxification genes like cytochrome P450 genes, carboxylesterases, and glutathione S-transferases are also important. As some gene activity is tissue-specific and/or environmentally induced, gene regulatory variation may be overlooked when comparing expression from whole mosquito bodies under standard rearing conditions. We detected complex insecticide resistance in a 2014 An. coluzzii colony from southern Mali using bottle bioassays. Additional bioassays involving recombinant genotypes from a cross with a relatively susceptible 1995 An. coluzzii colony from Mali confirmed the importance of kdr and associated increased permethrin resistance to the CYP9K1 locus on the X chromosome. Significant differential expression of CYP9K1 was not observed among these colonies in Malpighian tubules. However, the P450 gene CYP6Z1 was overexpressed in resistant individuals following sublethal permethrin exposure and the carboxylesterase gene COEAE5G was constitutively overexpressed. The significant P450-related insecticide resistance observed in the 2014 An. coluzzii colony indicates that ITNs treated with the P450 inhibitor piperonyl butoxide (PBO) would be more effective in this region. The known insecticide resistance gene CYP6Z1 was differentially expressed exclusively in the context of sublethal permethrin exposure, highlighting the importance of tissue-specificity and environmental conditions in gene expression studies. The increased activity of the carboxylesterase

Effects of in vivo exposure to DEET on blood feeding behavior and fecundity in Anopheles quadrimaculatus (Diptera: Culicidae).

Science.gov (United States)

Xue, Rui-De; Ali, Arshad; Barnard, Donald R

2007-07-01

This study determined the effects of contact with DEET on guinea pig skin on mortality, probing time, blood feeding rate, engorgement time, and fecundity responses in female Anopheles quadrimaculatus Say. Exposure, in this manner, to 10% DEET (in ethanol) for 5 min, resulted in 98% mortality in mosquitoes after 24h. The median probing time (PT(50)) required by females, when exposed to 0.1%, 1.0%, and 10% DEET, was significantly (Pblood feeding rates in populations of females exposed to 1.0% DEET for feeding on the control guinea pigs (105.9s). The mean number of mature oöcytes per female (fecundity) in treatment (1.0% DEET) and control mosquitoes was not significantly different. The responses to DEET observed in this study suggest that repeated exposure of female A. quadrimaculatus populations to this repellent, in laboratory bioassays, could result in confounding of toxicant and repellent effects and inaccurate estimates of DEET repellency.

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.

Collection and control of tritium bioassay samples at Pantex

International Nuclear Information System (INIS)

Fairrow, N.L.; Ivie, W.E.

1992-01-01

Pantex is the final assembly/disassembly point for US nuclear weapons. The Pantex internal dosimetry section monitors radiation workers once a month for tritium exposure. In order to manage collection and control of the bioassay specimens efficiently, a bar code system for collection of samples was developed and implemented to speed up the process and decrease the number of errors probable when transferring data. In the past, all the bioassay data from samples were entered manually into a computer database. Transferring the bioassay data from the liquid scintillation counter to each individual's dosimetry record required as much as two weeks of concentrated effort

Internal dosimetry performing dose assessments via bioassay measurements

International Nuclear Information System (INIS)

Bailey, K.M.

1993-01-01

The Internal Dosimetry Department at the Y-12 Plant maintains a state-of-the-art bioassay program managed under the guidance and regulations of the Department of Energy. The two major bioassay techniques currently used at Y-12 are the in vitro (urinalysis) and in vivo (lung counting) programs. Fecal analysis (as part of the in vitro program) is another alternative; however, since both urine and fecal analysis provide essentially the same capabilities for detecting exposures to uranium, the urinalysis is the main choice primarily for aesthetic reasons. The bioassay frequency is based on meeting NCRP 87 objectives which are to monitor the accumulation of radioactive material in exposed individuals, and to ensure that significant depositions are detected

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

Comparison of ICRP Publication 30 lung model-based predictions with measured bioassay data for airborne natural UO2 exposure

International Nuclear Information System (INIS)

Thind, K.S.

1987-01-01

In this paper a comparison is made between the build-up of U thorax burdens and the predicted total lung (lung and lymph) burden, based on the lung model provided in ICRP Publication 30 for a group of 29 atomic radiation workers at a Canadian fuel fabrication facility. A similar comparison is made between the predicted ratio of the total lung burden to urinary excretion and the ratio obtained from bioassay data. The study period for the comparison is 5 y. The inhalation input for the lung model calculations was derived from air-sampling data and the choice of particle size activity median aerodynamic diameter (AMAD) was guided by particle size measurements made at representative work locations. The pulmonary clearance half-times studied were 100, 250 and 500 d. For the purpose of this comparison, averaged exposure and averaged bioassay data for the group were used. This comparison indicates that for the conditions of this facility, the assumption of a 500-d pulmonary clearance half-time and a particle size of 1 micron (AMAD) may be too conservative. It is suggested that measurements of air concentrations and particle size used as input parameters for the ICRP Publication 30 lung model may be used to calculate bioassay parameters which may then be tested against bioassay data obtained as part of an operational health physics program, thereby giving a useful step towards defining a derived air concentration value for U in the workplace

The BIDAS: bioassay data analysis software for evaluating radionuclide intake and dose

International Nuclear Information System (INIS)

Lee, Tae Young; Lee, Jong Il; Chang, Si Young

2003-01-01

The BIDAS (BIoassay Data Analysis Software) computer code was developed for the interpretation of bioassay measurements in terms of the intake and dose using the International Commission on Radiological Protection's(ICRP's) currently recommended respiratory tract, GI-tract and biokinetic models to describe the behavior of the radioactive materials within the body. The code consists of a data base module to the manage bioassay data, a data base module containing the predicted bioassay quantities of each radionuclide, and a computational module to the estimate radionuclide intake and dose from either an acute or a chronic exposure based on the measured bioassay quantities. This paper describes the features of the code as well as the results of the BIDAS validation

Light manipulation of mosquito behaviour: acute and sustained photic suppression of biting activity in the Anopheles gambiae malaria mosquito.

Science.gov (United States)

Sheppard, Aaron D; Rund, Samuel S C; George, Gary F; Clark, Erin; Acri, Dominic J; Duffield, Giles E

2017-06-16

Host-seeking behaviours in anopheline mosquitoes are time-of-day specific, with a greater propensity for nocturnal biting. We investigated how a short exposure to light presented during the night or late day can inhibit biting activity and modulate flight activity behaviour. Anopheles gambiae (s.s.), maintained on a 12:12 LD cycle, were exposed transiently to white light for 10-min at the onset of night and the proportion taking a blood meal in a human biting assay was recorded every 2 h over an 8-h duration. The pulse significantly reduced biting propensity in mosquitoes 2 h following administration, in some trials for 4 h, and with no differences detected after 6 h. Conversely, biting levels were significantly elevated when mosquitoes were exposed to a dark treatment during the late day, suggesting that light suppresses biting behaviour even during the late daytime. These data reveal a potent effect of a discrete light pulse on biting behaviour that is both immediate and sustained. We expanded this approach to develop a method to reduce biting propensity throughout the night by exposing mosquitoes to a series of 6- or 10-min pulses presented every 2 h. We reveal both an immediate suppressive effect of light during the exposure period and 2 h after the pulse. This response was found to be effective during most times of the night: however, differential responses that were time-of-day specific suggest an underlying circadian property of the mosquito physiology that results in an altered treatment efficacy. Finally, we examined the immediate and sustained effects of light on mosquito flight activity behaviour following exposure to a 30-min pulse, and observed activity suppression during early night, and elevated activity during the late night. As mosquitoes and malaria parasites are becoming increasingly resistant to insecticide and drug treatment respectively, there is a necessity for the development of innovative control strategies beyond insecticide

The use of bioassays to assess the toxicity of sediment in an acid ...

African Journals Online (AJOL)

Exposure of river sediment from 7 sampling sites to these bioassays provided an eco-toxicological estimation of the acute toxicity and chronic toxicity emanating from the contaminated sediments. Physico-chemical analyses revealed higher levels of sediment contamination closer to the mine. The bioassays displayed a ...

US Army Radiological Bioassay and Dosimetry: The RBD software package

International Nuclear Information System (INIS)

Eckerman, K.F.; Ward, R.C.; Maddox, L.B.

1993-01-01

The RBD (Radiological Bioassay and Dosimetry) software package was developed for the U. S. Army Material Command, Arlington, Virginia, to demonstrate compliance with the radiation protection guidance 10 CFR Part 20 (ref. 1). Designed to be run interactively on an IBM-compatible personal computer, RBD consists of a data base module to manage bioassay data and a computational module that incorporates algorithms for estimating radionuclide intake from either acute or chronic exposures based on measurement of the worker's rate of excretion of the radionuclide or the retained activity in the body. In estimating the intake,RBD uses a separate file for each radionuclide containing parametric representations of the retention and excretion functions. These files also contain dose-per-unit-intake coefficients used to compute the committed dose equivalent. For a given nuclide, if measurements exist for more than one type of assay, an auxiliary module, REPORT, estimates the intake by applying weights assigned in the nuclide file for each assay. Bioassay data and computed results (estimates of intake and committed dose equivalent) are stored in separate data bases, and the bioassay measurements used to compute a given result can be identified. The REPORT module creates a file containing committed effective dose equivalent for each individual that can be combined with the individual's external exposure

Towards a Hybrid Agent-based Model for Mosquito Borne Disease.

Science.gov (United States)

Mniszewski, S M; Manore, C A; Bryan, C; Del Valle, S Y; Roberts, D

2014-07-01

Agent-based models (ABM) are used to simulate the spread of infectious disease through a population. Detailed human movement, demography, realistic business location networks, and in-host disease progression are available in existing ABMs, such as the Epidemic Simulation System (EpiSimS). These capabilities make possible the exploration of pharmaceutical and non-pharmaceutical mitigation strategies used to inform the public health community. There is a similar need for the spread of mosquito borne pathogens due to the re-emergence of diseases such as chikungunya and dengue fever. A network-patch model for mosquito dynamics has been coupled with EpiSimS. Mosquitoes are represented as a "patch" or "cloud" associated with a location. Each patch has an ordinary differential equation (ODE) mosquito dynamics model and mosquito related parameters relevant to the location characteristics. Activities at each location can have different levels of potential exposure to mosquitoes based on whether they are inside, outside, or somewhere in-between. As a proof of concept, the hybrid network-patch model is used to simulate the spread of chikungunya through Washington, DC. Results are shown for a base case, followed by varying the probability of transmission, mosquito count, and activity exposure. We use visualization to understand the pattern of disease spread.

Insecticide resistance to permethrin and malathion and associated mechanisms in Aedes aegypti mosquitoes from St. Andrew Jamaica.

Directory of Open Access Journals (Sweden)

Sheena Francis

Full Text Available The emergence of novel diseases spread by the Aedes aegypti mosquito in Jamaica and the Caribbean, has prompted studies on insecticide resistance towards effective management of the vector. Though Jamaica has been using the organophosphate insecticide malathion in its vector control program for more than 30 years, resistance to the pesticide has not been tested in over a decade. We analyzed resistance to malathion and the pyrethroid insecticide, permethrin on mosquitoes collected across St. Andrew, Jamaica, and analyzed the molecular basis of resistance. The Center for Disease Control (CDC bioassay revealed that Ae. aegypti mosquitoes from St. Andrew, Jamaica were resistant to permethrin (15 μg/bottle with mortalities at 0-8% at 30 minute exposure time, while contact with malathion (50 μg/bottle revealed ≤ 50% mortality at 15 minutes, which increased to 100% at 45 minutes. The standard susceptible New Orleans (NO strain exhibited 100% mortality within15 minutes. The activities of multifunction oxidases and p-nitro phenyl-acetate esterases were significantly greater in most Jamaican populations in comparison to the NO strain, while activities of glutathione-S-transferase, acetylcholinesterase, α-esterase and ß-esterase activity were relatively equal, or lower than that of the control strain. The frequency of knockdown resistance mutations in the voltage dependent sodium channel gene were measured. All collections were fixed for Cys1,534 while 56% of mosquitoes were Ile1,016/Val1,016 heterozygotes, and 33% were Ile1,016 homozygotes. Aedes aegypti from St. Andrew Jamaica are resistant to permethrin with variations in the mode of mechanism, and possibly developing resistance to malathion. Continued monitoring of resistance is critically important to manage the spread of the vector in the country.

Larvicidal properties of two asclepiadaceous plant species against the mosquito Anopheles arabiensis Patton (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Amal Elsayed Edriss

2013-01-01

Full Text Available Certain mosquito species are important vectors of fatal human diseases, among which Anopheles arabiensis is known to be associated with malaria transmission in different tropical and subtropical areas. Since chemical control of mosquitoes was linked with numerous drawbacks, like resistance development, the search for effective environmentally sound alternatives is urgently needed. Therefore, it was aimed by this study to evaluate some extracts prepared from two asclepiadaceous plants, viz., Solenostemma argel “Hargel” (seeds and leaves and Calotropis procera “Usher” (leaves and flowers, as natural larvicides against An. arabiensis. The main parameters included bioassays of treatments for knockdown and residual effects, besides phytochemical analysis of the tested extracts. The results revealed variable groups of secondary metabolites in the two plants, with S. argel seemed to be the richest one. Hence, S. argel extracts caused higher larval mortalities than those of C. procera. This could be ascribed to some potent secondary metabolites in the former plant, which needs further studies. Almost all the high concentrations of S. argel extracts exerted the highest knockdown effect (90% mortality after 24 h, which were comparable with those obtained by two standard insecticides. The highest doses of petroleum ether and water extracts of this plant also manifested significantly higher residual effects than the other extracts after three days following treatments, but were surpassed by the chemical insecticides thereafter. However, S. argel seed petroleum ether extract at 0.5% was the most effective of all botanicals up to three weeks of exposure. This extract needs to be evaluated under field conditions for proper exploitation as mosquito larvicide.

Structuring a risk-based bioassay program for uranium usage in university laboratories

Science.gov (United States)

Dawson, Johnne Talia

Bioassay programs are integral in a radiation safety program. They are used as a method of determining whether individuals working with radioactive material have been exposed and have received a resulting dose. For radionuclides that are not found in nature, determining an exposure is straightforward. However, for a naturally occurring radionuclide like uranium, it is not as straightforward to determine whether a dose is the result of an occupational exposure. The purpose of this project is to address this issue within the University of Nevada, Las Vegas's (UNLV) bioassay program. This project consisted of two components that studied the effectiveness of a bioassay program in determining the dose for an acute inhalation of uranium. The first component of the plan addresses the creation of excretion curves, utilizing MATLAB that would allow UNLV to be able to determine at what time an inhalation dose can be attributed to. The excretion curves were based on the ICRP 30 lung model, as well as the Annual Limit Intake (ALI) values located in the Nuclear Regulatory Commission's 10CFR20 which is based on ICRP 30 (International Commission on Radiological Protection). The excretion curves would allow UNLV to be able to conduct in-house investigations of inhalation doses without solely depending on outside investigations and sources. The second component of the project focused on the creation of a risk based bioassay program to be utilized by UNLV that would take into account bioassay frequency that depended on the individual. Determining the risk based bioassay program required the use of baseline variance in order to minimize the investigation of false positives among those individuals who undergo bioassays for uranium work. The proposed program was compared against an evaluation limit of 10 mrem per quarter, an investigational limit of 125 mrem per quarter, and the federal/state requirement of 1.25 rem per quarter. It was determined that a bioassay program whose bioassay

Analysis and optimization of a synthetic milkweed floral attractant for mosquitoes.

Science.gov (United States)

Otienoburu, Philip E; Ebrahimi, Babak; Phelan, P Larry; Foster, Woodbridge A

2012-07-01

A pentane extract of flowers of common milkweed, Asclepias syriaca (Asclepiadaceae), elicited significant orientation from both male and female Culex pipiens in a dual-port flight olfactometer. Analysis of the extract by gas chromatography-mass spectrometry revealed six major constituents in order of relative abundance: benzaldehyde, (E)-β-ocimene, phenylacetaldehyde, benzyl alcohol, nonanal, and (E)-2-nonenal. Although not all were collected from the headspace profile of live flowers, a synthetic blend of these six compounds, when presented to mosquitoes in the same levels and proportions that occur in the extract, elicited a response comparable to the extract. Subtractive behavioral bioassays demonstrated that a three-component blend consisting of benzaldehyde, phenylacetaldehyde, and (E)-2-nonenal was as attractive as the full blend. These findings suggest the potential use of synthetic floral-odor blends for monitoring or control of both male and female disease-vectoring mosquitoes.

Studies on Erythropoietin Bioassay Method

Energy Technology Data Exchange (ETDEWEB)

Cho, Kyoung Sam; Ro, Heung Kyu; Lee, Mun Ho [Seoul National University College of Medicine, Seoul (Korea, Republic of)

1975-09-15

It is the purpose of this paper to design the most preferable method of erythropoietin bioassay in Korea. Bioassay utilizing polycythemic mice are currently in general use for the indirect determination of erythropoietin. Assay animals are usually prepared either by transfusion or by exposure to reduced oxygen tension in specially constructed chamber. We prepared the polycythemic mice by the specially constructed hypobaric chamber. We observed weights and hematocrits of the mice in the hypobaric chamber, then hematocrits and 72 hours {sup 59}Fe red cell uptake ratio of the polycythemic mice induced by hypoxia after removal from the hypobaric chamber. We designed the method of erythropoietin bioassay according to the results obtained by above experiments. Then we measured the 72 hours {sup 59}Fe red cell uptake ratio of the polycythemic mice with normal saline, normal plasma and anemic plasma according to the method we designed. The results are followed:1) The hematocrits of the mice in hypobaric chamber increased to 74% in 11 days. It is preferable to maintain the pressure of the chamber to 400 mmHg for first 4 days then 300 mmHg for last 10 days to reduce the death rate and time consuming in hypobaric chamber. 2) After removal from the hypobaric chamber, the 72 hours {sup 59}Fe red cell uptake ratio decreased rapidly and maintained the lowest level from the fourth day to tenth day. 3) We design the method of erythropoietin bioassay according to the results of above experiment and to the half life of erythropoietin. 4) The Korean product {sup 59}Fe is mixture of {sup 55}Fe and {sup 59}Fe. And the {sup 59}Fe red cell uptake ratio in normal mice was far less with Korean product {sup 59}Fe than with pure {sup 59}Fe of foreign product. So it is desirable to use pure {sup 59}Fe in this method of erythropoietin bioassay. 5) Considering the cost, the technique, the time consuming and the sensitivity it is the most preferable method of erythropoietin bioassay in Korea

Integration of laboratory bioassays into the risk-based corrective action process

International Nuclear Information System (INIS)

Edwards, D.; Messina, F.; Clark, J.

1995-01-01

Recent data generated by the Gas Research Institute (GRI) and others indicate that residual hydrocarbon may be bound/sequestered in soil such that it is unavailable for microbial degradation, and thus possibly not bioavailable to human/ecological receptors. A reduction in bioavailability would directly equate to reduced exposure and, therefore, potentially less-conservative risk-based cleanup soil goals. Laboratory bioassays which measure bioavailability/toxicity can be cost-effectively integrated into the risk-based corrective action process. However, in order to maximize the cost-effective application of bioassays several site-specific parameters should be addressed up front. This paper discusses (1) the evaluation of parameters impacting the application of bioassays to soils contaminated with metals and/or petroleum hydrocarbons and (2) the cost-effective integration of bioassays into a tiered ASTM type framework for risk-based corrective action

Efficacy of Advanced Odomos repellent cream (N, N-diethyl-benzamide) against mosquito vectors.

Science.gov (United States)

Mittal, P K; Sreehari, U; Razdan, R K; Dash, A P; Ansari, M A

2011-04-01

Repellents are commonly used personal protection measures to avoid mosquito bites. In the present study, Advanced Odomos cream (12% N, N-diethyl-benzamide) was tested for its efficacy against mosquitoes in comparison to DEET (N,N-diethyl-3-methyl benzamide). Bioassays were conducted to assess the repellency of Advanced Odomos and DEET creams against Anopheles stephensi and Aedes aegypti. Their efficacy was tested on human volunteers applied with different concentrations of test creams ranging from 1 to 12 mg/cm 2 and by exposing them to mosquitoes at hourly intervals. Field evaluation was also carried out to test the duration of protection of the test creams against Anopheles and Aedes mosquitoes during whole night and day time collections, respectively on human volunteers. Mosquito collections were done using torch light and aspirator. Complete (100%) protection was achieved at 10 mg/cm 2 cream formulation of Advanced Odomos (1.2 mg a.i/cm 2 ) dose against An. stephensi and 12 mg/cm 2 (1.44 mg a.i./cm 2 ) against Ae. aegypti on human baits. There was no statistically significant differences in per cent protection against mosquito bites between Advanced Odomos and DEET cream (P>0.05) in respective doses. Complete protection up to 11 h was observed against Anopheles mosquitoes during whole night collections and up to 6 h against Ae. aegypti in day time collections. No adverse reactions such as itching, irritation, vomiting, nausea, etc. were reported by the volunteers. Advanced Odomos cream applied at 10 mg/cm 2 concentration provided 100% protection from Anopheles mosquitoes up to 11 h whereas about 6 h protection was recorded against Ae. aegypti. The laboratory and field trials indicate that for longer protection against Anopheles mosquitoes 10 mg/cm 2 will be appropriate and in case of Ae. aegypti more than 10 mg/cm 2 application is required for complete protection. In conclusion, the Advanced Odomos cream was comparable to the known repellent cream DEET for

Bioassay guideline 1: general guidlines for bioassay programs

International Nuclear Information System (INIS)

1980-01-01

This guideline is the first of a series of documents which elaborate criteria for bioassay programs, to be presented as recommendations to the Atomic Energy Control Board. It specifies which workers require routine bioassays, the accuracy and frequency of measurements, the dose levels at which specific actions must be taken, and the documentation required

Expectoration of Flaviviruses during sugar feeding by mosquitoes (Diptera: Culicidae).

Science.gov (United States)

van den Hurk, Andrew F; Johnson, Petrina H; Hall-Mendelin, Sonja; Northill, Judy A; Simmons, Russell J; Jansen, Cassie C; Frances, Stephen P; Smith, Greg A; Ritchie, Scott A

2007-09-01

Biological transmission of arboviruses to a vertebrate host occurs when virions are expelled along with saliva during blood feeding by a hematophagous arthropod. We undertook experiments to determine whether mosquitoes expectorate flaviviruses in their saliva while sugar feeding. Batches of Culex annulirostris Skuse and Culex gelidus Theobald (Diptera: Culicidae) were orally infected with Japanese encephalitis (family Flaviviridae, genus Flavivirus, JEV), Kunjin (family Flaviviridae, genus Flavivirus, KUNV; a subtype of West Nile virus), and Murray Valley encephalitis (family Flaviviridae, genus Flavivirus, MVEV) viruses. After a 7-d extrinsic incubation, these mosquitoes were offered sucrose meals via cotton pledgets, which were removed daily and processed for viral RNA by using real-time TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR) assays. JEV, MVEV, and KUNV RNA was detected in all pledgets removed from batches of Cx. gelidus on days 7-14 postexposure. In contrast, detection rates were variable for Cx. annulirostris, with KUNV detected in 0.3 M sucrose pledgets on all days postexposure, and JEV and MVEV detected on 57 and 50% of days postexposure, respectively. Higher concentrations of sucrose in the pledget did not increase virus detection rates. When individual JEV-infected Cx. gelidus were exposed to the sucrose pledget, 73% of mosquitoes expectorated virus with titers that were detectable by TaqMan RT-PCR. These results clearly show that flaviviruses are expectorated by infected mosquitoes during the process of sugar feeding on artificial pledgets. Potential applications of the method for arboviral bioassays and field surveillance are discussed.

Co-Infection of Mosquitoes with Chikungunya and Dengue Viruses Reveals Modulation of the Replication of Both Viruses in Midguts and Salivary Glands of Aedes aegypti Mosquitoes.

Science.gov (United States)

Le Coupanec, Alain; Tchankouo-Nguetcheu, Stéphane; Roux, Pascal; Khun, Huot; Huerre, Michel; Morales-Vargas, Ronald; Enguehard, Margot; Lavillette, Dimitri; Missé, Dorothée; Choumet, Valérie

2017-08-04

Arthropod-borne virus (arbovirus) infections cause several emerging and resurgent infectious diseases in humans and animals. Chikungunya-affected areas often overlap with dengue-endemic areas. Concurrent dengue virus (DENV) and chikungunya virus (CHIKV) infections have been detected in travelers returning from regions of endemicity. CHIKV and DENV co-infected Aedes albopictus have also been collected in the vicinity of co-infected human cases, emphasizing the need to study co-infections in mosquitoes. We thus aimed to study the pathogen-pathogen interaction involved in these co-infections in DENV/CHIKV co-infected Aedes aegypti mosquitoes. In mono-infections, we detected CHIKV antigens as early as 4 days post-virus exposure in both the midgut (MG) and salivary gland (SG), whereas we detected DENV serotype 2 (DENV-2) antigens from day 5 post-virus exposure in MG and day 10 post-virus exposure in SG. Identical infection rates were observed for singly and co-infected mosquitoes, and facilitation of the replication of both viruses at various times post-viral exposure. We observed a higher replication for DENV-2 in SG of co-infected mosquitoes. We showed that mixed CHIKV and DENV infection facilitated viral replication in Ae. aegypti . The outcome of these mixed infections must be further studied to increase our understanding of pathogen-pathogen interactions in host cells.

Natural variation in virulence of the entomopathogenic fungus Beauveria bassiana against malaria mosquitoes.

Science.gov (United States)

Valero-Jiménez, Claudio A; Debets, Alfons J M; van Kan, Jan A L; Schoustra, Sijmen E; Takken, Willem; Zwaan, Bas J; Koenraadt, Constantianus J M

2014-12-06

Insecticide resistance is greatly hampering current efforts to control malaria and therefore alternative methods are needed. Entomopathogenic fungi have been proposed as an alternative with a special focus on the cosmopolitan species Beauveria bassiana. However, few studies have analysed the effects of natural variation within fungal isolates on mosquito survival, and the implications and possible exploitation for malaria control. Laboratory bioassays were performed on adult female mosquitoes (Anopheles coluzzii) with spores from 29 isolates of B. bassiana, originating from different parts of the world. In addition, phenotypic characteristics of the fungal isolates such as sporulation, spore size and growth rate were studied to explore their relationship with virulence. All tested isolates of B. bassiana killed An. coluzzii mosquitoes, and the rate at which this happened differed significantly among the isolates. The risk of mosquitoes dying was around ten times higher when they were exposed to the most virulent as compared to the least virulent isolate. There was significant variation among isolates in spore size, growth rate and sporulation, but none of these morphological characteristics were correlated, and thus predictive, for the ability of the fungal isolate to kill malaria mosquitoes. This study shows that there is a wide natural variation in virulence of isolates of B. bassiana, and that selecting an appropriate fungal isolate is highly relevant in killing and thus controlling malaria mosquitoes, particularly if used as part of an integrated vector management strategy. Also, the wide variation observed in virulence offers the opportunity to better understand the molecular and genetic mechanisms that drive this variation and thus to address the potential development of resistance against entomopathogenic fungi.

A rapid bioassay for detecting saxitoxins using a Daphnia acute toxicity test

Energy Technology Data Exchange (ETDEWEB)

Ferrao-Filho, Aloysio da S., E-mail: aloysio@ioc.fiocruz.b [Laboratorio de Avaliacao e Promocao da Saude Ambiental, Departamento de Biologia, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ 21045-900 (Brazil); Soares, Maria Carolina S., E-mail: mcarolsoares@gmail.co [Departamento de Engenharia Sanitaria e Ambiental Faculdade de Engenharia, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36036-900 (Brazil); Freitas de Magalhaes, Valeria, E-mail: valeria@biof.ufrj.b [Laboratorio de Ecofisiologia e Toxicologia de Cianobacterias, Instituto de Biofisica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Rio de Janeiro, RJ 21949-900 (Brazil); Azevedo, Sandra M.F.O., E-mail: sazevedo@biof.ufrj.b [Laboratorio de Ecofisiologia e Toxicologia de Cianobacterias, Instituto de Biofisica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Rio de Janeiro, RJ 21949-900 (Brazil)

2010-06-15

Bioassays using Daphnia pulex and Moina micrura were designed to detect cyanobacterial neurotoxins in raw water samples. Phytoplankton and cyanotoxins from seston were analyzed during 15 months in a eutrophic reservoir. Effective time to immobilize 50% of the exposed individuals (ET{sub 50}) was adopted as the endpoint. Paralysis of swimming movements was observed between approx0.5-3 h of exposure to lake water containing toxic cyanobacteria, followed by an almost complete recovery of the swimming activity within 24 h after being placed in control water. The same effects were observed in bioassays with a saxitoxin-producer strain of Cylindrospermopsis raciborskii isolated from the reservoir. Regression analysis showed significant relationships between ET{sub 50}vs. cell density, biomass and saxitoxins content, suggesting that the paralysis of Daphnia in lake water samples was caused by saxitoxins found in C. raciborskii. Daphnia bioassay was found to be a sensitive method for detecting fast-acting neurotoxins in natural samples, with important advantages over mouse bioassays. - A new Daphnia bioassay, as an alternative to the mouse bioassay, is able to detect effects of fast-acting, potent neurotoxins in raw water.

A rapid bioassay for detecting saxitoxins using a Daphnia acute toxicity test

International Nuclear Information System (INIS)

Ferrao-Filho, Aloysio da S.; Soares, Maria Carolina S.; Freitas de Magalhaes, Valeria; Azevedo, Sandra M.F.O.

2010-01-01

Bioassays using Daphnia pulex and Moina micrura were designed to detect cyanobacterial neurotoxins in raw water samples. Phytoplankton and cyanotoxins from seston were analyzed during 15 months in a eutrophic reservoir. Effective time to immobilize 50% of the exposed individuals (ET 50 ) was adopted as the endpoint. Paralysis of swimming movements was observed between ∼0.5-3 h of exposure to lake water containing toxic cyanobacteria, followed by an almost complete recovery of the swimming activity within 24 h after being placed in control water. The same effects were observed in bioassays with a saxitoxin-producer strain of Cylindrospermopsis raciborskii isolated from the reservoir. Regression analysis showed significant relationships between ET 50 vs. cell density, biomass and saxitoxins content, suggesting that the paralysis of Daphnia in lake water samples was caused by saxitoxins found in C. raciborskii. Daphnia bioassay was found to be a sensitive method for detecting fast-acting neurotoxins in natural samples, with important advantages over mouse bioassays. - A new Daphnia bioassay, as an alternative to the mouse bioassay, is able to detect effects of fast-acting, potent neurotoxins in raw water.

Olfactory memory in the mosquito Culex quinquefasciatus.

Science.gov (United States)

McCall, P J; Eaton, G

2001-06-01

The cosmotropical urban mosquito Culex quinquefasciatus Say (Diptera: Culicidae) uses chemical cues to locate suitable water pools for oviposition. Although gravid females are innately attracted to or repelled by certain compounds, this study found that an individual mosquito's preferences for these odours could be altered greatly by prior experience. Mosquitoes reared in water containing skatole, at a level normally repellent to ovipositing females, preferred to oviposit in water containing that compound rather than in water with an otherwise attractive odour compound (P-cresol). This behaviour occurred regardless of whether mosquitoes were tested individually or in groups of up to 50 per cage. The F1 progeny of conditioned mosquitoes did not exhibit the parental preference, but were as susceptible to conditioning as their parents. Moreover, rearing mosquitoes in infusions of hay or animal (guinea-pig) faeces produced a similar although less dramatic change, such that the innate propensity for hay infusion could be cancelled by rearing in guinea-pig faeces infusion. The results demonstrated a change in odour preference by Cx. quinquefasciatus following exposure to the odour during development or pupal eclosion, suggesting that some form of larval conditioning or early adult imprinting occurred. Precisely when that conditioning occurred remains to be determined.

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.

Hierarchical responses to organic contaminants in aquatic ecotoxicological bioassays: from microcystins to biodegradation

OpenAIRE

Montenegro, Katia

2008-01-01

In this thesis I explore the ecotoxicological responses of aquatic organisms at different hierarchical levels to organic contaminants by means of bioassays. The bioassays use novel endpoints or approaches to elucidate the effects of exposure to contaminants and attempt to give mechanistic explanations that could be used to interpret effects at higher hierarchical scales. The sensitivity of population growth rate in the cyanobacteria species Microcystis aeruginosa to the herbicide glyp...

Mosquito Control

Science.gov (United States)

... Labs and Research Centers Contact Us Share 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 ...

Development of a chick bioassay for determination of infectivity of viral pathogens in poultry litter.

Science.gov (United States)

Islam, A F M F; Walkden-Brown, S W; Groves, P J; Wells, B

2013-01-01

To develop a chicken bioassay to detect infective viral pathogens in poultry litter and to determine the effects of type of chicken and age of exposure, as well as the effect of simulated litter transportation, on the level of viral infectivity detected. A 5 × 2 × 2 factorial design, plus negative controls. Five chicken litters, including two with deliberate contamination (one transported and one not), two chicken types (specific-pathogen-free (SPF) Leghorns and Cobb broilers) and two ages at initial exposure (days 1 and 8). Two replicates of each treatment combination. The 10 chickens in each of 22 isolators were either exposed (20 isolators) or not (2 isolators) to 8 L of previously used or deliberately contaminated poultry litter in two deep scratch trays. At day 35 post-exposure, sera were assayed for antibodies against chicken anaemia virus (CAV), infectious bronchitis virus (IBV), infectious bursal disease virus (IBDV), Newcastle disease virus (NDV) and fowl adenovirus (FAV). Spleen samples were tested for Marek's disease virus (MDV) using real-time polymerase chain reaction. The bioassay detected CAV, IBDV and FAV, but not NDV, IBV or MDV, in chickens exposed to infected litters. Infection in SPF chickens was detected with greater sensitivity than in the broiler chickens. Sensitivity increased with age at exposure in broiler but not SPF chickens. Simulated transportation for 24 h had little effect on pathogen detection. A bioassay based on the exposure of day-old SPF chickens to poultry litter and measurement of seroconversion at day 35 post-exposure is a useful semi-quantitative assay for viral infectivity in poultry litter, with overnight transportation of litter having little effect on the level of viral infectivity detected. This bioassay has applications in research on litter treatment protocols. © 2013 The Authors. Australian Veterinary Journal © 2013 Australian Veterinary Association.

Bioassay-guided investigation of two monarda essential oils as repellents of yellow fever mosquito Aedes aegypti

Science.gov (United States)

As part of an ongoing research program to identify active mosquito repellents, Monarda bradburiana Beck and M. fistulosa L. essential oils showed potent repellents with minimum effective dosages (MED) of 0.055 ± 0.036 and 0.078 ± 0.027 mg/cm2, respectively, compared to reference standard N,N-diethyl...

Bioassay-Guided Investigation of Two Monarda Essential Oils as Repellents of Yellow Fever Mosquito Aedes aegypti

Science.gov (United States)

2013-08-06

suppressed the postprandial elevation of blood triacylglycerol concentrations in mice in vivo; however, five other monoterpene glycosides that were isolated...components, leading to the isolation of compounds with mosquito repellent activity, but without any cytotoxicity. The monoterpene hydrocarbon p-cymene...Kobayashi, K.; Miyase, T.; Yoshizaki, F. A lipase inhibitor monoterpene and monoterpene glycosides from Monarda punctata. Phytochemistry 2010, 71, 1884

Development by flow cytometry of bioassays based on chlorella for environmental monitoring

Directory of Open Access Journals (Sweden)

Petrescu C-M,

2016-05-01

Full Text Available In ecotoxicological assessments, bioassays (ecotoxicity tests or biotests are one of the main tools, defined as methods which use living cells, tissues, organism or communities to assess exposure-related effects of chemicals. The increasing complexity of environmental degradation requires an increase in the capacity of scientific approach in monitoring and notification as early as possible risks. Our own objective concerns the detection of aquatic environment pollution in Romania and particularly in the Danube basin. For assessing aquatic environment pollution degree or for assessing cytotoxicity or ecotoxicity of pollutants (heavy metals, nanoparticles, pesticides, etc. we developed news experimental bioassays based on the use of viability and apoptosis biomarkers of Chlorella cells by flow cytometry. Our proposed bioassays could be rapid and very sensitive tests for in laboratory aquatic risk assessment and biomonitoring.

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

Directory of Open Access Journals (Sweden)

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.

Limitation of using synthetic human odours to test mosquito repellents

Directory of Open Access Journals (Sweden)

Mbeyela Edgar

2009-07-01

Full Text Available Abstract Background Gold-standard tests of mosquito repellents involve exposing human volunteers to host-seeking mosquitoes, to assess the protective efficacy of the repellents. These techniques are not exposure-free and cannot be performed prior to toxicological evaluation. It is postulated that synthetic lures could provide a useful assay that mimics in-vivo conditions for use in high-throughput screening for mosquito repellents. Methods This paper reports on a semi-field evaluation of repellents using a synthetic blend of human derived attractants for the malaria vector, Anopheles gambiae sensu stricto Different concentrations of known repellents, N, N diethyl-3-methylbenzamide (deet and Para-methane-3, 8, diol (PMD were added into traps baited with the synthetic blend, and resulting changes in mosquito catches were measured. Results All test concentrations of deet (0.001% to 100% reduced the attractiveness of the synthetic blend. However, PMD was repellent only at 0.25%. Above this concentration, it significantly increased the attractiveness of the blend. There was no relationship between the repellent concentrations and the change in mosquito catches when either deet (r2 = 0.033, P = 0.302 or PMD (r2 = 0.020, P = 0.578 was used. Conclusion It is concluded that while some repellents may reduce the attractiveness of synthetic human odours, others may instead increase their attractiveness. Such inconsistencies indicate that even though the synthetic attractants may provide exposure-free and consistent test media for repellents, careful selection and multiple-repellent tests are necessary to ascertain their suitability for use in repellent screening. The synthetic odour blend tested here is not yet sufficiently refined to serve as replacement for humans in repellent testing, but may be developed further and evaluated in different formats for exposure free repellent testing purposes.

A rapid bioassay for detecting saxitoxins using a Daphnia acute toxicity test.

Science.gov (United States)

Ferrão-Filho, Aloysio da S; Soares, Maria Carolina S; de Magalhães, Valéria Freitas; Azevedo, Sandra M F O

2010-06-01

Bioassays using Daphnia pulex and Moina micrura were designed to detect cyanobacterial neurotoxins in raw water samples. Phytoplankton and cyanotoxins from seston were analyzed during 15 months in a eutrophic reservoir. Effective time to immobilize 50% of the exposed individuals (ET50) was adopted as the endpoint. Paralysis of swimming movements was observed between approximately 0.5-3 h of exposure to lake water containing toxic cyanobacteria, followed by an almost complete recovery of the swimming activity within 24 h after being placed in control water. The same effects were observed in bioassays with a saxitoxin-producer strain of Cylindrospermopsis raciborskii isolated from the reservoir. Regression analysis showed significant relationships between ET50 vs. cell density, biomass and saxitoxins content, suggesting that the paralysis of Daphnia in lake water samples was caused by saxitoxins found in C. raciborskii. Daphnia bioassay was found to be a sensitive method for detecting fast-acting neurotoxins in natural samples, with important advantages over mouse bioassays. Copyright 2010 Elsevier Ltd. All rights reserved.

Evaluation of bifenthrin applications in tires to prevent Aedes mosquito breeding.

Science.gov (United States)

Nguyen, Huy T; Whelan, Peter I; Shortus, Matthew S; Jacups, Susan P

2009-03-01

The efficacy of maximum label rates of bifenthrin applications to dry tires to prevent Aedes mosquito breeding was investigated by field colonization and bioassay trials in shaded and unshaded locations. Aedes notoscriptus and Culex quinquefasciatus larvae were the most abundant species present in the field colonization trial. Colonization and survival of Ae. notoscriptus larvae to the late instar occurred significantly earlier in treated tires in shaded compared with unshaded locations (P = 0.002). Bifenthrin applications in shaded tires only prevented early instar survival for approximately 2.6 wk. Aedes notoscriptus late instars did not appear in the treated unshaded tires. Culex quinquefasciatus colonized treated tires from the 2nd wk in both shaded and unshaded treatments. In the bioassay, water from bifenthrin-treated tires, through extrapolation, was found to kill approximately 100% of late instar Ae. notoscriptus for only approximately 2.0-2.2 wk in shaded and unshaded tires. Under conditions optimal for Aedes breeding, such as shaded locations, high ambient temperatures, high relative humidity, and high amounts of leaf/organic matter accumulations, bifenthrin may not be effective as a larval control measure in tires for greater than 2.0-2.6 wk.

Screening of Bacillus thuringiensis strains effective against mosquitoes Prospecção de estirpes de Bacillus thuringiensis efetivas contra mosquitos

Directory of Open Access Journals (Sweden)

Rose Gomes Monnerat

2005-02-01

Full Text Available The objective of this work was to evaluate 210 Bacillus thuringiensis strains against Aedes aegypti and Culex quinquefasciatus larvae to select the most effective. These strains were isolated from different regions of Brazil and are stored in a Bacillus spp. collection at Embrapa Recursos Genéticos e Biotecnologia, Brasília, Brazil. The selected strains were characterized by morphological (microscopy, biochemical (SDS-PAGE 10% and molecular (PCR methods. Six B. thuringiensis strains were identified as mosquito-toxic after the selective bioassays. None of the strains produced the expected PCR products for detection of cry4, cry11 and cyt1A genes. These results indicate that the activity of mosquitocidal Brazilian strains are not related with Cry4, Cry11 or Cyt proteins, so they could be used as an alternative bioinsecticide against mosquitoes.Neste trabalho foram realizados testes de patogenicidade com 210 estirpes de Bacillus thuringiensis contra larvas de Aedes aegypti e Culex quinquefasciatus, a fim de se determinar as mais eficazes. Estas estirpes foram isoladas de diversas regiões do Brasil e estão armazenadas na coleção de Bacillus spp. da Embrapa Recursos Genéticos e Biotecnologia. As estirpes selecionadas foram caracterizadas por métodos morfológicos (microscopia, bioquímicos (SDS-PAGE 10% e moleculares (Reação em Cadeia da Polimerase. Foram selecionadas seis estirpes entomopatogênicas de Bacillus thuringiensis. Nenhuma das estirpes de Bacillus thuringiensis apresentou produtos de PCR esperados para a detecção dos genes cry4, cry11 e cyt1A. A patogenicidade das estirpes não está associada à presença das toxinas Cry4, Cry11 ou Cyt, assim, essas estirpes poderão ser utilizadas para a formatação de um bioinseticida alternativo contra mosquitos.

Blocking the transmission of heartworm (Dirofilaria immitis to mosquitoes (Aedes aegypti by weekly exposure for one month to microfilaremic dogs treated once topically with dinotefuran-permethrin-pyriproxyfen

Directory of Open Access Journals (Sweden)

John W. McCall

2017-11-01

Full Text Available Abstract Background This study assessed the influence of a topical ectoparasiticide (dinotefuran-permethrin-pyriproxyfen, DPP, Vectra®3D, Ceva Animal Health on the acquisition of heartworm microfilariae by mosquitoes exposed to microfilaremic dogs weekly for 1 month. Methods Six beagle dogs (9.2 ± 1.6 kg body weight infected with Dirofilaria immitis were allocated to two groups of three dogs: an untreated control group and a DPP-treated group. Dogs were treated on Day 0 and exposed under sedation for 1 h to 80 ± 20 unfed Aedes aegypti. Each dog was exposed to mosquitoes released into mosquito-proof containers on Days −7 (pretreatment, 7, 14, 21 and 28. Up to 20 engorged mosquitoes were aspirated from the cage as soon as they were blood-fed. They were dissected and the blood from each midgut was stained for a microfilaria (MF count. After each exposure, mosquitoes were classified as live, moribund or dead and engorged or nonengorged. The number of dead mosquitoes was recorded daily for 16 days, when the live mosquitoes were dissected to count the infective third-stage larvae (L3. Results Prior to treatment, 95% of the engorged mosquitoes in both groups had MF. After treatment, engorgement rates for the treated group were 0%, 2.3%, 2.7% and 2.2% for Days 7, 14, 21 and 28, respectively, with anti-feeding efficacy (repellency of 100%, 98.0%, 95.8% and 97.0%, respectively. A total of 22 mosquitoes fed on treated dogs; most of them were dead within 24 h, and all were dead within 72 h. Only 2 unfed mosquitoes exposed to treated dogs survived the incubation period and no L3 were found in them. A total of 121 of the 132 (91.6% surviving mosquitoes that had engorged on untreated dogs had an average of 12.3 L3 per mosquito (range, 0-39. Conclusions DPP was more than 95% effective in inhibiting blood-feeding and killing both engorged and nonengorged mosquitoes exposed weekly to microfilaremic dogs for 28 days after treatment. Treatment with

Evaluation of immature mosquitocidal properties of Xanthium strumarium Linn. plant extracts against Culex mosquitoes (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Kasim Roba

2015-11-01

Full Text Available Objective: To evaluate immature mosquitocidal properties of Xanthium strumarium plant extracts against Culex mosquitoes at Entomology Laboratory, Maraki Campus, University of Gondar. Methods: The immature mosquitocidal activity of plant extracts was tested by following World Health Organization recommended protocol. Acetone, methanol and water extracts were prepared at 50, 100, 150, 200 and 250 mg/L concentrations and tested against third and fourth instar larvae and pupae of Culex mosquitoes. The mortality rate of immature mosquitoes was recorded after 24, 48 and 72 h exposure period continuously. Results: Third instar larvae after 24 h exposure period, maximum mortality of 77.80% was recorded at 250 mg/L concentration of acetone extract. After 48 h and 72 h exposure period, maximum mortality of 88.90% was recorded in acetone extract in all the tested concentration. The maximum mortality of fourth instar larvae was 88.90% in acetone extract at 200 and 250 mg/L concentrations. Pupal mortality was also greater in acetone extract. The percentage of mortality in all the stage of mosquitoes was higher in acetone extract followed by methanol and water extract. Conclusions: The percentage of mortality is associated with concentration of the extracts tested and exposure period. This laboratory study confirmed immature mosquitocidal activity of Xanthium strumarium leaf extracts against Culex mosquitoes. The aqueous leaf extract can be used by applying on small man-made breeding places to prevent adult emergence.

Expression of trypsin modulating oostatic factor (TMOF in an entomopathogenic fungus increases its virulence towards Anopheles gambiae and reduces fecundity in the target mosquito

Directory of Open Access Journals (Sweden)

Kamareddine Layla

2013-01-01

Full Text Available Abstract Background Adult and larval mosquitoes regulate food digestion in their gut with trypsin modulating oostatic factor (TMOF, a decapeptide hormone synthesized by the ovaries and the neuroendocrine system. TMOF is currently being developed as a mosquitocide, however, delivery of the peptide to the mosquito remains a significant challenge. Entomopathogenic fungi offer a means for targeting mosquitoes with TMOF. Findings The efficacy of wild type and transgenic Beauveria bassiana strains expressing Aedes aegypti TMOF (Bb-Aa1 were evaluated against larvae and sugar- and blood-fed adult Anopheles gambiae mosquitoes using insect bioassays. Bb-Aa1 displayed increased virulence against larvae, and sugar and blood fed adult A. gambiae when compared to the wild type parent strain. Median lethal dose (LD50 values decreased by ~20% for larvae, and ~40% for both sugar and blood-fed mosquitoes using Bb-Aa1 relative to the wild type parent. Median lethal time (LT50 values were lower for blood-fed compared to sugar-fed mosquitoes in infections with both wild type and Bb-Aa1. However, infection using Bb-Aa1 resulted in 15% to 25% reduction in LT50 values for sugar- and blood fed mosquitoes, and ~27% for larvae, respectively, relative to the wild type parent. In addition, infection with Bb-Aa1 resulted in a dramatic reduction in fecundity of the target mosquitoes. Conclusions B. bassiana expressing Ae. aegypti TMOF exhibited increased virulence against A. gambiae compared to the wild type strain. These data expand the range and utility of entomopathogenic fungi expressing mosquito-specific molecules to improve their biological control activities against mosquito vectors of disease.

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.

Dietary exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans via fish consumption and dioxin-like activity in fish determined by H4IIE-luc bioassay

Energy Technology Data Exchange (ETDEWEB)

Chan, Janet Kit Yan [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong SAR (China); School of Biological Sciences, The University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam, Hong Kong (China); Man, Yu Bon [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong SAR (China); Xing, Guan Hua [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong SAR (China); China National Environmental Monitoring Center, 100012, Beijing (China); Wu, Sheng Chun [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong SAR (China); State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Murphy, Margaret B. [Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China); Xu, Ying [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, 430072, Wuhan, Hubei Province (China); Wong, Ming H., E-mail: mhwong@hkbu.edu.hk [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong SAR (China)

2013-10-01

Dietary exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) via fish consumption in two major electronic (e) waste sites: Guiyu (GY), Guangdong Province and Taizhou (TZ), Zhejiang Province, and dioxin-like activity in fish determined by H4IIE-luc bioassay. In the present study, all fish were below EU's maximum allowable concentration in muscle of fish (4 pg WHO-TEQ/g wet wt), except crucian (4.28 pg WHO-TEQ/g wet wt) and silver carps (7.49 pg WHO-TEQ/g wet wt) collected from GY rivers. Moreover, the residual concentration in bighead carp collected from GY (2.15 pg WHO-TEQ/g wet wt) was close to the EU's action level (3 pg WHO-TEQ/g wet wt) which gives “early warning” to the competent authorities and operators to take measures to eliminate contamination. In addition, results indicated that the maximum human intake of PCDD/Fs via freshwater fish consumption in GY was 4.31 pg WHO-TEQ/kg bw/day, which exceeds the higher end of the tolerable daily intake recommended by the WHO, EC-SCF and JECFA (1–4, 2 and 2.3 pg WHO-TEQ/kg bw/day respectively). Furthermore, H4IIE-luc cell bioassay provides a very sensitive and cost-efficient screening tool for assessing the overall dioxin-like toxicity in the study, and is therefore valuable for high-throughput environmental monitoring studies. - Highlights: ► Freshwater fish are contaminated by PCDD/F at 2 e-waste sites in China. ► Guiyu residents are exposed to unsafe levels of PCDD/Fs through dietary exposure. ► H4IIE-luc cell bioassay provides a very sensitive screening tool for PCDD/Fs.

Dietary exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans via fish consumption and dioxin-like activity in fish determined by H4IIE-luc bioassay

International Nuclear Information System (INIS)

Chan, Janet Kit Yan; Man, Yu Bon; Xing, Guan Hua; Wu, Sheng Chun; Murphy, Margaret B.; Xu, Ying; Wong, Ming H.

2013-01-01

Dietary exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) via fish consumption in two major electronic (e) waste sites: Guiyu (GY), Guangdong Province and Taizhou (TZ), Zhejiang Province, and dioxin-like activity in fish determined by H4IIE-luc bioassay. In the present study, all fish were below EU's maximum allowable concentration in muscle of fish (4 pg WHO-TEQ/g wet wt), except crucian (4.28 pg WHO-TEQ/g wet wt) and silver carps (7.49 pg WHO-TEQ/g wet wt) collected from GY rivers. Moreover, the residual concentration in bighead carp collected from GY (2.15 pg WHO-TEQ/g wet wt) was close to the EU's action level (3 pg WHO-TEQ/g wet wt) which gives “early warning” to the competent authorities and operators to take measures to eliminate contamination. In addition, results indicated that the maximum human intake of PCDD/Fs via freshwater fish consumption in GY was 4.31 pg WHO-TEQ/kg bw/day, which exceeds the higher end of the tolerable daily intake recommended by the WHO, EC-SCF and JECFA (1–4, 2 and 2.3 pg WHO-TEQ/kg bw/day respectively). Furthermore, H4IIE-luc cell bioassay provides a very sensitive and cost-efficient screening tool for assessing the overall dioxin-like toxicity in the study, and is therefore valuable for high-throughput environmental monitoring studies. - Highlights: ► Freshwater fish are contaminated by PCDD/F at 2 e-waste sites in China. ► Guiyu residents are exposed to unsafe levels of PCDD/Fs through dietary exposure. ► H4IIE-luc cell bioassay provides a very sensitive screening tool for PCDD/Fs

Polymeric nanoencapsulation of insect repellent: Evaluation of its bioefficacy on Culex quinquefasciatus mosquito population and effective impregnation onto cotton fabrics for insect repellent clothing

Directory of Open Access Journals (Sweden)

A.P.B. Balaji

2017-10-01

Full Text Available Diethylphenylacetamide (Bulk-DEPA, an organic insect repellent was subjected to Poly(ethylene glycol (PEG polymerization followed by Phase Inversion Temperature (PIT emulsification method to yield the polymeric nanodroplets of DEPA (Nano-DEPA. The mean hydrodynamic diameter was found to be 149 ± 1.06 nm. The efficacy of Bulk-DEPA and Nano-DEPA was comparatively investigated on the Culex quinquefasciatus mosquito population. The larvicidal bioassay was performed on the 1st, 2nd, and 3rd instar larvae of Culex quinquefasciatus and the median lethal indices (LC50 of was found to be 0.055, 0.208, 1.397 mg/L and 0.023, 0.144, 0.260 mg/L for Bulk-DEPA and Nano-DEPA respectively. The histopathological studies were found to be corroborative with the larvicidal bioassay. The median knockdown indices (KD50 on 2–3 day old sucrose fed adult mosquitoes determined by WHO cone bioassay and was found to be 55.168 and 33.277 mg/L for Bulk-DEPA and Nano-DEPA. The obtained results indicate the improved efficacy possessed by the Nano-DEPA as comparative to Bulk-DEPA even at lower concentrations. Further, the Nano-DEPA was impregnated onto the alginate cross-linked (ACL and Plain (PL cotton fabrics, and the Washing resistance index (WRI was determined. The obtained results indicate the higher WRI possessed by the ACL cotton fabric than the PL cotton fabric. This was owing to the effective physical entrapment of Nano-DEPA onto the alginate matrices, which was further substantiated by high-resolution scanning electron microscopic (HR-SEM studies. Overall, the present study has emphasized the benefit of formulating Bulk-DEPA into Nano-DEPA to exert higher efficacy on the mosquito population. In addition, study has provided the methodology for the effective impregnation of Nano-DEPA onto the cotton fabrics for the reliable application in long lasting insect repellent clothing.

Controlling Mosquitoes Outside

Centers for Disease Control (CDC) Podcasts

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.

Fluconazole Pharmacokinetics in Galleria mellonella Larvae and Performance Evaluation of a Bioassay Compared to Liquid Chromatography-Tandem Mass Spectrometry for Hemolymph Specimens

DEFF Research Database (Denmark)

Astvad, Karen Marie Thyssen; Meletiadis, Joseph; Whalley, Sarah

2017-01-01

The invertebrate model organism Galleria mellonella can be used to assess the efficacy of treatment of fungal infection. The fluconazole dose best mimicking human exposure during licensed dosing is unknown. We validated a bioassay for fluconazole detection in hemolymph and determined...... the fluconazole pharmacokinetics and pharmacodynamics in larval hemolymph in order to estimate a humanized dose for future experiments. A bioassay using 4-mm agar wells, 20 μl hemolymph, and the hypersusceptible Candida albicans DSY2621 was established and compared to a validated liquid chromatography-tandem mass...... spectrometry (LC-MS-MS) method. G. mellonella larvae were injected with fluconazole (5, 10, and 20 mg/kg of larval weight), and hemolymph was harvested for 24 h for pharmacokinetics calculations. The exposure was compared to the human exposure during standard licensed dosing. The bioassay had a linear standard...

Research Contributing to Improvements in Controlling Florida’s Mosquitoes and Mosquito-borne Diseases

OpenAIRE

Walter J. Tabachnick

2016-01-01

Research on mosquitoes and mosquito-borne diseases has contributed to improvements in providing effective, efficient, and environmentally proper mosquito control. Florida has benefitted from several research accomplishments that have increased the state?s mosquito control capabilities. Research with Florida?s mosquitoes has resulted in the development of ecologically sound management of mosquito impoundments on Florida?s east coast. This strategy, called Rotational Impoundment Management (RIM...

Rapid bioassay for oil-contaminated soil

Energy Technology Data Exchange (ETDEWEB)

Ashworth, J. [ALS Environmental, Edmonton, AB (Canada); Oosterbroek, L. [HydroQual, Calgary, AB (Canada)

2010-07-01

This PowerPoint presentation described a study conducted to develop a rapid bioassay for soils contaminated with oil. The bioassay method was designed for a weight of evidence (WoE) approach and eco-contact guideline derivation protocol. Microtox bioassays were conducted on cyclodextrin extracts of soil quantified by solvent extraction and gas chromatography. The method was demonstrated using straight {beta}-cyclodextrin soil extracts and activated {beta}-cyclodextrin soil extracts. An analysis of the methods showed that the activation step weakens or breaks the cyclodextrin and polycyclic hydrocarbon (PHC) inclusion complex. The released PHC became toxic to the microtox organism. Results from the bioassays were then correlated with earthworm reproduction bioassay results. tabs., figs.

The costs of infection and resistance as determinants of West Nile virus susceptibility in Culex mosquitoes

Directory of Open Access Journals (Sweden)

Styer Linda M

2011-10-01

Full Text Available Abstract Background Understanding the phenotypic consequences of interactions between arthropod-borne viruses (arboviruses and their mosquito hosts has direct implications for predicting the evolution of these relationships and the potential for changes in epidemiological patterns. Although arboviruses are generally not highly pathogenic to mosquitoes, pathology has at times been noted. Here, in order to evaluate the potential costs of West Nile virus (WNV infection and resistance in a primary WNV vector, and to assess the extent to which virus-vector relationships are species-specific, we performed fitness studies with and without WNV exposure using a highly susceptible Culex pipiens mosquito colony. Specifically, we measured and compared survival, fecundity, and feeding rates in bloodfed mosquitoes that were (i infected following WNV exposure (susceptible, (ii uninfected following WNV exposure (resistant, or (iii unexposed. Results In contrast to our previous findings with a relatively resistant Cx. tarsalis colony, WNV infection did not alter fecundity or blood-feeding behaviour of Cx. pipiens, yet results do indicate that resistance to infection is associated with a fitness cost in terms of mosquito survival. Conclusions The identification of species-specific differences provides an evolutionary explanation for variability in vector susceptibility to arboviruses and suggests that understanding the costs of infection and resistance are important factors in determining the potential competence of vector populations for arboviruses.

Fluconazole Pharmacokinetics in Galleria mellonella Larvae and Performance Evaluation of a Bioassay Compared to Liquid Chromatography-Tandem Mass Spectrometry for Hemolymph Specimens

Science.gov (United States)

Astvad, Karen Marie Thyssen; Meletiadis, Joseph; Whalley, Sarah

2017-01-01

ABSTRACT The invertebrate model organism Galleria mellonella can be used to assess the efficacy of treatment of fungal infection. The fluconazole dose best mimicking human exposure during licensed dosing is unknown. We validated a bioassay for fluconazole detection in hemolymph and determined the fluconazole pharmacokinetics and pharmacodynamics in larval hemolymph in order to estimate a humanized dose for future experiments. A bioassay using 4-mm agar wells, 20 μl hemolymph, and the hypersusceptible Candida albicans DSY2621 was established and compared to a validated liquid chromatography-tandem mass spectrometry (LC–MS-MS) method. G. mellonella larvae were injected with fluconazole (5, 10, and 20 mg/kg of larval weight), and hemolymph was harvested for 24 h for pharmacokinetics calculations. The exposure was compared to the human exposure during standard licensed dosing. The bioassay had a linear standard curve between 1 and 20 mg/liter. Accuracy and coefficients of variation (percent) values were below 10%. The Spearman coefficient between assays was 0.94. Fluconazole larval pharmacokinetics followed one-compartment linear kinetics, with the 24-h area under the hemolymph concentration-time curve (AUC24 h) being 93, 173, and 406 mg · h/liter for the three doses compared to 400 mg · h/liter in humans under licensed treatment. In conclusion, a bioassay was validated for fluconazole determination in hemolymph. The pharmacokinetics was linear. An exposure comparable to the human exposure during standard licensed dosing was obtained with 20 mg/kg. PMID:28760893

Comparison of mouse and swine bioassays for determination of soil arsenic relative bioavailability

Science.gov (United States)

Evaluation of soil arsenic (As) relative bioavailability (RBA) is essential to accurately assess human exposure to As contaminated soils via the incidental ingestion pathway. A variety of animal bioassays have been developed to estimate As RBA in contaminated soils and dusts, wit...

Requirements for radiation emergency urine bioassay techniques for the public and first responders.

Science.gov (United States)

Li, Chunsheng; Vlahovich, Slavica; Dai, Xiongxin; Richardson, Richard B; Daka, Joseph N; Kramer, Gary H

2010-11-01

Following a radiation emergency, the affected public and the first responders may need to be quickly assessed for internal contamination by the radionuclides involved. Urine bioassay is one of the most commonly used methods for assessing radionuclide intake and radiation dose. This paper attempts to derive the sensitivity requirements (from inhalation exposure) for the urine bioassay techniques for the top 10 high-risk radionuclides that might be used in a terrorist attack. The requirements are based on a proposed reference dose to adults of 0.1 Sv (CED, committed effective dose). In addition, requirements related to sample turnaround time and field deployability of the assay techniques are also discussed. A review of currently available assay techniques summarized in this paper reveals that method development for ²⁴¹Am, ²²⁶Ra, ²³⁸Pu, and ⁹⁰Sr urine bioassay is needed.

Some environmental and biological factors influencing the activity of entomopathogenic Bacillus on mosquito larvae in Brazil

Directory of Open Access Journals (Sweden)

R. A. G. B Consoli

1995-02-01

Full Text Available The influence of environmental and biological factors on the efficacy of Bacillus thuringiensis serovar israelensis and B. sphaericus as mosquito larvicides are reviewed. The importance of strain dependence, cultivating media/methods, mosquito species/specificity, formulations and their relation to mosquito feeding habits, as well as temperature, solar exposure, larval density and concomitant presence of other aquatic organisms are addressed with reference to the present status of knowledge in Brazil.

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.

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.

Mediation of deet repellency in mosquitoes (Diptera: Culicidae) by species, age, and parity.

Science.gov (United States)

Barnard, D R

1998-05-01

Laboratory bioassays assessed differences in the protection time provided by the repellent deet (N,N-diethyl-3-methylbenzamide) against 5-d-old nulliparous and 10-, 15-, and 20-d-old nulliparous and parous female Aedes aegypti (L.), Anopheles albimanus (Weidemann), and Anopheles quadrimaculatus Say sensu lato. Mean protection time was shortest against An. albimanus (1.6 h) and An. quadrimaculatus (1.5 h) and longest against Ae. aegypti (6.5 h), but was not significantly influenced by mosquito age or parity. Mean percentage of biting at repellent failure time was highest in An. albimanus (14.2%), followed by An. quadrimaculatus (7.0%) and Ae. aegypti (2.9%), was higher in parous females (10.8%) than in nulliparous females (5.9%), and was highest overall (35%) in 20-d-old parous An. albimanus. Interaction between mosquito species and parity and between parity and age factors, respectively, resulted from a significant decrease in percentage of biting by parous An. quadrimaculatus compared with other females, and a significant increase in biting by 20-d-old parous females compared with other females. The main finding of this study is that repellent protection time is unaffected by parity; this is important because parous mosquitoes are the primary target of personal-protection measures in disease-endemic areas. When repellent failure did occur, there was a higher risk of bite by old, parous An. albimanus than for any other species, age, or parity grouping of females.

Larvicidal, ovicidal, and oviposition-deterrent activities of four plant extracts against three mosquito species.

Science.gov (United States)

Prathibha, K P; Raghavendra, B S; Vijayan, V A

2014-05-01

In mosquito control programs, insecticides of botanical origin have the potential to eliminate eggs, larvae, and adults. So, the larvicidal, ovicidal, and oviposition-deterrent activities of petroleum ether and ethyl acetate extracts of the leaves of Eugenia jambolana, Solidago canadensis, Euodia ridleyi, and Spilanthes mauritiana were assayed against the three vector mosquito species, namely Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The larval bioassay was conducted following the World Health Organization method. The maximum larval mortality was found with ethyl acetate extract of S. mauritiana against the larvae of A. stephensi, A. aegypti, and C. quinquefasciatus with LC50 values of 11.51, 28.1, 14.10 ppm, respectively. The mean percent hatchability of the ovicidal activity was observed at 48-h post-treatment. The percent hatchability was found to be inversely proportional to the concentration of the extract and directly proportional to the number of eggs. The flower head extract of S. mauritiana gave 100% mortality followed by E. ridleyi, S. canadensis, and E. jambolana against the eggs of the three mosquito vectors. For oviposition-deterrent effect, out of the five concentrations tested (20, 40, 60, 80, and 100 ppm), the concentration of 100 ppm showed a significant egg laying-deterrent capacity. The oviposition activity index value of E. jambolana, E. ridleyi, S. canadensis, and S. mauritiana against A. aegypti, A. stephensi, C. quinquefasciatus at 100 ppm were -0.71, -0.71, -0.90, -0.93, -0.85, -0.91, -1, -1, -0.71, -0.85, -1, and -1, respectively. These results suggest that the leaf/flower extracts of certain local plants have the potential to be developed as possible eco-friendly means for the control of mosquitoes.

Evaluation of the toxicity of two soils from Jales Mine (Portugal) using aquatic bioassays.

Science.gov (United States)

Loureiro, Susana; Ferreira, Abel L G; Soares, Amadeu M V M; Nogueira, António J A

2005-10-01

Soil contamination can be one path for streams and groundwater contamination. As a complement of chemical analysis and total contaminants determination, bioassays can provide information on the bioavailable fraction of chemical compounds, focusing on the retention and habitat function of soils. In this study the evaluation of the toxicity of two soils from the abandoned Jales Mine (Portugal) regarded both functions. The buffer capacity of soils was tested with bioassays carried out using the cladoceran Daphnia magna and the marine bacteria Vibrio fischeri. The habitat function of soils was evaluated with the reproduction bioassay with the collembolan Folsomia candida. The Microtox solid-phase test was performed with V. fischeri using soil as test medium, and soil elutriates were extracted to perform the Microtox basic test, and an immobilization and reproduction bioassay with D. magna. The marine bacteria showed high sensitivity to the soil with low heavy metal content (JNC soil) and to JNC soil elutriates, while the soil with highest heavy metal content (JC soil) or soil elutriates exposure did not cause any toxic effect. In the bioassays with D. magna, organisms showed sensitivity to JNC and also to JC soil elutriates. Both mobilization and reproduction features were inhibited. The bioassay with F. candida did not reflect any influence of the contaminants on their reproduction. Although JNC soil presented lower heavy metal contents, elutriates showed different patterns of contamination when compared to JC soil and elutriates, which indicates different retention and buffer capacities between soils. Results obtained in this study underlined the sensitivity and importance of soil elutriate bioassays with aquatic organisms in the evaluation strategy in soil ERA processes.

Bioassay Laboratory

Data.gov (United States)

Federal Laboratory Consortium — The Bioassay Laboratory is an accredited laboratory capable of conducting standardized and innovative environmental testing in the area of aquatic ecotoxicology. The...

Research Contributing to Improvements in Controlling Florida's Mosquitoes and Mosquito-borne Diseases.

Science.gov (United States)

Tabachnick, Walter J

2016-09-28

Research on mosquitoes and mosquito-borne diseases has contributed to improvements in providing effective, efficient, and environmentally proper mosquito control. Florida has benefitted from several research accomplishments that have increased the state's mosquito control capabilities. Research with Florida's mosquitoes has resulted in the development of ecologically sound management of mosquito impoundments on Florida's east coast. This strategy, called Rotational Impoundment Management (RIM), has improved the ability to target the delivery of pesticides and has helped to reduce non-target effects and environmental damage. Research has led to the development of an arbovirus surveillance system which includes sentinel chicken surveillance, real time use of environmental contributing factors like meteorology and hydrology to target mosquito control, as well as public health efforts to mitigate disease outbreaks to areas with risk of disease. These research driven improvements have provided substantial benefits to all of Florida. More research is needed to meet the future challenges to reduce emerging pathogens like Zika virus and the consequences of environmental changes like global climate change that are likely to influence the effects of mosquito-borne pathogens on human health and well-being.

Does mosquito control have an effect on mosquito-borne disease? The case of Ross River virus disease and mosquito management in Queensland, Australia.

Science.gov (United States)

Tomerini, Deanna M; Dale, Pat E; Sipe, Neil

2011-03-01

We examined the relationship between types of mosquito control programs and the mosquito-borne Ross River virus (RRV) disease in Queensland, Australia. Mosquito control information was collected through a survey of the responsible agencies (local governments), and RRV disease notification data were provided by the Queensland state health authority. The study developed a typology of mosquito control programs, based on the approaches used. Based on the analysis of data on RRV disease rates between mosquito control types within 4 climatic regions, each region had different combinations of mosquito control strategies in their programs; there were also general similarities in the relationship between program types and RRV rates between the regions. The long-term RRV disease rates were lower in areas where the mosquito control program included pre-emptive (rather than reactive) surveillance based on an extensive (rather than incomplete) knowledge of mosquito habitats, and where treatment of both saltwater and freshwater habitats (compared to only saltwater habitats, in coastal areas) occurred. The data indicate that mosquito control is an effective public health intervention to reduce mosquito-borne disease; hence, climate change adaptation strategies should ensure that adequate resources are available for effective vector control so as to manage the risk of mosquito-borne diseases.

Nest Mosquito Trap quantifies contact rates between nesting birds and mosquitoes.

Science.gov (United States)

Caillouët, Kevin A; Riggan, Anna E; Rider, Mark; Bulluck, Lesley P

2012-06-01

Accurate estimates of host-vector contact rates are required for precise determination of arbovirus transmission intensity. We designed and tested a novel mosquito collection device, the Nest Mosquito Trap (NMT), to collect mosquitoes as they attempt to feed on unrestrained nesting birds in artificial nest boxes. In the laboratory, the NMT collected nearly one-third of the mosquitoes introduced to the nest boxes. We then used these laboratory data to estimate our capture efficiency of field-collected bird-seeking mosquitoes collected over 66 trap nights. We estimated that 7.5 mosquitoes per trap night attempted to feed on nesting birds in artificial nest boxes. Presence of the NMT did not have a negative effect on avian nest success when compared to occupied nest boxes that were not sampled with the trap. Future studies using the NMT may elucidate the role of nestlings in arbovirus transmission and further refine estimates of nesting bird and vector contact rates. © 2012 The Society for Vector Ecology.

Repellent Action Of Neem (Azadiracta India Seed Oil Against Aedes Aegypti Mosquitoes

Directory of Open Access Journals (Sweden)

Hati A K

1995-01-01

Full Text Available Neem (Azadiracta India seed oil in appropriate amount when smeared on the surface of the hand showed excellent repellent action against Aedes aegypti mosquitoes. When 1 ml of oil was spread on the hand, with an approximate area of 160 sq cm the percentage of alighting and blood fed mosquitoes in the experimental cages varied from 14 to 78 and 4 to 46 respectively. This percentage decreased to 6 to 18 and 0 to 16 respectively when the amount of oil applied was 1.5 ml. Only 0-4% of the mosquitoes alighted on the skin of which 2% only took the blood meal when 2 ml of the oil was used to cover the hand. In the control cages cent percent of the mosquitoes alighted and sucked blood. The repellent action was directly proportional to the hour of exposure to the oil. It was also observed that even after alighting on a oil- smeared skin a sizeable proportion of mosquitoes were not able to imbibe blood meal. Neem seed oil was non-toxic, non- irritating to skin.

Mosquito Bites

Science.gov (United States)

... virus to humans. Other mosquito-borne infections include yellow fever, malaria and some types of brain infection (encephalitis). ... certain diseases, such as West Nile virus, malaria, yellow fever and dengue fever. The mosquito obtains a virus ...

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

Full Text Available Viral diseases transmitted via Aedes mosquitoes are on the rise, such as Zika, dengue, and chikungunya. Novel tools to mitigate Aedes mosquitoes-transmitted diseases are urgently needed. We tested whether commercially insecticide-impregnated school uniforms can reduce dengue incidence in school children.We designed a cluster-randomised controlled trial in Thailand. The primary endpoint was laboratory-confirmed dengue infections. Secondary endpoints were school absenteeism; and impregnated uniforms' 1-hour knock-down and 24 hour mosquito mortality as measured by standardised WHOPES bioassay cone tests at baseline and after repeated washing. Furthermore, entomological assessments inside classrooms and in outside areas of schools were conducted.We enrolled 1,811 pupils aged 6-17 from 5 intervention and 5 control schools. Paired serum samples were obtained from 1,655 pupils. In the control schools, 24/641 (3.7% and in the intervention schools 33/1,014 (3.3% students had evidence of new dengue infections during one school term (5 months. There was no significant difference in proportions of students having incident dengue infections between the intervention and control schools, with adjustment for clustering by school. WHOPES cone tests showed a 100% knock down and mortality of Aedes aegypti mosquitoes exposed to impregnated clothing at baseline and up to 4 washes, but this efficacy rapidly declined to below 20% after 20 washes, corresponding to a weekly reduction in knock-down and mosquito mortality by 4.7% and 4.4% respectively. Results of the entomological assessments showed that the mean number of Aedes aegypti mosquitoes caught inside the classrooms of the intervention schools was significantly reduced in the month following the introduction of the impregnated uniforms, compared to those collected in classrooms of the control schools (p = 0.04.Entomological assessments showed that the intervention had some impact on the number of Aedes

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

Viral diseases transmitted via Aedes mosquitoes are on the rise, such as Zika, dengue, and chikungunya. Novel tools to mitigate Aedes mosquitoes-transmitted diseases are urgently needed. We tested whether commercially insecticide-impregnated school uniforms can reduce dengue incidence in school children. We designed a cluster-randomised controlled trial in Thailand. The primary endpoint was laboratory-confirmed dengue infections. Secondary endpoints were school absenteeism; and impregnated uniforms' 1-hour knock-down and 24 hour mosquito mortality as measured by standardised WHOPES bioassay cone tests at baseline and after repeated washing. Furthermore, entomological assessments inside classrooms and in outside areas of schools were conducted. We enrolled 1,811 pupils aged 6-17 from 5 intervention and 5 control schools. Paired serum samples were obtained from 1,655 pupils. In the control schools, 24/641 (3.7%) and in the intervention schools 33/1,014 (3.3%) students had evidence of new dengue infections during one school term (5 months). There was no significant difference in proportions of students having incident dengue infections between the intervention and control schools, with adjustment for clustering by school. WHOPES cone tests showed a 100% knock down and mortality of Aedes aegypti mosquitoes exposed to impregnated clothing at baseline and up to 4 washes, but this efficacy rapidly declined to below 20% after 20 washes, corresponding to a weekly reduction in knock-down and mosquito mortality by 4.7% and 4.4% respectively. Results of the entomological assessments showed that the mean number of Aedes aegypti mosquitoes caught inside the classrooms of the intervention schools was significantly reduced in the month following the introduction of the impregnated uniforms, compared to those collected in classrooms of the control schools (p = 0.04). Entomological assessments showed that the intervention had some impact on the number of Aedes mosquitoes inside

Countering a bioterrorist introduction of pathogen-infected mosquitoes through mosquito control.

Science.gov (United States)

Tabachnick, Walter J; Harvey, William R; Becnel, James J; Clark, Gary G; Connelly, C Roxanne; Day, Jonathan F; Linser, Paul J; Linthicum, Kenneth J

2011-06-01

The release of infected mosquitoes or other arthropods by bioterrorists, i.e., arboterrorism, to cause disease and terror is a threat to the USA. A workshop to assess mosquito control response capabilities to mount rapid and effective responses to eliminate an arboterrorism attack provided recommendations to improve capabilities in the USA. It is essential that mosquito control professionals receive training in possible responses, and it is recommended that a Council for Emergency Mosquito Control be established in each state to coordinate training, state resources, and actions for use throughout the state.

Larvicidal activity of Zanthoxylum acanthopodium essential oil against the malaria mosquitoes, Anopheles anthropophagus and Anopheles sinensis.

Science.gov (United States)

He, Qi; Wang, Wenxia; Zhu, Liang

2018-05-15

Zanthoxylum acanthopodium has insecticidal effect in Chinese traditional medicine. In this study, the essential oil from the dried Zanthoxylum plant was used as a larvicidal compound against the malaria mosquitoes, Anopheles anthropophagus and Anopheles sinensis. Compounds in the Zanthoxylum essential oil were investigated by gas chromatography and mass spectroscopy (GC-MS). The larvicidal bioassays of the whole oil, as well as the main compounds in the oil (estragole and eucalyptol) were performed using WHO method. In total, 63 main compounds (99.32%) were found in the oils, including estragole (15.46%), eucalyptol (10.94%), β-caryophyllene (5.52%), cis-linalool oxide (3.76%), cis-limonene oxide (3.06%). A dose-dependent effect on mortality was recorded with increasing concentrations of essential oil and compounds increasing mortality of the larvae. Larvicidal bioassays revealed that 24 h LC 50 of the whole essential oil was 36.00 mg/L and LC 90 was 101.49 mg/L against An. anthropophagus, while LC 50 was 49.02 mg/L and LC 90 was 125.18 mg/L against An. sinensis. Additionally, 24 h LC 50 of estragole were 38.56 and 41.67 mg/L against An. anthropophagus and An. sinensis, respectively, while the related LC 90 were 95.90 and 107.89 mg/L. LC 50 of eucalyptol were 42.41 and 45.49 mg/L against An. anthropophagus and An. sinensis, while the related LC 90 were 114.45 and 124.95 mg/L. The essential oil of Z. acanthopodium and its several major compounds may have potential for use in the control of malaria mosquitoes.

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

A Bioassay System Using Bioelectric Signals from Small Fish

Science.gov (United States)

Terawaki, Mitsuru; Soh, Zu; Hirano, Akira; Tsuji, Toshio

Although the quality of tap water is generally examined using chemical assay, this method cannot be used for examination in real time. Against such a background, the technique of fish bioassay has attracted attention as an approach that enables constant monitoring of aquatic contamination. The respiratory rhythms of fish are considered an efficient indicator for the ongoing assessment of water quality, since they are sensitive to chemicals and can be indirectly measured from bioelectric signals generated by breathing. In order to judge aquatic contamination accurately, it is necessary to measure bioelectric signals from fish swimming freely as well as to stably discriminate measured signals, which vary between individuals. However, no bioassay system meeting the above requirements has yet been established. This paper proposes a bioassay system using bioelectric signals generated from small fish in free-swimming conditions. The system records signals using multiple electrodes to cover the extensive measurement range required in a free-swimming environment, and automatically discriminates changes in water quality from signal frequency components. This discrimination is achieved through an ensemble classification method using probability neural networks to solve the problem of differences between individual fish. The paper also reports on the results of related validation experiments, which showed that the proposed system was able to stably discriminate between water conditions before and after bleach exposure.

In vitro bioassays for detecting dioxin-like activity--application potentials and limits of detection, a review.

Science.gov (United States)

Eichbaum, Kathrin; Brinkmann, Markus; Buchinger, Sebastian; Reifferscheid, Georg; Hecker, Markus; Giesy, John P; Engwall, Magnus; van Bavel, Bert; Hollert, Henner

2014-07-15

Use of in vitro assays as screening tool to characterize contamination of a variety of environmental matrices has become an increasingly popular and powerful toolbox in the field of environmental toxicology. While bioassays cannot entirely substitute analytical methods such as gas chromatography-mass spectrometry (GC-MS), the increasing improvement of cell lines and standardization of bioassay procedures enhance their utility as bioanalytical pre-screening tests prior to more targeted chemical analytical investigations. Dioxin-receptor-based assays provide a holistic characterization of exposure to dioxin-like compounds (DLCs) by integrating their overall toxic potential, including potentials of unknown DLCs not detectable via e.g. GC-MS. Hence, they provide important additional information with respect to environmental risk assessment of DLCs. This review summarizes different in vitro bioassay applications for detection of DLCs and considers the comparability of bioassay and chemical analytically derived toxicity equivalents (TEQs) of different approaches and various matrices. These range from complex samples such as sediments through single reference to compound mixtures. A summary of bioassay derived detection limits (LODs) showed a number of current bioassays to be equally sensitive as chemical methodologies, but moreover revealed that most of the bioanalytical studies conducted to date did not report their LODs, which represents a limitation with regard to low potency samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Bioassay criteria for environmental restoration workers

International Nuclear Information System (INIS)

Carbaugh, E.H.; Bihl, D.E.

1993-01-01

Environmental restoration (ER) work at the U. S. Department of Energy Hanford Site posed questions concerning when to perform bioassay monitoring of workers for potential intakes of radioactivity. Application of criteria originally developed for use inside radionuclide processing facilities to ER work resulted in overly restrictive bioassay requirements. ER work typically involves site characterization or, excavating large quantities of potentially contaminated soil, rather than working with concentrated quantities of radioactivity as in a processing facility. An improved approach, tailored to ER work, provided soil contamination concentrations above which worker bioassay would be required. Soil concentrations were derived assuming acute or chronic intakes of 2% of an Annual Limit on Intake (ALI), or a potential committed effective dose equivalent of 100 mrem, and conservative dust loading of air from the work. When planning ER work, the anticipated soil concentration and corresponding need for bioassay could be estimated from work-site historical records. Once site work commenced, soil sampling and work-place surveys could be used to determine bioassay needs. This approach substantially reduced the required number of bioassay samples with corresponding reductions in analytical costs, schedules, and more flexible work-force management. (Work supported by the US Department of Energy under contract DOE-AC06-76RLO 1830.)

Evidence of anopheline mosquito resistance to agrochemicals in northern Thailand.

Science.gov (United States)

Overgaard, Hans J; Sandve, Simen R; Suwonkerd, Wannapa

2005-01-01

The objective of this study was to assess insecticide resistance in anopheline mosquito populations in agroecosystems with high and low insecticide use in a malaria endemic area in Chiang Mai province in northern Thailand. Anopheline mosquitoes were collected in May and June 2004 from two locations with different agricultural insecticide intensity (HIGH and LOW), but similar in vector control strategies. The F1-generation of Anopheles maculatus s.s. and An. sawadwongporni were subjected to diagnostic doses of methyl parathion (MeP) and cypermethrin (Cyp), both commonly used insecticides in fruit orchards in Thailand. An. minimus A from the HIGH location was subjected to diagnostic doses to Cyp. CDC bottle bioassays were used to determine insecticide susceptibility. Time-mortality data were subjected to Probit analyses to estimate lethal time values (LT50 and LT90). Lethal time ratios (LTR) were computed to determine differences in lethal time response between populations from HIGH and LOW locations. The mortality of An. maculatus to MeP was 74% and 92% in the HIGH and LOW locations, respectively. The corresponding figures for An. sawadwongporni were 94% and 99%. There was no indication of resistance to Cyp for all species tested in either location. The LT90 and LT50 values of An. maculatus s.s. subjected to diagnostic doses of MeP were significantly different between locations (p<0.05). Reduced susceptibility to MeP in mosquito populations in the HIGH location is caused by intensive agricultural pest control and not by vector control activities, because organophosphates have never been used for vector control in the area. Our results indicate that there are still susceptible anopheline populations to pyrethroids, which is consistent with other research from the region. Therefore, there is presently no direct threat to vector control. However increased use of pyrethroids in agriculture may cause problems for future vector control.

Bioassay programs for radiation protection

International Nuclear Information System (INIS)

1979-01-01

This report discusses the rationale for the establishment of bioassay programs as a means of protection for radiation workers in the nuclear industry. The bioassay program of the Radiation Protection Bureau is described for the years 1966-1978 and plans for future changes are outlined. (auth)

Research Contributing to Improvements in Controlling Florida’s Mosquitoes and Mosquito-Borne Diseases

Science.gov (United States)

Tabachnick, Walter J.

2016-01-01

Research on mosquitoes and mosquito-borne diseases has contributed to improvements in providing effective, efficient, and environmentally proper mosquito control. Florida has benefitted from several research accomplishments that have increased the state’s mosquito control capabilities. Research with Florida’s mosquitoes has resulted in the development of ecologically sound management of mosquito impoundments on Florida’s east coast. This strategy, called Rotational Impoundment Management (RIM), has improved the ability to target the delivery of pesticides and has helped to reduce non-target effects and environmental damage. Research has led to the development of an arbovirus surveillance system which includes sentinel chicken surveillance, real time use of environmental contributing factors like meteorology and hydrology to target mosquito control, as well as public health efforts to mitigate disease outbreaks to areas with risk of disease. These research driven improvements have provided substantial benefits to all of Florida. More research is needed to meet the future challenges to reduce emerging pathogens like Zika virus and the consequences of environmental changes like global climate change that are likely to influence the effects of mosquito-borne pathogens on human health and well-being. PMID:27690112

Research Contributing to Improvements in Controlling Florida’s Mosquitoes and Mosquito-borne Diseases

Directory of Open Access Journals (Sweden)

Walter J. Tabachnick

2016-09-01

Full Text Available Research on mosquitoes and mosquito-borne diseases has contributed to improvements in providing effective, efficient, and environmentally proper mosquito control. Florida has benefitted from several research accomplishments that have increased the state’s mosquito control capabilities. Research with Florida’s mosquitoes has resulted in the development of ecologically sound management of mosquito impoundments on Florida’s east coast. This strategy, called Rotational Impoundment Management (RIM, has improved the ability to target the delivery of pesticides and has helped to reduce non-target effects and environmental damage. Research has led to the development of an arbovirus surveillance system which includes sentinel chicken surveillance, real time use of environmental contributing factors like meteorology and hydrology to target mosquito control, as well as public health efforts to mitigate disease outbreaks to areas with risk of disease. These research driven improvements have provided substantial benefits to all of Florida. More research is needed to meet the future challenges to reduce emerging pathogens like Zika virus and the consequences of environmental changes like global climate change that are likely to influence the effects of mosquito-borne pathogens on human health and well-being.

Larval application of sodium channel homologous dsRNA restores pyrethroid insecticide susceptibility in a resistant adult mosquito population.

Science.gov (United States)

Bona, Ana Caroline Dalla; Chitolina, Rodrigo Faitta; Fermino, Marise Lopes; de Castro Poncio, Lisiane; Weiss, Avital; Lima, José Bento Pereira; Paldi, Nitzan; Bernardes, Emerson Soares; Henen, Jonathan; Maori, Eyal

2016-07-14

Mosquitoes host and pass on to humans a variety of disease-causing pathogens such as infectious viruses and other parasitic microorganisms. The emergence and spread of insecticide resistance is threatening the effectiveness of current control measures for common mosquito vector borne diseases, such as malaria, dengue and Zika. Therefore, the emerging resistance to the widely used pyrethroid insecticides is an alarming problem for public health. Herein we demonstrated the use of RNA interference (RNAi) to increase susceptibility of adult mosquitoes to a widely used pyrethroid insecticide. Experiments were performed on a field-collected pyrethroid resistant strain of Ae. aegypti (Rio de Janeiro; RJ). Larvae from the resistant Ae. aegypti population were soaked with double-stranded RNAs (dsRNAs) that correspond either to voltage-gate sodium channel (VGSC), P-glycoprotein, or P450 detoxification genes and reared to adulthood. Adult mortality rates in the presence of various Deltamethrin pyrethroid concentrations were used to assess mosquito insecticide susceptibility. We characterized the RJ Ae. aegypti strain with regard to its level of resistance to a pyrethroid insecticide and found that it was approximately 6 times more resistant to Deltamethrin compared to the laboratory Rockefeller strain. The RJ strain displayed a higher frequency of Val1016Ile and Phe1534Cys substitutions of the VGSC gene. The resistant strain also displayed a higher basal expression level of VGSC compared to the Rockefeller strain. When dsRNA-treated mosquitoes were subjected to a standard pyrethroid contact bioassay, only dsRNA targeting VGSC increased the adult mortality of the pyrethroid resistant strain. The dsRNA treatment proved effective in increasing adult mosquito susceptibility over a range of pyrethroid concentrations and these results were associated with dsRNA-specific small interfering RNAs in treated adults, and the corresponding specific down regulation of VGSC gene expression

Artificial Diets for Mosquitoes

Directory of Open Access Journals (Sweden)

Kristina K. Gonzales

2016-12-01

Full Text Available Mosquito-borne diseases are responsible for more than a million human deaths every year. Modern mosquito control strategies such as sterile insect technique (SIT, release of insects carrying a dominant lethal (RIDL, population replacement strategies (PR, and Wolbachia-based strategies require the rearing of large numbers of mosquitoes in culture for continuous release over an extended period of time. Anautogenous mosquitoes require essential nutrients for egg production, which they obtain through the acquisition and digestion of a protein-rich blood meal. Therefore, mosquito mass production in laboratories and other facilities relies on vertebrate blood from live animal hosts. However, vertebrate blood is expensive to acquire and hard to store for longer times especially under field conditions. This review discusses older and recent studies that were aimed at the development of artificial diets for mosquitoes in order to replace vertebrate blood.

'In-vivo' and bioassay results from two contrasting cases of plutonium-239 inhalation

International Nuclear Information System (INIS)

Ramsden, D.; Bains, M.E.D.; Fraser, D.C.

1969-06-01

'In-vivo' and bioassay measurements following two incidents involving plutonium-239 inhalation are described and contrasted. Incident 1, involving the inhalation of insoluble plutonium oxide, resulted in a lung content of about 20 nCi after the initial clearance. Urine excretion was negligible and the estimation of exposure was based on 'in-vivo' data and faecal excretion. Incident,2, involving the inhalation of soluble plutonium, proved negligible and the estimation of exposure, based on urinary excretion, was 0.6 nCi. (author)

Effects of truck-mounted, ultra low volume mosquito adulticides on honey bees (Apis mellifera) in a suburban field setting

Science.gov (United States)

DeLisi, Nicholas A.; Danka, Robert G.; Walker, Todd W.; Ottea, James A.; Healy, Kristen B.

2018-01-01

Few studies have examined the impact of mosquito adulticides on honey bees under conditions that reflect actual field exposure. Whereas several studies have evaluated the toxicity of mosquito control products on honey bees, most have been laboratory based and have focused solely on acute mortality as a measure of impact. The goal of this study was to determine effects of routine applications of truck-based ultra-low volume (ULV) mosquito adulticides (i.e., Scourge, Duet, and Deltagard) on honey bees in a suburban setting. The mosquito adulticides used in this study were pyrethroids with active ingredients resmethrin (Scourge), prallethrin and sumithrin (Duet), and deltamethrin (Deltagard), in which resmethrin, prallethrin, and sumithrin were synergized with piperonyl butoxide. We measured and compared mortality and detoxification enzyme activities (esterase and glutathione S-transferase) from sentinel beehives within and outside of mosquito control areas. Concurrently, colony health (i.e., number of adult bees, brood quantity and brood quality) was compared throughout the study period. No significant differences were observed in honey bee mortality, colony health or detoxification enzyme activities between treated (five sprayed areas each received one to three insecticide treatment) and control sites (four unsprayed areas that did not receive insecticide treatment) over the seven week study period. However, our laboratory study showed that exposure to resmethrin, the active ingredient in Scourge, caused significant inhibition of esterase activity compared with the control group. Our findings suggest that proper application of truck based insecticides for mosquito control results in little or no exposure and therefore minimal effects on domestic honey bees. PMID:29494661

Metabolic fate and evaluation of injury in rats and dogs following exposure to the hydrolysis products of uranium hexafluoride: implications for a bioassay program related to potential releases of uranium hexafluoride, July 1979-October 1981

International Nuclear Information System (INIS)

Morrow, P.E.; Leach, L.J.; Smith, F.A.

1982-12-01

This final report summarizes the experimental studies undertaken in rats and dogs in order to help provide adequate biological bases for quantifying and evaluating uranium hexafluoride (UF 6 ) exposures. Animals were administered the hydrolysis products of UF 6 by inhalation exposures, intratracheal instillations and intravenous injections. Attention was given to dose-effect relationships appropriate to the kidney, the unique site of subacute toxicity; to the rates of uranium excretion; and to uranium retention in renal tissue. These criteria were examined in both naive and multiply-exposed animals. The findings of these studies partly substantiate the ICRP excretion model for hexavalent uranium; generally provide a lower renal injury threshold concentration than implicit in the MPC for natural uranium; indicate distinctions in response (for example, uranium excretion) are based on exposure history; compare and evaluate various biochemical indices of renal injury; raise uncertainties about prevailing views of reversible renal injury, renal tolerance and possible hydrogen fluoride synergism with uranium effects; and reveal species differences in several areas, for example, renal retention of uranium. While these studies present some complicating features to extant bioassay practice, they nevertheless supply data supportive of the bioassay concept

Natural products phytotoxicity A bioassay suitable for small quantities of slightly water-soluble compounds.

Science.gov (United States)

Dornbos, D L; Spencer, G F

1990-02-01

A large variety of secondary metabolites that can inhibit germination and/or seedling growth are produced by plants in low quantities. The objective of this study was to develop a bioassay capable of reliably assessing reductions in germination percentage and seedling length of small-seeded plant species caused by exposure to minute quantities of these compounds. The germination and growth of alfalfa (Medicago saliva), annual ryegrass (Lolium multiflorum), and velvetleaf (Abutilon theophrasti) were evaluated against six known phytotoxins from five chemical classes; cinmethylin (a herbicidal cineole derivative) was selected as a comparison standard. Each phytotoxin, dissolved in a suitable organic solvent, was placed on water-agar in small tissue culture wells. After the solvent evaporated, imbibed seeds were placed on the agar; after three days, germination percentages and seedling lengths were measured. Compared to a commonly used filter paper procedure, this modified agar bioassay required smaller quantities of compound per seed for comparable bioassay results. This bioassay also readily permitted the measurement of seedling length, a more sensitive indicator of phytotoxicity than germination. Seedling length decreased sigmoidally as the toxin concentration increased logarithmically. Phytotoxicity was a function of both compound and plant species. Cinmethylin, a grass herbicide, reduced the length of annual ryegrass seedlings by 90-100%, whereas that of alfalfa and velvetleaf was inhibited slightly. The agar bioassay facilitated the rapid and reliable testing of slightly water-soluble compounds, requiring only minute quantities of each compound to give reproducible results.

Effectiveness of Mosquito Trap with Sugar Fermented Attractant to the Vector of Dengue Hemorrhagic Fever

Directory of Open Access Journals (Sweden)

Endang Puji Astuti

2011-06-01

Full Text Available Aedes aegypti is the main vector of dengue fever that is still become health problem in the world. Various control efforts has been done at several areas through chemically or naturally control. Developing mosquitoes trapping tool is an alternative method to control mosquitoes besides insecticides utilization. This laboratorium research utilize sugar fermented process to yield CO2 as one of attractan to mosquito. Production of ethanol and CO2 can be yielded from anaerob sugar fermentation proccess (without O2 by khamir Saccharomyces cerevisiae activities. The trapped mosquitoes was observed up to 48 hours exposure, the highest average of mosquito trapped is on solution treatment with yeast 1 gram (43.2% and 40 gr sugar (48.4%. The highest effectivity of trapping tool both inside or outside was on the 14th day. There were declained amount of trapped mosquitos on 16th and 18th days. This laboratorium research has described that trapping tool with sugar fermented solution were effective to control population of dengue vector.

Diagnostic doses and times for Phlebotomus papatasi and Lutzomyia longipalpis sand flies (Diptera: Psychodidae: Phlebotominae) using the CDC bottle bioassay to assess insecticide resistance.

Science.gov (United States)

Denlinger, David S; Creswell, Joseph A; Anderson, J Laine; Reese, Conor K; Bernhardt, Scott A

2016-04-15

Insecticide resistance to synthetic chemical insecticides is a worldwide concern in phlebotomine sand flies (Diptera: Psychodidae), the vectors of Leishmania spp. parasites. The CDC bottle bioassay assesses resistance by testing populations against verified diagnostic doses and diagnostic times for an insecticide, but the assay has been used limitedly with sand flies. The objective of this study was to determine diagnostic doses and diagnostic times for laboratory Lutzomyia longipalpis (Lutz & Nieva) and Phlebotomus papatasi (Scopoli) to ten insecticides, including pyrethroids, organophosphates, carbamates, and DDT, that are used worldwide to control vectors. Bioassays were conducted in 1,000-ml glass bottles each containing 10-25 sand flies from laboratory colonies of L. longipalpis or P. papatasi. Four pyrethroids, three organophosphates, two carbamates and one organochlorine, were evaluated. A series of concentrations were tested for each insecticide, and four replicates were conducted for each concentration. Diagnostic doses were determined only during the exposure bioassay for the organophosphates and carbamates. For the pyrethroids and DDT, diagnostic doses were determined for both the exposure bioassay and after a 24-hour recovery period. Both species are highly susceptible to the carbamates as their diagnostic doses are under 7.0 μg/ml. Both species are also highly susceptible to DDT during the exposure assay as their diagnostic doses are 7.5 μg/ml, yet their diagnostic doses for the 24-h recovery period are 650.0 μg/ml for Lu. longipalpis and 470.0 μg/ml for P. papatasi. Diagnostic doses and diagnostic times can now be incorporated into vector management programs that use the CDC bottle bioassay to assess insecticide resistance in field populations of Lu. longipalpis and P. papatasi. These findings provide initial starting points for determining diagnostic doses and diagnostic times for other sand fly vector species and wild populations using the CDC

Adulticidal activity of essential oil of Lantana camara leaves against mosquitoes.

Science.gov (United States)

Dua, V K; Pandey, A C; Dash, A P

2010-03-01

Development of insect resistance to synthetic pesticides, high operational cost and environmental pollution have created the need for developing alternative approaches to control vector-borne diseases. In the present study we have investigated the insecticidal activity of essential oil isolated from the leaves of Lantana camara against mosquito vectors. Essential oil was isolated from the leaves of L. camara using hydro-distillation method. Bioassay test was carried out by WHO method for determination of adulticidal activity against mosquitoes. Different compounds were identified by gas chromatography-mass spectrometry analysis. LD(50) values of the oil were 0.06, 0.05, 0.05, 0.05 and 0.06 mg/cm(2) while LD(90) values were 0.10, 0.10, 0.09, 0.09 and 0.10 mg/cm(2) against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluvialitis and An. stephensi respectively. KDT(50) of the oil were 20, 18, 15, 12, and 14 min and KDT(90) values were 35, 28 25, 18, 23 min against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluviatilis and An. stephensi, respectively on 0.208 mg/cm(2) impregnated paper. Studies on persistence of essential oil of L. camara on impregnated paper revealed that it has more adulticidal activity for longer period at low storage temperature. Gas chromatographic-mass spectrometric analysis of essential oil showed 45 peaks. Caryophyllene (16.37%), eucalyptol (10.75%), alpha-humelene (8.22%) and germacrene (7.41%) were present in major amounts and contributed 42.75 per cent of the total constituents. Essential oil from the leaves of L. camara possesses adulticidal activity against different mosquito species that could be utilized for development of oil-based insecticide as supplementary to synthetic insecticides.

Determination of an Environmental Background Level of Sr-90 in Urine for the Hanford Bioassay Program

International Nuclear Information System (INIS)

Antonio, Cheryl L.; Rivard, James W.

2009-01-01

During the decommissioning and maintenance of some of the facilities at the U.S. Department of Energy Hanford Site in Washington State, workers have potential for a 90Sr intake. However, because of worldwide radioactive fallout, 90Sr is present in our environment, and can be detectable in routine urine bioassay samples. It is important for the Hanford Site bioassay program to discern an occupational intake from a non-occupational environmental one. A detailed study of the background 90Sr in the urine of unexposed Hanford workers was performed. A survey of the Hanford Site bioassay database found 128 Hanford workers who were hired between 1997 and 2002 and who had a very low potential for an occupational exposure prior to the baseline strontium urinalysis. Each urinalysis sample represented excretion during an approximate 24-hr period. The arithmetic mean value for the 128 pre-exposure baselines was 3.6 ± 5.1 mBq d-1. The 90Sr activities in urine varied from -12 to 20 mBq. The 99th percentile result was 16.4 mBqd-1, which was interpreted to mean that 1% of Hanford workers not occupationally exposed to strontium might exceed 16.4 mBq d-1.

Bioassay guideline 2: guidelines for tritium bioassay

International Nuclear Information System (INIS)

1983-01-01

This guideline is one of a series under preparation by the Federal-Provincial Working Group on Bioassay and In Vivo Monitoring Criteria. In this report tritium compounds have been grouped into four categories for the purpose of calculating Annual Limits on Intake and Investigation Levels: tritium gas, tritiated water, tritium-labelled compounds and nucleic acid precursors

Bioassay method for Uranium in urine by Delay Neutron counting; Metoda Bioassay Uranium dalam urin dengan pencacahan Netron Kasip

Energy Technology Data Exchange (ETDEWEB)

Suratman,; Purwanto,; Sukarman-Aminjoyo, [Yogyakarta Nuclear Research Centre, National Atomic Energy Agency, Yogyakarta (Indonesia)

1996-04-15

A bioassay method for uranium in urine by neutron counting has been studied. The aim of this research is to obtain a bioassay method for uranium in urine which is used for the determination of internal dose of radiation workers. The bioassay was applied to the artificially uranium contaminated urine. The weight of the contaminant was varied. The uranium in the urine was irradiated in the Kartini reactor core, through pneumatic system. The delayed neutron was counted by BF3 neutron counter. Recovery of the bioassay was between 69.8-88.8 %, standard deviation was less than 10 % and the minimum detection was 0.387 {mu}g.

Studies on effects of Andrographis paniculata (Burm.f.) and Andrographis lineata nees (Family: Acanthaceae) extracts against two mosquitoes Culex quinquefasciatus (Say.) and Aedes aegypti (Linn.).

Science.gov (United States)

Renugadevi, G; Ramanathan, T; Shanmuga, priya R; Thirunavukkarasu, P

2013-03-01

To investigate the studies on effects of Andrographis paniculata (A. paniculata) (Burm.f.) and Andrographis lineata (A. lineata) nees (Family: Acanthaceae) extracts against two mosquitoes Culex quinquefasciatus (Cx. quinquefasciatus) (Say.) and Aedes aegypti (Ae. aegypti) (Linn.). The aqueous and petroleum ether extracts of two plant species, A. paniculata and A. lineate were examined against the larvae of A. aegypti (L.) and Cx. quinquefasciatus with gradually increasing concentration ie. from 50 to 200 ppm of solvent extracts and to test their activity in combination with each other. In a 24 h bioassay experiment with plant extracts, highest mortalities were recorded at 200 ppm of concentrations for leaves of A. lineta and A. paniculata individually. For combination effect, only 150 ppm of the mixture of solvent extracts of petroleum ether: aqueous (1:1) extracts showed 100% mortality after 24 h of exposure. The results show that, insecticides of plant combination is ecofriend and has better larvicidal activity compared to individual extracts. Copyright © 2013 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Intake retention functions and their applications to bioassay and the estimation of internal radiation doses

International Nuclear Information System (INIS)

Skrable, K.W.; Chabot, G.E.; French, C.S.; La Bone, T.R.

1988-01-01

This paper describes a way of obtaining and gives applications of intake retention functions. These functions give the fraction of an intake of radioactive material expected to be present in a specified bioassay compartment at any time after a single acute exposure or after onset of a continuous exposure. The intake retention functions are derived from a multicompartmental model and a recursive catenary kinetics equation that completely describe the metabolism of radioelements from intake to excretion, accounting for the delay in uptake from compartments in the respiratory and gastrointestinal tracts and the recycling of radioelements between systemic compartments. This approach, which treats excretion as the 'last' compartment of all catenary metabolic pathways, avoids the use of convolution integrals and provides algebraic solutions that can be programmed on hand held calculators or personal computers. The estimation of intakes and internal radiation doses and the use of intake retention functions in the design of bioassay programs are discussed along with several examples

Permethrin induction of multiple cytochrome P450 genes in insecticide resistant mosquitoes, Culex quinquefasciatus.

Science.gov (United States)

Gong, Youhui; Li, Ting; Zhang, Lee; Gao, Xiwu; Liu, Nannan

2013-01-01

The expression of some insect P450 genes can be induced by both exogenous and endogenous compounds and there is evidence to suggest that multiple constitutively overexpressed P450 genes are co-responsible for the development of resistance to permethrin in resistant mosquitoes. This study characterized the permethrin induction profiles of P450 genes known to be constitutively overexpressed in resistant mosquitoes, Culex quinquefasciatus. The gene expression in 7 of the 19 P450 genes CYP325K3v1, CYP4D42v2, CYP9J45, (CYP) CPIJ000926, CYP325G4, CYP4C38, CYP4H40 in the HAmCqG8 strain, increased more than 2-fold after exposure to permethrin at an LC50 concentration (10 ppm) compared to their acetone treated counterpart; no significant differences in the expression of these P450 genes in susceptible S-Lab mosquitoes were observed after permethrin treatment. Eleven of the fourteen P450 genes overexpressed in the MAmCqG6 strain, CYP9M10, CYP6Z12, CYP9J33, CYP9J43, CYP9J34, CYP306A1, CYP6Z15, CYP9J45, CYPPAL1, CYP4C52v1, CYP9J39, were also induced more than doubled after exposure to an LC50 (0.7 ppm) dose of permethrin. No significant induction in P450 gene expression was observed in the susceptible S-Lab mosquitoes after permethrin treatment except for CYP6Z15 and CYP9J39, suggesting that permethrin induction of these two P450 genes are common to both susceptible and resistant mosquitoes while the induction of the others are specific to insecticide resistant mosquitoes. These results demonstrate that multiple P450 genes are co-up-regulated in insecticide resistant mosquitoes through both constitutive overexpression and induction mechanisms, providing additional support for their involvement in the detoxification of insecticides and the development of insecticide resistance.

The potential for flower nectar to allow mosquito to mosquito transmission of Francisella tularensis.

Science.gov (United States)

Kenney, Adam; Cusick, Austin; Payne, Jessica; Gaughenbaugh, Anna; Renshaw, Andrea; Wright, Jenna; Seeber, Roger; Barnes, Rebecca; Florjanczyk, Aleksandr; Horzempa, Joseph

2017-01-01

Francisella tularensis is disseminated in nature by biting arthropods such as mosquitoes. The relationship between mosquitoes and F. tularensis in nature is highly ambiguous, due in part to the fact that mosquitoes have caused significant tularemia outbreaks despite being classified as a mechanical vector of F. tularensis. One possible explanation for mosquitoes being a prominent, yet mechanical vector is that these insects feed on flower nectar between blood meals, allowing for transmission of F. tularensis between mosquitoes. Here, we aimed to assess whether F. tularensis could survive in flower nectar. Moreover, we examined if mosquitoes could interact with or ingest and transmit F. tularensis from one source of nectar to another. F. tularensis exhibited robust survivability in flower nectar with concentrations of viable bacteria remaining consistent with the rich growth medium. Furthermore, F. tularensis was able to survive (albeit to a lesser extent) in 30% sucrose (a nectar surrogate) over a period of time consistent with that of a typical flower bloom. Although we observed diminished bacterial survival in the nectar surrogate, mosquitoes that fed on this material became colonized with F. tularensis. Finally, colonized mosquitoes were capable of transferring F. tularensis to a sterile nectar surrogate. These data suggest that flower nectar may be capable of serving as a temporary source of F. tularensis that could contribute to the amplification of outbreaks. Mosquitoes that feed on an infected mammalian host and subsequently feed on flower nectar could deposit some F. tularensis bacteria into the nectar in the process. Mosquitoes subsequently feeding on this nectar source could potentially become colonized by F. tularensis. Thus, the possibility exists that flower nectar may allow for vector-vector transmission of F. tularensis.

Bioassays with caged hyalella azteca to determine in situ toxicity downstream of two Saskatchewan, Canada, uranium operations.

Science.gov (United States)

Robertson, Erin L; Liber, Karsten

2007-11-01

The main objectives of this in situ study were to evaluate the usefulness of an in situ bioassay to determine if downstream water bodies at the Key Lake and Rabbit Lake uranium operations (Saskatchewan, Canada) were toxic to Hyalella azteca and, if toxicity was observed, to differentiate between the contribution of surface water and sediment contamination to in situ toxicity. These objectives were achieved by performing 4-d in situ bioassays with laboratory-reared H. azteca confined in specially designed, paired, surface water and sediment exposure chambers. Results from the in situ bioassays revealed significant mortality, relative to the respective reference site, at the exposure sites at both Key Lake (p exposure chambers at either Key Lake (p = 0.232) or Rabbit Lake (p = 0.072). This suggests that surface water (the common feature of both types of exposure chambers) was the primary cause of in situ mortality of H. azteca at both operations, although this relationship was stronger at Key Lake. At Key Lake, the primary cause of aquatic toxicity to H. azteca did not appear to be correlated with the variables measured in this study, but most likely with a pulse of organic mill-process chemicals released during the time of the in situ study-a transient event that was caused by a problem with the mill's solvent extraction process. The suspected cause of in situ toxicity to H. azteca at Rabbit Lake was high levels of uranium in surface water, sediment, and pore water.

Controle los mosquitos que están en el exterior (Controlling Mosquitoes Outside)

Centers for Disease Control (CDC) Podcasts

Los mosquitos pueden transmitir virus como el del zika. En este podcast, el Sr. Francisco le enseñará a usted y a su vecina Adriana diferentes maneras para ayudar a reducir la cantidad de mosquitos fuera de su casa. Los consejos incluyen eliminar áreas de agua estancada donde los mosquitos ponen sus huevos, usar larvicidas para matar mosquitos jóvenes, y reparar grietas y cubrir las ventilaciones de los pozos sépticos. También aprenderá cómo se usan los aviones que ayudan a rociar insecticida para los mosquitos.

Real-time PCR for the early detection and quantification of Coxiella burnetii as an alternative to the murine bioassay.

Science.gov (United States)

Howe, Gerald B; Loveless, Bonnie M; Norwood, David; Craw, Philip; Waag, David; England, Marilyn; Lowe, John R; Courtney, Bernard C; Pitt, M Louise; Kulesh, David A

2009-01-01

Real-time PCR was used to analyze archived blood from non-human primates (NHP) and fluid samples originating from a well-controlled Q fever vaccine efficacy trial. The PCR targets were the IS1111 element and the com1 gene of Coxiella burnetii. Data from that previous study were used to evaluate real-time PCR as an alternative to the use of sero-conversion by mouse bioassay for both quantification and early detection of C. burnetii bacteria. Real-time PCR and the mouse bioassay exhibited no statistical difference in quantifying the number of microorganisms delivered in the aerosol challenge dose. The presence of C. burnetii in peripheral blood of non-human primates was detected by real-time PCR as early after exposure as the mouse bioassay with results available within hours instead of weeks. This study demonstrates that real-time PCR has the ability to replace the mouse bioassay to measure dosage and monitor infection of C. burnetii in a non-human primate model.

Wolbachia-a foe for mosquitoes

Directory of Open Access Journals (Sweden)

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.

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.

Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques.

Science.gov (United States)

Mohammed, Muzaffer; Clement, Travis C; Aslan, Kadir

2014-12-02

In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400-800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72-24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally.

MosqTent: An individual portable protective double-chamber mosquito trap for anthropophilic mosquitoes.

Directory of Open Access Journals (Sweden)

José Bento Pereira Lima

2017-03-01

Full Text Available Here, we describe the development of the MosqTent, an innovative double-chamber mosquito trap in which a human being attracts mosquitoes while is protected from being bitten within the inner chamber of the trap, while mosquitoes are lured to enter an outer chamber where they are trapped. The MosqTent previously collected an average of 3,000 anophelines/man-hour compared to 240 anophelines/man-hour for the human landing catch (HLC, thereby providing high numbers of human host-seeking mosquitoes while protecting the collector from mosquito bites. The MosqTent performed well by collecting a high number of specimens of Anopheles marajoara, a local vector and anthropophilic mosquito species present in high density, but not so well in collecting An. darlingi, an anthropophilic mosquito species considered the main vector in Brazil but is present in low-density conditions in the area. The HLC showed a higher efficiency in collecting An. darlingi in these low-density conditions. The MosqTent is light (<1 kg, portable (comes as a bag with two handles, flexible (can be used with other attractants, adaptable (can be deployed in a variety of environmental settings and weather conditions, and it can be used in the intra-, peri-, and in the extradomicile. Also, the MosqTent collected similar portions of parous females and anthropophilic mosquito species and collects specimens suitable for downstream analysis. Further developments may include testing for other fabric colors, different mesh sizes and dimensions for other hematophagous insects and conditions, additional chemical mosquito attractants, and even the replacement of the human attractant in favor of other attractants. MosqTent modifications that would allow the trap to be applied as a vector control tool with killing action could also be explored.

The potential for flower nectar to allow mosquito to mosquito transmission of Francisella tularensis.

Directory of Open Access Journals (Sweden)

Adam Kenney

Full Text Available Francisella tularensis is disseminated in nature by biting arthropods such as mosquitoes. The relationship between mosquitoes and F. tularensis in nature is highly ambiguous, due in part to the fact that mosquitoes have caused significant tularemia outbreaks despite being classified as a mechanical vector of F. tularensis. One possible explanation for mosquitoes being a prominent, yet mechanical vector is that these insects feed on flower nectar between blood meals, allowing for transmission of F. tularensis between mosquitoes. Here, we aimed to assess whether F. tularensis could survive in flower nectar. Moreover, we examined if mosquitoes could interact with or ingest and transmit F. tularensis from one source of nectar to another. F. tularensis exhibited robust survivability in flower nectar with concentrations of viable bacteria remaining consistent with the rich growth medium. Furthermore, F. tularensis was able to survive (albeit to a lesser extent in 30% sucrose (a nectar surrogate over a period of time consistent with that of a typical flower bloom. Although we observed diminished bacterial survival in the nectar surrogate, mosquitoes that fed on this material became colonized with F. tularensis. Finally, colonized mosquitoes were capable of transferring F. tularensis to a sterile nectar surrogate. These data suggest that flower nectar may be capable of serving as a temporary source of F. tularensis that could contribute to the amplification of outbreaks. Mosquitoes that feed on an infected mammalian host and subsequently feed on flower nectar could deposit some F. tularensis bacteria into the nectar in the process. Mosquitoes subsequently feeding on this nectar source could potentially become colonized by F. tularensis. Thus, the possibility exists that flower nectar may allow for vector-vector transmission of F. tularensis.

Chikungunya Virus Infection of Aedes Mosquitoes.

Science.gov (United States)

Wong, Hui Vern; Chan, Yoke Fun; Sam, I-Ching; Sulaiman, Wan Yusof Wan; Vythilingam, Indra

2016-01-01

In vivo infection of mosquitoes is an important method to study and characterize arthropod-borne viruses. Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that is transmitted primarily by Aedes mosquitoes. In this chapter, we describe a protocol for infection of CHIKV in two species of Aedes mosquitoes, Aedes aegypti and Aedes albopictus, together with the isolation of CHIKV in different parts of the infected mosquito such as midgut, legs, wings, salivary gland, head, and saliva. This allows the study of viral infection, replication and dissemination within the mosquito vector.

Infection and transmission of Rift Valley fever viruses lacking the NSs and/or NSm genes in mosquitoes: potential role for NSm in mosquito infection.

Directory of Open Access Journals (Sweden)

Mary B Crabtree

Full Text Available BACKGROUND: Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. METHODOLOGY AND PRINCIPAL FINDINGS: Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. CONCLUSIONS/SIGNIFICANCE: In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.

Infection and transmission of Rift Valley fever viruses lacking the NSs and/or NSm genes in mosquitoes: potential role for NSm in mosquito infection.

Science.gov (United States)

Crabtree, Mary B; Kent Crockett, Rebekah J; Bird, Brian H; Nichol, Stuart T; Erickson, Bobbie Rae; Biggerstaff, Brad J; Horiuchi, Kalanthe; Miller, Barry R

2012-01-01

Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.

[Investigation on pattern and methods of quality control for Chinese materia medica based on dao-di herbs and bioassay - bioassay for Coptis chinensis].

Science.gov (United States)

Yan, Dan; Xiao, Xiao-he

2011-05-01

Establishment of bioassay methods is the technical issues to be faced with in the bioassay of Chinese materia medica. Taking the bioassay of Coptis chinensis Franch. as an example, the establishment process and application of the bioassay methods (including bio-potency and bio-activity fingerprint) were explained from the aspects of methodology, principle of selection, experimental design, method confirmation and data analysis. The common technologies were extracted and formed with the above aspects, so as to provide technical support for constructing pattern and method of the quality control for Chinese materia medica based on the dao-di herbs and bioassay.

Cómo controlar los mosquitos en interiores (Controlling Mosquitoes Indoors)

Centers for Disease Control (CDC) Podcasts

Los mosquitos pueden portar virus como el del Nilo Occidental o del Zika. En este podcast, Don Francisco le muestra a sus vecinos formas en las que pueden reducir el número de mosquitos dentro de su casa.

Mosquito-specific and mosquito-borne viruses: evolution, infection, and host defense

NARCIS (Netherlands)

Halbach, R.; Junglen, S.; Rij, R.P. van

2017-01-01

Recent virus discovery programs have identified an extensive reservoir of viruses in arthropods. It is thought that arthropod viruses, including mosquito-specific viruses, are ancestral to vertebrate-pathogenic arboviruses. Mosquito-specific viruses are restricted in vertebrate cells at multiple

Effect of the Changes of Respiratory Tract Model on the Uranium Bioassay Data

Energy Technology Data Exchange (ETDEWEB)

Kwon, Taeeun; Noh, Siwan; Kim, Meeryeong; Lee, Jaiki [Hanyang Univ., Seoul (Korea, Republic of); Lee, Jongil; Kim, Jang Lyul [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

The HRTM, however, was revised based on the recent experimental data in OIR (Occupational Intakes of Radionuclides) draft report of ICRP. The changes of respiratory tract model are predicted to directly affect bioassay data like retention and excretion functions. Lung retention function is especially important to internal exposure assessment for workers related to fuel manufacturing because the place could be contaminated by uranium. In addition, faecel samples are recommended to be used for in-vitro bioassay of uranium because of very slow excretion via urine. More reliable assessments for the workers in fuel manufacturing could be achieved by recalculation of bioassay data for uranium and the comparing study using original and revised HRTM. In this study, therefore, the lung retention and faecal excretion functions for inhalation of UO{sub 2} and U{sub 3}O{sub 8} were recalculated using revised HRTM and the results were compared with those of original HRTM. In this study the lung retention and faecal excretion functions for inhalation of UO{sub 2} and U{sub 3}O{sub 8} were calculated based on original and revised HRTM. The results show that the revised HRTM increases lung retention and uptakes to alimentary tract which cause the more faecal excretion. The results in this study confirm the effect of the changes of respiratory tract model on the uranium bioassay data although the more study is needed to apply to practical fields.

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 (RR 50 ) 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

North American Wetlands and Mosquito Control

Science.gov (United States)

Rey, Jorge R.; Walton, William E.; Wolfe, Roger J.; Connelly, Roxanne; O’Connell, Sheila M.; Berg, Joe; Sakolsky-Hoopes, Gabrielle E.; Laderman, Aimlee D.

2012-01-01

Wetlands are valuable habitats that provide important social, economic, and ecological services such as flood control, water quality improvement, carbon sequestration, pollutant removal, and primary/secondary production export to terrestrial and aquatic food chains. There is disagreement about the need for mosquito control in wetlands and about the techniques utilized for mosquito abatement and their impacts upon wetlands ecosystems. Mosquito control in wetlands is a complex issue influenced by numerous factors, including many hard to quantify elements such as human perceptions, cultural predispositions, and political climate. In spite of considerable progress during the last decades, habitat protection and environmentally sound habitat management still remain inextricably tied to politics and economics. Furthermore, the connections are often complex, and occur at several levels, ranging from local businesses and politicians, to national governments and multinational institutions. Education is the key to lasting wetlands conservation. Integrated mosquito abatement strategies incorporate many approaches and practicable options, as described herein, and need to be well-defined, effective, and ecologically and economically sound for the wetland type and for the mosquito species of concern. The approach will certainly differ in response to disease outbreaks caused by mosquito-vectored pathogens versus quality of life issues caused by nuisance-biting mosquitoes. In this contribution, we provide an overview of the ecological setting and context for mosquito control in wetlands, present pertinent information on wetlands mosquitoes, review the mosquito abatement options available for current wetlands managers and mosquito control professionals, and outline some necessary considerations when devising mosquito control strategies. Although the emphasis is on North American wetlands, most of the material is applicable to wetlands everywhere. PMID:23222252

Controle los mosquitos que están en el exterior (Controlling Mosquitoes Outside)

Centers for Disease Control (CDC) Podcasts

2016-07-11

Los mosquitos pueden transmitir virus como el del zika. En este podcast, el Sr. Francisco le enseñará a usted y a su vecina Adriana diferentes maneras para ayudar a reducir la cantidad de mosquitos fuera de su casa. Los consejos incluyen eliminar áreas de agua estancada donde los mosquitos ponen sus huevos, usar larvicidas para matar mosquitos jóvenes, y reparar grietas y cubrir las ventilaciones de los pozos sépticos. También aprenderá cómo se usan los aviones que ayudan a rociar insecticida para los mosquitos.  Created: 7/11/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 7/11/2016.

A versatile and low-cost open source pipetting robot for automation of toxicological and ecotoxicological bioassays.

Science.gov (United States)

Steffens, Sebastian; Nüßer, Leonie; Seiler, Thomas-Benjamin; Ruchter, Nadine; Schumann, Mark; Döring, Ricarda; Cofalla, Catrina; Ostfeld, Avi; Salomons, Elad; Schüttrumpf, Holger; Hollert, Henner; Brinkmann, Markus

2017-01-01

In the past decades, bioassays and whole-organism bioassay have become important tools not only in compliance testing of industrial chemicals and plant protection products, but also in the monitoring of environmental quality. With few exceptions, such test systems are discontinuous. They require exposure of the biological test material in small units, such as multiwell plates, during prolonged incubation periods, and do not allow online read-outs. It is mostly due to these shortcomings that applications in continuous monitoring of, e.g., drinking or surface water quality are largely missing. We propose the use of pipetting robots that can be used to automatically exchange samples in multiwell plates with fresh samples in a semi-static manner, as a potential solution to overcome these limitations. In this study, we developed a simple and low-cost, versatile pipetting robot constructed partly using open-source hardware that has a small footprint and can be used for online monitoring of water quality by means of an automated whole-organism bioassay. We tested its precision in automated 2-fold dilution series and used it for exposure of zebrafish embryos (Danio rerio)-a common model species in ecotoxicology-to cadmium chloride and permethrin. We found that, compared to conventional static or semi-static exposure scenarios, effects of the two chemicals in zebrafish embryos generally occurred at lower concentrations, and analytically verified that the increased frequency of media exchange resulted in a greater availability of the chemical. In combination with advanced detection systems this custom-made pipetting robot has the potential to become a valuable tool in future monitoring strategies for drinking and surface water.

A versatile and low-cost open source pipetting robot for automation of toxicological and ecotoxicological bioassays.

Directory of Open Access Journals (Sweden)

Sebastian Steffens

Full Text Available In the past decades, bioassays and whole-organism bioassay have become important tools not only in compliance testing of industrial chemicals and plant protection products, but also in the monitoring of environmental quality. With few exceptions, such test systems are discontinuous. They require exposure of the biological test material in small units, such as multiwell plates, during prolonged incubation periods, and do not allow online read-outs. It is mostly due to these shortcomings that applications in continuous monitoring of, e.g., drinking or surface water quality are largely missing. We propose the use of pipetting robots that can be used to automatically exchange samples in multiwell plates with fresh samples in a semi-static manner, as a potential solution to overcome these limitations. In this study, we developed a simple and low-cost, versatile pipetting robot constructed partly using open-source hardware that has a small footprint and can be used for online monitoring of water quality by means of an automated whole-organism bioassay. We tested its precision in automated 2-fold dilution series and used it for exposure of zebrafish embryos (Danio rerio-a common model species in ecotoxicology-to cadmium chloride and permethrin. We found that, compared to conventional static or semi-static exposure scenarios, effects of the two chemicals in zebrafish embryos generally occurred at lower concentrations, and analytically verified that the increased frequency of media exchange resulted in a greater availability of the chemical. In combination with advanced detection systems this custom-made pipetting robot has the potential to become a valuable tool in future monitoring strategies for drinking and surface water.

Repelling mosquitoes with essential oils

Science.gov (United States)

Riley, L.

2017-12-01

Mosquitoes carry diseases than can lead to serious illness and death. According to the World Health Organization, mosquitoes infect over 300 million people a year with Malaria and Dengue Fever, two life threatening diseases vectored by mosquitoes. Although insecticides are the most effective way to control mosquitoes, they are not always environmentally friendly. Therefore, alternative tactics should be considered. In this study, we looked at the repellency of various essential oils on female Aedes aegypti through a series of laboratory assays.

Synergistic effect of some essential oils on toxicity and knockdown effects, against mosquitos, cockroaches and housefly

Directory of Open Access Journals (Sweden)

Idin Zibaee

2015-12-01

Full Text Available The toxicity and knockdown effect of Eucalyptus globulus, Rosmarinus officinalis essential oils and their mixed formulation on Periplaneta Americana (L., Blattella germanica (L., Supella longipalpa, Culex pipiens, Anopheles stephensi and Musca domestica were evaluated in a series of laboratory experiments. In all bioassay five different doses (0.625, 1.25, 2.5, 5 and 10% were used by filter paper (cm2 and aerosol (cm3 bioassay methods, all essential oils was toxic to cockroaches, mosquitos and housefly species the lowest and the highest LC50 belong to mixed formulation on B. germanica (LC50 6.1 and E. globulus on P. americana (LC50 27.7 respectively. In continuous exposure experiments, Mortality (LT50 values for cockroaches ranged from 1403.3 min with 0.625% E. globulus (for P. americana to 2.2 min with 10% mixed formulation for A. stephensi. The KT50 values ranged from 0.1 to 1090.8 min for 10% and 0.625 for mixed formulation and R. officinalis respectively. The mortality after 24 h for mixed formulation was 100% but for single essential oils ranged from 81.5 to 98.3 for P. americana treated with R. officinalis and A. stephensi treated with E. globulus respectively. Studies on persistence of essential oils on impregnated paper revealed that it has more adulticidal activity for longer period at low storage temperature. Gas chromatographic-mass spectrometric analysis of essential oil showed 14 and 16 peaks for E. globules and R. officinalis respectively. α-Pinene (39.8%, 1, 8-Cineole (13.2%, Camphene (9.1% and Borneol (3.7% were present in major amounts for R. officinalis and 1,8-Cineole (31.4%, α-Pinene (15.3%, d-Limonene (9.7% and α-Terpinolen (5.3% were present in major amounts for E. globulus respectively. Our results showed that two surveyed essential oils has compatible with synergistic effect on various insect species, furthermore it is useful for applying as integrated pest management tool for studied insects management, especially in

Oviposition responses of Aedes mosquitoes to bacterial isolates from attractive bamboo infusions.

Science.gov (United States)

Ponnusamy, Loganathan; Schal, Coby; Wesson, Dawn M; Arellano, Consuelo; Apperson, Charles S

2015-09-23

The mosquitoes Aedes aegypti and Aedes albopictus are vectors of pathogenic viruses that cause major human illnesses including dengue, yellow fever and chikungunya. Both mosquito species are expanding their geographic distributions and now occur worldwide in temperate and tropical climates. Collection of eggs in oviposition traps (ovitraps) is commonly used for monitoring and surveillance of container-inhabiting Aedes populations by public health agencies charged with managing mosquito-transmitted illness. Addition of an organic infusion in these traps increases the number of eggs deposited. Gravid females are guided to ovitraps by volatile chemicals produced from the breakdown of organic matter by microbes. We previously isolated and cultured 14 species of bacteria from attractive experimental infusions, made from the senescent leaves of canebrake bamboo (Arundinaria gigantea). Cultures were grown for 24 h at 28 °C with constant shaking (120 rpm) and cell densities were determined with a hemocytometer. Behavioral responses to single bacterial isolates and to a mix of isolates at different cell densities were evaluated using two-choice sticky-screen bioassay methods with gravid Ae. aegypti and Ae. albopictus. In behavioral assays of a mix of 14 bacterial isolates, significantly greater attraction responses were exhibited by Ae. aegypti and Ae. albopictus to bacterial densities of 10(7) and 10(8) cells/mL than to the control medium. When we tested single bacterial isolates, seven isolates (B1, B2, B3, B5, B12, B13 and B14) were significantly attractive to Ae. aegypti, and six isolates (B1, B5, B7, B10, B13 and B14) significantly attracted Ae. albopictus. Among all the isolates tested at three different cell densities, bacterial isolates B1, B5, B13 and B14 were highly attractive to both Aedes species. Our results show that at specific cell densities, some bacteria significantly influence the attraction of gravid Ae. aegypti and Ae. albopictus females to

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

Directory of Open Access Journals (Sweden)

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.

Quantitative Analysis of Aedes albopictus Movement Behavior Following Sublethal Exposure To Prallethrin.

Science.gov (United States)

Dye-Braumuller, Kyndall C; Haynes, Kenneth F; Brown, Grayson C

2017-12-01

The pyrethroid prallethrin, an AI in DUET™ (Clarke Mosquito Control, St. Charles, IL), is widely marketed ultra-low volume (ULV) mosquito adulticide. Volatilized prallethrin is intended to stimulate mosquito flight, increasing its adulticide effectiveness. However, field tests using volatilized prallethrin have not produced significant differences in mosquito trap catches, leading to questions regarding prallethrin's behavioral impact efficacy. Thus, we conducted laboratory tests of prallethrin's effect on flight behavior of adult female Asian tiger mosquitoes, Aedes albopictus. Mosquitoes were divided into 3 groups: untreated control, exposed to volatilized prallethrin, and exposed to a liquid spray calibrated to simulate a ULV application at label rates. After exposure, mosquito behavior in an airstream of 0.5 m/sec was recorded and analyzed using motion-tracking software. No significant differences in flight behavior were found between the control and treated mosquitoes exposed to volatilized prallethrin. The ULV-sprayed mosquitoes exhibited a significant increase in the number of flight events, the turning frequency, overall movement speed, and flight speed compared to the control-a significant difference in locomotor stimulation response that would increase exposure to a ULV spray cloud. However, our results showed that volatilization alone was insufficient to increase ULV efficacy in the field and suggested that incorporating a more volatile flight stimulant into ULV adulticides would provide a measurable improvement in mosquito control.

Comparative performances of eggs and embryos of sea urchin (Paracentrotus lividus) in toxicity bioassays used for assessment of marine sediment quality.

Science.gov (United States)

Khosrovyan, A; Rodríguez-Romero, A; Salamanca, M J; Del Valls, T A; Riba, I; Serrano, F

2013-05-15

The potential toxicity of sediments from various ports was assessed by means of two different liquid-phase toxicity bioassays (acute and chronic) with embryos and eggs of sea urchin Paracentrotus lividus. Performances of embryos and eggs of P. lividus in these bioassays were compared for their interchangeable applicability in integrated sediment quality assessment. The obtained endpoints (percentages of normally developed plutei and fertilized eggs) were linked to physical and chemical properties of sediments and demonstrated dependence on sediment contamination. The endpoints in the two bioassays were strongly correlated and generally exhibited similar tendency throughout the samples. Therein, embryos demonstrated higher sensitivity to elutriate exposure, compared to eggs. It was concluded that these tests could be used interchangeably for testing toxicity of marine sediments. Preferential use of any of the bioassays can be determined by the discriminatory capacity of the test or vulnerability consideration of the test subject to the surrounding conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fluorescent bioassays for toxic metals in milk and yoghurt

Science.gov (United States)

2012-01-01

Background From a human health viewpoint, contaminated milk and its products could be a source of long-term exposure to toxic metals. Simple, inexpensive, and on-site assays would enable constant monitoring of their contents. Bioassays that can measure toxic metals in milk or yoghurt might reduce the risk. For this purpose, the green fluorescent protein (GFP)-tagged trans factors, ArsR-GFP and CadC-GFP, together with their cis elements were used to develop such bioassays. Results ArsR-GFP or CadC-GFP, which binds either toxic metal or DNA fragment including cis element, was directly mixed with cow’s milk or yoghurt within a neutral pH range. The fluorescence of GFP, which is reflected by the association/dissociation ratio between cis element and trans factor, significantly changed with increasing externally added As (III) or Cd (II) whereas smaller responses to externally added Pb (II) and Zn (II) were found. Preparation and dilution of whey fraction at low pH were essential to intrinsic zinc quantification using CadC-GFP. Using the extraction procedure and bioassay, intrinsic Zn (II) concentrations ranging from 1.4 to 4.8 mg/l for milk brands and from 1.2 to 2.9 mg/kg for yoghurt brands were determined, which correlated to those determined using inductively coupled plasma atomic emission spectroscopy. Conclusions GFP-tagged bacterial trans factors and cis elements can work in the neutralized whole composition and diluted whey fraction of milk and yoghurt. The feature of regulatory elements is advantageous for establishment of simple and rapid assays of toxic metals in dairy products. PMID:23098077

Fluorescent bioassays for toxic metals in milk and yoghurt

Directory of Open Access Journals (Sweden)

Siddiki Mohammad Shohel

2012-10-01

Full Text Available Abstract Background From a human health viewpoint, contaminated milk and its products could be a source of long-term exposure to toxic metals. Simple, inexpensive, and on-site assays would enable constant monitoring of their contents. Bioassays that can measure toxic metals in milk or yoghurt might reduce the risk. For this purpose, the green fluorescent protein (GFP-tagged trans factors, ArsR-GFP and CadC-GFP, together with their cis elements were used to develop such bioassays. Results ArsR-GFP or CadC-GFP, which binds either toxic metal or DNA fragment including cis element, was directly mixed with cow’s milk or yoghurt within a neutral pH range. The fluorescence of GFP, which is reflected by the association/dissociation ratio between cis element and trans factor, significantly changed with increasing externally added As (III or Cd (II whereas smaller responses to externally added Pb (II and Zn (II were found. Preparation and dilution of whey fraction at low pH were essential to intrinsic zinc quantification using CadC-GFP. Using the extraction procedure and bioassay, intrinsic Zn (II concentrations ranging from 1.4 to 4.8 mg/l for milk brands and from 1.2 to 2.9 mg/kg for yoghurt brands were determined, which correlated to those determined using inductively coupled plasma atomic emission spectroscopy. Conclusions GFP-tagged bacterial trans factors and cis elements can work in the neutralized whole composition and diluted whey fraction of milk and yoghurt. The feature of regulatory elements is advantageous for establishment of simple and rapid assays of toxic metals in dairy products.

Efficient algal bioassay based on short-term photosynthetic response

International Nuclear Information System (INIS)

Giddings, J.M.; Stewart, A.J.; O'Neill, R.V.; Gardner, R.H.

1983-01-01

A procedure is described for measuring the effects of toxicants on algal photosynthesis (carbon-14 bicarbonate (H 14 CO 3 )uptake) in 4-h experiments. The results for individual aromatic compounds and the water-soluble fraction (WSF) of a synthetic oil are presented as examples of applications of the bioassay. The toxicity of the WSF varied among the seven algal species tested, and the responses of some species were pH-dependent. With Selenastrum capricornutum as the test organism, the bioassay results were unaffected by variations in pH from 7.0 to 9.0, light intensity from 40 to 200 μeinsteins m -2 s -1 , culture density up to 0.5 mg chlorophyll a per litre, and agitation up to 100 rpm. The photosynthesis bioassay is simpler and faster (4 h versus 4 to 14 days), uses smaller culture volumes, and requires less space than static culture-growth tests. One person can conveniently test four materials per day, and the entire procedure, including preparation, exposure, and analysis, takes less than two days. The short incubation time reduces bottle effects such as pH changes, accumulation of metabolic products, nutrient depletion, and bacterial growth. Processes that remove or alter the test materials are also minimized. The data presented here indicate that algal photosynthesis is inhibited at toxicant concentrations similar to those that cause acute effects in aquatic animals. A model of a pelagic ecosystem is used to demonstrate that even temporary (seven-day) inhibition of algal photosynthesis can have a measurable impact on other trophic levels, particularly if the other trophic levels are also experiencing toxic effects. 25 references, 6 figures, 1 table

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.

Chemical Exacerbation of Light-induced Retinal Degeneration in F344/N Rats in National Toxicology Program Rodent Bioassays

OpenAIRE

Yamashita, Haruhiro; Hoenerhoff, Mark J.; Peddada, Shyamal D.; Sills, Robert C.; Pandiri, Arun R.

2016-01-01

Retinal degeneration due to chronic ambient light exposure is a common spontaneous age-related finding in albino rats, but it can also be related to exposures associated with environmental chemicals and drugs. Typically, light induced retinal degeneration has a central/hemispherical localization where as chemical induced retinal degeneration has a diffuse localization. This study was conducted to identify National Toxicology Program (NTP) rodent bioassays with treatment-related retinal degene...

MosquitoMap and the Mal-area calculator: new web tools to relate mosquito species distribution with vector borne disease.

Science.gov (United States)

Foley, Desmond H; Wilkerson, Richard C; Birney, Ian; Harrison, Stanley; Christensen, Jamie; Rueda, Leopoldo M

2010-02-18

Mosquitoes are important vectors of diseases but, in spite of various mosquito faunistic surveys globally, there is a need for a spatial online database of mosquito collection data and distribution summaries. Such a resource could provide entomologists with the results of previous mosquito surveys, and vector disease control workers, preventative medicine practitioners, and health planners with information relating mosquito distribution to vector-borne disease risk. A web application called MosquitoMap was constructed comprising mosquito collection point data stored in an ArcGIS 9.3 Server/SQL geodatabase that includes administrative area and vector species x country lookup tables. In addition to the layer containing mosquito collection points, other map layers were made available including environmental, and vector and pathogen/disease distribution layers. An application within MosquitoMap called the Mal-area calculator (MAC) was constructed to quantify the area of overlap, for any area of interest, of vector, human, and disease distribution models. Data standards for mosquito records were developed for MosquitoMap. MosquitoMap is a public domain web resource that maps and compares georeferenced mosquito collection points to other spatial information, in a geographical information system setting. The MAC quantifies the Mal-area, i.e. the area where it is theoretically possible for vector-borne disease transmission to occur, thus providing a useful decision tool where other disease information is limited. The Mal-area approach emphasizes the independent but cumulative contribution to disease risk of the vector species predicted present. MosquitoMap adds value to, and makes accessible, the results of past collecting efforts, as well as providing a template for other arthropod spatial databases.

Heritability of attractiveness to mosquitoes.

Directory of Open Access Journals (Sweden)

G Mandela Fernández-Grandon

Full Text Available Female mosquitoes display preferences for certain individuals over others, which is determined by differences in volatile chemicals produced by the human body and detected by mosquitoes. Body odour can be controlled genetically but the existence of a genetic basis for differential attraction to insects has never been formally demonstrated. This study investigated heritability of attractiveness to mosquitoes by evaluating the response of Aedes aegypti (=Stegomyia aegypti mosquitoes to odours from the hands of identical and non-identical twins in a dual-choice assay. Volatiles from individuals in an identical twin pair showed a high correlation in attractiveness to mosquitoes, while non-identical twin pairs showed a significantly lower correlation. Overall, there was a strong narrow-sense heritability of 0.62 (SE 0.124 for relative attraction and 0.67 (0.354 for flight activity based on the average of ten measurements. The results demonstrate an underlying genetic component detectable by mosquitoes through olfaction. Understanding the genetic basis for attractiveness could create a more informed approach to repellent development.

Controlling Mosquitoes Indoors

Centers for Disease Control (CDC) Podcasts

2016-08-23

Mosquitoes can carry viruses, like West Nile and Zika. In this podcast, Mr. Hubbard teaches his neighbors, the Smith family, ways to help reduce the number of mosquitoes inside their home.  Created: 8/23/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/23/2016.

Mosquito inspired medical needles

DEFF Research Database (Denmark)

Lenau, Torben Anker; Hesselberg, Thomas; Drakidis, Alexandros Dimitrios

2017-01-01

The stinging proboscis in mosquitos have diameters of only 40-100 μm which is much less than the thinnest medical needles and the mechanics of these natural stinging mechanisms have therefore attracted attention amongst developers of injection devises. The mosquito use a range of different...... strategies to lower the required penetration force hence allowing a thinner and less stiff proboscis structure. Earlier studies of the mosquito proboscis insertion strategies have shown how each of the single strategies reduces the required penetration force. The present paper gives an overview...... of the advanced set of mechanisms that allow the mosquito to penetrate human skin and also presents other biological mechanisms that facilitate skin penetration. Results from experiments in a skin mimic using biomimetic equivalents to the natural mechanisms are presented. This includes skin stretching, insertion...

Ocular Manifestations of Mosquito-Transmitted Diseases.

Science.gov (United States)

Karesh, James W; Mazzoli, Robert A; Heintz, Shannon K

2018-03-01

Of the 3,548 known mosquito species, about 100 transmit human diseases. Mosquitoes are distributed globally throughout tropical and temperate regions where standing water sources are available for egg laying and the maturation of larva. Female mosquitoes require blood meals for egg production. This is the main pathway for disease transmission. Mosquitoes carry several pathogenic organisms responsible for significant ocular pathology and vision loss including West Nile, Rift Valley, chikungunya, dengue viruses, various encephalitis viruses, malarial parasites, Francisella tularensis, microfilarial parasites, including Dirofilaria, Wuchereria, and Brugia spp., and human botfly larvae. Health care providers may not be familiar with many of these mosquito-transmitted diseases or their associated ocular findings delaying diagnosis, treatment, and recovery of visual function. This article aims to provide an overview of the ocular manifestations associated with mosquito-transmitted diseases.

Plant extracts as potential mosquito larvicides.

Science.gov (United States)

Ghosh, Anupam; Chowdhury, Nandita; Chandra, Goutam

2012-05-01

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.

Approaches to passive mosquito surveillance in the EU

NARCIS (Netherlands)

Kampen, H.; Medlock, J.M.; Vaux, A.G.C.; Koenraadt, C.J.M.; Vliet, van A.J.H.; Bartumeus, F.; Oltra, A.; Sousa, C.A.; Chouin, S.; Werner, D.

2015-01-01

The recent emergence in Europe of invasive mosquitoes and mosquito-borne disease associated with both invasive and native mosquito species has prompted intensified mosquito vector research in most European countries. Central to the efforts are mosquito monitoring and surveillance activities in order

Y-12 Uranium Exposure Study

Energy Technology Data Exchange (ETDEWEB)

Eckerman, K.F.; Kerr, G.D.

1999-08-05

Following the recent restart of operations at the Y-12 Plant, the Radiological Control Organization (RCO) observed that the enriched uranium exposures appeared to involve insoluble rather than soluble uranium that presumably characterized most earlier Y-12 operations. These observations necessitated changes in the bioassay program, particularly the need for routine fecal sampling. In addition, it was not reasonable to interpret the bioassay data using metabolic parameter values established during earlier Y-12 operations. Thus, the recent urinary and fecal bioassay data were interpreted using the default guidance in Publication 54 of the International Commission on Radiological Protection (ICRP); that is, inhalation of Class Y uranium with an activity median aerodynamic diameter (AMAD) of 1 {micro}m. Faced with apparently new workplace conditions, these actions were appropriate and ensured a cautionary approach to worker protection. As additional bioassay data were accumulated, it became apparent that the data were not consistent with Publication 54. Therefore, this study was undertaken to examine the situation.

Bioassay measurements of individuals living near the US Department of Energy's Hanford Site in Washington State, Fall 1985

International Nuclear Information System (INIS)

Sula, M.J.; Bihl, D.E.

1986-05-01

The purpose of the bioassay measurements was to provide individuals, living within a specific area near the Hanford Site, information on the current levels of radionuclides in their bodies. The measurements included whole body counter (in vivo) examinations and urine sample analyses for detecting the presence of major radionuclides related to current and historical operations at Hanford. Notifications of the special measurements were sent by letter to 515 residences in north Franklin County. Eighty-nine individuals from 52 of the 515 residences requested and received whole body counts. Of these, 32 also provided urine samples. The measurements gave no evidence of unusual levels of radioactivity in any individual. The ability of bioassay measurements to detect the presence of radioactivity in an individual following an exposure is dependent on the quality of the measurement and the nature of the exposure. This report includes a discussion of the capability, under various circumstances, of the measurements that were provided

A specific bioassay for the inhibition of flowering.

Science.gov (United States)

Blake, J

1972-06-01

A bioassay for the inhibition of flowering involving the in vitro culture of excised, partially-induced, apices of Viscaria candida is described. This bioassay has been used to detect flowering inhibition in extracts from Kalanchoe blossfeldiana.

Genotoxic evaluation of an industrial effluent from an oil refinery using plant and animal bioassays.

Science.gov (United States)

Rodrigues, Fernando Postalli; Angeli, José Pedro Friedmann; Mantovani, Mário Sérgio; Guedes, Carmen Luisa Barbosa; Jordão, Berenice Quinzani

2010-01-01

Polycyclic aromatic hydrocarbons (PAHs) are genotoxic chemicals commonly found in effluents from oil refineries. Bioassays using plants and cells cultures can be employed for assessing environmental safety and potential genotoxicity. In this study, the genotoxic potential of an oil refinery effluent was analyzed by means of micronucleus (MN) testing of Alium cepa, which revealed no effect after 24 h of treatment. On the other hand, primary lesions in the DNA of rat (Rattus norvegicus) hepatoma cells (HTC) were observed through comet assaying after only 2 h of exposure. On considering the capacity to detect DNA damage of a different nature and of these cells to metabolize xenobiotics, we suggest the association of the two bioassays with these cell types, plant (Allium cepa) and mammal (HTC) cells, for more accurately assessing genotoxicity in environmental samples.

Detection of estrogen receptor endocrine disruptor potency of commonly used organochlorine pesticides using the LUMI-CELL ER bioassay

Energy Technology Data Exchange (ETDEWEB)

Gordon, J D; Chu, A C; Clark, G C [Xenobiotic Detection Systems, Inc., Durham, NC (United States); Chu, M D [Alta Analytical Perspectives, Wilmington, NC (United States); Denison, M S [Dept. of Environmental Toxicology, Univ. of California, Davis, CA (United States)

2004-09-15

In order to detect the endocrine disrupting potency of organochlorine pesticides and other compounds, BG-1 (human ovarian carcinoma) cells containing a stably transfected estrogenresponsive luciferase reporter gene plasmid (BG1Luc4E2), was used. This cell line, termed the LUMI-CELL trademark ER estrogenic cell bioassay system, responds in a time-, dose dependent- and chemical-specific manner with the induction of luciferase gene expression in response to exposure to estrogen (but not other steroid hormones) and estrogenic chemicals in a high-throughput screening (HTPS) format6. Here we describe studies in which the LUMI-CELL trademark ER estrogenic cell bioassay system was used for high throughput screening (HTPS) analysis of the estrogenic disrupting potency of several commonly used pesticides and organochlorines: p,p'DDT; p,p'-DDE; DDD; {alpha}a-chlordane; {psi}-chlordane; Kepone; Methoxychlor; Vinclozolin; Fenarimol; 2,4,5-Trichlorophenoxyacetic Acid; and Dieldrin. Our results demonstrate the utility of XDS's LUMI-CELL trademark ER bioassay HTPS system for screening chemicals for estrogenic activity.

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.

Mosquito larvicidal activity of Cassia tora seed extract and its key anthraquinones aurantio-obtusin and obtusin

Directory of Open Access Journals (Sweden)

Valentine C. Mbatchou

2017-11-01

Full Text Available Abstract Background The edible and medicinal leguminous plant Cassia tora L. (Fabaceae is known to possess insecticidal properties against a wide range of plant-feeding insects. However, the bioactivity of extracts of this plant and their constituents against vectors of medical importance has been largely unexplored. We investigated the mosquito larvicidal activity of the seed extract and its major anthraquinones against larvae of the African malaria vector Anopheles gambiae (s.s.. Methods Third-fourth instar larval mortality was observed after 24, 48, 72 and 96 h of exposure to varying doses of the extracts, and two anthraquinones isolates identified using liquid chromatography- quadrupole time of flight mass spectrometry (LC-QtoF-MS. The mosquito larval mortality was evaluated relative to the natural insecticide azadirachtin. Results Fractionation of the crude extract decreased mosquito larvicidal activity, however, larvicidal activity increased with increasing dose of the treatment and exposure time. The known anthraquinones aurantio-obtusin and obtusin were identified as key larvicidal compounds. Aurantio-obtusin and obtusin, exhibited similar toxicity to larvae of A. gambiae (s.s. with LD50 values of 10 and 10.2 ppm, respectively. However, the two anthraquinones were four- and ~ six-fold less potent than that of the crude seed extract and azadirachtin, which had comparable LD50 values of 2.5 and 1.7 ppm, respectively. Conclusion Both aurantio-obtusin and obtusin showed mosquito larvicidal activity which were comparable to their respective fractions although they were less potent relative to the crude extract and azadirachtin. Further studies need to be conducted on C. tora for its exploitation as a potential eco-friendly tool in mosquito larval source reduction.

Mosquito host choices on livestock amplifiers of Rift Valley fever virus in Kenya

Science.gov (United States)

Animal hosts may vary in their attraction and acceptability as components of the host location process for assessing biting rates of vectors and risk of exposure to pathogens. However, these parameters remain poorly understood for mosquito vectors of the Rift Valley fever (RVF), an arboviral disease...

The Insect Growth Regulator Pyriproxyfen Terminates Egg Diapause in the Asian Tiger Mosquito, Aedes albopictus.

Directory of Open Access Journals (Sweden)

Devi S Suman

Full Text Available The Asian tiger mosquito, Aedes albopictus, is a highly invasive mosquito species that transmits chikungunya and dengue. This species overwinters as diapausing eggs in temperate climates. Early diapause termination may be a beneficial strategy for winter mosquito control; however, a mechanism to terminate the diapause process using chemicals is not known. We tested the hypothesis that a hormonal imbalance caused by the administration of juvenile hormone analog would terminate egg diapause in A. albopictus. We tested the insect growth regulator pyriproxyfen on all developmental stages to identify a susceptible stage for diapause termination. We found that pyriproxyfen treatment of mosquito eggs terminated embryonic diapause. The highest rates of diapause termination were recorded in newly deposited (78.9% and fully embryonated (74.7% eggs at 0.1 and 1 ppm, respectively. Hatching was completed earlier in newly deposited eggs (25-30 days compared to fully embryonated eggs (71-80 days. The combined mortality from premature diapause termination and ovicidal activity was 98.2% in newly deposited and >98.9% in fully embryonated eggs at 1 ppm. The control diapause eggs did not hatch under diapausing conditions. Pyriproxyfen exposure to larvae, pupae and adults did not prevent the females from ovipositing diapausing eggs. There was no effect of pyriproxyfen on diapausing egg embryonic developmental time. We also observed mortality in diapausing eggs laid by females exposed to pyriproxyfen immediately after blood feeding. There was no mortality in eggs laid by females that survived larval and pupal exposures. In conclusion, diapausing eggs were the more susceptible to pyriproxyfen diapause termination compared to other life stages. This is the first report of diapause termination in A. albopictus with a juvenile hormone analog. We believe our findings will be useful in developing a new control strategy against overwintering mosquito populations.

Cómo controlar los mosquitos en interiores (Controlling Mosquitoes Indoors)

Centers for Disease Control (CDC) Podcasts

2016-08-23

Los mosquitos pueden portar virus como el del Nilo Occidental o del Zika. En este podcast, Don Francisco le muestra a sus vecinos formas en las que pueden reducir el número de mosquitos dentro de su casa.  Created: 8/23/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/23/2016.

Retrospective internal radiation exposure assessment in occupational epidemiology

International Nuclear Information System (INIS)

Neton, J.W.; Flora, J.T.; Spitz, H.B.; Taulbee, T.D.

2000-01-01

Epidemiologic studies of workers at U.S. Department of Energy facilities are being conducted by the U.S. National Institute for Occupational Safety and Health to evaluate the health risk associated with exposure to sources of external and internal ionizing radiation. While exposure to external sources of radiation can be estimated from personal dosimeter data, reconstruction of exposure due to internally deposited radioactivity is more challenging because bioassay monitoring data is frequently less complete. Although comprehensive monitoring was provided for workers with the highest internal exposures, the majority of workers were monitored relatively infrequently. This monitoring was conducted to demonstrate compliance with regulations rather than to evaluate exposure for use in epidemiologic studies. Attributes of past internal monitoring programs that challenge accurate exposure assessment include: incomplete characterization of the workplace source term; a lack of timely measurements; insensitive and/or nonspecific bioassay measurements; and the presence of censored data. In spite of these limitations, many facilities have collected a large amount of worker and workplace monitoring information that can be used to evaluate internal exposure while minimizing worker misclassification. This paper describes a systematic approach for using the available worker and workplace monitoring data that can lead to either a qualitative or quantitative retrospective assessment of internal exposures. Various aspects of data analysis will be presented, including the evaluation of minimum detectable dose, the treatment of censored data, and the use of combinations of bioassay and workplace data to characterize exposures. Examples of these techniques applied to a cohort study involving chronic exposure scenarios to uranium are provided. A strategy for expressing exposure or dose in fundamental, unweighted units related to the quantity of radiation delivered to an organ will also

Bioassay of naturally occurring allelochemicals for phytotoxicity.

Science.gov (United States)

Leather, G R; Einhellig, F A

1988-10-01

The bioassay has been one of the most widely used tests to demonstrate allelopathic activity. Often, claims that a particular plant species inhibits the growth of another are based entirely on the seed germination response to solvent extracts of the suspected allelopathic plant; few of these tests are of value in demonstrating allelopathy under natural conditions. The veracity of the bioassay for evaluating naturally occurring compounds for phytotoxicity depends upon the physiological and biochemical response capacity of the bioassay organism and the mechanism(s) of action of the allelochemicals. The possibility that more than one allelochemical, acting in concert at very low concentrations, may be responsible for an observed allelopathic effect makes it imperative that bioassays be extremely sensitive to chemical growth perturbation agents. Among the many measures of phytotoxicity of allelochemicals, the inhibition (or stimulation) of seed germination, radicle elongation, and/or seedling growth have been the parameters of choice for most investigations. Few of these assays have been selected with the view towards the possible mechanism of the allelopathic effect.

Aquatic insect predators and mosquito control.

Science.gov (United States)

Shaalan, Essam Abdel-Salam; Canyon, Deon V

2009-12-01

Mosquitoes are serious biting pests and obligate vectors of many vertebrate pathogens. Their immature larval and pupal life stages are a common feature in most tropical and many temperate water bodies and often form a significant proportion of the biomass. Control strategies rely primarily on the use of larvicides and environmental modification to reduce recruitment and adulticides during periods of disease transmission. Larvicides are usually chemical but can involve biological toxins, agents or organisms. The use of insect predators in mosquito control has been exploited in a limited fashion and there is much room for further investigation and implementation. Insects that are recognized as having predatorial capacity with regard to mosquito prey have been identified in the Orders Odonata, Coleoptera, Diptera (primarily aquatic predators), and Hemiptera (primarily surface predators). Although their capacity is affected by certain biological and physical factors, they could play a major role in mosquito control. Furthermore, better understanding for the mosquitoes-predators relationship(s) could probably lead to satisfactory reduction of mosquito-borne diseases by utilizing either these predators in control programs, for instance biological and/or integrated control, or their kairomones as mosquitoes' ovipoisting repellents. This review covers the predation of different insect species on mosquito larvae, predator-prey-habitat relationships, co-habitation developmental issues, survival and abundance, oviposition avoidance, predatorial capacity and integrated vector control.

Herbicide impact on Hormosira banksii gametes measured by fluorescence and germination bioassays

International Nuclear Information System (INIS)

Seery, Cliff R.; Gunthorpe, Leanne; Ralph, Peter J.

2006-01-01

The innovative bioassay described here involves chlorophyll a fluorescence measurements of gametes from the macroalgae, Hormosira banksii, where gametes (eggs) were exposed to Diuron, Irgarol and Bromacil. Response was assessed as percent inhibition from control of effective quantum yield (ΔF/Fm') of photosystem II, herein referred to as % PSII Inhibition. This was measured with the dual-channelled pulse amplitude modulated (PAM) fluorometer, ToxY-PAM. The fluorescence bioassay was run simultaneously with an established H. banksii germination bioassay to compare sensitivity, precision, and time-to-result. The fluorescence bioassay gave highly sensitive results evidenced by EC 5 s (% PSII Inhibition) for Diuron, Irgarol and Bromacil being three, four and three orders of magnitude (respectively) lower than EC 5 s generated from the germination bioassays. Precision of the fluorescence bioassay was demonstrated with low coefficient of variations (<30%) for all three toxicants. With regard to time, the fluorescence bioassay gave results within 6 h, as opposed to more than 50 h for the germination bioassay. - Chlorophyll a fluorescence measurements form the basis of a macroalgal bioassay with many advantages over germination-based methods

Surveillance should be strengthened to improve epidemiological understandings of mosquito-borne Barmah Forest virus infection

Directory of Open Access Journals (Sweden)

David Durrheim

2012-08-01

Full Text Available Introduction: Barmah Forest virus (BFV is a mosquito-borne virus causing epidemic polyarthritis in Australia. This study used case follow-up of cases from the surveillance system to demonstrate that routinely collected BFV notification data were an unreliable indicator of the true location of exposure.Methods: BFV notifications from June 2001 to May 2011 were extracted from the New South Wales (NSW Notifiable Conditions Information Management System to study case distribution. Disease cluster analysis was performed using spatial scan statistics. Exposure history data were collected from cases notified in 2010 and 2011 to accurately determine travel to high-risk areas.Results: Cluster analysis using address data identified an area of increased BFV disease incidence in the mid-north coast of NSW contiguous with estuarine wetlands. When travel to this area was investigated, 96.7% (29/30 cases reported having visited coastal regions within four weeks of developing symptoms.Discussion: Along the central NSW coastline, extensive wetlands occur in close proximity to populated areas. These wetlands provide ideal breeding habitats for a range of mosquito species implicated in the transmission of BFV. This is the first study to fully assess case exposure with findings suggesting that sporadic cases of BFV in people living further away from the coast do not reflect alternative exposure sites but are likely to result from travel to coastal regions. Spatial analysis by case address alone may lead to inaccurate understandings of the true distribution of arboviral diseases. Subsequently, this information has important implications for the collection of mosquito-borne disease surveillance information and public health response strategies.

Integrating bioassays and analytical chemistry as an improved approach to support safety assessment of food contact materials.

Science.gov (United States)

Veyrand, Julien; Marin-Kuan, Maricel; Bezencon, Claudine; Frank, Nancy; Guérin, Violaine; Koster, Sander; Latado, Hélia; Mollergues, Julie; Patin, Amaury; Piguet, Dominique; Serrant, Patrick; Varela, Jesus; Schilter, Benoît

2017-10-01

Food contact materials (FCM) contain chemicals which can migrate into food and result in human exposure. Although it is mandatory to ensure that migration does not endanger human health, there is still no consensus on how to pragmatically assess the safety of FCM since traditional approaches would require extensive toxicological and analytical testing which are expensive and time consuming. Recently, the combination of bioassays, analytical chemistry and risk assessment has been promoted as a new paradigm to identify toxicologically relevant molecules and address safety issues. However, there has been debate on the actual value of bioassays in that framework. In the present work, a FCM anticipated to release the endocrine active chemical 4-nonyphenol (4NP) was used as a model. In a migration study, the leaching of 4NP was confirmed by LC-MS/MS and GC-MS. This was correlated with an increase in both estrogenic and anti-androgenic activities as measured with bioassays. A standard risk assessment indicated that according to the food intake scenario applied, the level of 4NP measured was lower, close or slightly above the acceptable daily intake. Altogether these results show that bioassays could reveal the presence of an endocrine active chemical in a real-case FCM migration study. The levels reported were relevant for safety assessment. In addition, this work also highlighted that bioactivity measured in migrate does not necessarily represent a safety issue. In conclusion, together with analytics, bioassays contribute to identify toxicologically relevant molecules leaching from FCM and enable improved safety assessment.

Survival and swimming behavior of insecticide-exposed larvae and pupae of the yellow fever mosquito Aedes aegypti

Science.gov (United States)

2014-01-01

Background The yellow fever mosquito Aedes aegypti is essentially a container-inhabiting species that is closely associated with urban areas. This species is a vector of human pathogens, including dengue and yellow fever viruses, and its control is of paramount importance for disease prevention. Insecticide use against mosquito juvenile stages (i.e. larvae and pupae) is growing in importance, particularly due to the ever-growing problems of resistance to adult-targeted insecticides and human safety concerns regarding such use in human dwellings. However, insecticide effects on insects in general and mosquitoes in particular primarily focus on their lethal effects. Thus, sublethal effects of such compounds in mosquito juveniles may have important effects on their environmental prevalence. In this study, we assessed the survival and swimming behavior of A. aegypti 4th instar larvae (L4) and pupae exposed to increasing concentrations of insecticides. We also assessed cell death in the neuromuscular system of juveniles. Methods Third instar larvae of A. aegypti were exposed to different concentrations of azadirachtin, deltamethrin, imidacloprid and spinosad. Insect survival was assessed for 10 days. The distance swam, the resting time and the time spent in slow swimming were assessed in 4th instar larvae (L4) and pupae. Muscular and nervous cells of L4 and pupae exposed to insecticides were marked with the TUNEL reaction. The results from the survival bioassays were subjected to survival analysis while the swimming behavioral data were subjected to analyses of covariance, complemented with a regression analysis. Results All insecticides exhibited concentration-dependent effects on survival of larvae and pupae of the yellow fever mosquito. The pyrethroid deltamethrin was the most toxic insecticide followed by spinosad, imidacloprid, and azadirachtin, which exhibited low potency against the juveniles. All insecticides except azadirachtin reduced L4 swimming speed and

Survival and swimming behavior of insecticide-exposed larvae and pupae of the yellow fever mosquito Aedes aegypti.

Science.gov (United States)

Tomé, Hudson Vv; Pascini, Tales V; Dângelo, Rômulo Ac; Guedes, Raul Nc; Martins, Gustavo F

2014-04-24

The yellow fever mosquito Aedes aegypti is essentially a container-inhabiting species that is closely associated with urban areas. This species is a vector of human pathogens, including dengue and yellow fever viruses, and its control is of paramount importance for disease prevention. Insecticide use against mosquito juvenile stages (i.e. larvae and pupae) is growing in importance, particularly due to the ever-growing problems of resistance to adult-targeted insecticides and human safety concerns regarding such use in human dwellings. However, insecticide effects on insects in general and mosquitoes in particular primarily focus on their lethal effects. Thus, sublethal effects of such compounds in mosquito juveniles may have important effects on their environmental prevalence. In this study, we assessed the survival and swimming behavior of A. aegypti 4th instar larvae (L4) and pupae exposed to increasing concentrations of insecticides. We also assessed cell death in the neuromuscular system of juveniles. Third instar larvae of A. aegypti were exposed to different concentrations of azadirachtin, deltamethrin, imidacloprid and spinosad. Insect survival was assessed for 10 days. The distance swam, the resting time and the time spent in slow swimming were assessed in 4th instar larvae (L4) and pupae. Muscular and nervous cells of L4 and pupae exposed to insecticides were marked with the TUNEL reaction. The results from the survival bioassays were subjected to survival analysis while the swimming behavioral data were subjected to analyses of covariance, complemented with a regression analysis. All insecticides exhibited concentration-dependent effects on survival of larvae and pupae of the yellow fever mosquito. The pyrethroid deltamethrin was the most toxic insecticide followed by spinosad, imidacloprid, and azadirachtin, which exhibited low potency against the juveniles. All insecticides except azadirachtin reduced L4 swimming speed and wriggling movements. A

Biomarkers and bioassays as alternative screening methods for the presence and effects of PCDD, PCDF and PCB

International Nuclear Information System (INIS)

Bosveld, A.T.C.B.; Berg, M.V.

1994-01-01

Polyhalogenated aromatic hydrocarbons (PHAH) are wide spread, highly toxic, environmental contaminants. As such they pose risks for both humans and wildlife. For risk assessment purposes, concentrations are generally analyzed by HRGC-HR/LRMS. With the analytical data, mixture toxicity is calculated using the TEF concept. With this method only the defined congeners are taken into account and additivity for all congeners is assumed, whereas synergistic and antagonistic effects for several PCDD/F in combination with PCB have also been reported. To avoid these problems and high analytical costs, bioassays can be used for screening purposes. Cytochrome P 450 1 A 1 induction and vitamin A and thyroid hormone levels are shown to be useful markers for PHAH exposure. When bioassays based on cytochrome P 450 1 A 1 induction, in cultured cells, in multi-well culturing plates, are used, 2,3,7,8-TCDD detection limits <0.2 pg are possible. As such these bioassays are highly sensitive, cost effective and time saving. This application can be used as a pre-screening method to determine total ''dioxin'' content of environmental samples. (orig.)

Herbicide impact on Hormosira banksii gametes measured by fluorescence and germination bioassays

Energy Technology Data Exchange (ETDEWEB)

Seery, Cliff R. [Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, Westbourne Street, Gore Hill, 2065 NSW (Australia); Gunthorpe, Leanne [Primary Industries Research Victoria (PIRVic), VIC (Australia); Ralph, Peter J. [Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, Westbourne Street, Gore Hill, 2065 NSW (Australia)]. E-mail: peter.ralph@uts.edu.au

2006-03-15

The innovative bioassay described here involves chlorophyll a fluorescence measurements of gametes from the macroalgae, Hormosira banksii, where gametes (eggs) were exposed to Diuron, Irgarol and Bromacil. Response was assessed as percent inhibition from control of effective quantum yield ({delta}F/Fm') of photosystem II, herein referred to as % PSII Inhibition. This was measured with the dual-channelled pulse amplitude modulated (PAM) fluorometer, ToxY-PAM. The fluorescence bioassay was run simultaneously with an established H. banksii germination bioassay to compare sensitivity, precision, and time-to-result. The fluorescence bioassay gave highly sensitive results evidenced by EC{sub 5}s (% PSII Inhibition) for Diuron, Irgarol and Bromacil being three, four and three orders of magnitude (respectively) lower than EC{sub 5}s generated from the germination bioassays. Precision of the fluorescence bioassay was demonstrated with low coefficient of variations (<30%) for all three toxicants. With regard to time, the fluorescence bioassay gave results within 6 h, as opposed to more than 50 h for the germination bioassay. - Chlorophyll a fluorescence measurements form the basis of a macroalgal bioassay with many advantages over germination-based methods.

Large-Scale Removal of Invasive Honeysuckle Decreases Mosquito and Avian Host Abundance.

Science.gov (United States)

Gardner, Allison M; Muturi, Ephantus J; Overmier, Leah D; Allan, Brian F

2017-12-01

Invasive species rank second only to habitat destruction as a threat to native biodiversity. One consequence of biological invasions is altered risk of exposure to infectious diseases in human and animal populations. The distribution and prevalence of mosquito-borne diseases depend on the complex interactions between the vector, the pathogen, and the human or wildlife reservoir host. These interactions are highly susceptible to disturbance by invasive species, including terrestrial plants. We conducted a 2-year field experiment using a Before-After/Control-Impact design to examine how removal of invasive Amur honeysuckle (Lonicera maackii) in a forest fragment embedded within a residential neighborhood affects the abundance of mosquitoes, including two of the most important vectors of West Nile virus, Culex pipiens and Cx. restuans. We also assessed any potential changes in avian communities and local microclimate associated with Amur honeysuckle removal. We found that (1) removal of Amur honeysuckle reduces the abundance of both vector and non-vector mosquito species that commonly feed on human hosts, (2) the abundance and composition of avian hosts is altered by honeysuckle removal, and (3) areas invaded with honeysuckle support local microclimates that are favorable to mosquito survival. Collectively, our investigations demonstrate the role of a highly invasive understory shrub in determining the abundance and distribution of mosquitoes and suggest potential mechanisms underlying this pattern. Our results also give rise to additional questions regarding the general impact of invasive plants on vector-borne diseases and the spatial scale at which removal of invasive plants may be utilized to effect disease control.

Cooler temperatures destabilize RNA interference and increase susceptibility of disease vector mosquitoes to viral infection.

Directory of Open Access Journals (Sweden)

Zach N Adelman

Full Text Available The impact of global climate change on the transmission dynamics of infectious diseases is the subject of extensive debate. The transmission of mosquito-borne viral diseases is particularly complex, with climatic variables directly affecting many parameters associated with the prevalence of disease vectors. While evidence shows that warmer temperatures often decrease the extrinsic incubation period of an arthropod-borne virus (arbovirus, exposure to cooler temperatures often predisposes disease vector mosquitoes to higher infection rates. RNA interference (RNAi pathways are essential to antiviral immunity in the mosquito; however, few experiments have explored the effects of temperature on the RNAi machinery.We utilized transgenic "sensor" strains of Aedes aegypti to examine the role of temperature on RNA silencing. These "sensor" strains express EGFP only when RNAi is inhibited; for example, after knockdown of the effector proteins Dicer-2 (DCR-2 or Argonaute-2 (AGO-2. We observed an increase in EGFP expression in transgenic sensor mosquitoes reared at 18°C as compared with 28°C. Changes in expression were dependent on the presence of an inverted repeat with homology to a portion of the EGFP sequence, as transgenic strains lacking this sequence, the double stranded RNA (dsRNA trigger for RNAi, showed no change in EGFP expression when reared at 18°C. Sequencing small RNAs in sensor mosquitoes reared at low temperature revealed normal processing of dsRNA substrates, suggesting the observed deficiency in RNAi occurs downstream of DCR-2. Rearing at cooler temperatures also predisposed mosquitoes to higher levels of infection with both chikungunya and yellow fever viruses.This data suggest that microclimates, such as those present in mosquito breeding sites, as well as more general climactic variables may influence the dynamics of mosquito-borne viral diseases by affecting the antiviral immunity of disease vectors.

Avian Plasmodium in Eastern Austrian mosquitoes.

Science.gov (United States)

Schoener, Ellen; Uebleis, Sarah Susanne; Butter, Julia; Nawratil, Michaela; Cuk, Claudia; Flechl, Eva; Kothmayer, Michael; Obwaller, Adelheid G; Zechmeister, Thomas; Rubel, Franz; Lebl, Karin; Zittra, Carina; Fuehrer, Hans-Peter

2017-09-29

Insect vectors, namely mosquitoes (Diptera: Culicidae), are compulsory for malaria parasites (Plasmodium spp.) to complete their life cycle. Despite this, little is known about vector competence of different mosquito species for the transmission of avian malaria parasites. In this study, nested PCR was used to determine Plasmodium spp. occurrence in pools of whole individuals, as well as the diversity of mitochondrial cytochrome b gene sequences in wild-caught mosquitoes sampled across Eastern Austria in 2013-2015. A total of 45,749 mosquitoes in 2628 pools were collected, of which 169 pools (6.43%) comprising 9 mosquito species were positive for avian Plasmodium, with the majority of positives in mosquitoes of Culex pipiens s.l./Culex torrentium. Six different avian Plasmodium lineages were found, the most common were Plasmodium vaughani SYAT05, Plasmodium sp. Linn1 and Plasmodium relictum SGS1. In 2014, mosquitoes of the Culex pipiens complex were genetically identified and Culex pipiens f. pipiens presented with the highest number of avian Plasmodium positives (n = 37; 16.74%). Despite this, the minimum infection rate (MIR) was highest in Culex torrentium (5.36%) and Culex pipiens f. pipiens/f. molestus hybrids (5.26%). During 2014 and 2015, seasonal and annual changes in Plasmodium lineage distribution were also observed. In both years P. vaughani SYAT05 dominated at the beginning of the sampling period to be replaced later in the year by P. relictum SGS1 (2014) and Plasmodium sp. Linn1 (2015). This is the first large-scale study of avian Plasmodium parasites in Austrian mosquitoes. These results are of special interest, because molecular identification of the taxa of the Cx. pipiens complex and Cx. torrentium enabled the determination of Plasmodium prevalence in the different mosquito taxa and hybrids of this complex. Since pools of whole insects were used, it is not possible to assert any vector competence in any of the examined mosquitoes, but the results

Laboratory algal bioassays using PAM fluorometry: effects of test conditions on the determination of herbicide and field sample toxicity.

Science.gov (United States)

Sjollema, Sascha B; van Beusekom, Sebastiaan A M; van der Geest, Harm G; Booij, Petra; de Zwart, Dick; Vethaak, A Dick; Admiraal, Wim

2014-05-01

Pulse Amplitude Modulation (PAM) fluorometry, based on chlorophyll a fluorescence, is a frequently used technique in algal bioassays to assess toxicity of single compounds or complex field samples. Several test conditions can influence the test results, and because a standardized test protocol is currently lacking, linking the results of different studies is difficult. Therefore, the aim of the present study was to gain insight into the effects of test conditions of laboratory algal bioassays using PAM fluorometry on the outcome of toxicity tests. To this purpose, we described the results from several pilot studies on test development in which information is provided on the effects of the main test factors during the pretest phase, the test preparation, the exposure period, and the actual measurement. The experiments were focused on individual herbicides and complex field samples and included the effects of culturing conditions, cell density, solvent concentration, exposure time, and the presence of actinic light. Several of these test conditions were found to influence the outcome of the toxicity test, and the presented information provides important background information for the interpretation of toxicity results and describes which test conditions should be taken into account when using an algal bioassay with PAM fluorometry. Finally, the application of PAM fluorometry in algal toxicity testing is discussed. © 2014 SETAC.

Genotoxic evaluation of an industrial effluent from an oil refinery using plant and animal bioassays

Directory of Open Access Journals (Sweden)

Fernando Postalli Rodrigues

2010-01-01

Full Text Available Polycyclic aromatic hydrocarbons (PAHs are genotoxic chemicals commonly found in effluents from oil refineries. Bioassays using plants and cells cultures can be employed for assessing environmental safety and potential genotoxicity. In this study, the genotoxic potential of an oil refinery effluent was analyzed by means of micronucleus (MN testing of Alium cepa, which revealed no effect after 24 h of treatment. On the other hand, primary lesions in the DNA of rat (Rattus norvegicus hepatoma cells (HTC were observed through comet assaying after only 2 h of exposure. On considering the capacity to detect DNA damage of a different nature and of these cells to metabolize xenobiotics, we suggest the association of the two bioassays with these cell types, plant (Allium cepa and mammal (HTC cells, for more accurately assessing genotoxicity in environmental samples.

Rickettsia Species in African Anopheles Mosquitoes

Science.gov (United States)

Socolovschi, Cristina; Pages, Frédéric; Ndiath, Mamadou O.; Ratmanov, Pavel; Raoult, Didier

2012-01-01

Background There is higher rate of R. felis infection among febrile patients than in healthy people in Sub-Saharan Africa, predominantly in the rainy season. Mosquitoes possess a high vectorial capacity and, because of their abundance and aggressiveness, likely play a role in rickettsial epidemiology. Methodology/Principal Findings Quantitative and traditional PCR assays specific for Rickettsia genes detected rickettsial DNA in 13 of 848 (1.5%) Anopheles mosquitoes collected from Côte d’Ivoire, Gabon, and Senegal. R. felis was detected in one An. gambiae molecular form S mosquito collected from Kahin, Côte d’Ivoire (1/77, 1.3%). Additionally, a new Rickettsia genotype was detected in five An. gambiae molecular form S mosquitoes collected from Côte d’Ivoire (5/77, 6.5%) and one mosquito from Libreville, Gabon (1/88, 1.1%), as well as six An. melas (6/67, 9%) mosquitoes collected from Port Gentil, Gabon. A sequence analysis of the gltA, ompB, ompA and sca4 genes indicated that this new Rickettsia sp. is closely related to R. felis. No rickettsial DNA was detected from An. funestus, An. arabiensis, or An. gambiae molecular form M mosquitoes. Additionally, a BLAST analysis of the gltA sequence from the new Rickettsia sp. resulted in a 99.71% sequence similarity to a species (JQ674485) previously detected in a blood sample of a Senegalese patient with a fever from the Bandafassi village, Kedougou region. Conclusion R. felis was detected for the first time in An. gambiae molecular form S, which represents the major African malaria vector. The discovery of R. felis, as well as a new Rickettsia species, in mosquitoes raises new issues with respect to African rickettsial epidemiology that need to be investigated, such as bacterial isolation, the degree of the vectorial capacity of mosquitoes, the animal reservoirs, and human pathogenicity. PMID:23118963

Applied in vitro radio bioassay

International Nuclear Information System (INIS)

Gaburo, J.C.G.; Sordi, G.M.A.A.

1992-11-01

The aim of this publication is to show the concepts and in vitro bioassay techniques as well as experimental procedures related with internal contamination evaluation. The main routes of intake, metabolic behavior, and the possible types of bioassay samples that can be collected for radionuclides analysis are described. Both biological processes and the chemical and physical behavior of the radioactive material of interest are considered and the capabilities of analytical techniques to detect and quantify the radionuclides are discussed. Next, the need of quality assurance throughout procedures are considered and finally a summary of the techniques applied to the internal routine monitoring of IPEN workers is given. (author)

Evaluation and modeling of the parameters affecting fluoride toxicity level in aquatic environments by bioassay method

Directory of Open Access Journals (Sweden)

Hamid Reza Shamsollahi

2014-04-01

Full Text Available Background: Fluoride exists in various forms in nature and water resources. , The rising level of fluoride in water resources due to discharge of industrial effluents can cause toxicity in aquatic organisms. To prevent toxicity, it is necessary to determine maximum fluoride toxicity as well as effluent discharge limits. The aim of this study was to determine the maximum fluoride toxicity and the factors affecting fluoride toxicity to provide a model in order to determine the effluent discharge limits. Methods: Daphnia magna bioassay in the absence of confounding factors was used to determine the maximum level of fluoride toxicity. Then, bioassay was repeated in the presence of the confounding factors (hardness, temperature and exposure time to determine their effects. Results: In the absence of intervening factors, fluoride LC50 levels determined after 24, 48 and 72 hours exposure were 4.9, 46.5 and 38.7 mg/l, respectively.. Also, the influence of confounding factors on LC50 values was reported significant by Minitab software. Conclusion: Increasing the water hardness reduced fluoride toxicity, and increasing the water temperature and exposure time increased fluoride toxicity in aquatic environments. Therefore, while determining the wastewater discharge limit in terms of fluoride concentration, it is essential to take the effect of confounding factors on fluoride toxicity into account in order to prevent toxicity in the open water resources.

Tips to Prevent Mosquito Bites

Science.gov (United States)

... discourage mosquitoes, ticks and other biting insects from landing on you. Here are tips for other preventive ... CDC Mosquito Control Methods - NPIC Exit Top of Page Contact Us to ask a question, provide feedback, ...

Toxicological effects of prolonged and intense use of mosquito coil emission in rats and its implications on malaria control

Directory of Open Access Journals (Sweden)

Emmanuel Taiwo Idowu

2013-09-01

Full Text Available Efectos toxicológicos del uso prolongado e intenso de emisiones de espirales contra mosquitos en ratas y sus implicaciones sobre el control de la malaria. Mosquito coil is a vector control option used to prevent malaria in low income counties, while some studies have addressed this issue, additional reseach is required to increase knowledge on the adverse health effects caused by the prolonged use of coils. In this study we investigated the toxicological effects of fumes from two locally manufactured mosquito coil insecticides (with pyrethroids: transfluthrin and d-allethrin as active ingredients on male albino rats. For this, we recorded the haematological and biochemical indices, and made histopathology and mutagenicity evaluations in rats exposed to mosquito fumes during 2, 4, 8, 12 and 16 week periods. Haematological determination was performed using automated hematology analyzer to determine White Blood Cell (WBC, Packed Cell Volume (PCV, Red Blood Cell (RBC and Platelet (PLT counts, while biochemical evaluations were determined using available commercial kits. Gross histopathological changes were studied for the kidney, liver and lungs in sacrificed rats. The rat sperm head abnormalities assessment was used to evaluate mutagenicity. Mosquito coil fumes produced significant increase (P0.05. Mutagenicity assessment revealed sperm abnormality was statistically significant (P<0.05 compared with the control at 8, 12 and 16 weeks post exposure to transfluthrin. Histological studies revealed severe lung damage evidenced by interstitial accumulations, pulmonary oedema and emphysema in exposed rats. Intracellular accumulations and severe sinusoidal congestion of liver cells were observed from 12 weeks exposure, indicating liver damage. Our studies indicate that mosquito coil fumes do initiate gradual damage to the host. These pathological effects must be taken into consideration by the malaria control program, particularly when regulating their

Bioassay method for Uranium in urine by Delay Neutron counting

International Nuclear Information System (INIS)

Suratman; Purwanto; Sukarman-Aminjoyo

1996-01-01

A bioassay method for uranium in urine by neutron counting has been studied. The aim of this research is to obtain a bioassay method for uranium in urine which is used for the determination of internal dose of radiation workers. The bioassay was applied to the artificially uranium contaminated urine. The weight of the contaminant was varied. The uranium in the urine was irradiated in the Kartini reactor core, through pneumatic system. The delayed neutron was counted by BF3 neutron counter. Recovery of the bioassay was between 69.8-88.8 %, standard deviation was less than 10 % and the minimum detection was 0.387 μg

Detection of estrogen receptor endocrine disruptor potency of commonly used organochlorine pesticides using the LUMI-CELL ER bioassay

Energy Technology Data Exchange (ETDEWEB)

Gordon, J.D.; Chu, A.C.; Clark, G.C. [Xenobiotic Detection Systems, Inc., Durham, NC (United States); Chu, M.D. [Alta Analytical Perspectives, Wilmington, NC (United States); Denison, M.S. [Dept. of Environmental Toxicology, Univ. of California, Davis, CA (United States)

2004-09-15

In order to detect the endocrine disrupting potency of organochlorine pesticides and other compounds, BG-1 (human ovarian carcinoma) cells containing a stably transfected estrogenresponsive luciferase reporter gene plasmid (BG1Luc4E2), was used. This cell line, termed the LUMI-CELL trademark ER estrogenic cell bioassay system, responds in a time-, dose dependent- and chemical-specific manner with the induction of luciferase gene expression in response to exposure to estrogen (but not other steroid hormones) and estrogenic chemicals in a high-throughput screening (HTPS) format6. Here we describe studies in which the LUMI-CELL trademark ER estrogenic cell bioassay system was used for high throughput screening (HTPS) analysis of the estrogenic disrupting potency of several commonly used pesticides and organochlorines: p,p'DDT; p,p'-DDE; DDD; {alpha}a-chlordane; {psi}-chlordane; Kepone; Methoxychlor; Vinclozolin; Fenarimol; 2,4,5-Trichlorophenoxyacetic Acid; and Dieldrin. Our results demonstrate the utility of XDS's LUMI-CELL trademark ER bioassay HTPS system for screening chemicals for estrogenic activity.

A global assembly of adult female mosquito mark-release-recapture data to inform the control of mosquito-borne pathogens

NARCIS (Netherlands)

Guerra, C.A.; Reiner Jr, R.C.; Perkins, T.A.; Lindsay, S.W.; Midega, J.T.; Brady, O.J.; Barker, C.M.; Reisen, W.K.; Harrington, L.C.; Takken, W.; Kitron, U.; Lloyd, A.L.; Hay, S.I.; Scott, T.W.; Smith, D.L.

2014-01-01

Background Pathogen transmission by mosquitos is known to be highly sensitive to mosquito bionomic parameters. Mosquito mark-release-recapture (MMRR) experiments are a standard method for estimating such parameters including dispersal, population size and density, survival, blood feeding frequency

Estimation of insecticide persistence, biological activity and mosquito resistance to PermaNet® 2 long-lasting insecticidal nets over three to 32 months of use in Ethiopia.

Science.gov (United States)

Anshebo, Gedeon Yohannes; Graves, Patricia M; Smith, Stephen C; Wills, Aprielle B; Damte, Mesele; Endeshaw, Tekola; Shargie, Estifanos Biru; Gebre, Teshome; Mosher, Aryc W; Patterson, Amy E; Emerson, Paul M

2014-03-06

Information is needed on the expected durability of insecticidal nets under operational conditions. The persistence of insecticidal efficacy is important to estimate the median serviceable life of nets under field conditions and to plan for net replacement. Deltamethrin residue levels were evaluated by the proxy method of X-ray fluorescence spectrometry on 189 nets used for three to six months from nine sites, 220 nets used for 14-20 months from 11 sites, and 200 nets used for 26-32 months from ten sites in Ethiopia. A random sample of 16.5-20% of nets from each time period (total 112 of 609 nets) were tested by bioassay with susceptible mosquitoes, and nets used for 14-20 months and 26-32 months were also tested with wild caught mosquitoes. Mean insecticide levels estimated by X-ray fluorescence declined by 25.9% from baseline of 66.2 (SD 14.6) mg/m2 at three to six months to 44.1 (SD 21.2) mg/m2 at 14-20 months and by 30.8% to 41.1 (SD 18.9) mg/m2 at 26-32 months. More than 95% of nets retained greater than 10 mg/m2 of deltamethrin and over 79% had at least 25 mg/m2 at all time periods. By bioassay with susceptible Anopheles, mortality averaged 89.0% on 28 nets tested at three to six months, 93.3% on 44 nets at 14-20 months and 94.1% on 40 nets at 26-32 months. With wild caught mosquitoes, mortality averaged 85.4% (range 79.1 to 91.7%) at 14-20 months but had dropped significantly to 47.2% (39.8 to 54.7%) at 26-32 months. Insecticide residue level, as estimated by X-ray fluorescence, declined by about one third between three and six months and 14-20 months, but remained relatively stable and above minimum requirements thereafter up to 26-32 months. The insecticidal activity of PermaNet® 2.0 long-lasting insecticidal nets in the specified study area may be considered effective to susceptible mosquitoes at least for the duration indicated in this study (32 months). However, results indicated that resistance in the wild population is already rendering nets with

Bioassay Phantoms Using Medical Images and Computer Aided Manufacturing

International Nuclear Information System (INIS)

Xu, X. Geroge

2011-01-01

A radiation bioassay program relies on a set of standard human phantoms to calibrate and assess radioactivity levels inside a human body for radiation protection and nuclear medicine imaging purposes. However, the methodologies in the development and application of anthropomorphic phantoms, both physical and computational, had mostly remained the same for the past 40 years. We herein propose a 3-year research project to develop medical image-based physical and computational phantoms specifically for radiation bioassay applications involving internally deposited radionuclides. The broad, long-term objective of this research was to set the foundation for a systematic paradigm shift away from the anatomically crude phantoms in existence today to realistic and ultimately individual-specific bioassay methodologies. This long-term objective is expected to impact all areas of radiation bioassay involving nuclear power plants, U.S. DOE laboratories, and nuclear medicine clinics.

Comparison of five bioassay techniques for assessing sediment-bound contaminants

OpenAIRE

Ahlf, Wolfgang; Calmano, Wolfgang; Erhard, Judith; Förstner, Ulrich

1989-01-01

Biological response could not be predicted based on chemical concentration of the sediment contaminants. Bioassays integrate the response of test organisms to contaminants and nutrients. Comparative results of five acute bioassays indicated that Neubauer phytoassay was the most sensitive. The mircobial biomass and algal growth tests indicated a response to the availability of contaminants and nutrients. These results suggest the usefulness of a diversity of bioassays in toxicity testing of se...

Effects of sublethal exposure to metofluthrin on the fitness of Aedes aegypti in a domestic setting in Cairns, Queensland

OpenAIRE

Buhagiar, Tamara S.; Devine, Gregor J.; Ritchie, Scott A.

2017-01-01

Background Metofluthrin is highly effective at reducing biting activity in Aedes aegypti. Its efficacy lies in the rapid onset of confusion, knockdown, and subsequent kill of a mosquito. In the field, there are a variety of scenarios that might result in sublethal exposure to metofluthrin, including mosquitoes that are active at the margins of the chemical?s lethal range, brief exposure as mosquitoes fly in and out of treated spaces or decreasing efficacy of the emanators with time. Sublethal...

Mosquito Control: Do Your Part

Centers for Disease Control (CDC) Podcasts

Everyone can do their part to help control mosquitoes that can carry viruses like West Nile, Zika, dengue and chikungunya. In each episode of this podcast, you will learn ways to help reduce the number of mosquitoes in and around your home.

Chikungunya virus adapts to tiger mosquito via evolutionary convergence: a sign of things to come?

Directory of Open Access Journals (Sweden)

Higgs Stephen

2008-02-01

Full Text Available Abstract Since 2004, several million indigenous cases of Chikungunya virus disease occurred in Africa, the Indian Ocean, India, Asia and, recently, Europe. The virus, usually transmitted by Aedes aegypti mosquitoes, has now repeatedly been associated with a new vector, Ae. Albopictus. Analysis of full-length viral sequences reveals three independent events of virus exposure to Ae. Albopictus, each followed by the acquisition of a single adaptive mutation providing selective advantage for transmission by this mosquito. This disconcerting and current unique example of "evolutionary convergence" occurring in nature illustrates rapid pathogen adaptation to ecological perturbation, driven directly as a consequence of human activities.

Exotic mosquito threats require strategic surveillance and response planning.

Science.gov (United States)

Webb, Cameron E; Doggett, Stephen L

2016-12-14

Mosquito-borne diseases caused by endemic pathogens such as Ross River, Barmah Forest and Murray Valley encephalitis viruses are an annual concern in New South Wales (NSW), Australia. More than a dozen mosquito species have been implicated in the transmission of these pathogens, with each mosquito occupying a specialised ecological niche that influences their habitat associations, host feeding preferences and the environmental drivers of their abundance. The NSW Arbovirus Surveillance and Mosquito Monitoring Program provides an early warning system for potential outbreaks of mosquito-borne disease by tracking annual activity of these mosquitoes and their associated pathogens. Although the program will effectively track changes in local mosquito populations that may increase with a changing climate, urbanisation and wetland rehabilitation, it will be less effective with current surveillance methodologies at detecting or monitoring changes in exotic mosquito threats, where different surveillance strategies need to be used. Exotic container-inhabiting mosquitoes such as Aedes aegypti and Ae. albopictus pose a threat to NSW because they are nuisance-biting pests and vectors of pathogens such as dengue, chikungunya and Zika viruses. International movement of humans and their belongings have spread these mosquitoes to many regions of the world. In recent years, these two mosquitoes have been detected by the Australian Government Department of Agriculture and Water Resources at local airports and seaports. To target the detection of these exotic mosquitoes, new trapping technologies and networks of surveillance locations are required. Additionally, incursions of these mosquitoes into urban areas of the state will require strategic responses to minimise substantial public health and economic burdens to local communities.

GLOBE Goes GO with Mosquitoes

Science.gov (United States)

Boger, R. A.; Low, R.

2016-12-01

The GLOBE Mosquito Larvae protocol and a new citizen science initiative, GLOBE Observers (GO), were both launched in Summer 2016. While the GLOBE Mosquito Larvae Protocol and associated educational materials target K-16 student inquiry and research, the GO protocol version is simplified to enable citizen scientists of all ages from all walks of life to participate. GO allows citizen scientists to collect and submit environmental data through an easy-to-use smart phone app available for both Apple and Android mobile devices. GO mosquito asks for photos of larvae mosquito genus or species, location, and type of water source (e.g., container or pond) where the larvae were found. To initiate the new mosquito GLOBE/GO opportunities, workshops have been held in Barbuda, Thailand, West Indies, US Gulf Coast, New York City, and at the GLOBE Annual Meeting in Colorado. Through these venues, the protocols have been refined and a field campaign has been initiated so that GO and GLOBE citizen scientists (K-16 students and all others) can contribute data. Quality assurance measures are taken through the online training required to participate and the validation of identification by other citizen sciences and mosquito experts. Furthermore, initial research is underway to develop optical recognition software starting with the species that carry the Zika virus (Aedes aegypti and A. albopictus). With this launch, we plan to move forward by providing opportunities throughout the world to engage people in meaningful environmental and public health data collection and to promote citizen scientists to become agents of change in their communities.

The Potential Use of Wolbachia-Based Mosquito Biocontrol Strategies for Japanese Encephalitis.

Directory of Open Access Journals (Sweden)

Claire L Jeffries

Full Text Available Japanese encephalitis virus (JEV is a zoonotic pathogen transmitted by the infectious bite of Culex mosquitoes. The virus causes the development of the disease Japanese encephalitis (JE in a small proportion of those infected, predominantly affecting children in eastern and southern Asia. Annual JE incidence estimates range from 50,000-175,000, with 25%-30% of cases resulting in mortality. It is estimated that 3 billion people live in countries in which JEV is endemic. The virus exists in an enzootic transmission cycle, with mosquitoes transmitting JEV between birds as reservoir hosts and pigs as amplifying hosts. Zoonotic infection occurs as a result of spillover events from the main transmission cycle. The reservoir avian hosts include cattle egrets, pond herons, and other species of water birds belonging to the family Ardeidae. Irrigated rice fields provide an ideal breeding ground for mosquitoes and attract migratory birds, maintaining the transmission of JEV. Although multiple vaccines have been developed for JEV, they are expensive and require multiple doses to maintain efficacy and immunity. As humans are a "dead-end" host for the virus, vaccination of the human population is unlikely to result in eradication. Therefore, vector control of the principal mosquito vector, Culex tritaeniorhynchus, represents a more promising strategy for reducing transmission. Current vector control strategies include intermittent irrigation of rice fields and space spraying of insecticides during outbreaks. However, Cx. Tritaeniorhynchus is subject to heavy exposure to pesticides in rice fields, and as a result, insecticide resistance has developed. In recent years, significant advancements have been made in the potential use of the bacterial endosymbiont Wolbachia for mosquito biocontrol. The successful transinfection of Wolbachia strains from Drosophila flies to Aedes (Stegomyia mosquitoes has resulted in the generation of "dengue-refractory" mosquito

Nanoparticles for mosquito control: Challenges and constraints

Directory of Open Access Journals (Sweden)

Giovanni Benelli

2017-10-01

Full Text Available Mosquito control programs are facing important and timely challenges, including the recent outbreaks of novel arbovirus, the development of resistance in several Culicidae species, and the rapid spreading of highly invasive mosquitoes worldwide. Current control tools mainly rely on the employment of (i synthetic or microbial pesticides, (ii insecticide-treated bed nets, (iii adult repellents, (iv biological control agents against mosquito young instars (mainly fishes, amphibians and copepods (v Sterile Insect Technique (SIT, (vi “boosted SIT”, (vii symbiont-based methods and (viii transgenic mosquitoes. Currently, none of these single strategies is fully successful. Novel eco-friendly strategies to manage mosquito vectors are urgently needed. The plant-mediated fabrication of nanoparticles is advantageous over chemical and physical methods, since it is cheap, single-step, and does not require high pressure, energy, temperature, or the use of highly toxic chemicals. In the latest years, a growing number of plant-borne compounds have been proposed for efficient and rapid extracellular synthesis of metal nanoparticles effective against mosquitoes at very low doses (i.e. 1–30 ppm. In this review, we focused on the promising potential of green-fabricated nanoparticles as toxic agents against mosquito young instars, and as adult oviposition deterrents. Furthermore, we analyzed current evidences about non-target effects of these nanocomposites used for mosquito control, pointing out their moderate acute toxicity for non-target aquatic organisms, absence of genotoxicity at the doses tested against mosquitoes, and the possibility to boost the predation rates of biological control agents against mosquitoes treating the aquatic environment with ultra-low doses (e.g. 1–3 ppm of green-synthesized nanoparticles, which reduce the motility of mosquito larvae. Challenges for future research should shed light on (i the precise mechanism(s of action of

Flavivirus-Mosquito Interactions

Directory of Open Access Journals (Sweden)

Yan-Jang S. Huang

2014-11-01

Full Text Available The Flavivirus genus is in the family Flaviviridae and is comprised of more than 70 viruses. These viruses have a broad geographic range, circulating on every continent except Antarctica. Mosquito-borne flaviviruses, such as yellow fever virus, dengue virus serotypes 1–4, Japanese encephalitis virus, and West Nile virus are responsible for significant human morbidity and mortality in affected regions. This review focuses on what is known about flavivirus-mosquito interactions and presents key data collected from the field and laboratory-based molecular and ultrastructural evaluations.

Mosquito bite anaphylaxis: immunotherapy with whole body extracts.

Science.gov (United States)

McCormack, D R; Salata, K F; Hershey, J N; Carpenter, G B; Engler, R J

1995-01-01

Adverse reactions to mosquito bites have been recognized for some time. These usually consist of large local swellings and redness, generalized urticaria, angioedema and less easily definable responses such as nausea, dizziness, headaches, and lethargy. We report two patients who experienced systemic anaphylaxis from mosquito bites. Both were skin tested and given immunotherapy using whole body mosquito extracts. Skin testing using whole body mosquito extracts was positive to Aedes aegypti at 1/1,000 weight/volume (wt/vol) in one patient and to Aedes aegypti at 1/100,000 wt/vol, and Culex pipiens at 1/10,000 wt/vol in the other. Skin testing of ten volunteers without a history of adverse reactions to mosquito bites was negative. Immunotherapy using these extracts resulted in resolution of adverse reactions to mosquito bites in one patient and a decrease in reactions in the other. Immunotherapy with whole body mosquito extracts is a viable treatment option that can play a role in patients with mosquito bite-induced anaphylaxis. It may also result in severe side effects and one must determine the benefit versus risks for each individual patient.

Polycyclic aromatic hydrocarbons bioavailability in industrial and agricultural soils: Linking SPME and Tenax extraction with bioassays.

Science.gov (United States)

Guo, Meixia; Gong, Zongqiang; Li, Xiaojun; Allinson, Graeme; Rookes, James; Cahill, David

2017-06-01

The aims of this study were to evaluate the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in industrial and agricultural soils using chemical methods and a bioassay, and to study the relationships between the methods. This was conducted by comparing the quantities of PAHs extracted from two manufactured gas plant (MGP) soils and an agricultural soil with low level contamination by solid-phase micro-extraction (SPME) and Tenax-TA extraction with the quantities taken up by the earthworm (Eisenia fetida). In addition, a biodegradation experiment was conducted on one MGP soil (MGP-A) to clarify the relationship between PAH removal by biodegradation and the variation in PAH concentrations in soil pore water. Results demonstrated that the earthworm bioassay could not be used to examine PAH bioavailability in the tested MGP soils; which was the case even in the diluted MGP-A soils after biodegradation. However, the bioassay was successfully applied to the agricultural soil. These results suggest that earthworms can only be used for bioassays in soils with low toxicity. In general, rapidly desorbing concentrations extracted by Tenax-TA could predict PAH concentrations accumulated in earthworms (R 2 =0.66), while SPME underestimated earthworm concentrations by a factor of 2.5. Both SPME and Tenax extraction can provide a useful tool to predict PAH bioavailability for earthworms, but Tenax-TA extraction was proven to be a more sensitive and precise method than SPME for the prediction of earthworm exposure in the agricultural soil. Copyright © 2017. Published by Elsevier Inc.

Looking Backward, Looking Forward: The Long, Torturous Struggle with Mosquitoes

Directory of Open Access Journals (Sweden)

Gordon M. Patterson

2016-10-01

Full Text Available The American anti-mosquito movement grew out of the discovery of the role of mosquitoes in transferring pathogens and public concern about pest and nuisance mosquitoes in the late 1800s. In the 20th century, organized mosquito control in the United States passed through three eras: mechanical, chemical, and integrated mosquito control. Mosquito control in the 21st century faces the challenge of emerging pathogens, invasive mosquito species, and balancing concerns about the environment with effective control strategies.

Bioassays for risk assessment of coal conversion products

Energy Technology Data Exchange (ETDEWEB)

Schacht, S.; Sinder, C.; Pfeifer, F.; Klein, J. [DMT-Gesellschaft fuer Forschung und Pruefung mbH, Essen (Germany)

1999-07-01

Traditional as well as biotechnological processing coal leads to complex mixtures of products. Besides chemical and physical characterization, which provides the information for product application, there is a need for bioassays to monitor properties that are probably toxic, mutagenic or cancerogenic. Investigations carried out focused on the selection, adaptation and validation of bioassays for the sensitive estimation of toxic effects. Organisms like bacteria, Daphnia magna and Scenedesmus subspicatus, representing different complexities in the biosphere, were selected as test systems for ecotoxicological and mutagenicity studies. The results obtained indicate that bioassays are, in principle, suitable tools for characterization and evaluation of coal-derived substances and bioconversion products. Using coal products, coal-relevant model compounds and bioconversion products, data for risk assessment are presented. (orig.)

Novel acetylcholinesterase target site for malaria mosquito control.

Directory of Open Access Journals (Sweden)

Yuan-Ping Pang

2006-12-01

Full Text Available Current anticholinesterase pesticides were developed during World War II and are toxic to mammals because they target a catalytic serine residue of acetylcholinesterases (AChEs in insects and in mammals. A sequence analysis of AChEs from 73 species and a three-dimensional model of a malaria-carrying mosquito (Anopheles gambiae AChE (AgAChE reported here show that C286 and R339 of AgAChE are conserved at the opening of the active site of AChEs in 17 invertebrate and four insect species, respectively. Both residues are absent in the active site of AChEs of human, monkey, dog, cat, cattle, rabbit, rat, and mouse. The 17 invertebrates include house mosquito, Japanese encephalitis mosquito, African malaria mosquito, German cockroach, Florida lancelet, rice leaf beetle, African bollworm, beet armyworm, codling moth, diamondback moth, domestic silkworm, honey bee, oat or wheat aphid, the greenbug, melon or cotton aphid, green peach aphid, and English grain aphid. The four insects are house mosquito, Japanese encephalitis mosquito, African malaria mosquito, and German cockroach. The discovery of the two invertebrate-specific residues enables the development of effective and safer pesticides that target the residues present only in mosquito AChEs rather than the ubiquitous serine residue, thus potentially offering an effective control of mosquito-borne malaria. Anti-AgAChE pesticides can be designed to interact with R339 and subsequently covalently bond to C286. Such pesticides would be toxic to mosquitoes but not to mammals.

Genotoxic and mutagenic effects of polluted surface water in the midwestern region of Brazil using animal and plant bioassays

Directory of Open Access Journals (Sweden)

Priscila Leocádia Rosa Dourado

Full Text Available Abstract This study aimed to evaluate DNA damage in animal and plant cells exposed to water from the Água Boa stream (Dourados, Mato Grosso do Sul, Brazil by using bioassays, and to identify the chemical compounds in the water to determine the water quality in the area. Through the cytotoxicity bioassay with Allium cepa, using micronucleus test, and comet assay, using Astyanax altiparanae fish, the results indicated that biological samples were genetically altered. Micronuclei were observed in erythrocytes of A. altiparanae after exposure to water from locations close to industrial waste discharge. The highest DNA damage observed with the comet assay in fish occurred with the exposure to water from locations where the presence of metals (Cu, Pb, Cd, Ni was high, indicating the possibility of genotoxic effects of these compounds. Thus, these results reinforce the importance of conducting genotoxicity tests for developing management plans to improve water quality, and indicate the need for waste management before domestic and industrial effluents are released into the rivers and streams.

Visualization of house-entry behaviour of malaria mosquitoes.

Science.gov (United States)

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

2016-04-25

Malaria mosquitoes often blood feed indoors on human hosts. The mosquitoes predominantly enter houses via open eaves. Host-seeking is odour-driven, and finding a host depends on the quality of the odour plume and whether the route towards the host is free of obstructions. Little is known about in-flight behaviour of mosquitoes during house entry. This semi-field study visualizes mosquito house entry in three dimensions (3D) and offers new insights for optimizing vector control interventions. The approach and house entry of Anopheles gambiae sensu stricto was studied in a semi-field set-up using video-recorded flight tracks and 3D analysis. Behavioural parameters of host-seeking female mosquitoes were visualized with respect to their position relative to the eave as well as whether a mosquito would enter or not. Host odour was standardized using an attractive synthetic blend in addition to CO2. The study was conducted in western Kenya at the Thomas Odhiambo Campus of the International Centre of Insect Physiology and Ecology, Mbita. The majority of host-seeking An. gambiae approached a house with a flight altitude at eave level, arriving within a horizontal arc of 180°. Fifty-five per cent of mosquitoes approaching a house did not enter or made multiple attempts before passing through the eave. During approach, mosquitoes greatly reduced their speed and the flight paths became more convoluted. As a result, mosquitoes that passed through the eave spent more than 80 % of the observed time within 30 cm of the eave. Mosquitoes that exited the eave departed at eave level and followed the edge of the roof (12.5 %) or quickly re-entered after exiting (9.6 %). The study shows that host-seeking mosquitoes, when entering a house, approach the eave in a wide angle to the house at eave level. Less than 25 % of approaching mosquitoes entered the house without interruption, whereas 12.5 % of mosquitoes that had entered left the house again within the time of observation

Impact of Wolbachia on infection with chikungunya and yellow fever viruses in the mosquito vector Aedes aegypti.

Directory of Open Access Journals (Sweden)

Andrew F van den Hurk

Full Text Available Incidence of disease due to dengue (DENV, chikungunya (CHIKV and yellow fever (YFV viruses is increasing in many parts of the world. The viruses are primarily transmitted by Aedes aegypti, a highly domesticated mosquito species that is notoriously difficult to control. When transinfected into Ae. aegypti, the intracellular bacterium Wolbachia has recently been shown to inhibit replication of DENVs, CHIKV, malaria parasites and filarial nematodes, providing a potentially powerful biocontrol strategy for human pathogens. Because the extent of pathogen reduction can be influenced by the strain of bacterium, we examined whether the wMel strain of Wolbachia influenced CHIKV and YFV infection in Ae. aegypti. Following exposure to viremic blood meals, CHIKV infection and dissemination rates were significantly reduced in mosquitoes with the wMel strain of Wolbachia compared to Wolbachia-uninfected controls. However, similar rates of infection and dissemination were observed in wMel infected and non-infected Ae. aegypti when intrathoracic inoculation was used to deliver virus. YFV infection, dissemination and replication were similar in wMel-infected and control mosquitoes following intrathoracic inoculations. In contrast, mosquitoes with the wMelPop strain of Wolbachia showed at least a 10(4 times reduction in YFV RNA copies compared to controls. The extent of reduction in virus infection depended on Wolbachia strain, titer and strain of the virus, and mode of exposure. Although originally proposed for dengue biocontrol, our results indicate a Wolbachia-based strategy also holds considerable promise for YFV and CHIKV suppression.

Mosquitoes of Middle America.

Science.gov (United States)

1976-09-30

data on bionomics and disease relations. 0. P. Forattini’s treatment of the Culicidae in “ Entomologia Medica” (Sao Paulo , Faculdade de Higiene e Saude...Canal Zone and U.S.A. Casal. Osvaldo H., Depart amento de Entomologia Sanitaria , Instituto de Microbio logi a, Buenos Aires, Argen tina.— Mosquitoes...976 17 Garcia , M iguel, Departamento de Entomologia Sanitaria , Instituto de Microbiologia , Buenos Aires, Argentina . — Mosquitoes from Argentina

Protection Ability Comparison of Several Mosquito Repellent Lotion Incorporated with Essential Oils of Mosquito Repellent Plants

Directory of Open Access Journals (Sweden)

Pramono Putro Utomo

2014-12-01

Full Text Available Most mosquito repellent lotions available on the market today contain the active ingredient diethyltoluamide (DEET which is very harmful to the skin. Natural mosquito repellent research using various essential oils (geranium oil, lemon oil, citronella oil and lavender oil as the active ingredient and the addition of aloe vera gel as a moisturizer has been done on a laboratory scale. The purpose of this study was to compare the protection ability of the mosquito repellent plants in Indonesia. The results showed that geranium oil, lemongrass oil, lavender oil and lemon oil could act as mosquito repellent. Best lotion formula all containing 15% essential oils have the effectiveness above 50% until the sixth hour were geranium oil, citronella oil and lavender oil while lemon oil only giving effectiveness above 50% until the second hour.

Guide to the bioassay of uranium at uranium mine-mill facilities

International Nuclear Information System (INIS)

1981-01-01

As a result of occupational exposure, uranium may be taken into the body by inhalation, ingestion or absorption through skin wounds. The organs at risk are the lung, kidney, and bones. Analysis of urine samples for uranium is recommended on a regular monthly basis, before and after a rest period, and it is suggested that a worker be removed from a working area if a level above 300 μg/l is found before a rest period, or 150 μg/l after a rest period. Background information on the development of a bioassay program is given, and a recommended program for uranium mine and mill facilities is included. (L.L.)

Daily oviposition patterns of the African malaria mosquito Anopheles gambiae Giles (Diptera: Culicidae on different types of aqueous substrates

Directory of Open Access Journals (Sweden)

Knols Bart GJ

2004-12-01

Full Text Available Abstract Background Anopheles gambiae Giles is the most important vector of human malaria in sub-Saharan Africa. Knowledge of the factors that influence its daily oviposition pattern is crucial if field interventions targeting gravid females are to be successful. This laboratory study investigated the effect of oviposition substrate and time of blood feeding on daily oviposition patterns of An. gambiae mosquitoes. Methods Greenhouse-reared gravid and hypergravid (delayed oviposition onset An. gambiae sensu stricto and wild-caught An. gambiae sensu lato were exposed to three types of substrates in choice and no-choice cage bioassays: water from a predominantly anopheline colonised ground pool (anopheline habitat water, swamp water mainly colonised by culicine larvae (culicine habitat water and distilled water. The daily oviposition pattern and the number of eggs oviposited on each substrate during the entire egg-laying period were determined. The results were subjected to analysis of variance using the General Linear Model (GLM procedure. Results The main oviposition time for greenhouse-reared An. gambiae s.s. was between 19:00 and 20:00 hrs, approximately one hour after sunset. Wild-caught gravid An. gambiae s.l. displayed two distinct peak oviposition times between 19:00 and 20:00 hrs and between 22:00 and 23:00 hrs, respectively. During these times, both greenhouse-reared and wild-caught mosquitoes significantly (P P Conclusion This study shows that the peak oviposition time of An. gambiae s.l. may be regulated by the light-dark cycle rather than oviposition habitat characteristics or feeding times. However, the number of eggs laid by the female mosquito during the peak oviposition time is affected by the suitability of the habitat.

Metallic copper spray--a new control technique to combat invasive container-inhabiting mosquitoes.

Science.gov (United States)

Becker, Norbert; Oo, Thin Thin; Schork, Nino

2015-11-09

The control of container-inhabiting mosquitoes is mainly based on environmental management with special emphasis on community participation e.g. source reduction by elimination or modification of water bodies. However, citizens are often not aware of the problems related to urban mosquito control or just ignore the advice provided during anti-mosquito control campaigns. In particular, cemeteries contain favourite breeding sites for container-inhabiting mosquitoes like Ochlerotatus j. japonicus, Culex pipiens s.l./Cx. torrentium, Aedes aegypti or Aedes albopictus. In our study, we investigated whether metallic copper e.g. in form of copper spray can be a suitable and cost-effective tool to combat mosquito breeding in vases or other similar small containers where no commonly used insecticides can be applied. The effect of metallic copper spray in comparison to 5 Euro cent coins or copper tubes at different dosages and water qualities applied in small water collections such as widely used plastic grave vases were evaluated by assessing the mortality rates of larvae of Oc.j. japonicus, Cx. pipiens s.l./Cx. torrentium and Ae.aegypti. Different water qualities were tested to assess the influence of pH on the solubility of the copper ions. The copper concentrations were quantified using ICP/MS (Inductively coupled plasma/Mass spectrometry) in relation to the exposure time and mortality rates of mosquito larvae. All statistical analyses were computed using JMP 10.0.2 (SAS Institute Inc., 2012, Cary, NC, USA). Dosages of less than 500 ppb of copper in the water of small containers led to a 100% mortality rate after 2 weeks for all tested mosquito species by using one or more 5 Euro cent coins/vase. When the interior surface of plastic grave vases was covered by metallic copper spray, all of the tested larvae died after 7-10 days in the laboratory and under field conditions the reduction rate was 99.44% for Oc.j. japonicus and 99.6% for Culex pipiens s.l./Cx. torrentium

Mosquito Bites

Science.gov (United States)

... weeks. Some female mosquitoes can hibernate in the winter, and they can live for months. What health ... gutters, buckets, pool covers, pet water dishes, discarded tires, or birdbaths. If you plan to travel, get ...

Larvicidal efficacies and chemical composition of essential oils of Pinus sylvestris and Syzygium aromaticum against mosquitoes.

Science.gov (United States)

Fayemiwo, Kehinde Adenike; Adeleke, Monsuru Adebayo; Okoro, Ovie Princewill; Awojide, Shola Hezekiah; Awoniyi, Ilias Olufemi

2014-01-01

To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris (P. sylvestris) and Syzygium aromaticum (S. aromaticum) against Aedes aegypti (A. aegypti) and Culex quinquefasciatus (C. quinquefasciatus). The chemical composition of the essential oils of both plants was determined using GC-MS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A. aegypti and C. quinquefasciatus in accordance with the standard protocol. The results as determined by GC-MS showed that oil of S. aromaticum has eugenol (80.5%) as its principal constituent while P. sylvestris has 3-Cyclohexene-1-methanol, .alpha., .alpha.4-trimethyl (27.1%) as its dominant constituent. Both oils achieved over 85% larval mortality within 24 h. The larvae of A. aegypti were more susceptible to the oils [LC50 (S. aromaticum)=92.56 mg/L, LC50(P. sylvestris)=100.39 mg/L] than C. quinquefasciatus [LC50(S. aromaticum)=124.42 mg/L; LC50(P. sylvestris)=128.00 mg/L]. S. aromaticum oil was more toxic to the mosquito larvae than oil of P. sylvestris but the difference in lethal concentrations was insignificant (P>0.05). The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control. Copyright © 2014 Asian Pacific Tropical Biomedical Magazine. Published by Elsevier B.V. All rights reserved.

Use of biocidal products (insect sprays and electro-vaporizer) in indoor areas--exposure scenarios and exposure modeling.

Science.gov (United States)

Berger-Preiss, Edith; Koch, Wolfgang; Gerling, Susanne; Kock, Heiko; Appel, Klaus E

2009-09-01

Five commercially available insect sprays were applied in a model room. Spraying was performed in accordance with the manufacturers' instructions and in an overdosed manner in order to simulate worst-case conditions or an unforeseeable misuse. In addition, we examined electro-vaporizers. The Respicon aerosol monitoring system was applied to determine inhalation exposure. During normal spraying (10 seconds) and during the following 2-3 minutes, exposure concentrations ranged from 70 to 590 microg/m3 for the pyrethroids tetramethrin, d-phenothrin, cyfluthrin, bioallethrin, and the pyrethrins. Calculated inhalable doses were 2-16 microg. A concentration of approximately 850 microg chlorpyrifos/m(3) (inhalable dose: approximately 20 microg) was determined when the "Contra insect fly spray" was applied. Highest exposure concentrations (1100-2100 microg/m3) were measured for piperonyl butoxide (PBO), corresponding to an inhalation intake of 30-60microg. When simulating worst-case conditions, exposure concentrations of 200-3400microg/m3 and inhalable doses of 10-210microg were determined for the various active substances. Highest concentrations (4800-8000 microg/m3) were measured for PBO (inhalable: 290-480 microg). By applying the electro-vaporizer "Nexa Lotte" plug-in mosquito killer concentrations for d-allethrin were in the range of 5-12microg/m3 and 0.5-2 microg/m3 for PBO while with the "Paral" plug-in mosquito killer concentrations of 0.4-5microg/m3 for pyrethrins and 1-7 microg/m3 for PBO were measured. Potential dermal exposures were determined using exposure pads. Between 80 and 1000microg active substance (tetramethrin, phenothrin, cyfluthrin, bioallethrin, pyrethrins, chlorpyrifos) were deposited on the clothing of the total body surface area of the spray user. Highest levels (up to 3000 microg) were determined for PBO. Worst-case uses of the sprays led to 5-9 times higher concentrations. Also a 2-hour stay nearby an operating electro-vaporizer led to a

Detection of the V1016G mutation in the voltage-gated sodium channel gene of Aedes aegypti (Diptera: Culicidae) by allele-specific PCR assay, and its distribution and effect on deltamethrin resistance in Thailand.

Science.gov (United States)

Stenhouse, Steven A; Plernsub, Suriya; Yanola, Jintana; Lumjuan, Nongkran; Dantrakool, Anchalee; Choochote, Wej; Somboon, Pradya

2013-08-30

Resistance to pyrethroid insecticides is widespread among populations of Aedes aegypti, the main vector for the dengue virus. Several different point mutations within the voltage-gated sodium channel (VGSC) gene contribute to such resistance. A mutation at position 1016 in domain II, segment 6 of the VGSC gene in Ae. aegypti leads to a valine to glycine substitution (V1016G) that confers resistance to deltamethrin. This study developed and utilized an allele-specific PCR (AS-PCR) assay that could be used to detect the V1016G mutation. The assay was validated against a number of sequenced DNA samples of known genotype and was determined to be in complete agreement. Larvae and pupae were collected from various localities throughout Thailand. Samples were reared to adulthood and their resistance status against deltamethrin was determined by standard WHO susceptibility bioassays. Deltamethrin-resistant and susceptible insects were then genotyped for the V1016G mutation. Additionally, some samples were genotyped for a second mutation at position 1534 in domain III (F1534C) which is also known to confer pyrethroid resistance. The bioassay results revealed an overall mortality of 77.6%. Homozygous 1016G individuals survived at higher rates than either heterozygous or wild-type (1016 V) mosquitoes. The 1016G mutation was significantly and positively associated with deltamethrin resistance and was widely distributed throughout Thailand. Interestingly, wild-type 1016 V mosquitoes tested were homozygous for the 1534C mutation, and all heterozygous mosquitoes were also heterozygous for 1534C. Mutant homozygous (G/G) mosquitoes expressed the wild-type (F/F) at position 1534. However, the presence of the 1534C mutation was not associated with deltamethrin resistance. Our bioassay results indicate that all populations sampled display some degree of resistance to deltamethrin. Homozygous 1016G mosquitoes were far likelier to survive such exposure. However, resistance in some

Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

OpenAIRE

Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

2015-01-01

We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based mi...

rAed a 4: A New 67-kDa Aedes aegypti Mosquito Salivary Allergen for the Diagnosis of Mosquito Allergy.

Science.gov (United States)

Peng, Zhikang; Caihe, Li; Beckett, Andrew N; Guan, Qingdong; James, Anthony A; Simons, F Estelle R

2016-01-01

Accurate diagnosis of mosquito allergy has been hampered by the laborious task of obtaining mosquito salivary allergens. We have previously studied 3 recombinant (r) Aedes aegypti mosquito salivary allergens: rAed a 1, rAed a 2 and rAed a 3. Here, we report the expression, purification, identification and evaluation of rAed a 4, a 67-kDa α-glucosidase. rAed a 4 was expressed using a baculovirus/insect cell system, purified by a combination of anion- and cation-exchange chromatography, and identified by immunoblotting. A. aegypti saliva extract was prepared in our laboratory. An indirect enzyme-linked immunosorbent assay (ELISA) was developed to measure rAed a 4-specific immunoglobulin E (IgE) and IgG antibodies in sera from 13 individuals with a positive mosquito-bite test from a laboratory-reared mosquito. Sera from 18 individuals with a negative bite test served as controls. Purified rAed a 4 bound to the IgE in mosquito-allergic sera, as detected by ELISA and immunoblotting. The binding of rAed a 4 to IgE could be inhibited in a dose-dependent manner by the addition of an A. aegypti extract. Mosquito-allergic individuals had significantly higher mean levels of rAed a 4-specific IgE and IgG than controls. Using the mean of the controls ± 2 SD as a cut-off level, 46% of the 13 allergic individuals had a positive IgE, while none of the controls was positive (p < 0.001). Aed a 4 is a major allergen in mosquito saliva. Its recombinant form has the hydrolase function and can be used for the diagnosis of mosquito allergy. © 2016 S. Karger AG, Basel.

Distribution of mosquitoes and mosquito-borne arboviruses in Yunnan Province near the China-Myanmar-Laos border.

Science.gov (United States)

Wang, Jinglin; Zhang, Hailin; Sun, Xiaohong; Fu, Shihong; Wang, Huanqin; Feng, Yun; Wang, Huanyu; Tang, Qing; Liang, Guo-Dong

2011-05-01

Economic development and increased tourism in the southern region of Yunnan Province in China, adjacent to several countries in Southeast Asia, has increased the likelihood of import and export of vectors and vector-borne diseases. We report the results of surveillance of mosquitoes and mosquito-borne arboviruses along the border of China-Myanmar-Laos in 2005 and 2006, and information associating several arboviruses with infections and possibly disease in local human populations. Seventeen mosquito species representing four genera were obtained, and 14 strains of mosquito-borne viruses representing six viruses in five genera were isolated from Culex tritaeniorhynchus. In addition, IgM against Japanese encephalitis virus, Sindbis virus, Yunnan orbivirus and novel Banna virus was detected in acute-phase serum samples obtained from hospitalized patients with fever and encephalitis near the areas where the viruses were isolated. This investigation suggests that Japanese encephalitis virus, Sindbis virus, and lesser-known arboviruses circulate and may be infecting humans in the China-Myanmar-Laos border region.

MosquitoNet: investigating the use of UAV and artificial neural networks for integrated mosquito management

Science.gov (United States)

Case, E.; Ren, Y.; Shragai, T.; Erickson, D.

2017-12-01

Integrated mosquito control is expensive and resource intensive, and changing climatic factors are predicted to expand the habitable range of disease-carrying mosquitoes into new regions in the United States. Of particular concern in the northeastern United States are aedes albopictus, an aggressive, invasive species of mosquito that can transmit both native and exotic disease. Ae. albopictus prefer to live near human populations and breed in artificial containers with as little as two millimeters of standing water, exponentially increasing the difficulty of source control in suburban and urban areas. However, low-cost unmanned aerial vehicles (UAVs) can be used to photograph large regions at centimeter-resolution, and can image containers of interest in suburban neighborhoods. While proofs-of-concepts have been shown using UAVs to identify naturally occurring bodies of water, they have not been used to identify mosquito habitat in more populated areas. One of the primary challenges is that post-processing high-resolution aerial imagery is still time intensive, often labelled by hand or with programs built for satellite imagery. Artificial neural networks have been highly successful at image recognition tasks; in the past five years, convolutional neural networks (CNN) have surpassed or aided trained humans in identification of skin cancer, agricultural crops, and poverty levels from satellite imagery. MosquitoNet, a dual classifier built from the Single Shot Multibox Detector and VGG16 architectures, was trained on UAV­­­­­ aerial imagery taken during a larval study in Westchester County in southern New York State in July and August 2017. MosquitoNet was designed to assess the habitat risk of suburban properties by automating the identification and counting of containers like tires, toys, garbage bins, flower pots, etc. The SSD-based architecture marked small containers and other habitat indicators while the VGG16-based architecture classified the type of

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.

Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States.

Directory of Open Access Journals (Sweden)

Andrew J Golnar

2014-09-01

Full Text Available Rift Valley fever virus (RVFV is a mosquito-borne virus in the family Bunyaviridiae that has spread throughout continental Africa to Madagascar and the Arabian Peninsula. The establishment of RVFV in North America would have serious consequences for human and animal health in addition to a significant economic impact on the livestock industry. Published and unpublished data on RVFV vector competence, vertebrate host competence, and mosquito feeding patterns from the United States were combined to quantitatively implicate mosquito vectors and vertebrate hosts that may be important to RVFV transmission in the United States. A viremia-vector competence relationship based on published mosquito transmission studies was used to calculate a vertebrate host competence index which was then combined with mosquito blood feeding patterns to approximate the vector and vertebrate amplification fraction, defined as the relative contribution of the mosquito or vertebrate host to pathogen transmission. Results implicate several Aedes spp. mosquitoes and vertebrates in the order Artiodactyla as important hosts for RVFV transmission in the U.S. Moreover, this study identifies critical gaps in knowledge which would be necessary to complete a comprehensive analysis identifying the different contributions of mosquitoes and vertebrates to potential RVFV transmission in the U.S. Future research should focus on (1 the dose-dependent relationship between viremic exposure and the subsequent infectiousness of key mosquito species, (2 evaluation of vertebrate host competence for RVFV among North American mammal species, with particular emphasis on the order Artiodactyla, and (3 identification of areas with a high risk for RVFV introduction so data on local vector and host populations can help generate geographically appropriate amplification fraction estimates.

Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States.

Science.gov (United States)

Golnar, Andrew J; Turell, Michael J; LaBeaud, A Desiree; Kading, Rebekah C; Hamer, Gabriel L

2014-09-01

Rift Valley fever virus (RVFV) is a mosquito-borne virus in the family Bunyaviridiae that has spread throughout continental Africa to Madagascar and the Arabian Peninsula. The establishment of RVFV in North America would have serious consequences for human and animal health in addition to a significant economic impact on the livestock industry. Published and unpublished data on RVFV vector competence, vertebrate host competence, and mosquito feeding patterns from the United States were combined to quantitatively implicate mosquito vectors and vertebrate hosts that may be important to RVFV transmission in the United States. A viremia-vector competence relationship based on published mosquito transmission studies was used to calculate a vertebrate host competence index which was then combined with mosquito blood feeding patterns to approximate the vector and vertebrate amplification fraction, defined as the relative contribution of the mosquito or vertebrate host to pathogen transmission. Results implicate several Aedes spp. mosquitoes and vertebrates in the order Artiodactyla as important hosts for RVFV transmission in the U.S. Moreover, this study identifies critical gaps in knowledge which would be necessary to complete a comprehensive analysis identifying the different contributions of mosquitoes and vertebrates to potential RVFV transmission in the U.S. Future research should focus on (1) the dose-dependent relationship between viremic exposure and the subsequent infectiousness of key mosquito species, (2) evaluation of vertebrate host competence for RVFV among North American mammal species, with particular emphasis on the order Artiodactyla, and (3) identification of areas with a high risk for RVFV introduction so data on local vector and host populations can help generate geographically appropriate amplification fraction estimates.

Adult vector control, mosquito ecology and malaria transmission.

Science.gov (United States)

Brady, Oliver J; Godfray, H Charles J; Tatem, Andrew J; Gething, Peter W; Cohen, Justin M; McKenzie, F Ellis; Alex Perkins, T; Reiner, Robert C; Tusting, Lucy S; Scott, Thomas W; Lindsay, Steven W; Hay, Simon I; Smith, David L

2015-03-01

Standard advice regarding vector control is to prefer interventions that reduce the lifespan of adult mosquitoes. The basis for this advice is a decades-old sensitivity analysis of 'vectorial capacity', a concept relevant for most malaria transmission models and based solely on adult mosquito population dynamics. Recent advances in micro-simulation models offer an opportunity to expand the theory of vectorial capacity to include both adult and juvenile mosquito stages in the model. In this study we revisit arguments about transmission and its sensitivity to mosquito bionomic parameters using an elasticity analysis of developed formulations of vectorial capacity. We show that reducing adult survival has effects on both adult and juvenile population size, which are significant for transmission and not accounted for in traditional formulations of vectorial capacity. The elasticity of these effects is dependent on various mosquito population parameters, which we explore. Overall, control is most sensitive to methods that affect adult mosquito mortality rates, followed by blood feeding frequency, human blood feeding habit, and lastly, to adult mosquito population density. These results emphasise more strongly than ever the sensitivity of transmission to adult mosquito mortality, but also suggest the high potential of combinations of interventions including larval source management. This must be done with caution, however, as policy requires a more careful consideration of costs, operational difficulties and policy goals in relation to baseline transmission. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.

Transgenic Mosquitoes - Fact or Fiction?

Science.gov (United States)

Wilke, André B B; Beier, John C; Benelli, Giovanni

2018-06-01

Technologies for controlling mosquito vectors based on genetic manipulation and the release of genetically modified mosquitoes (GMMs) are gaining ground. However, concrete epidemiological evidence of their effectiveness, sustainability, and impact on the environment and nontarget species is lacking; no reliable ecological evidence on the potential interactions among GMMs, target populations, and other mosquito species populations exists; and no GMM technology has yet been approved by the WHO Vector Control Advisory Group. Our opinion is that, although GMMs may be considered a promising control tool, more studies are needed to assess their true effectiveness, risks, and benefits. Overall, several lines of evidence must be provided before GMM-based control strategies can be used under the integrated vector management framework. Copyright © 2018 Elsevier Ltd. All rights reserved.

Blood-feeding ecology of mosquitoes in zoos.

Science.gov (United States)

Tuten, H C; Bridges, W C; Paul, K S; Adler, P H

2012-12-01

To determine if the unique host assemblages in zoos influence blood-feeding by mosquitoes (Diptera: Culicidae), a sampling programme was conducted in Greenville and Riverbanks Zoos, South Carolina, U.S.A., from April 2009 to October 2010. A total of 4355 female mosquitoes of 14 species were collected, of which 106 individuals of nine species were blood-fed. The most common taxa were Aedes albopictus (Skuse), Aedes triseriatus (Say), Anopheles punctipennis (Say), Culex erraticus (Dyar & Knab), Culex pipiens complex (L.) and Culex restuans (Theobald). Molecular analyses (cytochrome b) of bloodmeals revealed that mosquitoes fed on captive animals, humans and wildlife, and took mixed bloodmeals. Host species included one amphibian, 16 birds, 10 mammals (including humans) and two reptiles. Minimum dispersal distances after feeding on captive hosts ranged from 15.5 m to 327.0 m. Mosquito-host associations generally conformed to previous accounts, indicating that mosquito behaviour inside zoos reflects that outside zoos. However, novel variation in host use, including new, exotic host records, warrants further investigation. Zoos, thus, can be used as experiment environments in which to study mosquito behaviour, and the findings extrapolated to non-zoo areas, while providing medical and veterinary benefits to zoo animals, employees and patrons. © 2012 The Authors. Medical and Veterinary Entomology © 2012 The Royal Entomological Society.

Pond dyes are Culex mosquito oviposition attractants

Directory of Open Access Journals (Sweden)

Natali Ortiz Perea

2017-05-01

Full Text Available Background British mosquito population distribution, abundance, species composition and potential for mosquito disease transmission are intimately linked to the physical environment. The presence of ponds and water storage can significantly increase the density of particular mosquito species in the garden. Culex pipiens is the mosquito most commonly found in UK gardens and a potential vector of West Nile Virus WNV, although the current risk of transmission is low. However any factors that significantly change the distribution and population of C. pipiens are likely to impact subsequent risk of disease transmission. Pond dyes are used to control algal growth and improve aesthetics of still water reflecting surrounding planting. However, it is well documented that females of some species of mosquito prefer to lay eggs in dark water and/or containers of different colours and we predict that dyed ponds will be attractive to Culex mosquitoes. Methods Black pond dye was used in oviposition choice tests using wild-caught gravid C. pipiens. Larvae from wild-caught C. pipiens were also reared in the pond dye to determine whether it had any impact on survival. An emergence trap caught any adults that emerged from the water. Water butts (80 L were positioned around university glasshouses and woodland and treated with black pond dye or left undyed. Weekly sampling over a six month period through summer and autumn was performed to quantified numbers of larvae and pupae in each treatment and habitat. Results Gravid female Culex mosquitoes preferred to lay eggs in dyed water. This was highly significant in tests conducted under laboratory conditions and in a semi-field choice test. Despite this, survivorship in black dyed water was significantly reduced compared to undyed water. Seasonal analysis of wild larval and pupal numbers in two habitats with and without dye showed no impact of dye but a significant impact of season and habitat. Mosquitoes were more

Effects of Preexposure to DEET on the Downstream Blood-Feeding Behaviors of Aedes aegypti (Diptera: Culicidae) Mosquitoes.

Science.gov (United States)

Sugiharto, Victor A; Grieco, John P; Murphy, Jittawadee R; Olsen, Cara H; Colacicco-Mayhugh, Michelle G; Stewart, V Ann; Achee, Nicole L; Turell, Michael J

2016-06-10

Mosquito behavior is heavily influenced by the chemical molecules in the environment. This knowledge can be used to modify insect behaviors; particularly to reduce vector-host contact as a powerful method for disease prevention. N,N-Diethyl-meta-toluamide (DEET) is the most widely used insect repellent in the market and an excellent example of a chemical that has been used to modify insect behavior for disease prevention. However, genetic insensitivity and habituation in Aedes aegypti (L.) mosquitoes after preexposure to DEET have been reported. In this study, we investigated the effect of preexposure to DEET on the downstream blood-feeding behavior of Ae. aegypti mosquitoes and the duration of the effect. We exposed mosquitoes to four different DEET concentrations: 0.10, 0.12, 0.14, and 0.16% for 10 min then allowed the mosquitoes to blood-feed on an artificial blood-feeding system either immediately or after being held for 1, 3, 6, or 24 h following DEET exposure. We found that preexposing Ae. aegypti mosquitoes to 0.14 or 0.16% DEET lowered their blood engorgement level, but did not alter their landing and probing behavior when compared to the control test populations. The reduction in complete blood-feeding was observed at all time periods tested, but was only statistically significant at 3 and 6 h after the preexposure process. Because reduction in blood meal has been associated with increased refeeding, future studies analyzing the effect of this behavior using arbovirus-infected mosquitoes are needed to address the concern of potentially increased vectorial capacity. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Assessing soil ecotoxicity of methyl tert-butyl ether using earthworm bioassay; closed soil microcosm test for volatile organic compounds

International Nuclear Information System (INIS)

An, Youn-Joo

2005-01-01

An earthworm bioassay was conducted to assess ecotoxicity in methyl tert-butyl ether (MTBE)-amended soils. Ecotoxicity of MTBE to earthworms was evaluated by a paper contact method, natural field soil test, and an OECD artificial soil test. All tests were conducted in closed systems to prevent volatilization of MTBE out of test units. Test earthworm species were Perionyx excavatus and Eisenia andrei. Mortality and abnormal morphology of earthworms exposed to different concentrations of MTBE were examined. MTBE was toxic to both earthworm species and the severity of response increased with increasing MTBE concentrations. Perionyx excavatus was more sensitive to MTBE than Eisenia andrei in filter papers and two different types of soils. MTBE toxicity was more severe in OECD artificial soils than in field soils, possibly due to the burrowing behavior of earthworms into artificial soils. The present study demonstrated that ecotoxicity of volatile organic compounds such as MTBE can be assessed using an earthworm bioassay in closed soil microcosm with short-term exposure duration. - Earthworm bioassay can be a good protocol to assess soil ecotoxicity of volatile organic compounds such as MTBE

Comparing the impacts of sediment-bound bifenthrin on aquatic macroinvertebrates in laboratory bioassays and field microcosms.

Science.gov (United States)

Boyle, Rhianna L; Hoak, Molly N; Pettigrove, Vincent J; Hoffmann, Ary A; Long, Sara M

2016-11-01

We conducted two laboratory bioassays and two field microcosm exposures with bifenthrin (a synthetic pyrethroid) in order to evaluate the capacity of single-species laboratory bioassays to predict lethal and sublethal impacts on aquatic invertebrates in microcosms. For the laboratory species, Chironomus tepperi, larval survival was reduced by 24% at 53.66µg/g OC, while adult emergence was reduced at concentrations of 33.33µg/g OC and higher, with a 61% decrease at 77.78µg/g OC and no emergence at 126.67µg/g OC. The abundance of several other microcosm taxa was reduced in the microcosms at a similar concentration range (33.33µg/g OC and above), however there was no impact on the abundance of the congeneric species, Chironomus oppositus. The differences in impacts between test systems were potentially due to both differing species sensitivity and the interaction of ambient temperature with bifenthrin toxicity. Bifenthrin also was associated with early emergence of Chironomus sp. in both test systems, at concentrations of 10µg/g OC and higher (laboratory) and 43.90µg/g OC (microcosm), and with a significant decrease in the proportion of C. oppositus males in a microcosm. These findings indicate that while laboratory bioassays accurately predict many impacts in the field, there are some limitations to the predictive capacity of these tests. Copyright © 2016 Elsevier Inc. All rights reserved.

Vision-Based Perception and Classification of Mosquitoes Using Support Vector Machine

Directory of Open Access Journals (Sweden)

Masataka Fuchida

2017-01-01

Full Text Available The need for a novel automated mosquito perception and classification method is becoming increasingly essential in recent years, with steeply increasing number of mosquito-borne diseases and associated casualties. There exist remote sensing and GIS-based methods for mapping potential mosquito inhabitants and locations that are prone to mosquito-borne diseases, but these methods generally do not account for species-wise identification of mosquitoes in closed-perimeter regions. Traditional methods for mosquito classification involve highly manual processes requiring tedious sample collection and supervised laboratory analysis. In this research work, we present the design and experimental validation of an automated vision-based mosquito classification module that can deploy in closed-perimeter mosquito inhabitants. The module is capable of identifying mosquitoes from other bugs such as bees and flies by extracting the morphological features, followed by support vector machine-based classification. In addition, this paper presents the results of three variants of support vector machine classifier in the context of mosquito classification problem. This vision-based approach to the mosquito classification problem presents an efficient alternative to the conventional methods for mosquito surveillance, mapping and sample image collection. Experimental results involving classification between mosquitoes and a predefined set of other bugs using multiple classification strategies demonstrate the efficacy and validity of the proposed approach with a maximum recall of 98%.

Mosquito control pesticides and sea surface temperatures have differential effects on the survival and oxidative stress response of coral larvae.

Science.gov (United States)

Ross, Cliff; Olsen, Kevin; Henry, Michael; Pierce, Richard

2015-04-01

The declining health of coral reefs is intensifying worldwide at an alarming rate due to the combined effects of land-based sources of pollution and climate change. Despite the persistent use of mosquito control pesticides in populated coastal areas, studies examining the survival and physiological impacts of early life-history stages of non-targeted marine organisms are limited. In order to better understand the combined effects of mosquito pesticides and rising sea surface temperatures, we exposed larvae from the coral Porites astreoides to selected concentrations of two major mosquito pesticide ingredients, naled and permethrin, and seawater elevated +3.5 °C. Following 18-20 h of exposure, larvae exposed to naled concentrations of 2.96 µg L(-1) or greater had significantly reduced survivorship compared to controls. These effects were not detected in the presence of permethrin or elevated temperature. Furthermore, larval settlement, post-settlement survival and zooxanthellae density were not impacted by any treatment. To evaluate the sub-lethal stress response of larvae, several oxidative stress endpoints were utilized. Biomarker responses to pesticide exposure were variable and contingent upon pesticide type as well as the specific biomarker being employed. In some cases, such as with protein carbonylation and catalase gene expression, the effects of naled exposure and temperature were interactive. In other cases pesticide exposure failed to induce any sub-lethal stress response. Overall, these results demonstrate that P. astreoides larvae have a moderate degree of resistance against short-term exposure to ecologically relevant concentrations of pesticides even in the presence of elevated temperature. In addition, this work highlights the importance of considering the complexity and differential responses encountered when examining the impacts of combined stressors that occur on varying spatial scales.

Assessment of Sediment Heavy Metals Pollution Using Screening Methods (XRF, TGA/MS, XRPD and Earthworms Bioassay)

Science.gov (United States)

Findoráková, Lenka; Šestinová, Ol'ga; Hančul'ák, Jozef; Fedorová, Erika; Zorkovská, Anna

2016-10-01

The aim of this study is focused on the use of screening methods (TG/DTA coupled with MS, XRF, AAS, XRPD and earthworm bioassay) for sediments pollution assessing by heavy metals (Cu, Zn, Pb, Hg) coming from the former mining workloads in the central Spis, Eastern Slovakia. The screening methods (XRF, AAS) indicated pollution of studied sediments by Cu, Zn, Pb, Hg. The earthworms Dendrobaena veneta caused in some studied samples decrease of heavy metals concentration after their 7 days’ exposure in sediments. The other screening methods such as thermal analysis and XRPD analysis, does not confirm the specifically changes in physicochemical properties comparing the properties before and after 7 days’ earthworm's exposure.

Microorganism-mediated behaviour of malaria mosquitoes

NARCIS (Netherlands)

Busula, Annette O.

2017-01-01

Host-seeking is an important component of mosquito vectorial capacity on which the success of the other behavioural determinants depends. Blood-seeking mosquitoes are mainly guided by chemical cues released by their blood hosts. This thesis describes results of a study that determined the effect

Effect of ebastine on mosquito bites.

Science.gov (United States)

Reunala, T; Brummer-Korvenkontio, H; Petman, L; Palosuo, T; Sarna, S

1997-07-01

Mosquito bites usually cause wealing and delayed bite papules. Cetirizine decreases wealing, bite papules and pruritus but the effect of other antihistamines on mosquito bites is unknown. We studied the effect of ebastine in 30 mosquito bite-sensitive adult subjects. Ebastine 10 mg or 20 mg and placebo were given for 4 days in a cross-over fashion. Aedes aegypti bites were given on forearms. The size of the bite lesions and pruritus (visual analogue score) were measured at 15 min, 2, 6, and 24 h after the bites. Twenty-five subjects were evaluable in the study. At 15 min ebastine decreased significantly the size of the bite lesion (p = 0.0017) and pruritus (ptime points were compiled the size of the bite lesion and pruritus score decreased significantly. Sedation occurred during ebastine treatment in 6 (21%) and during placebo treatment in 2 (7%) subjects. The present results show that prophylactically given ebastine is effective against immediate mosquito bite symptoms.

Using exposure bands for rapid decision making in the ...

Science.gov (United States)

The ILSI Health and Environmental Sciences Institute (HESI) Risk Assessment in the 21st Century (RISK21) project was initiated to address and catalyze improvements in human health risk assessment. RISK21 is a problem formulation-based conceptual roadmap and risk matrix visualization tool, facilitating transparent evaluation of both hazard and exposure components. The RISK21 roadmap is exposure-driven, i.e. exposure is used as the second step (after problem formulation) to define and focus the assessment. This paper describes the exposure tiers of the RISK21 matrix and the approaches to adapt readily available information to more quickly inform exposure at a screening level. In particular, exposure look-up tables were developed from available exposure tools (European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) for worker exposure, ECETOC TRA, European Solvents Industry Group (ESIG) Generic Exposure Scenario (GES) Risk and Exposure Tool (EGRET) for consumer exposure, and USEtox for indirect exposure to humans via the environment) were tested in a hypothetical mosquito bed netting case study. A detailed WHO risk assessment for a similar mosquito net use served as a benchmark for the performance of the RISK21 approach. The case study demonstrated that the screening methodologies provided suitable conservative exposure estimates for risk assessment. The results of this effort showed that the RISK21 approach is useful f

Pathogenesis of Dengue Vaccine Viruses in Mosquitoes.

Science.gov (United States)

1980-01-01

1973). Sabin (1948) showed that attenuated dpngiie, passed through mosquitoes, did not revert to pathogenicity frnr man. -7- Thus even if the vaccine ...AD-A138 518 PATHOGENESIS OF DENGUE VACCINE YIRUSES IN MOSQUITOES 1/ (U) YALE UNIV NEW HAVEN CONN SCHOOL OF MEDICINE B J BEATY ET AL. 9i JAN 80 DRND7...34 ’ UNCLASSIFIED 0{) AD 0Pathogenesis of dengue vaccine viruses in mosquitoes -First Annual Report Barry I. Beaty, Ph.D. Thomas H. G

Vector competence of Anopheles and Culex mosquitoes for Zika virus

Directory of Open Access Journals (Sweden)

Brittany L. Dodson

2017-03-01

Full Text Available Zika virus is a newly emergent mosquito-borne flavivirus that has caused recent large outbreaks in the new world, leading to dramatic increases in serious disease pathology including Guillain-Barre syndrome, newborn microcephaly, and infant brain damage. Although Aedes mosquitoes are thought to be the primary mosquito species driving infection, the virus has been isolated from dozens of mosquito species, including Culex and Anopheles species, and we lack a thorough understanding of which mosquito species to target for vector control. We exposed Anopheles gambiae, Anopheles stephensi, and Culex quinquefasciatus mosquitoes to blood meals supplemented with two Zika virus strains. Mosquito bodies, legs, and saliva were collected five, seven, and 14 days post blood meal and tested for infectious virus by plaque assay. Regardless of titer, virus strain, or timepoint, Anopheles gambiae, Anopheles stephensi, and Culex quinquefasciatus mosquitoes were refractory to Zika virus infection. We conclude that Anopheles gambiae, Anopheles stephensi, and Culex quinquefasciatus mosquitoes likely do not contribute significantly to Zika virus transmission to humans. However, future studies should continue to explore the potential for other novel potential vectors to transmit the virus.

Systems for animal exposure in full-scale fire tests

Science.gov (United States)

Hilado, C. J.; Cumming, H. J.; Kourtides, D. A.; Parker, J. A.

1977-01-01

Two systems for exposing animals in full-scale fire tests are described. Both systems involve the simultaneous exposure of two animal species, mice and rats, in modular units; determination of mortality, morbidity, and behavioral response; and analysis of the blood for carboxyhemoglobin. The systems described represent two of many possible options for obtaining bioassay data from full-scale fire tests. In situations where the temperatures to which the test animals are exposed can not be controlled, analytical techniques may be more appropriate than bioassay techniques.

The potential impacts of 21st century climatic and population changes on human exposure to the virus vector mosquito Aedes aegypti.

Science.gov (United States)

Monaghan, A J; Sampson, K M; Steinhoff, D F; Ernst, K C; Ebi, K L; Jones, B; Hayden, M H

2018-02-01

The mosquito Aedes (Ae). aegypti transmits the viruses that cause dengue and chikungunya, two globally-important vector-borne diseases. We investigate how choosing alternate emissions and/or socioeconomic pathways may modulate future human exposure to Ae. aegypti . Occurrence patterns for Ae. aegypti for 2061-2080 are mapped globally using empirically downscaled air temperature and precipitation projections from the Community Earth System Model, for the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Population growth is quantified using gridded global population projections consistent with two Shared Socioeconomic Pathways (SSPs), SSP3 and SSP5. Change scenarios are compared to a 1950-2000 reference period. A global land area of 56.9 M km 2 is climatically suitable for Ae. aegypti during the reference period, and is projected to increase by 8% (RCP4.5) to 13% (RCP8.5) by 2061-2080. The annual average number of people exposed globally to Ae. aegypti for the reference period is 3794 M, a value projected to statistically significantly increase by 298-460 M (8-12%) by 2061-2080 if only climate change is considered, and by 4805-5084 M (127-134%) for SSP3 and 2232-2483 M (59-65%) for SSP5 considering both climate and population change (lower and upper values of each range represent RCP4.5 and RCP8.5 respectively). Thus, taking the lower-emissions RCP4.5 pathway instead of RCP8.5 may mitigate future human exposure to Ae. aegypti globally, but the effect of population growth on exposure will likely be larger. Regionally, Australia, Europe and North America are projected to have the largest percentage increases in human exposure to Ae. aegypti considering only climate change.

Validation of a Novel Bioassay for Low-level Perchlorate Determination

Science.gov (United States)

2014-04-01

was not attractive, since these reduce PMS2 , and it was thought they would interfere with the stoichiometry of NADH and perchlorate in the bioassay...these reduce PMS2 directly, and would interfere with the stoichiometry of NADH and perchlorate in the bioassay. Thus the only approach that could be

Nesting Bird “Host Funnel” Increases Mosquito-Bird Contact Rate

OpenAIRE

CAILLOUËT, KEVIN A.; RIGGAN, ANNA E.; BULLUCK, LESLEY P.; CARLSON, JOHN C.; SABO, ROY T.

2013-01-01

Increases in vector-host contact rates can enhance arbovirus transmission intensity. We investigated weekly fluctuations in contact rates between mosquitoes and nesting birds using the recently described Nest Mosquito Trap (NMT). The number of mosquitoes per nestling increased from < 1 mosquito per trap night to 36.2 in the final 2 wk of the nesting season. Our evidence suggests the coincidence of the end of the avian nesting season and increasing mosquito abundances may have caused a “host f...

Development and validation of microbial bioassay for quantification of Levofloxacin in pharmaceutical preparations

Directory of Open Access Journals (Sweden)

Nishant A. Dafale

2015-02-01

Full Text Available The aim of this study was to develop and validate a simple, sensitive, precise and cost-effective one-level agar diffusion (5+1 bioassay for estimation of potency and bioactivity of Levofloxacin in pharmaceutical preparation which has not yet been reported in any pharmacopoeia. Among 16 microbial strains, Bacillus pumilus ATCC-14884 was selected as the most significant strain against Levofloxacin. Bioassay was optimized by investigating several factors such as buffer pH, inoculums concentration and reference standard concentration. Identification of Levofloxacin in commercial sample Levoflox tablet was done by FTIR spectroscopy. Mean potency recovery value for Levofloxacin in Levoflox tablet was estimated as 100.90%. A validated bioassay method showed linearity (r2=0.988, precision (Interday RSD=1.05%, between analyst RSD=1.02% and accuracy (101.23%, RSD=0.72%. Bioassay was correlated with HPLC using same sample and estimated potencies were 100.90% and 99.37%, respectively. Results show that bioassay is a suitable method for estimation of potency and bioactivity of Levofloxacin pharmaceutical preparations. Keywords: Levofloxacin, Antibiotic resistance, Microbiological bioassay, HPLC, Pharmacopoeia

Effects of Zika Virus Strain and Aedes Mosquito Species on Vector Competence

Science.gov (United States)

Bialosuknia, Sean M.; Zink, Steven D.; Brecher, Matthew; Ehrbar, Dylan J.; Morrissette, Madeline N.; Kramer, Laura D.

2017-01-01

In the Western Hemisphere, Zika virus is thought to be transmitted primarily by Aedes aegypti mosquitoes. To determine the extent to which Ae. albopictus mosquitoes from the United States are capable of transmitting Zika virus and the influence of virus dose, virus strain, and mosquito species on vector competence, we evaluated multiple doses of representative Zika virus strains in Ae. aegypti and Ae. albopictus mosquitoes. Virus preparation (fresh vs. frozen) significantly affected virus infectivity in mosquitoes. We calculated 50% infectious doses to be 6.1–7.5 log10 PFU/mL; minimum infective dose was 4.2 log10 PFU/mL. Ae. albopictus mosquitoes were more susceptible to infection than Ae. aegypti mosquitoes, but transmission efficiency was higher for Ae. aegypti mosquitoes, indicating a transmission barrier in Ae. albopictus mosquitoes. Results suggest that, although Zika virus transmission is relatively inefficient overall and dependent on virus strain and mosquito species, Ae. albopictus mosquitoes could become major vectors in the Americas. PMID:28430564

Effects of Zika Virus Strain and Aedes Mosquito Species on Vector Competence.

Science.gov (United States)

Ciota, Alexander T; Bialosuknia, Sean M; Zink, Steven D; Brecher, Matthew; Ehrbar, Dylan J; Morrissette, Madeline N; Kramer, Laura D

2017-07-01

In the Western Hemisphere, Zika virus is thought to be transmitted primarily by Aedes aegypti mosquitoes. To determine the extent to which Ae. albopictus mosquitoes from the United States are capable of transmitting Zika virus and the influence of virus dose, virus strain, and mosquito species on vector competence, we evaluated multiple doses of representative Zika virus strains in Ae. aegypti and Ae. albopictus mosquitoes. Virus preparation (fresh vs. frozen) significantly affected virus infectivity in mosquitoes. We calculated 50% infectious doses to be 6.1-7.5 log 10 PFU/mL; minimum infective dose was 4.2 log 10 PFU/mL. Ae. albopictus mosquitoes were more susceptible to infection than Ae. aegypti mosquitoes, but transmission efficiency was higher for Ae. aegypti mosquitoes, indicating a transmission barrier in Ae. albopictus mosquitoes. Results suggest that, although Zika virus transmission is relatively inefficient overall and dependent on virus strain and mosquito species, Ae. albopictus mosquitoes could become major vectors in the Americas.

Mosquito salivary gland protein preservation in the field for immunological and biochemical analysis

Directory of Open Access Journals (Sweden)

Almeras L

2011-03-01

Full Text Available Abstract Mosquito salivary proteins are involved in several biological processes that facilitate their blood feeding and have also been reported to elicit an IgG response in vertebrates. A growing number of studies have focused on this immunological response for its potential use as a biological marker of exposure to arthropod bites. As mosquito saliva collection is extremely laborious and inefficient, most research groups prefer to work on mosquito salivary glands (SGs. Thus, SG protein integrity is a critical factor in obtaining meaningful data from immunological and biochemical analysis. Current methodologies rely on an immediate freezing of SGs after their collection. However, the maintenance of samples in a frozen environment can be hard to achieve in field conditions. In this study, SG proteins from two mosquito species (Aedes aegypti and Anopheles gambiae s.s. stored in different media for 5 days at either +4°C or room temperature (RT were evaluated at the quantitative (i.e., ELISA and qualitative (i.e., SDS-PAGE and immunoblotting levels. Our results indicated that PBS medium supplemented with an anti-protease cocktail seems to be the best buffer to preserve SG antigens for 5 days at +4°C for ELISA analysis. Conversely, cell-lysis buffer (Urea-Thiourea-CHAPS-Tris was best at preventing protein degradation both at +4°C and RT for further qualitative analysis. These convenient storage methods provide an alternative to freezing and are expected to be applicable to other biological samples collected in the field.

Characteristics of Aedes aegypti adult mosquitoes in rural and urban areas of western and coastal Kenya.

Directory of Open Access Journals (Sweden)

Bryson Alberto Ndenga

Full Text Available Aedes aegypti is the main vector for yellow fever, dengue, chikungunya and Zika viruses. Recent outbreaks of dengue and chikungunya have been reported in Kenya. Presence and abundance of this vector is associated with the risk for the occurrence and transmission of these diseases. This study aimed to characterize the presence and abundance of Ae. aegypti adult mosquitoes from rural and urban sites in western and coastal regions of Kenya. Presence and abundance of Ae. aegypti adult mosquitoes were determined indoors and outdoors in two western (urban Kisumu and rural Chulaimbo and two coastal (urban Ukunda and rural Msambweni sites in Kenya. Sampling was performed using quarterly human landing catches, monthly Prokopack automated aspirators and monthly Biogents-sentinel traps. A total of 2,229 adult Ae. aegypti mosquitoes were collected: 785 (35.2% by human landing catches, 459 (20.6% by Prokopack aspiration and 985 (44.2% by Biogents-sentinel traps. About three times as many Ae. aegypti mosquitoes were collected in urban than rural sites (1,650 versus 579. Comparable numbers were collected in western (1,196 and coastal (1,033 sites. Over 80% were collected outdoors through human landing catches and Prokopack aspiration. The probability of collecting Ae. aegypti mosquitoes by human landing catches was significantly higher in the afternoon than morning hours (P<0.001, outdoors than indoors (P<0.001 and in urban than rural sites (P = 0.008. Significantly more Ae. aegypti mosquitoes were collected using Prokopack aspiration outdoors than indoors (P<0.001 and in urban than rural areas (P<0.001. Significantly more mosquitoes were collected using Biogents-sentinel traps in urban than rural areas (P = 0.008 and in western than coastal sites (P = 0.006. The probability of exposure to Ae. aegypti bites was highest in urban areas, outdoors and in the afternoon hours. These characteristics have major implications for the possible transmission of arboviral

Eilat virus displays a narrow mosquito vector range.

Science.gov (United States)

Nasar, Farooq; Haddow, Andrew D; Tesh, Robert B; Weaver, Scott C

2014-12-17

Most alphaviruses are arthropod-borne and utilize mosquitoes as vectors for transmission to susceptible vertebrate hosts. This ability to infect both mosquitoes and vertebrates is essential for maintenance of most alphaviruses in nature. A recently characterized alphavirus, Eilat virus (EILV), isolated from a pool of Anopheles coustani s.I. is unable to replicate in vertebrate cell lines. The EILV host range restriction occurs at both attachment/entry as well as genomic RNA replication levels. Here we investigated the mosquito vector range of EILV in species encompassing three genera that are responsible for maintenance of other alphaviruses in nature. Susceptibility studies were performed in four mosquito species: Aedes albopictus, A. aegypti, Anopheles gambiae, and Culex quinquefasciatus via intrathoracic and oral routes utilizing EILV and EILV expressing red fluorescent protein (-eRFP) clones. EILV-eRFP was injected at 10(7) PFU/mL to visualize replication in various mosquito organs at 7 days post-infection. Mosquitoes were also injected with EILV at 10(4)-10(1) PFU/mosquito and virus replication was measured via plaque assays at day 7 post-infection. Lastly, mosquitoes were provided bloodmeals containing EILV-eRFP at doses of 10(9), 10(7), 10(5) PFU/mL, and infection and dissemination rates were determined at 14 days post-infection. All four species were susceptible via the intrathoracic route; however, replication was 10-100 fold less than typical for most alphaviruses, and infection was limited to midgut-associated muscle tissue and salivary glands. A. albopictus was refractory to oral infection, while A. gambiae and C. quinquefasciatus were susceptible only at 10(9) PFU/mL dose. In contrast, A. aegypti was susceptible at both 10(9) and 10(7) PFU/mL doses, with body infection rates of 78% and 63%, and dissemination rates of 26% and 8%, respectively. The exclusion of vertebrates in its maintenance cycle may have facilitated the adaptation of EILV to a single

Mosquito population regulation and larval source management in heterogeneous environments.

Directory of Open Access Journals (Sweden)

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.

Fresh, dried or smoked? repellent properties of volatiles emitted from ethnomedicinal plant leaves against malaria and yellow fever vectors in Ethiopia

Directory of Open Access Journals (Sweden)

Dube Fitsum

2011-12-01

repellent in the laboratory. In addition to its repellent properties, ß-ocimene has long approved safe for use in food and cosmetics, making this volatile an intriguing compound to pursue in further tests in the laboratory and field to validate its mosquito repellent activity and potential for use in a commercial product. Also, the landing bioassay with humanised membranes is a potentially useful repellent screening technique that does not require the exposure of humans to the vectors, however further tests in parallel with conventional techniques are advised.

Bioassay for aquatic ecosystems review and classification; Rassegna dei principali test di ecotossicologia acquatica

Energy Technology Data Exchange (ETDEWEB)

Sanci, Antonella; Rosa, Silvia [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

1997-09-01

Bioassay play a crucial role in assessing the actual or potential impacts of anthropogenic agents on the natural environment. In this technical report, literature on bioassays for aquatic ecosystems has been reviewed and classified. Problems associated with the choice and application of bioassays are discussed.

Emerging mosquito species in Germany-a synopsis after 6 years of mosquito monitoring (2011-2016).

Science.gov (United States)

Kampen, Helge; Schuhbauer, Astrid; Walther, Doreen

2017-12-01

Globalisation and climate change are the main drivers of invasion of non-endemic regions by mosquitoes. Mass transportation of people, animals and goods facilitate accidental long-distance displacement while climate warming supports active spread and establishment of thermophilic species. In the framework of a mosquito-monitoring programme, eight non-indigenous culicid species have been registered in Germany since 2011, with four of them being more or less efficient vectors of disease agents and another four now considered established. The eight newly emerged species include Aedes albopictus, Ae. japonicus, Ae. aegypti, Ae. koreicus, Ae. berlandi, Ae. pulcritarsis, Anopheles petragnani and Culiseta longiareolata. We here review recent findings and at the same time present new findings of specimens of non-native mosquito species in Germany.

Comparison of solid and liquid-phase bioassays using ecoscores to assess contaminated soils

Energy Technology Data Exchange (ETDEWEB)

Lors, Christine [Universite Lille Nord de France, 1bis rue Georges Lefevre, 59044 Lille Cedex (France); Ecole des Mines de Douai, LGCgE-MPE-GCE, 941 rue Charles-Bourseul, 59500 Douai (France); Centre National de Recherche sur les Sites et Sols Pollues, 930 Boulevard Lahure, BP 537, 59505 Douai Cedex (France); Ponge, Jean-Francois, E-mail: ponge@mnhn.fr [Museum National d' Histoire Naturelle, Departement Ecologie et Gestion de la Biodiversite, CNRS UMR 7179, 4 Avenue du Petit-Chateau, 91800 Brunoy (France); Martinez Aldaya, Maite [Museum National d' Histoire Naturelle, Departement Ecologie et Gestion de la Biodiversite, CNRS UMR 7179, 4 Avenue du Petit-Chateau, 91800 Brunoy (France); Damidot, Denis [Universite Lille Nord de France, 1bis rue Georges Lefevre, 59044 Lille Cedex (France); Ecole des Mines de Douai, LGCgE-MPE-GCE, 941 rue Charles-Bourseul, 59500 Douai (France)

2011-10-15

Bioassays on aqueous and solid phases of contaminated soils were compared, belonging to a wide array of trophic and response levels and using ecoscores for evaluating ecotoxicological and genotoxicological endpoints. The method was applied to four coke factory soils contaminated mainly with PAHs, but also to a lesser extent by heavy metals and cyanides. Aquatic bioassays do not differ from terrestrial bioassays when scaling soils according to toxicity but they are complementary from the viewpoint of ecological relevance. Both aquatic and terrestrial endpoints are strongly correlated with concentrations of 3-ring PAHs. This evaluation procedure allows us to propose a cost-effective battery which embraces a wide array of test organisms and response levels: it includes two rapid bioassays (Microtox) and springtail avoidance), a micronucleus test and three bioassays of a longer duration (algal growth, lettuce germination and springtail reproduction). This battery can be recommended for a cost-effective assessment of polluted/remediated soils. - Highlights: > Comparison of liquid- and solid-phase bioassays on contaminated soils, using ecoscores. > Complementarity of liquid- and solid-phase bioassays for the evaluation of environmental hazards. > Proposal for a restricted battery of 5 most sensitive tests. > Use of this restricted battery for a cost-effective assessment of polluted/remediated soils. - Aqueous and solid phases of contaminated soils give similar results in terms of toxicity but are complementary for the evaluation of environmental hazards by ecoscores.

Modulation of Host Learning in Aedes aegypti Mosquitoes.

Science.gov (United States)

Vinauger, Clément; Lahondère, Chloé; Wolff, Gabriella H; Locke, Lauren T; Liaw, Jessica E; Parrish, Jay Z; Akbari, Omar S; Dickinson, Michael H; Riffell, Jeffrey A

2018-02-05

How mosquitoes determine which individuals to bite has important epidemiological consequences. This choice is not random; most mosquitoes specialize in one or a few vertebrate host species, and some individuals in a host population are preferred over others. Mosquitoes will also blood feed from other hosts when their preferred is no longer abundant, but the mechanisms mediating these shifts between hosts, and preferences for certain individuals within a host species, remain unclear. Here, we show that olfactory learning may contribute to Aedes aegypti mosquito biting preferences and host shifts. Training and testing to scents of humans and other host species showed that mosquitoes can aversively learn the scent of specific humans and single odorants and learn to avoid the scent of rats (but not chickens). Using pharmacological interventions, RNAi, and CRISPR gene editing, we found that modification of the dopamine-1 receptor suppressed their learning abilities. We further show through combined electrophysiological and behavioral recordings from tethered flying mosquitoes that these odors evoke changes in both behavior and antennal lobe (AL) neuronal responses and that dopamine strongly modulates odor-evoked responses in AL neurons. Not only do these results provide direct experimental evidence that olfactory learning in mosquitoes can play an epidemiological role, but collectively, they also provide neuroanatomical and functional demonstration of the role of dopamine in mediating this learning-induced plasticity, for the first time in a disease vector insect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Towards the genetic manipulation of mosquito disease vectors

International Nuclear Information System (INIS)

Crampton, J.M.; Lycett, G.J.; Warren, A.

1998-01-01

Our research is aimed at developing the technologies necessary to undertake the genetic manipulation of insect vector genomes. In the longer term, we wish to explore the potential that this technology may have for developing novel strategies for the control of vector-borne diseases. The focus of our current research has been to: i) identify and characterise endogenous transposable elements in the genomes of mosquito vectors -research has focussed on identifying both Class I and Class 11 elements and determining their structure and distribution within mosquito genomes; ii) develop and use transfection systems for mosquito cells in culture as a test bed for transformation vectors and promoters - transfection techniques, vector constructs and different promoters driving reporter genes have been utilised to optimise the transformation of both Aedes aegypti and Anopheles gambiae cells in culture; iii) identify putative promoter sequences which are induced in the female mosquito midgut when it takes a blood meal - the Anopheles gambiae trypsin gene locus has been cloned and sequenced and the intergenic regions assessed for their ability to induce reporter gene expression in mosquito gut cells. The progress we have made in each of these areas will be described and discussed in the context of our longer term aim which is to introduce genes coding for antiparasitic agents into mosquito genomes in such a way that they are expressed in the mosquito midgut and disrupt transmission of the malaria parasite. (author)

Towards the genetic manipulation of mosquito disease vectors

Energy Technology Data Exchange (ETDEWEB)

Crampton, J M; Lycett, G J; Warren, A [Division of Molecular Biology and Immunology, Liverpool School of Tropical Medicine, Liverpool (United Kingdom)

1998-01-01

Our research is aimed at developing the technologies necessary to undertake the genetic manipulation of insect vector genomes. In the longer term, we wish to explore the potential that this technology may have for developing novel strategies for the control of vector-borne diseases. The focus of our current research has been to: i) identify and characterise endogenous transposable elements in the genomes of mosquito vectors -research has focussed on identifying both Class I and Class 11 elements and determining their structure and distribution within mosquito genomes; ii) develop and use transfection systems for mosquito cells in culture as a test bed for transformation vectors and promoters - transfection techniques, vector constructs and different promoters driving reporter genes have been utilised to optimise the transformation of both Aedes aegypti and Anopheles gambiae cells in culture; iii) identify putative promoter sequences which are induced in the female mosquito midgut when it takes a blood meal - the Anopheles gambiae trypsin gene locus has been cloned and sequenced and the intergenic regions assessed for their ability to induce reporter gene expression in mosquito gut cells. The progress we have made in each of these areas will be described and discussed in the context of our longer term aim which is to introduce genes coding for antiparasitic agents into mosquito genomes in such a way that they are expressed in the mosquito midgut and disrupt transmission of the malaria parasite. (author). 41 refs, 2 figs.

Soil bioassays as tools for sludge compost quality assessment

International Nuclear Information System (INIS)

Domene, Xavier; Sola, Laura; Ramirez, Wilson; Alcaniz, Josep M.; Andres, Pilar

2011-01-01

Composting is a waste management technology that is becoming more widespread as a response to the increasing production of sewage sludge and the pressure for its reuse in soil. In this study, different bioassays (plant germination, earthworm survival, biomass and reproduction, and collembolan survival and reproduction) were assessed for their usefulness in the compost quality assessment. Compost samples, from two different composting plants, were taken along the composting process, which were characterized and submitted to bioassays (plant germination and collembolan and earthworm performance). Results from our study indicate that the noxious effects of some of the compost samples observed in bioassays are related to the low organic matter stability of composts and the enhanced release of decomposition endproducts, with the exception of earthworms, which are favored. Plant germination and collembolan reproduction inhibition was generally associated with uncomposted sludge, while earthworm total biomass and reproduction were enhanced by these materials. On the other hand, earthworm and collembolan survival were unaffected by the degree of composting of the wastes. However, this pattern was clear in one of the composting procedures assessed, but less in the other, where the release of decomposition endproducts was lower due to its higher stability, indicating the sensitivity and usefulness of bioassays for the quality assessment of composts.

Biomonitoring of cyanotoxins in two tropical reservoirs by cladoceran toxicity bioassays.

Science.gov (United States)

da S Ferrão-Filho, Aloysio; Soares, Maria Carolina S; de Freitas Magalhães, Valeria; Azevedo, Sandra M F O

2009-02-01

This study evaluates the potential for the use of cladocerans in biomonitoring of cyanobacterial toxins. Two zooplankton species (Daphnia gessneri and Moina micrura) were cultivated in the laboratory for use in acute (48 h) and chronic (10 days) bioassays. Water samples were collected from two reservoirs and diluted in mineral water at four concentrations. Survivorship in the acute bioassays was used to calculate LC50, and survivorship and fecundity in chronic bioassays were used to calculate the intrinsic population growth rate (r) and the EC50. Analysis of phytoplankton in the water samples from one reservoir revealed that cyanobacteria were the dominant group, represented by the genera Anabaena, Cylindrospermopsis, and Microcystis. Results of bioassays showed adverse effects including death, paralysis, and reduced population growth rate, generally proportional to the reservoir water concentration. These effects may be related to the presence of cyanobacteria toxins (microcystins or saxitoxins) in the water.

Chromobacterium Csp_P reduces malaria and dengue infection in vector mosquitoes and has entomopathogenic and in vitro anti-pathogen activities.

Science.gov (United States)

Ramirez, Jose Luis; Short, Sarah M; Bahia, Ana C; Saraiva, Raul G; Dong, Yuemei; Kang, Seokyoung; Tripathi, Abhai; Mlambo, Godfree; Dimopoulos, George

2014-10-01

Plasmodium and dengue virus, the causative agents of the two most devastating vector-borne diseases, malaria and dengue, are transmitted by the two most important mosquito vectors, Anopheles gambiae and Aedes aegypti, respectively. Insect-bacteria associations have been shown to influence vector competence for human pathogens through multi-faceted actions that include the elicitation of the insect immune system, pathogen sequestration by microbes, and bacteria-produced anti-pathogenic factors. These influences make the mosquito microbiota highly interesting from a disease control perspective. Here we present a bacterium of the genus Chromobacterium (Csp_P), which was isolated from the midgut of field-caught Aedes aegypti. Csp_P can effectively colonize the mosquito midgut when introduced through an artificial nectar meal, and it also inhibits the growth of other members of the midgut microbiota. Csp_P colonization of the midgut tissue activates mosquito immune responses, and Csp_P exposure dramatically reduces the survival of both the larval and adult stages. Ingestion of Csp_P by the mosquito significantly reduces its susceptibility to Plasmodium falciparum and dengue virus infection, thereby compromising the mosquito's vector competence. This bacterium also exerts in vitro anti-Plasmodium and anti-dengue activities, which appear to be mediated through Csp_P -produced stable bioactive factors with transmission-blocking and therapeutic potential. The anti-pathogen and entomopathogenic properties of Csp_P render it a potential candidate for the development of malaria and dengue control strategies.

Analysis of Culex and Aedes mosquitoes in southwestern Nigeria ...

African Journals Online (AJOL)

Introduction: Amplification and transmission of West Nile virus (WNV) by mosquitoes are driven by presence and number of viraemic/susceptible avian hosts. Methods: in order to predict risk of WNV infection to humans, we collected mosquitoes from horse stables in Lagos and Ibadan, southwestern Nigeria. The mosquitoes ...

Potential for Co-Infection of a Mosquito-Specific Flavivirus, Nhumirim Virus, to Block West Nile Virus Transmission in Mosquitoes

Directory of Open Access Journals (Sweden)

Silvina Goenaga

2015-11-01

Full Text Available Nhumirim virus (NHUV is an insect-specific virus that phylogenetically affiliates with dual-host mosquito-borne flaviviruses. Previous in vitro co-infection experiments demonstrated prior or concurrent infection of Aedes albopictus C6/36 mosquito cells with NHUV resulted in a 10,000-fold reduction in viral production of West Nile virus (WNV. This interference between WNV and NHUV was observed herein in an additional Ae. albopictus mosquito cell line, C7-10. A WNV 2K peptide (V9M mutant capable of superinfection with a pre-established WNV infection demonstrated a comparable level of interference from NHUV as the parental WNV strain in C6/36 and C7-10 cells. Culex quinquefasciatus and Culex pipiens mosquitoes intrathoracically inoculated with NHUVandWNV, or solely withWNVas a control, were allowed to extrinsically incubate the viruses up to nine and 14 days, respectively, and transmissibility and replication of WNV was determined. The proportion of Cx. quinquefasciatus mosquitoes capable of transmitting WNV was significantly lower for the WNV/NHUV group than the WNV control at seven and nine days post inoculation (dpi, while no differences were observed in the Cx. pipiens inoculation group. By dpi nine, a 40% reduction in transmissibility in mosquitoes from the dual inoculation group was observed compared to the WNV-only control. These data indicate the potential that infection of some Culex spp. vectors with NHUV could serve as a barrier for efficient transmissibility of flaviviruses associated with human disease.

Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa.

Science.gov (United States)

Soti, Valérie; Tran, Annelise; Degenne, Pascal; Chevalier, Véronique; Lo Seen, Danny; Thiongane, Yaya; Diallo, Mawlouth; Guégan, Jean-François; Fontenille, Didier

2012-01-01

Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV) is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes) involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961-2003). We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends the identification of rainfall patterns favourable for RVFV amplification.

Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa.

Directory of Open Access Journals (Sweden)

Valérie Soti

Full Text Available BACKGROUND: Rift Valley fever (RVF is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. METHODOLOGY/PRINCIPAL FINDINGS: A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961-2003. We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. CONCLUSION/SIGNIFICANCE: Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends

Establishment of a bioassay for the toxicity evaluation and quality control of Aconitum herbs

International Nuclear Information System (INIS)

Qin, Yi; Wang, Jia-bo; Zhao, Yan-ling; Shan, Li-mei; Li, Bao-cai; Fang, Fang; Jin, Cheng; Xiao, Xiao-he

2012-01-01

Highlights: ► A new bioassay was optimized to evaluate the toxicity of Aconitum herbs. ► Characterizing total toxicity is its unique advantage over chemical analysis methods. ► The application of this bioassay promotes the safe use of Aconitum herbs in clinic. - Abstract: Currently, no bioassay is available for evaluating the toxicity of Aconitum herbs, which are well known for their lethal cardiotoxicity and neurotoxicity. In this study, we established a bioassay to evaluate the toxicity of Aconitum herbs. Test sample and standard solutions were administered to rats by intravenous infusion to determine their minimum lethal doses (MLD). Toxic potency was calculated by comparing the MLD. The experimental conditions of the method were optimized and standardized to ensure the precision and reliability of the bioassay. The application of the standardized bioassay was then tested by analyzing 18 samples of Aconitum herbs. Additionally, three major toxic alkaloids (aconitine, mesaconitine, and hypaconitine) in Aconitum herbs were analyzed using a liquid chromatographic method, which is the current method of choice for evaluating the toxicity of Aconitum herbs. We found that for all Aconitum herbs, the total toxicity of the extract was greater than the toxicity of the three alkaloids. Therefore, these three alkaloids failed to account for the total toxicity of Aconitum herbs. Compared with individual chemical analysis methods, the chief advantage of the bioassay is that it characterizes the total toxicity of Aconitum herbs. An incorrect toxicity evaluation caused by quantitative analysis of the three alkaloids might be effectively avoided by performing this bioassay. This study revealed that the bioassay is a powerful method for the safety assessment of Aconitum herbs.

“Looking over the Backyard Fence”: Householders and Mosquito Control

Directory of Open Access Journals (Sweden)

Samir Mainali

2017-03-01

Full Text Available (1 Background: Vector-borne diseases are a significant public health problem in Western Australia. Mosquitoes are responsible for the transmission of a number of pathogens and may pose a serious nuisance problem. Prevention efforts in the State are multi-faceted and include physical, chemical, and cultural control methods for restricting mosquito breeding. This is less complex where breeding areas are located within public open spaces. In Australia’s developed urban areas, breeding sites are, however, frequently located within private residential landholdings, where the scope of public health officials to act is constrained by law and practicality. Consequently, mosquito prevention in these locations is predominantly the responsibility of the residents. This research addressed a gap, both in understanding the degree to which “backyard” mosquito breeding has the potential to contribute to local mosquito problems, and in assessing what residents “think and do” about mosquito control within their home environment. (2 Methods: The study was conducted in the Town of Bassendean, a metropolitan Local Government Area of Perth, Western Australia, in close proximity to two natural, productive mosquito breeding sites, namely Ashfield Flats and Bindaring Park. A total of 150 householders were randomly surveyed during the summer of 2015–2016, to gauge residents’ knowledge, attitudes, and practices (KAP (knowledge, attitudes, and practices Survey in regards to mosquitoes, their breeding and ecology, and avoidance or minimization strategies. The survey comprised nine questions covering residents’ knowledge (3 questions, attitudes (3 questions, and practices (3 questions, as well as additional questions regarding the basic demographics of the resident. Larvae were collected from backyard containers and reared to adults for species identification. A series of Encephalitis Vector Surveillance carbon dioxide (EVS CO2 traps were also deployed, to

The effects of x-irradiation in the mosquito Aedes aegypti (L)

International Nuclear Information System (INIS)

Read, N.G.

1980-01-01

Newly emerged mosquitoes (Aedes aegypti (L)) were exposed to doses of 500 to 32,000 rad X-irradiation and the LD 50 and mean survival time determined. Radiation doses between 500 and 8,000 rad had only a slight effect on longevity whereas exposure to 32,000 had an appreciable effect. The midgut structure of newly emerged, X-irradiated female Aedes aegypti imagines was examined at set intervals after irradiation. The cytochemical localization of midgut acid phosphatase, alkaline phosphatase and adenosine triphosphatase, and also quantitative estimates of midgut acid and alkaline phosphatase were carried out on mosquitoes exposed to 32,000 rad. Considerable changes in the structure of the midgut cells were apparent. With 500, 4,000 and 8,000 rad there was evidence of cellular repair and recovery. However, with 32,000 rad cellular damage was most extensive, with considerable loss of cell structure. The ultrastructural changes noted suggest that the primary radiation damage was to the plasma and organelle membranes, which is in agreement with the membrane-damage/enzyme release hypothesis. (author)

Integrating the Public in Mosquito Management: Active Education by Community Peers Can Lead to Significant Reduction in Peridomestic Container Mosquito Habitats

Science.gov (United States)

Healy, Kristen; Hamilton, George; Crepeau, Taryn; Healy, Sean; Unlu, Isik; Farajollahi, Ary; Fonseca, Dina M.

2014-01-01

Mosquito species that utilize peridomestic containers for immature development are commonly aggressive human biters, and because they often reach high abundance, create significant nuisance. One of these species, the Asian tiger mosquito Aedes albopictus, is an important vector of emerging infectious diseases, such as dengue, chikungunya, and Zika fevers. Integrated mosquito management (IMM) of Ae. albopictus is particularly difficult because it requires access to private yards in urban and suburban residences. It has become apparent that in the event of a public health concern due to this species, homeowners will have to be active participants in the control process by reducing mosquito habitats in their properties, an activity known as source reduction. However, limited attempts at quantifying the effect of source reduction by homeowners have had mixed results. Of note, many mosquito control programs in the US have some form of education outreach, however the primary approach is often passive focusing on the distribution of education materials as flyers. In 2010, we evaluated the use of active community peer education in a source reduction program, using AmeriCorps volunteers. The volunteers were mobilized over a 4-week period, in two areas with approximately 1,000 residences each in urban Mercer and suburban Monmouth counties in New Jersey, USA. The volunteers were first provided training on peridomestic mosquitoes and on basic approaches to reducing the number of container habitats for mosquito larvae in backyards. Within the two treatment areas the volunteers successfully engaged 758 separate homes. Repeated measures analysis of variance showed a significant reduction in container habitats in the sites where the volunteers actively engaged the community compared to untreated control areas in both counties. Our results suggest that active education using community peer educators can be an effective means of source reduction, and a critical tool in the arsenal

Using mobile phones as acoustic sensors for high-throughput mosquito surveillance.

Science.gov (United States)

Mukundarajan, Haripriya; Hol, Felix Jan Hein; Castillo, Erica Araceli; Newby, Cooper; Prakash, Manu

2017-10-31

The direct monitoring of mosquito populations in field settings is a crucial input for shaping appropriate and timely control measures for mosquito-borne diseases. Here, we demonstrate that commercially available mobile phones are a powerful tool for acoustically mapping mosquito species distributions worldwide. We show that even low-cost mobile phones with very basic functionality are capable of sensitively acquiring acoustic data on species-specific mosquito wingbeat sounds, while simultaneously recording the time and location of the human-mosquito encounter. We survey a wide range of medically important mosquito species, to quantitatively demonstrate how acoustic recordings supported by spatio-temporal metadata enable rapid, non-invasive species identification. As proof-of-concept, we carry out field demonstrations where minimally-trained users map local mosquitoes using their personal phones. Thus, we establish a new paradigm for mosquito surveillance that takes advantage of the existing global mobile network infrastructure, to enable continuous and large-scale data acquisition in resource-constrained areas.

Hey! A Mosquito Bit Me! (For Kids)

Science.gov (United States)

... First Aid & Safety Doctors & Hospitals Videos Recipes for Kids Kids site Sitio para niños How the Body Works ... Español Hey! A Mosquito Bit Me! KidsHealth / For Kids / Hey! A Mosquito Bit Me! Print en español ¡ ...

Successful human infection with P. falciparum using three aseptic Anopheles stephensi mosquitoes: a new model for controlled human malaria infection.

Directory of Open Access Journals (Sweden)

Matthew B Laurens

Full Text Available Controlled human malaria infection (CHMI is a powerful method for assessing the efficacy of anti-malaria vaccines and drugs targeting pre-erythrocytic and erythrocytic stages of the parasite. CHMI has heretofore required the bites of 5 Plasmodium falciparum (Pf sporozoite (SPZ-infected mosquitoes to reliably induce Pf malaria. We reported that CHMI using the bites of 3 PfSPZ-infected mosquitoes reared aseptically in compliance with current good manufacturing practices (cGMP was successful in 6 participants. Here, we report results from a subsequent CHMI study using 3 PfSPZ-infected mosquitoes reared aseptically to validate the initial clinical trial. We also compare results of safety, tolerability, and transmission dynamics in participants undergoing CHMI using 3 PfSPZ-infected mosquitoes reared aseptically to published studies of CHMI using 5 mosquitoes. Nineteen adults aged 18-40 years were bitten by 3 Anopheles stephensi mosquitoes infected with the chloroquine-sensitive NF54 strain of Pf. All 19 participants developed malaria (100%; 12 of 19 (63% on Day 11. The mean pre-patent period was 258.3 hours (range 210.5-333.8. The geometric mean parasitemia at first diagnosis by microscopy was 9.5 parasites/µL (range 2-44. Quantitative polymerase chain reaction (qPCR detected parasites an average of 79.8 hours (range 43.8-116.7 before microscopy. The mosquitoes had a geometric mean of 37,894 PfSPZ/mosquito (range 3,500-152,200. Exposure to the bites of 3 aseptically-raised, PfSPZ-infected mosquitoes is a safe, effective procedure for CHMI in malaria-naïve adults. The aseptic model should be considered as a new standard for CHMI trials in non-endemic areas. Microscopy is the gold standard used for the diagnosis of Pf malaria after CHMI, but qPCR identifies parasites earlier. If qPCR continues to be shown to be highly specific, and can be made to be practical, rapid, and standardized, it should be considered as an alternative for diagnosis

Mosquito larvicidal activities of Solanum villosum berry extract against the dengue vector Stegomyia aegypti

Directory of Open Access Journals (Sweden)

Chandra Goutam

2008-04-01

Full Text Available Abstract Background Vector control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. Although several plants have been reported for mosquitocidal activity, only a few botanicals have moved from the laboratory to field use, because they are poorly characterized, in most cases active principals are not determined and most of the works are restricted to preliminary screening. Solanum villosum is a common weed distributed in many parts of India with medicinal properties, but the larvicidal activity of this plant has not been reported so far. Methods Aqueous and polar/non-polar solvent extract of fresh, mature, green berries of S. villosum was tested against Stegomyia aegypti, a common vector of dengue fever. A phytochemical analysis of chloroform:methanol extract was performed to search for the active toxic ingredient. The lethal concentration was determined (log probit analysis and compared with Malathion. The chemical nature of the active substance was also evaluated following ultraviolet-visual (UV-Vis and infrared (IR analysis. Results In a 72 hour bioassay experiment with the aqueous extract, the highest mortality was recorded in 0.5% extract. When the mortality of different solvent extracts was compared, the maximum (p p Y was positively correlated with the period of exposure (X and the log probit analysis (95% confidence level recorded lowest value (5.97 ppm at 72 hours of exposure. Phytochemical analysis of the chlororm:methanol extract reported the presence of many bioactive phytochemicals. Two toxic compounds were detected having Rf = 0.82 (70% and 73.33% mortality in 24 and 48 hours, respectively and Rf = 0.95 (40% and 50% mortality in 24 and 48 hours, respectively. IR analysis provided preliminary information about the steroidal nature of the active ingredient. Conclusion S. villosum offers promise as

Development and characterization of a green fluorescent protein-based rat cell bioassay system for detection of AH receptor ligands

Energy Technology Data Exchange (ETDEWEB)

Zhao Bin; Denison, M. [California Univ., Davis, CA (United States). Dept. of Environmental Toxicology

2004-09-15

Proper epidemiological, risk assessment and exposure analysis of TCDD and related HAHs requires accurate measurements of these chemicals both in the species of interest and in various exposure matrices (i.e. biological, environmental, food and feed). While high-resolution instrumental analysis techniques are established for these chemicals, these procedures are very costly, time-consuming and are impractical for large scale sampling studies. Accordingly, numerous bioanalytical methods have been developed for the detection of these chemicals in extracts from a variety of matrices, the majority of which take the advantage of the ability of these chemicals to activate one or more aspects of the AhR-dependent mechanism of action. One of the most sensitive bioassay systems developed to date is the so-called CALUX (Chemically Activated Luciferase Expression) assay, which is based on novel recombinant cell lines that contain a stably transfected dioxin (AhR)-responsive firefly luciferase gene. Treatment of these cells with TCDD and related HAHs and polycyclic aromatic hydrocarbons (PAHs), as well as other AhR ligands, results in induction of reporter gene expression in a time-, dose-, AhR-, and chemical-specific manner. The level of reporter gene expression correlates with the total concentration of the TCDD-like AhR inducers (agonists) present in the sample. Although the firefly luciferase reporter gene contributes to the high degree of sensitivity of the assay, it also has limitations with respect to our need for a rapid and inexpensive bioassay for high-throughput screening analysis. Accordingly, we previously developed a stably transfected murine cell line containing an AhRresponsive enhanced green fluorescent protein (EGFP) reporter gene. This cell line provided us with a high-throughput cell bioassay system for identification and characterization of AhR agonists and antagonists. Here we have extended these studies and describe the development, optimization, and

Using a macroalgal δ15N bioassay to detect cruise ship waste water effluent inputs

International Nuclear Information System (INIS)

Kaldy, James

2011-01-01

Highlights: → Green macroalgae exposed to nutrient solutions exhibited changes in tissue 15 N signatures. → Macroalgae exhibited no fractionation with NO 3 and slight fractionation with NH 4 . → Algae exposed to cruise ship waste water had increased tissue δ 15 N indicating a heavy N source. → Field bioassays exhibited decreased δ 15 N indicating isotopically light riverine δ 15 N-NO 3 was likely the dominant N source. → Algal bioassays could not detect a δ 15 N cruise ship waste water signal in this system. - Abstract: Green macroalgae bioassays were used to determine if the δ 15 N signature of cruise ship waste water effluent (CSWWE) could be detected in a small harbor. Opportunistic green macroalgae (Ulva spp.) were collected, cultured under nutrient depleted conditions and characterized with regard to N content and δ 15 N. Samples of algae were used in controlled incubations to evaluate the direction of isotope shift from exposure to CSWWE. Algae samples exposed to CSWWE exhibited an increase of 1-2.5 per mille in δ 15 N values indicating that the CSWWE had an enriched isotope signature. In contrast, algae samples exposed to field conditions exhibited a significant decrease in the observed δ 15 N indicating that a light N source was used. Isotopically light, riverine nitrogen derived from N 2 -fixing trees in the watershed may be a N source utilized by algae. These experiments indicate that the δ 15 N CSWWE signature was not detectable under the CSWWE loading conditions of this experiment.

Are bioassays useful tools to assess redox processes and biodegradation?

DEFF Research Database (Denmark)

Albrechtsen, Hans-Jørgen; Pedersen, Philip Grinder; Ludvigsen, L.

2002-01-01

sensitive hydrochemical or geochemical parameters, levels of hydrogen, and redox potential. However, all these approaches have to be evaluated against TEAP-bioassays as the most direct measure. We assessed successfully ongoing microbial-mediated redox processes by TEAP-bioassays in degradation studies...... of aromatic and chlorinated aliphatic compounds in landfill leachate plumes, and of pesticides in aquifers with various redox conditions....

Comparison of solid and liquid-phase bioassays using ecoscores to assess contaminated soils

International Nuclear Information System (INIS)

Lors, Christine; Ponge, Jean-Francois; Martinez Aldaya, Maite; Damidot, Denis

2011-01-01

Bioassays on aqueous and solid phases of contaminated soils were compared, belonging to a wide array of trophic and response levels and using ecoscores for evaluating ecotoxicological and genotoxicological endpoints. The method was applied to four coke factory soils contaminated mainly with PAHs, but also to a lesser extent by heavy metals and cyanides. Aquatic bioassays do not differ from terrestrial bioassays when scaling soils according to toxicity but they are complementary from the viewpoint of ecological relevance. Both aquatic and terrestrial endpoints are strongly correlated with concentrations of 3-ring PAHs. This evaluation procedure allows us to propose a cost-effective battery which embraces a wide array of test organisms and response levels: it includes two rapid bioassays (Microtox) and springtail avoidance), a micronucleus test and three bioassays of a longer duration (algal growth, lettuce germination and springtail reproduction). This battery can be recommended for a cost-effective assessment of polluted/remediated soils. - Highlights: → Comparison of liquid- and solid-phase bioassays on contaminated soils, using ecoscores. → Complementarity of liquid- and solid-phase bioassays for the evaluation of environmental hazards. → Proposal for a restricted battery of 5 most sensitive tests. → Use of this restricted battery for a cost-effective assessment of polluted/remediated soils. - Aqueous and solid phases of contaminated soils give similar results in terms of toxicity but are complementary for the evaluation of environmental hazards by ecoscores.

Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction.

Science.gov (United States)

Pujol-Vila, F; Vigués, N; Guerrero-Navarro, A; Jiménez, S; Gómez, D; Fernández, M; Bori, J; Vallès, B; Riva, M C; Muñoz-Berbel, X; Mas, J

2016-03-03

Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. Microtox(®), rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation

Avian phenotypic traits related to feeding preferences in two Culex mosquitoes

Science.gov (United States)

Yan, Jiayue; Gangoso, Laura; Martínez-de la Puente, Josué; Soriguer, Ramón; Figuerola, Jordi

2017-10-01

Host choice by mosquitoes affects the transmission dynamics of vector-borne infectious diseases. Although asymmetries in mosquito attraction to vertebrate species have been reported, the relative importance of host characteristics in mosquito blood-feeding behavior is still poorly studied. Here, we investigate the relationship between avian phenotypic traits—in particular, morphometry, plumage coloration, and nesting and roosting behavior—and the blood-feeding patterns in two common Culex mosquito species on a North American avian community. Forage ratios of the mosquito species were unrelated to the phylogenetic relationships among bird species. Culex pipiens fed preferably on birds with lighter-colored plumage and longer tarsi; furthermore, solitary roosting avian species were both bitten by Cx. pipiens and Cx. restuans more often than expected. These associations may be explained by greater mosquito attraction towards larger birds with a greater color contrast against the background. Although communally roosting birds may release more cues and attract more mosquitoes, individuals may in fact receive fewer bites due to the encounter-dilution effect. Mosquito feeding behavior is a highly complex phenomenon, and our results may improve understanding of the non-random interaction between birds and mosquitoes in natural communities.

Relative Abundance of Adult Mosquitoes in University of Abuja Main ...

African Journals Online (AJOL)

Relative Abundance of Adult Mosquitoes in University of Abuja Main ... relative abundance of adult mosquitoes in four selected sites in University of Abuja ... These results indicated that vectors of mosquito-borne diseases are breeding in the ...

Primary blood-hosts of mosquitoes are influenced by social and ecological conditions in a complex urban landscape.

Science.gov (United States)

Goodman, Heather; Egizi, Andrea; Fonseca, Dina M; Leisnham, Paul T; LaDeau, Shannon L

2018-04-10

Temperate urban landscapes support persistent and growing populations of Culex and Aedes mosquito vectors. Large urban mosquito populations can represent a significant risk for transmission of emergent arboviral infection. However, even large mosquito populations are only a risk to the animals they bite. The purpose of this study is to identify and assess spatial patterns of host-use in a temperate urban landscape with heterogeneous socio-economic and ecological conditions. Mosquito blood meals were collected from neighborhoods categorized along a socio-economic gradient in Baltimore, MD, USA. Blood meal hosts were identified for two Aedes (Ae. albopictus and Ae. japonicus) and three Culex (Cx. pipiens, Cx. restuans and Cx. salinarius) species. The brown rat (Rattus norvegicus) was the most frequently detected host in both Aedes species and Cx. salinarius. Human biting was evident in Aedes and Culex species and the proportion of human blood meals from Ae. albopictus varied significantly with neighborhood socio-economic status. Aedes albopictus was most likely to feed on human blood hosts (at 50%) in residential blocks categorized as having income above the city median, although there were still more total human bites detected from lower income blocks where Ae. albopictus was more abundant. Birds were the most frequently detected Culex blood hosts but were absent from all Aedes sampled. This study highlights fine-scale variation in host-use by medically important mosquito vectors and specifically investigates blood meal composition at spatial scales relevant to urban mosquito dispersal and human exposure. Further, the work emphasizes the importance of neighborhood economics and infrastructure management in shaping both the relative abundance of vectors and local blood feeding strategies. The invasive brown rat was an important blood source across vector species and neighborhoods in Baltimore. We show that social and economic conditions can be important predictors of

Bioassay requirements for 125I and 131I in medical, teaching and research institutions

International Nuclear Information System (INIS)

1983-09-01

The more widespread use of radioactive isotopes of iodine (collectively referred to as radioiodines) as a research tool, coupled with their diagnostic and therapeutic uses in nuclear medicine, has resulted in an increased number of personnel who are exposed to these radioisotopes and who therefore should be monitored for internal radioiodine contamination. This document describes the minimum acceptable features of a bioassay programme which the Atomic Energy Control Board (AECB) requires to be available in institutions holding a prescribed substance licence authorising the use of significant quantities of 125 I or 131 I or both. A licensee may submit details of his own proposed bioassay programme to the AECB for approval. If such a programme fails to be approved, the programme described below shall be adhered to. This document does not deal with individuals who are likely to maintain a significant chronic thyroid burden of radioiodine. It is assumed that the radioiodine taken into the body is in a soluble, inorganic form (I 2 , iodide or iodate) or in an organic form (e.g. methyl iodide) which is metabolised in the body with a resultant release of iodide. Radioiodinated organic compounds which are not catabolised to iodide in the body to any significant degree are not the subject of this document, since the metabolism of the radioiodine will be dictated by the metabolism of the compound. This means that individuals whose only exposure to radioiodine is in the form of prepared radioiodinated compounds such as antigens and antibodies (e.g. individuals using radio immuno assay kits in which the antigen or antibody is supplied as radioiodinated material) are not required to participate in this bioassay programme for radioiodine

Non-Genetic Determinants of Mosquito Competence for Malaria Parasites

Science.gov (United States)

Lefèvre, Thierry; Vantaux, Amélie; Dabiré, Kounbobr R.; Mouline, Karine; Cohuet, Anna

2013-01-01

Understanding how mosquito vectors and malaria parasites interact is of fundamental interest, and it also offers novel perspectives for disease control. Both the genetic and environmental contexts are known to affect the ability of mosquitoes to support malaria development and transmission, i.e., vector competence. Although the role of environment has long been recognized, much work has focused on host and parasite genetic effects. However, the last few years have seen a surge of studies revealing a great diversity of ways in which non-genetic factors can interfere with mosquito-Plasmodium interactions. Here, we review the current evidence for such environmentally mediated effects, including ambient temperature, mosquito diet, microbial gut flora, and infection history, and we identify additional factors previously overlooked in mosquito-Plasmodium interactions. We also discuss epidemiological implications, and the evolutionary consequences for vector immunity and parasite transmission strategies. Finally, we propose directions for further research and argue that an improved knowledge of non-genetic influences on mosquito-Plasmodium interactions could aid in implementing conventional malaria control measures and contribute to the design of novel strategies. PMID:23818841

Non-genetic determinants of mosquito competence for malaria parasites.

Directory of Open Access Journals (Sweden)

Thierry Lefèvre

Full Text Available Understanding how mosquito vectors and malaria parasites interact is of fundamental interest, and it also offers novel perspectives for disease control. Both the genetic and environmental contexts are known to affect the ability of mosquitoes to support malaria development and transmission, i.e., vector competence. Although the role of environment has long been recognized, much work has focused on host and parasite genetic effects. However, the last few years have seen a surge of studies revealing a great diversity of ways in which non-genetic factors can interfere with mosquito-Plasmodium interactions. Here, we review the current evidence for such environmentally mediated effects, including ambient temperature, mosquito diet, microbial gut flora, and infection history, and we identify additional factors previously overlooked in mosquito-Plasmodium interactions. We also discuss epidemiological implications, and the evolutionary consequences for vector immunity and parasite transmission strategies. Finally, we propose directions for further research and argue that an improved knowledge of non-genetic influences on mosquito-Plasmodium interactions could aid in implementing conventional malaria control measures and contribute to the design of novel strategies.

Nesting bird "host funnel" increases mosquito-bird contact rate.

Science.gov (United States)

Caillouët, Kevin A; Riggan, Anna E; Bulluck, Lesley P; Carlson, John C; Sabo, Roy T

2013-03-01

Increases in vector-host contact rates can enhance arbovirus transmission intensity. We investigated weekly fluctuations in contact rates between mosquitoes and nesting birds using the recently described Nest Mosquito Trap (NMT). The number of mosquitoes per nestling increased from nesting season. Our evidence suggests the coincidence of the end of the avian nesting season and increasing mosquito abundances may have caused a "host funnel," concentrating host-seeking mosquitoes to the few remaining nestlings. The relative abundance of mosquitoes collected by the NMT suggests that significantly more Aedes albopictus (Skuse) and Culex pipiens (L.) /restuans (Theobald) sought nesting bird bloodmeals than were predicted by their relative abundances in CO2-baited Centers for Disease Control and Prevention light and gravid traps. Culex salinarius (Coquillett) and Culex erraticus Dyar and Knab were collected in NMTs in proportion to their relative abundances in the generic traps. Temporal host funnels and nesting bird host specificity may enhance arbovirus amplification and explain observed West Nile virus and St. Louis encephalitis virus amplification periods.

Review: artificial container-breeding mosquitoes and cemeteries: a perfect match.

Science.gov (United States)

Vezzani, Darío

2007-02-01

Artificial container-breeding mosquitoes, such as Aedes aegypti, Ae. albopictus, and Culex pipiens, are well-recognized vectors of diseases throughout the world. Cemeteries are considered major sources of mosquitoes and the results of more than 30 studies concerning mosquitoes in cemeteries have been published over the last decade. The characteristics of these environments in regard to the availability of resources for mosquito development were discussed. Also, studies about early detection of Aedes vectors, ecological issues, and mosquito control performed in cemeteries were reviewed. Among 31 mosquito species found breeding in cemeteries from 16 countries, the invasive Ae. aegypti and Ae. albopictus were the most frequent ones. Species of the genus Ochlerotatus, Culex, Toxorhynchites, Culiseta, Armigeres, Lutzia, Uranotaenia, and Tripteroides were also reported. Overall, cemeteries are highly suitable habitats for artificial container-breeding mosquitoes due to the great availability of the different resources that they need (i.e. sugar substances, blood, shelter and water-filled containers). In addition, these places are mostly ideal settings to perform studies in urbanized areas because of high mosquito abundance, heterogeneity of macro- and microhabitats, and an easier access in comparison with private premises. However, the feasibility of a cemetery as a study area must be evaluated in each case considering the objectives of the study and cemetery characteristics.

Distribution of Aedes mosquitoes in the Kilimanjaro Region of northern Tanzania.

Science.gov (United States)

Hertz, Julian T; Lyaruu, Lucille J; Ooi, Eng Eong; Mosha, Franklin W; Crump, John A

2016-05-01

Little is known about the presence and distribution of Aedes mosquitoes in northern Tanzania despite the occurence of viruses transmitted by these mosquitoes such as Chikungunya virus (CHIKV) and Dengue virus (DENV) in the region. Adult and larval mosquitoes were collected from rural and urban settings across a wide range of altitudes in the Kilimanjaro Region using the Mosquito Magnet CO2 Trap for collection of adults and old tires for breeding of larvae. Polymerase chain reaction assays were performed on captured adult mosquitoes to detect the presence of CHIKV and DENV. A total of 2609 Aedes aegypti adult mosquitoes were collected; no other Aedes species larvae were found. Mosquito yields were significantly higher in urban settings than rural settings (26.5 vs. 1.9 mosquitoes per day, p = 0.037). A total of 6570 Ae. aegypti larvae were collected from old tires; no other Aedes species larvae were found. Of the 2609 adult mosquitoes collected, none tested positive for CHIKV or DENV. As far as we are aware, this paper reports for the first time the presence of Ae. aegypti in the Kilimanjaro Region of northern Tanzania. Although CHIKV and DENV were not isolated from any of the collected mosquitoes in this study, the apparent absence of other Aedes species in the area suggests that Ae. aegypti is the primary local vector of these infections.

Determining airborne concentrations of spatial repellent chemicals in mosquito behavior assay systems.

Directory of Open Access Journals (Sweden)

Nicholas J Martin

Full Text Available BACKGROUND: Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR. Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions. METHODOLOGY/PRINCIPAL FINDINGS: A thermal desorption (TD gas chromatography-mass spectrometry (GC-MS method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3 (n = 17; SD = 0.45 and 1.42 µg/m(3 (n = 30; SD = 0.96. CONCLUSIONS/SIGNIFICANCE: The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h SR concentrations in small volume (<100 L samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.

Mosquito production from four constructed treatment wetlands in peninsular Florida.

Science.gov (United States)

Rey, Jorge R; O'Meara, George F; O'Connell, Sheila M; Cutwa-Francis, Michele M

2006-06-01

Several techniques were used to sample adult and immature mosquitoes in 4 constructed treatment wetlands in Florida. Adults of 19 species (7 genera) of mosquitoes were collected, and immatures of the most abundant species and of 60% of all species also were collected. Few significant differences between sites and stations in the numbers of mosquitoes collected were discovered. Culex nigripalpus Theobald was the most abundant mosquito found in adult (carbon dioxide-baited suction traps) and ovitrap collections, whereas Mansonia spp. and Uranotaenia spp. were most common in pump-dip-grab samples. The roles of rooted and floating vegetation and of water quality in determining mosquito production from these areas are discussed.

Evaluation of genotoxicity of liquid effluents from gas washing systems by means of bioassay Trad-MCN

International Nuclear Information System (INIS)

Machado, Alessandra Carla Fattori Ergesse; Alves, Edenise Segala

2007-01-01

In the gas washing systems the gaseous emissions from a facility are forced through an absorbing liquid preventing pollutants to be dispersed into the atmosphere. In the Centro Tecnologico da Marinha em Sao Paulo/Centro Experimental Aramar (CEA), the gas washing are used to control the emissions from the uranium enrichment facilities. Uranium. fluoride, ammonia and hydrogen fluoride are the main contaminants, all heavily toxic. Biological assays, using plants or other living organisms, have been used to assess genotoxic agents in the environment. Among the bioassays using plants, the Trad-MCN has been used extensively, as it allows the evaluation of liquid or gaseous contaminants. The species Tradescantia pallida (Rose) was exposed in a dynamic system to liquid effluents from CEA. A positive control was the exposure to formaldehyde 10% in water, known as a very toxic solution, and the negative control was the exposure to filtered air. The protocol established by Ma (1983) for hybrid clones and validated for the T. pallida by Guimaraes (2003) was used to perform the Trad-MCN assays. Only preparations containing early tetrads were scored. In that context, the present study objectifies to evaluate, by the Trad-MCN bioassay, the genotoxicity of the solution from the gas washing and, also, evaluate the efficiency of that system. The results obtained show that the T. pallida is a sensitive bioindicator for the pollutants tested and can be useful for in vitro environmental monitoring under controlled conditions. (author)

Evaluation of genotoxicity of liquid effluents from gas washing systems by means of bioassay Trad-MCN

Energy Technology Data Exchange (ETDEWEB)

Machado, Alessandra Carla Fattori Ergesse [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil). Div. de Monitoracao Ambiental], E-mail: alessandra@ctmsp.mar.mil.br; Alves, Edenise Segala [Instituto de Botanica de Sao Paulo, SP (Brazil). Secao de Anatomia], E-mail: ealves@ibot.sp.gov.br

2007-07-01

In the gas washing systems the gaseous emissions from a facility are forced through an absorbing liquid preventing pollutants to be dispersed into the atmosphere. In the Centro Tecnologico da Marinha em Sao Paulo/Centro Experimental Aramar (CEA), the gas washing are used to control the emissions from the uranium enrichment facilities. Uranium. fluoride, ammonia and hydrogen fluoride are the main contaminants, all heavily toxic. Biological assays, using plants or other living organisms, have been used to assess genotoxic agents in the environment. Among the bioassays using plants, the Trad-MCN has been used extensively, as it allows the evaluation of liquid or gaseous contaminants. The species Tradescantia pallida (Rose) was exposed in a dynamic system to liquid effluents from CEA. A positive control was the exposure to formaldehyde 10% in water, known as a very toxic solution, and the negative control was the exposure to filtered air. The protocol established by Ma (1983) for hybrid clones and validated for the T. pallida by Guimaraes (2003) was used to perform the Trad-MCN assays. Only preparations containing early tetrads were scored. In that context, the present study objectifies to evaluate, by the Trad-MCN bioassay, the genotoxicity of the solution from the gas washing and, also, evaluate the efficiency of that system. The results obtained show that the T. pallida is a sensitive bioindicator for the pollutants tested and can be useful for in vitro environmental monitoring under controlled conditions. (author)

Cacipacore virus as an emergent mosquito-borne Flavivirus

Directory of Open Access Journals (Sweden)

Mario Luis Garcia de Figueiredo

Full Text Available Abstract INTRODUCTION: Cacipacore virus (CPCV, a possible bird-associated flavivirus, has yet to be detected in mosquitoes. Our purpose is examining CPCV in mosquitoes from the Amazon region of Brazil. METHODS: Approximately 3,253 Culicidae (grouped into 264 pools were collected from the Amazon region during 2002-2006 and analyzed using a Flavivirus genus-specific reverse transcription- polymerase chain reaction followed by nested polymerase chain reaction assay and by nucleotide sequencing of amplicons. RESULTS: Nucleotide sequences from five mosquito samples showed high similarity to the those of CPCV originally isolated in the Amazon region. CONCLUSIONS: This is the first report of CPCV-infected mosquitoes which has implications on the arbovirus maintenance in nature and transmission to man.

Manual on theory and practical aspects of bioassay

International Nuclear Information System (INIS)

Nuraini Hambali.

1985-06-01

This manual is set to provide necessary basic guidance on theory and practical aspects of bioassay specially for the newcomer in this field and the man in the laboratory. The first part is a brief information on the entry of radionuclides into the body, the metabolism and the programs of bioassay. All other factors to be considered in assessing internal contamination in man have also been brought up. In the second part, various procedures of radiochemical separations, detection and measurements are abstracted from journals and other revisions. Some methods have been attempted and to be followed where appropriate. (author)

Review of literature on bioassay methods for estimating radionuclides in urine

International Nuclear Information System (INIS)

Prasad, M.V.R.; Surya Narayana, D.S.; Jeevanram, R.K.; Sundarajan, A.R.

1991-01-01

Bioassay methods of certain important radionuclides encountered in the nuclear fuel cycle operations, viz., thorium, uranium, sup(239)Pu, sup(241)Am, sup(90)Sr, sup(99)Tc, sup(106)Ru, sup(137)Cs are reviewed, with special emphasis on urinalysis. Since the preconcentration is an important prerequisite for bioassay, various preconcentration methods are also discussed. Brief account of various instruments both nuclear and analytical used in the bioassay programme is included. The sensitivities of the methods cited in the literature vis-a-vis the derived recording levels indicated in ICRP recommendations are compared. Literature surveyed up to 1990 is tabulated. (author). 96 refs., 1 fig ., 3 tabs

Natural Mosquito-Pathogen Hybrid IgG4 Antibodies in Vector Borne Diseases: A Hypothesis

Directory of Open Access Journals (Sweden)

Berlin L. Londono-Renteria

2016-09-01

Full Text Available Chronic exposure to antigens may favor the production of IgG4 antibodies over other antibody types. Recent studies have shown that up to a 30% of normal human IgG4 is bi-specific and is able to recognize two antigens of different nature. A requirement for this specificity is the presence of both eliciting antigens in the same time and at the same place where the immune response is induced. During transmission of most vector-borne diseases, the pathogen is delivered to the vertebrate host along with the arthropod saliva during blood feeding and previous studies have shown the existence of IgG4 antibodies against mosquito salivary allergens. However, there is very little ongoing research or information available regarding IgG4 bi-specificity with regards to infectious disease, particularly during immune responses to vector-borne diseases such as malaria, filariasis or dengue virus infection. Here, we provide background information and present our hypothesis that IgG4 may not only be a useful tool to measure exposure to infected mosquito bites, but that these bi-specific antibodies may also play an important role in modulation of the immune response against malaria and other vector-borne diseases in endemic settings.

Worldwide bioassay data resources for plutonium/americium internal dosimetry studies

International Nuclear Information System (INIS)

Miller, G.; Bertelli, L.; Little, T.; Guilmette, R.; Riddell, T.; Filipy, R.

2005-01-01

Full text: Biokinetic models are the scientific underpinning of internal dosimetry. These models describe how materials of interest taken into the body by various routes (for example inhalation) are transported through the body, allowing the modelling of bioassay measurements and the estimation of radiation dose. The International Commission on Radiation Protection (ICRP) publishes biokinetic models for use in internal dosimetry. These models represent the consensus judgement of a committee of experts, based on human and animal data. Nonetheless, it is important to validate biokinetic models using directly applicable data, in a scientifically transparent manner, especially for internal dosimetry research purposes (as opposed to radiation protection), as in epidemiology studies. Two major goals would be to determine individual variations of model parameters for the purpose of assessing this source of uncertainty in internal dose calculations, and to determine values of workplace specific parameters (such as particle solubility in lung fluids) for different representative workplaces. Furthermore, data on the observed frequency of intakes under various conditions can be used in the interpretation of bioassay data. All of the above may be couched in the terminology of Bayesian statistical analysis and amount to the determination of the Bayesian prior probability distributions needed in a Bayesian interpretation of bioassay data. The authors have direct knowledge of several significant databases of plutonium/americium bioassay data (including autopsy data). The purpose of this paper is to acquaint the worldwide community with these resources and to invite others who may know of other such databases to participate with us in a publication that would document the content, form, and the procedures for seeking access to these databases. These databases represent a tremendous scientific resource in this field. Examples of databases known to the authors include: the

Avoid Mosquito Bites

Science.gov (United States)

... visiting CDC Travelers’ Health website . Pack a travel health kit . Remember to pack insect repellent and use it as directed to prevent mosquito bites. See a healthcare provider familiar with travel medicine, ideally 4 to 6 weeks ...

A spatial model of mosquito host-seeking behavior.

Directory of Open Access Journals (Sweden)

Bree Cummins

Full Text Available Mosquito host-seeking behavior and heterogeneity in host distribution are important factors in predicting the transmission dynamics of mosquito-borne infections such as dengue fever, malaria, chikungunya, and West Nile virus. We develop and analyze a new mathematical model to describe the effect of spatial heterogeneity on the contact rate between mosquito vectors and hosts. The model includes odor plumes generated by spatially distributed hosts, wind velocity, and mosquito behavior based on both the prevailing wind and the odor plume. On a spatial scale of meters and a time scale of minutes, we compare the effectiveness of different plume-finding and plume-tracking strategies that mosquitoes could use to locate a host. The results show that two different models of chemotaxis are capable of producing comparable results given appropriate parameter choices and that host finding is optimized by a strategy of flying across the wind until the odor plume is intercepted. We also assess the impact of changing the level of host aggregation on mosquito host-finding success near the end of the host-seeking flight. When clusters of hosts are more tightly associated on smaller patches, the odor plume is narrower and the biting rate per host is decreased. For two host groups of unequal number but equal spatial density, the biting rate per host is lower in the group with more individuals, indicative of an attack abatement effect of host aggregation. We discuss how this approach could assist parameter choices in compartmental models that do not explicitly model the spatial arrangement of individuals and how the model could address larger spatial scales and other probability models for mosquito behavior, such as Lévy distributions.

Evaluating the effects of mosquito control adulticides on honey bees

Science.gov (United States)

While mosquito control adulticides can be effective in rapidly reducing mosquito populations during times of high arbovirus transmission, the impacts of these control measures on pollinators has been of recent interest. The purpose of our study was to evaluate mosquito and honey bee mortality using ...

Plasmodium ookinetes coopt mammalian plasminogen to invade the mosquito midgut

DEFF Research Database (Denmark)

Ghosh, Anil K; Coppens, Isabelle; Gårdsvoll, Henrik

2011-01-01

Ookinete invasion of the mosquito midgut is an essential step for the development of the malaria parasite in the mosquito. Invasion involves recognition between a presumed mosquito midgut receptor and an ookinete ligand. Here, we show that enolase lines the ookinete surface. An antienolase antibody...

In situ and laboratory bioassays to evaluate the impact of effluent discharges on receiving aquatic ecosystems

International Nuclear Information System (INIS)

Smolders, R.; Bervoets, L.; Blust, R.

2004-01-01

Effluents are a main source of direct and often continuous input of pollutants into aquatic ecosystems with long-term implications on ecosystem functioning. Therefore, the study of the effects of effluent exposure on organisms, populations or communities within the framework of impact assessment has a high ecological relevance. The aim of this study was to assess the toxicological impact of two effluents, one household wastewater treatment effluent (Effluent 1) and one industrial effluent (Effluent 2), on the receiving aquatic ecosystem using two test species under both in situ and laboratory conditions. Zebra mussel (Dreissena polymorpha) and common carp (Cyprinus carpio) were exposed under laboratory conditions in an online monitoring flow-through system (receiving different concentrations of Effluent 2) and under in situ conditions along the pollution gradient established by these two effluent discharges. Bioassays focussed on growth and condition related endpoints (i.e. condition, growth, lipid budget), since these are key functional processes within organisms and populations. Under laboratory conditions, increasing concentrations of the industrial effluent (Effluent 2) had a negative effect on both zebra mussel and carp energy reserves and condition. Under in situ conditions, the same negative impact of Effluent 2 was observed for zebra mussels, while Effluent 1 had no apparent effect on exposed zebra mussels. Carp growth and condition, on the other hand, were significantly increased at the discharge sites of both effluents when compared to the reference site, probably due to differences in food availability. The results indicate that a combination of in situ and laboratory exposures can illustrate how ecological processes influence bioassay studies. The incorporation of indirect, ecological effects, like changes in food availability, provides considerable benefit in understanding and predicting effects of effluents on selected species under realistic exposure

In situ and laboratory bioassays to evaluate the impact of effluent discharges on receiving aquatic ecosystems

Energy Technology Data Exchange (ETDEWEB)

Smolders, R. [Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp (Belgium)]. E-mail: roel.smolders@ua.ac.be; Bervoets, L. [Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Blust, R. [Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

2004-11-01

Effluents are a main source of direct and often continuous input of pollutants into aquatic ecosystems with long-term implications on ecosystem functioning. Therefore, the study of the effects of effluent exposure on organisms, populations or communities within the framework of impact assessment has a high ecological relevance. The aim of this study was to assess the toxicological impact of two effluents, one household wastewater treatment effluent (Effluent 1) and one industrial effluent (Effluent 2), on the receiving aquatic ecosystem using two test species under both in situ and laboratory conditions. Zebra mussel (Dreissena polymorpha) and common carp (Cyprinus carpio) were exposed under laboratory conditions in an online monitoring flow-through system (receiving different concentrations of Effluent 2) and under in situ conditions along the pollution gradient established by these two effluent discharges. Bioassays focussed on growth and condition related endpoints (i.e. condition, growth, lipid budget), since these are key functional processes within organisms and populations. Under laboratory conditions, increasing concentrations of the industrial effluent (Effluent 2) had a negative effect on both zebra mussel and carp energy reserves and condition. Under in situ conditions, the same negative impact of Effluent 2 was observed for zebra mussels, while Effluent 1 had no apparent effect on exposed zebra mussels. Carp growth and condition, on the other hand, were significantly increased at the discharge sites of both effluents when compared to the reference site, probably due to differences in food availability. The results indicate that a combination of in situ and laboratory exposures can illustrate how ecological processes influence bioassay studies. The incorporation of indirect, ecological effects, like changes in food availability, provides considerable benefit in understanding and predicting effects of effluents on selected species under realistic exposure

A novel bioassay to evaluate Beauveria bassiana strain NI8 and the insect growth regulator, novaluron, against Lygus lineolaris on a non-autoclaved solid artificial diet

Science.gov (United States)

Detailed life-tables studies or more quantitative estimates of the impact of control agents on TPB life history require a bioassay option to study the impact of prolonged exposure for weeks following contact with the control agent. This is difficult with plant tissue that must be routinely replaced ...

Aparelho de sucção tipo aspirador para captura de mosquitos A "vacuum-cleaner" type of suction apparatus for the collection of mosquitoes

Directory of Open Access Journals (Sweden)

Délsio Natal

1984-10-01

Full Text Available É feita a descrição de aparelho portátil de sucção tipo aspirador, para captura de mosquitos Culicidae. São sugeridas adaptações para coletas em diferentes situações. São feitos comentários sobre sua aplicação em pesquisa de mosquitos.A portable suction apparatus, which functions like a vacuum cleaner used for the collection of Culicidae mosquitoes is described. Adaptations for collecting in differents situations are suggested and some comments about its application in mosquitoes surveys are made.

Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria.

Science.gov (United States)

Molina-Cruz, Alvaro; Zilversmit, Martine M; Neafsey, Daniel E; Hartl, Daniel L; Barillas-Mury, Carolina

2016-11-23

Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.

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

Directory of Open Access Journals (Sweden)

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.

[Application of bioassay in quality control of Chinese materia medica-taking Radix Isatidis as an example].

Science.gov (United States)

Yan, Dan; Ren, Yongshen; Luo, Jiaoyang; Li, Hanbing; Feng, Xue; Xiao, Xiaohe

2010-10-01

Bioassay, which construct the characteristics consistents with Chinese medical science, is the core mode and methods for the quality control of Chinese materia medica. Taking the bioassay of Radix Isatidis as an example, the contribution, status and application of bioassay in the quality control of Chinese materia medica were introduced in this article, and two key issue (the selection of reference and measurement methods) in the process of establishing bioassay were also explained. This article expects to provide a reference for the development and improvement of the bioassay of Chinese materia medica in a practical manipulation level.

In vitro bioassays to evaluate complex chemical mixtures in recycled water

Science.gov (United States)

Jia, Ai; Escher, Beate I.; Leusch, Frederic D.L.; Tang, Janet Y.M.; Prochazka, Erik; Dong, Bingfeng; Snyder, Erin M.; Snyder, Shane A.

2016-01-01

With burgeoning population and diminishing availability of freshwater resources, the world continues to expand the use of alternative water resources for drinking, and the quality of these sources has been a great concern for the public as well as public health professionals. In vitro bioassays are increasingly being used to enable rapid, relatively inexpensive toxicity screening that can be used in conjunction with analytical chemistry data to evaluate water quality and the effectiveness of water treatment. In this study, a comprehensive bioassay battery consisting of 36 bioassays covering 18 biological endpoints was applied to screen the bioactivity of waters of varying qualities with parallel treatments. Samples include wastewater effluent, ultraviolet light (UV) and/or ozone advanced oxidation processed (AOP) recycled water, and infiltrated recycled groundwater. Based on assay sensitivity and detection frequency in the samples, several endpoints were highlighted in the battery, including assays for genotoxicity, mutagenicity, estrogenic activity, glucocorticoid activity, aryl hydrocarbon receptor activity, oxidative stress response, and cytotoxicity. Attenuation of bioactivity was found to be dependent on the treatment process and bioassay endpoint. For instance, ozone technology significantly removed oxidative stress activity, while UV based technologies were most efficient for the attenuation of glucocorticoid activity. Chlorination partially attenuated genotoxicity and greatly decreased herbicidal activity, while groundwater infiltration efficiently attenuated most of the evaluated bioactivity with the exception of genotoxicity. In some cases, bioactivity (e.g., mutagenicity, genotoxicity, and arylhydrocarbon receptor) increased following water treatment, indicating that transformation products of water treatment may be a concern. Furthermore, several types of bioassays with the same endpoint were compared in this study, which could help guide the selection

Part 3. Assessment of genotoxicity and oxidative stress after exposure to diesel exhaust from U.S. 2007-compliant diesel engines: report on 1- and 3-month exposures in the ACES bioassay.

Science.gov (United States)

Hallberg, L M; Ward, J B; Hernandez, C; Ameredes, B T; Wickliffe, J K

2012-09-01

Human health hazards due to diesel exhaust (DE*) exposure have been associated with both solvent and combustion components. In the past, diesel engine exhaust components have been linked to increased mutagenicity in cultures of Salmonella typhimurium and mammalian cells (Tokiwa and Ohnishi 1986). In addition, DE has been shown to increase both the incidence of tumors and the induction of 8-hydroxy-deoxyguanosine adducts (8-OHdG) in ICR mice (Ichinose et al. 1997). Furthermore, DE is composed of a complex mixture of polycyclic aromatic hydrocarbons (PAHs) and particulates. One such PAH, 3-nitrobenzanthrone (3-NBA), has been identified in DE and found in urban air. 3-NBA has been observed to induce micronucleus formation in DNA of human hepatoma cells (Lamy et al. 2004). The purpose of the current research, which is part of the Advanced Collaborative Emissions Study (ACES), a multidisciplinary program being carried out by the Health Effects Institute and the Coordinating Research Council, is to determine whether improvements in the engineering of heavy-duty diesel engines reduce the oxidative stress and genotoxic risk associated with exposure to DE components. To this end, the genotoxicity and oxidative stress of DE from an improved diesel engine was evaluated in bioassays of tissues from Wistar Han rats and C57BL/6 mice exposed to DE. Genotoxicity was measured as strand breaks using an alkaline-modified comet assay. To correlate possible DNA damage found by the comet assay, measurement of DNA-adduct formation was evaluated by a competitive enzyme-linked immunosorbent assay (ELISA) to determine the levels of free 8-OHdG found in the serum of the animals exposed to DE. 8-OHdG is a specific modified base indicating an oxidative type of DNA damage to DNA nucleotides. In addition, a thiobarbituric acid reactive substances (TBARS) assay was used to assess oxidative stress and damage in the form of lipid peroxidation in the hippocampus region of the brains of DE

Low-Level Plutonium Bioassay Measurements at the Lawrence Livermore National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Hamilton, T; Brown, T; Hickman, D; Marchetti, A; Williams, R; Kehl, S

2007-06-18

Plutonium-239 ({sup 239}Pu) and plutonium-240 ({sup 240}Pu) are important alpha emitting radionuclides contained in radioactive debris from nuclear weapons testing. {sup 239}Pu and {sup 240}Pu are long-lived radionuclides with half-lives of 24,400 years and 6580 years, respectively. Concerns over human exposure to plutonium stem from knowledge about the persistence of plutonium isotopes in the environment and the high relative effectiveness of alpha-radiation to cause potential harm to cells once incorporated into the human body. In vitro bioassay tests have been developed to assess uptakes of plutonium based on measured urinary excretion patterns and modeled metabolic behaviors of the absorbed radionuclides. Systemic plutonium absorbed by the deep lung or from the gastrointestinal tract after ingestion is either excreted or distributed to other organs, primarily to the liver and skeleton, where it is retained for biological half-times of around 20 and 50 years, respectively. Dose assessment and atoll rehabilitation programs in the Marshall Islands have historically given special consideration to residual concentrations of plutonium in the environment even though the predicted dose from inhalation and/or ingestion of plutonium accounts for less than 5% of the annual effective dose from exposure to fallout contamination. Scientists from the Lawrence Livermore National Laboratory (LLNL) have developed a state-of-the-art bioassay test to assess urinary excretion rates of plutonium from Marshallese populations. This new heavy-isotope measurement system is based on Accelerator Mass Spectrometry (AMS). The AMS system at LLNL far exceeds the standard measurement requirements established under the latest United States Department of Energy (DOE) regulation, 10CFR 835, for occupational monitoring of plutonium, and offers several advantages over classical as well as competing new technologies for low-level detection and measurement of plutonium isotopes. The United States

BROMOETHANE, CHLOROETHANE AND ETHYLENE OXIDE INDUCED UTERINE NEOPLASMS IN B6C3F1 MICE FROM 2-YEAR NTP INHALATION BIOASSAYS: PATHOLOGY AND INCIDENCE DATA REVISITED

Science.gov (United States)

SUMMARY: Chloroethane, bromoethane and etjulene oxide represent a unique set of three chemicals that induce endometrial neoplasms in the uterus of B6C3F1 mice following an inhalation route of exposure. The results of the NTP's chronic bioassays with these three compounds resu...

Use of Nicotiana tabacum L extract for anti-Aedes Aegypti mosquito paint

Science.gov (United States)

Sandralintang, Trisiana Chrysanthi; Fauzantoro, Ahmad; Hermansyah, Heri; Jufri, Mahdi; Gozan, Misri

2018-02-01

This study intended to formulate mosquito repellent paints based tobacco leaf extracts-free pyrethroid substance which is safe for users. The active substance which was added to the paint as a mosquito repellent was an extract of tobacco leaves. The result of Anti-mosquito paint formulation produced was according to the Indonesia National Standard (SNI). The results of anti-Aedes Aegypti mosquito paint effectiveness test showed that 5% concentration of tobacco extract could kill half of the mosquito population (LC50) for 2 hours, the concentration of tobacco extract between 3-5% killed half the mosquito population (LC50) during 4 hours, while 1-3% and 0-1% concentration of tobacco extract killed half the mosquito population (LC50) for 6 and 24 hours, respectively.

Biocontrol of larval mosquitoes by Acilius sulcatus (Coleoptera: Dytiscidae

Directory of Open Access Journals (Sweden)

Banerjee Siddhartha S

2008-10-01

Full Text Available Abstract Background Problems associated with resistant mosquitoes and the effects on non-target species by chemicals, evoke a reason to find alternative methods to control mosquitoes, like the use of natural predators. In this regard, aquatic coleopterans have been explored less compared to other insect predators. In the present study, an evaluation of the role of the larvae of Acilius sulcatus Linnaeus 1758 (Coleoptera: Dytiscidae as predator of mosquito immatures was made in the laboratory. Its efficacy under field condition was also determined to emphasize its potential as bio-control agent of mosquitoes. Methods In the laboratory, the predation potential of the larvae of A. sulcatus was assessed using the larvae of Culex quinquefasciatus Say 1823 (Diptera: Culicidae as prey at varying predator and prey densities and available space. Under field conditions, the effectiveness of the larvae of A. sulcatus was evaluated through augmentative release in ten cemented tanks hosting immatures of different mosquito species at varying density. The dip density changes in the mosquito immatures were used as indicator for the effectiveness of A. sulcatus larvae. Results A single larva of A. sulcatus consumed on an average 34 IV instar larvae of Cx. quinquefasciatus in a 24 h period. It was observed that feeding rate of A. sulcatus did not differ between the light-on (6 a.m. – 6 p.m., and dark (6 p.m. – 6 a.m. phases, but decreased with the volume of water i.e., space availability. The prey consumption of the larvae of A. sulcatus differed significantly (P A. sulcatus larvae, while with the withdrawal, a significant increase (p A. sulcatus in regulating mosquito immatures. In the control tanks, mean larval density did not differ (p > 0.05 throughout the study period. Conclusion the larvae of the dytiscid beetle A. sulcatus proved to be an efficient predator of mosquito immatures and may be useful in biocontrol of medically important mosquitoes.

Dengue virus serotype 2 infection alters midgut and carcass gene expression in the Asian tiger mosquito, Aedes albopictus.

Directory of Open Access Journals (Sweden)

Hitoshi Tsujimoto

Full Text Available The Asian tiger mosquito, Aedes albopictus is currently an important vector for dengue, chikungunya and Zika virus, and its role in transmission of arthropod-borne viruses (arboviruses may increase in the future due to its ability to colonize temperate regions. In contrast to Aedes aegypti, the dominant vector of dengue, chikungunya and Zika virus, genetic responses of Ae. albopictus upon infection with an arbovirus are not well characterized. Here we present a study of the changes in transcript expression in Ae. albopictus exposed to dengue virus serotype 2 via feeding on an artificial bloodmeal.We isolated midguts and midgut-free carcasses of Ae. albopictus fed on bloodmeals containing dengue virus as well as controls fed on virus-free control meals at day 1 and day 5 post-feeding. We confirmed infection of midguts from mosquitoes sampled on day 5 post-feeding via RT-PCR. RNAseq analysis revealed dynamic modulation of the expression of several putative immunity and dengue virus-responsive genes, some of whose expression was verified by qRT-PCR. For example, a serine protease gene was up-regulated in the midgut at 1 day post infection, which may potentially enhance mosquito susceptibility to dengue infection, while 14 leucine-rich repeat genes, previously shown to be involved in mosquito antiviral defenses, were down-regulated in the carcass at 5 days post infection. The number of significantly modulated genes decreased over time in midguts and increased in carcasses.Dengue virus exposure results in the modulation of genes in a time- and site-specific manner. Previous literature on the interaction between mosquitoes and mosquito-borne pathogens suggests that most of the changes that occurred in Ae. albopictus exposed to DENV would favor virus infection. Many genes identified in this study warrant further characterization to understand their role in viral manipulation of and antiviral response of Ae. albopictus.

[Mosquito complex (Diptera, Culicidae) in a West Nile fever focus in the Volgograd Region. II. Host-feeding patterns of mosquitoes in different habitats].

Science.gov (United States)

Platonova, O V; Fedorova, M V; Lopatina, Iu V; Bezzhonova, O V; Bulgakova, T V; Platonov, A E

2007-01-01

Host preference of the mosquitoes collected in the urban and rural habitats of Volgograd and its suburbs was studied by the precipitation reaction test. Human and avian blood was detected in Cx. pipiens, Cx. modestus, Ae. vexans, Ae. behningi, Ae. caspius, Ae. sticticus, and females of the Anopheles maculipennis. The proportion of the mosquitoes fed on birds was similar in the urban and rural biotopes whereas that of the mosquitoes feeding on humans was significantly higher in Volgograd than in its environs. The increase in the number of human blood-fed mosquitoes in the city resulted mainly from the females collected in its multi-storied buildings.

EPA-Registered Repellents for Mosquitoes Transmitting Emerging Viral Disease.

Science.gov (United States)

Patel, Radha V; Shaeer, Kristy M; Patel, Pooja; Garmaza, Aleksey; Wiangkham, Kornwalee; Franks, Rachel B; Pane, Olivia; Carris, Nicholas W

2016-12-01

In many parts of the United States, mosquitoes were previously nuisance pests. However, they now represent a potential threat in the spread of viral diseases. The Aedes aegypti, Aedes albopictus, and Culex species mosquitoes are endemic to the United States and together may transmit a variety of viral diseases of growing concern, including West Nile virus, chikungunya, dengue fever, and Zika virus. The Centers for Disease Control and Prevention and the Environmental Protection Agency (EPA) recommend N,N-diethyl-meta-toluamide (DEET) as a first-line mosquito repellent, but for patients refusing to use DEET or other conventional repellents, guidance is limited to any EPA-registered product. Therefore, we conducted a systematic review of the literature to identify which EPA-registered personal mosquito repellent provides the best protection from A. aegypti, A. albopictus, and Culex spp. mosquitoes. We abstracted data from 62 published reports of EPA-registered mosquito repellents. The conventional repellent picaridin has the strongest data to support its use as a second-line agent, while IR3535 and oil of lemon eucalyptus are reasonably effective natural products. Citronella, catnip, and 2-undecanone offer limited protection or have limited data. These results can be used by pharmacists and other health care professionals to advise patients on the selection of an EPA-registered mosquito repellent. Regardless of the repellent chosen, it is vital for patients to follow all instructions/precautions in the product labeling to ensure safe and effective use. © 2016 Pharmacotherapy Publications, Inc.

The Plasmodium bottleneck: malaria parasite losses in the mosquito vector

Science.gov (United States)

Smith, Ryan C; Vega-Rodríguez, Joel; Jacobs-Lorena, Marcelo

2014-01-01

Nearly one million people are killed every year by the malaria parasite Plasmodium. Although the disease-causing forms of the parasite exist only in the human blood, mosquitoes of the genus Anopheles are the obligate vector for transmission. Here, we review the parasite life cycle in the vector and highlight the human and mosquito contributions that limit malaria parasite development in the mosquito host. We address parasite killing in its mosquito host and bottlenecks in parasite numbers that might guide intervention strategies to prevent transmission. PMID:25185005

Habitat productivity and pyrethroid susceptibility status of Aedes aegypti mosquitoes in Dar es Salaam, Tanzania.

Science.gov (United States)

Mathias, Leah; Baraka, Vito; Philbert, Anitha; Innocent, Ester; Francis, Filbert; Nkwengulila, Gamba; Kweka, Eliningaya J

2017-06-09

Aedes aegypti (Diptera: Culicidae) is the main vector of the dengue virus globally. Dengue vector control is mainly based on reducing the vector population through interventions, which target potential breeding sites. However, in Tanzania, little is known about this vector's habitat productivity and insecticide susceptibility status to support evidence-based implementation of control measures. The present study aimed at assessing the productivity and susceptibility status of A. aegypti mosquitoes to pyrethroid-based insecticides in Dar es Salaam, Tanzania. An entomological assessment was conducted between January and July 2015 in six randomly selected wards in Dar es Salaam, Tanzania. Habitat productivity was determined by the number of female adult A. aegypti mosquitoes emerged per square metre. The susceptibility status of adult A. aegypti females after exposure to 0.05% deltamethrin, 0.75% permethrin and 0.05% lambda-cyhalothrin was evaluated using the standard WHO protocols. Mortality rates were recorded after 24 h exposure and the knockdown effect was recorded at the time points of 10, 15, 20, 30, 40, 50 and 60 min to calculate the median knockdown times (KDT 50 and KDT 95 ). The results suggest that disposed tyres had the highest productivity, while water storage tanks had the lowest productivity among the breeding habitats Of A. aegypti mosquitoes. All sites demonstrated reduced susceptibility to deltamethrin (0.05%) within 24 h post exposure, with mortalities ranging from 86.3 ± 1.9 (mean ± SD) to 96.8 ± 0.9 (mean ± SD). The lowest and highest susceptibilities were recorded in Mikocheni and Sinza wards, respectively. Similarly, all sites demonstrated reduced susceptibility permethrin (0.75%) ranging from 83.1 ± 2.1% (mean ± SD) to 96.2 ± 0.9% (mean ± SD), in Kipawa and Sinza, respectively. Relatively low mortality rates were observed in relation to lambda-cyhalothrin (0.05%) at all sites, ranging from 83.1 ± 0

Standardization of a fluconazole bioassay and correlation of results with those obtained by high-pressure liquid chromatography.

Science.gov (United States)

Rex, J H; Hanson, L H; Amantea, M A; Stevens, D A; Bennett, J E

1991-01-01

An improved bioassay for fluconazole was developed. This assay is sensitive in the clinically relevant range (2 to 40 micrograms/ml) and analyzes plasma, serum, and cerebrospinal fluid specimens; bioassay results correlate with results obtained by high-pressure liquid chromatography (HPLC). Bioassay and HPLC analyses of spiked plasma, serum, and cerebrospinal fluid samples (run as unknowns) gave good agreement with expected values. Analysis of specimens from patients gave equivalent results by both HPLC and bioassay. HPLC had a lower within-run coefficient of variation (less than 2.5% for HPLC versus less than 11% for bioassay) and a lower between-run coefficient of variation (less than 5% versus less than 12% for bioassay) and was more sensitive (lower limit of detection, 0.1 micrograms/ml [versus 2 micrograms/ml for bioassay]). The bioassay is, however, sufficiently accurate and sensitive for clinical specimens, and its relative simplicity, low sample volume requirement, and low equipment cost should make it the technique of choice for analysis of routine clinical specimens. PMID:1854166

Mosquitoes rely on their gut microbiota for development

Science.gov (United States)

Coon, Kerri L.; Vogel, Kevin J.; Brown, Mark R.; Strand, Michael R.

2014-01-01

Field studies indicate adult mosquitoes (Culicidae) host low diversity communities of bacteria that vary greatly among individuals and species. In contrast, it remains unclear how adult mosquitoes acquire their microbiome, what influences community structure, and whether the microbiome is important for survival. Here we used pyrosequencing of 16S rRNA to characterize the bacterial communities of three mosquito species reared under identical conditions. Two of these species, Aedes aegypti and Anopheles gambiae, are anautogenous and must blood feed to produce eggs, while one, Georgecraigius atropalpus, is autogenous and produces eggs without blood feeding. Each mosquito species contained a low diversity community comprised primarily of aerobic bacteria acquired primarily from the aquatic habitat in which larvae developed. Our results suggested the communities in Ae. aegypti and An. gambiae larvae share more similarities with one another than with Ge. atropalpus. Studies with Ae. aegypti also strongly suggested that adults transstadially acquired several members of the larval bacterial community, but only four genera of bacteria present in blood fed females were detected on eggs. Functional assays showed that axenic larvae of each species failed to develop beyond the first instar. Experiments with Ae. aegypti indicated several members of the microbial community and Escherichia coli successfully colonized axenic larvae and rescued development. Overall, our results provide new insights about the acquisition and structure of bacterial communities in mosquitoes. They also indicate three mosquito species spanning the breadth of the Culicidae depend on their gut microbiome for development. PMID:24766707

Effects of the mosquito larvicide GB-1111 on red-winged blackbird embryos

International Nuclear Information System (INIS)

Albers, P.H.; Hoffman, D.J.; Buscemi, D.M.; Melancon, M.J.

2003-01-01

Mosquito larvicide GB-1111 poses a minimal risk to red-winged blackbird embryos when applied according to product label guidance. - Golden Bear Oil (GB-1111; legal trade name for GB-1313) is a petroleum distillate that is used in the United States and other countries as a larvicide for mosquito suppression. As part of a multi-species evaluation of the potential effects of GB-1111 on birds, red-winged blackbird eggs were collected, artificially incubated, and treated with one of five amounts of GB-1111 varying from 0 to 10 times the expected exposure from a spray application of the maximum recommended amount (X=47 l/ha, 5 gal/ac). The application of 10 X caused a significant reduction in hatching success. A dose-related reduction of hepatic microsomal monooxygenase activity (EROD) was detected. Among body weights, skeletal measurements, and age at death, only crownrump length was different among experimental groups. Overall, the potential hazard to embryos of a representative wetland passerine appears minimal until the application rate exceeds 3 X

Mosquito transmission of the rodent malaria parasite Plasmodium chabaudi

Directory of Open Access Journals (Sweden)

Spence Philip J

2012-12-01

Full Text Available Abstract Background Serial blood passage of Plasmodium increases virulence, whilst mosquito transmission inherently regulates parasite virulence within the mammalian host. It is, therefore, imperative that all aspects of experimental malaria research are studied in the context of the complete Plasmodium life cycle. Methods Plasmodium chabaudi chabaudi displays many characteristics associated with human Plasmodium infection of natural mosquito vectors and the mammalian host, and thus provides a unique opportunity to study the pathogenesis of malaria in a single infection setting. An optimized protocol that permits efficient and reproducible vector transmission of P. c. chabaudi via Anopheles stephensi was developed. Results and conclusions This protocol was utilized for mosquito transmission of genetically distinct P. c. chabaudi isolates, highlighting differential parasite virulence within the mosquito vector and the spectrum of host susceptibility to infection initiated via the natural route, mosquito bite. An apposite experimental system in which to delineate the pathogenesis of malaria is described in detail.

Rift Valley fever potential mosquito vectors and their infection status ...

African Journals Online (AJOL)

Background: Rift Valley fever (RVF) is a mosquito-borne viral zoonotic disease. Rift Valley fever virus (RVFV) has been isolated from more than 40 species of mosquitoes from eight genera. This study was conducted to determine the abundance of potential mosquito vectors and their RVFV infection status in Ngorongoro ...

Factors influencing stakeholders attitudes toward genetically modified aedes mosquito.

Science.gov (United States)

Amin, Latifah; Hashim, Hasrizul

2015-06-01

Dengue fever is a debilitating and infectious disease that could be life-threatening. It is caused by the dengue virus which affects millions of people in the tropical area. Currently, there is no cure for the disease as there is no vaccine available. Thus, prevention of the vector population using conventional methods is by far the main strategy but has been found ineffective. A genetically modified (GM) mosquito is among the favoured alternatives to curb dengue fever in Malaysia. Past studies have shown that development and diffusion of gene technology products depends heavily upon public acceptance. The purpose of this study is to identify the relevant factors influencing stakeholders' attitudes toward the GM Aedes mosquito and to analyse the relationships between all the factors using the structural equation model. A survey was carried out on 509 respondents from various stakeholder groups in the Klang Valley region of Malaysia. Results of the survey have confirmed that public perception towards complex issues such as gene technology should be seen as a multi-faceted process. The perceived benefit-perceived risk balance is very important in determining the most predominant predictor of attitudes toward a GM mosquito. In this study the stakeholders perceived the benefit of the GM mosquito as outweighing its risk, translating perceived benefit as the most important direct predictor of attitudes toward the GM mosquito. Trust in key players has a direct influence on attitudes toward the GM mosquito while moral concern exhibited an indirect influence through perceived benefits. Other factors such as attitudes toward technology and nature were also indirect predictors of attitudes toward the GM mosquito while religiosity and engagement did not exhibited any significant roles. The research findings serve as a useful database to understand public acceptance and the social construct of public attitudes towards the GM mosquito to combat dengue.

BioAssay templates for the semantic web

Directory of Open Access Journals (Sweden)

Alex M. Clark

2016-05-01

Full Text Available Annotation of bioassay protocols using semantic web vocabulary is a way to make experiment descriptions machine-readable. Protocols are communicated using concise scientific English, which precludes most kinds of analysis by software algorithms. Given the availability of a sufficiently expressive ontology, some or all of the pertinent information can be captured by asserting a series of facts, expressed as semantic web triples (subject, predicate, object. With appropriate annotation, assays can be searched, clustered, tagged and evaluated in a multitude of ways, analogous to other segments of drug discovery informatics. The BioAssay Ontology (BAO has been previously designed for this express purpose, and provides a layered hierarchy of meaningful terms which can be linked to. Currently the biggest challenge is the issue of content creation: scientists cannot be expected to use the BAO effectively without having access to software tools that make it straightforward to use the vocabulary in a canonical way. We have sought to remove this barrier by: (1 defining a BioAssay Template (BAT data model; (2 creating a software tool for experts to create or modify templates to suit their needs; and (3 designing a common assay template (CAT to leverage the most value from the BAO terms. The CAT was carefully assembled by biologists in order to find a balance between the maximum amount of information captured vs. low degrees of freedom in order to keep the user experience as simple as possible. The data format that we use for describing templates and corresponding annotations is the native format of the semantic web (RDF triples, and we demonstrate some of the ways that generated content can be meaningfully queried using the SPARQL language. We have made all of these materials available as open source (http://github.com/cdd/bioassay-template, in order to encourage community input and use within diverse projects, including but not limited to our own

Application of Bioassays for the Ecotoxicity Assessment of Contaminated Soils

Science.gov (United States)

Fernández, María D.; Babín, Mar; Tarazona, José V.

The use of bioassays for soil characterization is receiving significant attention as a complementary tool to chemical analysis. Bioassays consist of direct toxicity assays of environmental samples that are transferred to the laboratory and analyzed for toxicity against selected organisms. Such soil samples contain the combination of the different pollutants present in situ and enable factors such as the bioavailability of contaminants or the interactions (synergic and antagonic) between them to be simultaneously studied.

7 Vascular Hydrophytes for Bioassay.cdr

African Journals Online (AJOL)

Administrator

4 water (see Table 1). tool. The greater extension growth of macrophyte shoots in water from downstream of STWs (Fig. 1) was supported by both chemical analysis, which showed increased phosphate concentration (Table 1), and by conventional Selenastrum bioassay in which higher cell concentrations were achieved.

The Plasmodium bottleneck: malaria parasite losses in the mosquito vector

Directory of Open Access Journals (Sweden)

Ryan C Smith

2014-08-01

Full Text Available Nearly one million people are killed every year by the malaria parasite Plasmodium. Although the disease-causing forms of the parasite exist only in the human blood, mosquitoes of the genus Anopheles are the obligate vector for transmission. Here, we review the parasite life cycle in the vector and highlight the human and mosquito contributions that limit malaria parasite development in the mosquito host. We address parasite killing in its mosquito host and bottlenecks in parasite numbers that might guide intervention strategies to prevent transmission.

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

Directory of Open Access Journals (Sweden)

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.

Radiation exposure records management

International Nuclear Information System (INIS)

Boiter, H.P.

1975-12-01

Management of individual radiation exposure records begins at employment with the accumulation of data pertinent to the individual and any previous occupational radiation exposure. Appropriate radiation monitorinng badges or devices are issued and accountability established. A computer master file is initiated to include the individual's name, payroll number, social security number, birth date, assigned department, and location. From this base, a radiation exposure history is accumulated to include external ionizing radiation exposure to skin and whole body, contributing neutron exposure, contributing tritium exposure, and extremity exposure. It is used also to schedule bioassay sampling and in-vivo counts and to provide other pertinent information. The file is used as a basis for providing periodic reports to management and monthly exposure summaries to departmental line supervision to assist in planning work so that individual annual exposures are kept as low as practical. Radiation exposure records management also includes documentation of radiation surveys performed by the health physicist to establish working rates and the individual estimating and recording his estimated exposure on a day-to-day basis. Exposure information is also available to contribute to Energy Research and Development Administration statistics and to the National Transuranium Registry

Midgut of the non-hematophagous mosquito Toxorhynchites theobaldi (Diptera, Culicidae).

Science.gov (United States)

Godoy, Raquel S M; Fernandes, Kenner M; Martins, Gustavo F

2015-10-30

In most mosquito species, the females require a blood-feeding for complete egg development. However, in Toxorhynchites mosquitoes, the eggs develop without blood-feeding, and both females and males exclusively feed on sugary diets. The midgut is a well-understood organ in blood-feeding mosquitoes, but little is known about it in non-blood-feeding ones. In the present study, the detailed morphology of the midgut of Toxorhynchites theobaldi were investigated using histochemical and ultrastructural methods. The midgut of female and male T. theobaldi adults consists of a long, slender anterior midgut (AMG), and a short, dilated posterior midgut (PMG). The AMG is subdivided into AMG1 (short, with folds) and AMG2 (long, without folds). Nerve branches and enteroendocrine cells are present in AMG and PMG, respectively. Compared with the PMG of blood-feeding female mosquitoes, the PMG of T. theobaldi is smaller; however, in both mosquitoes, PMG seems be the main region of food digestion and absorption, and protein secretion. The epithelial folds present in the AMG of T. theobaldi have not been reported in other mosquitoes; however, the midgut muscle organization and endocrine control of the digestion process are conserved in both T. theobaldi and blood-feeding mosquitoes.

Crowdsourcing for large-scale mosquito (Diptera: Culicidae) sampling

Science.gov (United States)

Sampling a cosmopolitan mosquito (Diptera: Culicidae) species throughout its range is logistically challenging and extremely resource intensive. Mosquito control programmes and regional networks operate at the local level and often conduct sampling activities across much of North America. A method f...

Bioassay-based risk assessment of hazardous waste

Energy Technology Data Exchange (ETDEWEB)

Donnelly, K.C.; Brown, K.W.; He, L.Y. [Texas A and M Univ., College Station, TX (United States)

1994-12-31

Microbial bioassays have been used to assess the genotoxic hazard at more than 30 different hazardous waste sites. Environmental samples were extracted with dichloromethane and methanol, and the resulting residue tested using GC/MS analysis as well as the Salmonella Microsomal and E. coli Prophage Induction assays. At a munitions wastewater contaminated site, there was no correlation between mutagenicity in bacteria, and the risk as estimated from chemical analysis data of trinitrotoluene. Samples 202 and 204 from a coal gasification site contained 72 mg/kg and 9 mg/kg benzo(a)pyrene, whereas the mutagenic responses of these samples were 231 net revertants/mg and 902 revertants/mg, respectively. The data suggest that microbial bioassays provide a valuable tool for monitoring the interactions of the components of a complex mixture.

Terrestrial vegetation and aquatic chemistry influence larval mosquito abundance in catch basins, Chicago, USA

Directory of Open Access Journals (Sweden)

Gardner Allison M

2013-01-01

Full Text Available Abstract Background An important determinant of mosquito-borne pathogen transmission is the spatial distribution of vectors. The primary vectors of West Nile virus (WNV in Illinois are Culex pipiens Linnaeus (Diptera: Culicidae and Culex restuans Theobald. In urban environments, these mosquitoes commonly oviposit in roadside storm water catch basins. However, use of this habitat is inconsistent, with abundance of larvae varying significantly across catch basins at a fine spatial scale. Methods We tested the hypothesis that attributes of the biotic and abiotic environment contribute to spatial and temporal variation in production of mosquito vectors, characterizing the relationship between terrestrial vegetation and aquatic chemistry and Culex abundance in Chicago, Illinois. Larvae were sampled from 60 catch basins from June 14 to October 3, 2009. Density of shrubs and 14 tree genera surrounding the basins were quantified, as well as aquatic chemistry content of each basin. Results We demonstrate that the spatial pattern of Culex abundance in catch basins is strongly influenced by environmental characteristics, resulting in significant variation across the urban landscape. Using regression and machine learning techniques, we described landscape features and microhabitat characteristics of four Chicago neighborhoods and examined the implications of these measures for larval abundance in adjacent catch basins. The important positive predictors of high larval abundance were aquatic ammonia, nitrates, and area of shrubs of height Culex during the fruit-bearing periods and early senescent periods in August and September. Conclusions This study identifies environmental predictors of mosquito production in urban environments. Because an abundance of adult Culex is integral to efficient WNV transmission and mosquitoes are found in especially high densities near larval habitats, identifying aquatic sites for Culex and landscape features that promote

Disrupting Mosquito Reproduction and Parasite Development for Malaria Control.

Directory of Open Access Journals (Sweden)

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.

Potential impacts of climate change on the ecology of dengue and its mosquito vector the Asian tiger mosquito (Aedes albopictus)

International Nuclear Information System (INIS)

Erickson, R A; Presley, S M; Cox, S B; Hayhoe, K; Allen, L J S; Long, K R

2012-01-01

Shifts in temperature and precipitation patterns caused by global climate change may have profound impacts on the ecology of certain infectious diseases. We examine the potential impacts of climate change on the transmission and maintenance dynamics of dengue, a resurging mosquito-vectored infectious disease. In particular, we project changes in dengue season length for three cities: Atlanta, GA; Chicago, IL and Lubbock, TX. These cities are located on the edges of the range of the Asian tiger mosquito within the United States of America and were chosen as test cases. We use a disease model that explicitly incorporates mosquito population dynamics and high-resolution climate projections. Based on projected changes under the Special Report on Emissions Scenarios (SRES) A1fi (higher) and B1 (lower) emission scenarios as simulated by four global climate models, we found that the projected warming shortened mosquito lifespan, which in turn decreased the potential dengue season. These results illustrate the difficulty in predicting how climate change may alter complex systems. (letter)

Potential impacts of climate change on the ecology of dengue and its mosquito vector the Asian tiger mosquito (Aedes albopictus)

Science.gov (United States)

Erickson, R. A.; Hayhoe, K.; Presley, S. M.; Allen, L. J. S.; Long, K. R.; Cox, S. B.

2012-09-01

Shifts in temperature and precipitation patterns caused by global climate change may have profound impacts on the ecology of certain infectious diseases. We examine the potential impacts of climate change on the transmission and maintenance dynamics of dengue, a resurging mosquito-vectored infectious disease. In particular, we project changes in dengue season length for three cities: Atlanta, GA; Chicago, IL and Lubbock, TX. These cities are located on the edges of the range of the Asian tiger mosquito within the United States of America and were chosen as test cases. We use a disease model that explicitly incorporates mosquito population dynamics and high-resolution climate projections. Based on projected changes under the Special Report on Emissions Scenarios (SRES) A1fi (higher) and B1 (lower) emission scenarios as simulated by four global climate models, we found that the projected warming shortened mosquito lifespan, which in turn decreased the potential dengue season. These results illustrate the difficulty in predicting how climate change may alter complex systems.

Comparison of solid-phase bioassays and ecoscores to evaluate the toxicity of contaminated soils.

OpenAIRE

Lors , Christine; Ponge , Jean-François; Martínez Aldaya , Maite; Damidot , Denis

2010-01-01

International audience; Five bioassays (inhibition of lettuce germination and growth, earthworm mortality, inhibition of springtail population growth, avoidance by springtails) were compared, using four coke factory soils contaminated by PAHs and trace elements, before and after biotreatment. For each bioassay, several endpoints were combined in an 'ecoscore', a measure of test sensitivity. Ecoscores pooled over all tested bioassays revealed that most organisms were highly sensitive to the co...

Mosquito (Diptera: Culicidae) Habitat Surveillance by Android Mobile Devices in Guangzhou, China.

Science.gov (United States)

Wu, Tai-Ping; Tian, Jun-Hua; Xue, Rui-De; Fang, Yi-Liang; Zheng, Ai-Hua

2016-12-17

In 2014, Guangzhou City, South China, suffered from its worst outbreak of dengue fever in decades. Larval mosquito habitat surveillance was carried out by using android mobile devices in four study sites in May 2015. The habitats with larval mosquitoes were recorded as photo waypoints in OruxMaps or in videos. The total number of potential mosquito habitats was 342, of which 166 (49%) were found to have mosquito larvae or pupae. Small containers were the most abundant potential habitats, accounting for 26% of the total number. More mosquito larvae and pupae, were found in small containers than in other objects holding water, for example, potted or hydroponic plants ( p Android mobile devices are a convenient and useful tool for surveillance of mosquito habitats, and the enhancement of source reduction may benefit the prevention and control of dengue vector mosquitoes.

Interpretation of thorium bioassay data

International Nuclear Information System (INIS)

Juliao, L.M.Q.C.; Azeredo, A.M.G.F.; Santos, M.S.; Melo, D.R.; Dantas, B.M.; Lipsztein, J.L.

1994-01-01

A comparison have been made between bioassay data of thorium-exposed workers from two different facilities. The first of these facilities is a monazite sand extraction plant. Isotopic equilibrium between 232 Th and 238 Th was not observed in excreta samples of these workers. The second facility is a gas mantle factory. An isotopic equilibrium between 232 Th and 228 Th was observed in extra samples. Whole body counter measurements have indicated a very low intake of thorium through inhalation. As the concentration of thorium in feces was very high it was concluded that the main pathway of entrance of the nuclide was ingestion, mainly via contamination through dirty hands. The comparison between the bioassay results of workers from the two facilities shows that the lack of Th isotopic equilibrium observed in the excretion from the workers at the monazite sand plant possibly occurred due to an additional Th intake by ingestion of contaminated fresh food. This is presumably because 228 Ra is more efficiently taken up from the soil by plants, in comparison to 228 Th or 232 Th, and subsequently, 228 Th grows in from its immediate parent, 228 Ra. (author) 5 refs.; 3 tabs

Micro-organism distribution sampling for bioassays

Science.gov (United States)

Nelson, B. A.

1975-01-01

Purpose of sampling distribution is to characterize sample-to-sample variation so statistical tests may be applied, to estimate error due to sampling (confidence limits) and to evaluate observed differences between samples. Distribution could be used for bioassays taken in hospitals, breweries, food-processing plants, and pharmaceutical plants.

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

Science.gov (United States)

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Initial sample extract stock concentration affects in vitro bioassay-based toxicological risk characterization

NARCIS (Netherlands)

Montano, M.; Loffmann, L.; Murk, A.J.; Gutleb, A.C.

2014-01-01

Purpose Bioassays have become an alternative for sediment risk profiling, including potential compliance with sediment quality criteria (SQC). In vitro functional bioassays have evolved through standardization and validation towards a confident toxicological hazard estimate of sediments. Sample

Ecological effects on arbovirus-mosquito cycles of transmission.

Science.gov (United States)

Tabachnick, Walter J

2016-12-01

Mosquitoes transmit many viruses to a variety of hosts. Cycles of mosquito borne arbovirus transmission are the result of complex interactions between the mosquito, the arbovirus and the host that are influenced by genetic variations in a variety of traits in each that are all influenced by many environmental factors. R 0 , the basic reproduction number or mean number of individuals infected from a single infected individual, is a measure of mosquito borne arbovirus transmission. Understanding the causes for the distribution of R 0 in any transmission cycle is a daunting challenge due to the lack of information on the genetic and environmental variances that influence R 0 . Information about the major factors influencing R 0 for specific transmission cycles is essential to develop efficient and effective strategies to reduce transmission in different cycles and locations. Copyright © 2016 Elsevier B.V. All rights reserved.

Biological Control Strategies for Mosquito Vectors of Arboviruses.

Science.gov (United States)

Huang, Yan-Jang S; Higgs, Stephen; Vanlandingham, Dana L

2017-02-10

Historically, biological control utilizes predatory species and pathogenic microorganisms to reduce the population of mosquitoes as disease vectors. This is particularly important for the control of mosquito-borne arboviruses, which normally do not have specific antiviral therapies available. Although development of resistance is likely, the advantages of biological control are that the resources used are typically biodegradable and ecologically friendly. Over the past decade, the advancement of molecular biology has enabled optimization by the manipulation of genetic materials associated with biological control agents. Two significant advancements are the discovery of cytoplasmic incompatibility induced by Wolbachia bacteria, which has enhanced replacement programs, and the introduction of dominant lethal genes into local mosquito populations through the release of genetically modified mosquitoes. As various arboviruses continue to be significant public health threats, biological control strategies have evolved to be more diverse and become critical tools to reduce the disease burden of arboviruses.

Primary lymph node responses to mosquito bites.

Science.gov (United States)

Mellink, J J; Vos, B J

1977-03-29

Post-auricular lymph node responses and changes in fresh weight of thymus and spleen of hamsters and mice at 4 and 8 days after primary exposure of both ears to 20 bites by the mosquito Aedes aegypti were studied quantitatively. In both hosts lymph node changes characteristic of the development of cell-mediated immune responses and those which are believed to lead to antibody production occurred, with the emphasis on the latter phenomena. No reactions of thymus and spleen were observed. The responses recorded are considered to be immunologically specific. In hamsters, but not in mice, the responses related to humoral sensitization coincided in time to a large extent with those of the cell-mediated immune processes. The stronger humoral responses in mice were probably in the first place the result of the relatively higher dosages applied.

Periodic dynamic systems for infected hosts and mosquitoes Sistemas dinâmicos periódicos para hospedeiros e mosquitos infectados

Directory of Open Access Journals (Sweden)

W. M. Oliva

1996-06-01

Full Text Available A mathematical model for the purpose of analysing the dynamic of the populations of infected hosts anf infected mosquitoes when the populations of mosquitoes are periodic in time is here presented. By the computation of a parameter lambda (the spectral radius of a certain monodromy matrix one can state that either the infection peters out naturally (lambda 1 the infection becomes endemic. The model generalizes previous models for malaria by considering the case of periodic coefficients; it is also a variation of that for gonorrhea. The main motivation for the consideration of this present model was the recent studies on mosquitoes at an experimental rice irrigation system, in the South-Eastern region of Brazil.Desenvolveu-se um modelo matemático para analisar a dinâmica das populações de indivíduos e mosquitos infectados quando as populações de mosquitos são periódicas no tempo. Pela determinação de um parâmetro lambda (o raio espectral de uma matriz de monodromia pode-se estabelecer que a infecção termina naturalmente (lambda 1 que a infecção torna-se endêmica. O modelo generaliza, para o caso de coeficientes periódicos, modelos anteriores para malária; como também é uma variação de modelo para a gonorréia. A principal motivação para a consideração do modelo proposto foram os recentes estudos sobre mosquitos numa estação experimental de arroz irrigado, na região Sudeste do Brasil.

Malpighian Tubules as Novel Targets for Mosquito Control

Directory of Open Access Journals (Sweden)

Peter M. Piermarini

2017-01-01

Full Text Available The Malpighian tubules and hindgut are the renal excretory tissues of mosquitoes; they are essential to maintaining hemolymph water and solute homeostasis. Moreover, they make important contributions to detoxifying metabolic wastes and xenobiotics in the hemolymph. We have focused on elucidating the molecular mechanisms of Malpighian tubule function in adult female mosquitoes and developing chemical tools as prototypes for next-generation mosquitocides that would act via a novel mechanism of action (i.e., renal failure. To date, we have targeted inward rectifier potassium (Kir channels expressed in the Malpighian tubules of the yellow fever mosquito Aedes aegypti and malaria mosquito Anopheles gambiae. Inhibition of these channels with small molecules inhibits transepithelial K+ and fluid secretion in Malpighian tubules, leading to a disruption of hemolymph K+ and fluid homeostasis in adult female mosquitoes. In addition, we have used next-generation sequencing to characterize the transcriptome of Malpighian tubules in the Asian tiger mosquito Aedes albopictus, before and after blood meals, to reveal new molecular targets for potentially disrupting Malpighian tubule function. Within 24 h after a blood meal, the Malpighian tubules enhance the mRNA expression of genes encoding mechanisms involved with the detoxification of metabolic wastes produced during blood digestion (e.g., heme, NH3, reactive oxygen species. The development of chemical tools targeting these molecular mechanisms in Malpighian tubules may offer a promising avenue for the development of mosquitocides that are highly-selective against hematophagous females, which are the only life stage that transmits pathogens.

Advances in insect physiology. Progress in mosquito research

Science.gov (United States)

This book review briefly summarizes the most interesting topics/chapters from the book: "Advances in Insect Physiology: Progress in mosquito Research". The book is an excellent overview of the recent advances in mosquito biology. This volume encompasses 13 chapters from 32 contributing authors who ...

Insecticide susceptibility status of human biting mosquitoes in ...

African Journals Online (AJOL)

Background: There has been a rapid emergence in insecticide resistance among mosquito population to commonly used public health insecticides. This situation presents a challenge to chemicals that are currently used to control mosquitoes in sub-Saharan African. Furthermore, there is limited information on insecticide ...

Differential utilization of blood meal amino acids in mosquitoes

OpenAIRE

Miesfeld, Roger

2009-01-01

Guoli Zhou, Roger MiesfeldDepartment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USAAbstract: Amino acids in the mosquito blood meal have two forms, protein-bound and plasma-free amino acids. To determine if the metabolic fate and flux of these two forms of blood meal amino acids are distinct, we fed mosquitoes eight [14C]-labeled amino acids, seven of which are essential for mosquitoes (leucine, valine, isoleucine, phenylalanine, lysine, arginine, histidine), and one th...

Activities of Jatropha curcas phorbol esters in various bioassays.

Science.gov (United States)

Devappa, Rakshit K; Rajesh, Sanjay K; Kumar, Vikas; Makkar, Harinder P S; Becker, Klaus

2012-04-01

Jatropha curcas seeds contain 30-35% oil, which can be converted to high quality biodiesel. However, Jatropha oil is toxic, ascribed to the presence of phorbol esters (PEs). In this study, isolated phorbol ester rich fraction (PEEF) was used to evaluate the activity of PEs using three aquatic species based bioassays (snail (Physa fontinalis), brine shrimp (Artemeia salina), daphnia (Daphnia magna)) and microorganisms. In all the bioassays tested, increase in concentration of PEs increased mortality with an EC(50) (48 h) of 0.33, 26.48 and 0.95 mg L(-1) PEs for snail, artemia and daphnia, respectively. The sensitivity of various microorganisms for PEs was also tested. Among the bacterial species tested, Streptococcus pyogenes and Proteus mirabilis were highly susceptible with a minimum inhibitory concentration (MIC) of 215 mg L(-1) PEs; and Pseudomonas putida were also sensitive with MIC of 251 mg L(-1) PEs. Similarly, Fusarium species of fungi exhibited EC(50) of 58 mg L(-1) PEs, while Aspergillus niger and Curvularia lunata had EC(50) of 70 mg L(-1). The snail bioassay was most sensitive with 100% snail mortality at 1 μg of PEs mL(-1). In conclusion, snail bioassay could be used to monitor PEs in Jatropha derived products such as oil, biodiesel, fatty acid distillate, kernel meal, cake, glycerol or for contamination in soil or other environmental matrices. In addition, PEs with molluscicidal/antimicrobial activities could be utilized for agricultural and pharmaceutical applications. Copyright © 2011 Elsevier Inc. All rights reserved.

Clinical categories of exaggerated skin reactions to mosquito bites and their pathophysiology.

Science.gov (United States)

Tatsuno, Kazuki; Fujiyama, Toshiharu; Matsuoka, Hiroyuki; Shimauchi, Takatoshi; Ito, Taisuke; Tokura, Yoshiki

2016-06-01

Mosquito bites are skin irritating reactions, which usually resolve spontaneously without intensive medical care. However, in certain situations, mosquito bites may form a more vicious reaction, sometimes accompanying fever and systemic symptoms. In such cases, the presence of rare hematological disorders, abnormalities in eosinophils and/or association with Epstein-Barr virus (EBV) may underlie. Importantly, hypersensitivity to mosquito bites (HMB), which is characterized by necrotic skin reactions to mosquito bites with various systemic symptoms, is often observed in association with EBV infection and natural killer (NK) cell lymphoproliferative disorder. Exaggerated skin reaction to mosquito bites is also seen in Wells' syndrome. While strong Th2-skewing immune dysregulation is apparent in the patients, they also show robust CD4(+) T cell proliferation in response to mosquito salivary gland extracts, indicating close association between Wells' syndrome and mosquito bites. Similar skin reaction to mosquito bites is also noticed in certain types of B cell neoplasm, although the role of B cells in this peculiar reaction to mosquito bites is yet to be elucidated. In this review, we will discuss the current knowledge of exaggerated reaction toward mosquito bites seen in conjunction with these unique hematological disorders, and examine the scientific studies and observations reported in previous literatures to organize our current understanding of the pathogenesis of this distinct disorder. Copyright © 2016 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Soil plate bioassay: an effective method to determine ecotoxicological risks.

Science.gov (United States)

Boluda, R; Roca-Pérez, L; Marimón, L

2011-06-01

Heavy metals have become one of the most serious anthropogenic stressors for plants and other living organisms. Having efficient and feasible bioassays available to assess the ecotoxicological risks deriving from soil pollution is necessary. This work determines pollution by Cd, Co, Cr, Cu, Ni, Pb, V and Zn in two soils used for growing rice from the Albufera Natural Park in Valencia (Spain). Both were submitted to a different degree of anthropic activity, and their ecotoxicological risk was assessed by four ecotoxicity tests to compare their effectiveness: Microtox test, Zucconi test, pot bioassay (PB) and soil plate bioassay (SPB). The sensitivity of three plant species (barley, cress and lettuce) was also assessed. The results reveal a different degree of effectiveness and level of inhibition in the target organisms' growth depending on the test applied, to such an extent that the one-way analysis of variance showed significant differences only for the plate bioassay results, with considerable inhibition of root and shoot elongation in seedlings. Of the three plant species selected, lettuce was the most sensitive species to toxic effects, followed by cress and barley. Finally, the results also indicate that the SPB is an efficient, simple and economic alternative to other ecotoxicological assays to assess toxicity risks deriving from soil pollution. Copyright © 2011 Elsevier Ltd. All rights reserved.

Malaria mosquitoes attracted by fatal fungus.

Directory of Open Access Journals (Sweden)

Justin George

Full Text Available Insect-killing fungi such as Beauveria bassiana are being evaluated as possible active ingredients for use in novel biopesticides against mosquito vectors that transmit malaria. Fungal pathogens infect through contact and so applications of spores to surfaces such as walls, nets, or other resting sites provide possible routes to infect mosquitoes in and around domestic dwellings. However, some insects can detect and actively avoid fungal spores to reduce infection risk. If true for mosquitoes, such behavior could render the biopesticide approach ineffective. Here we find that the spores of B. bassiana are highly attractive to females of Anopheles stephensi, a major anopheline mosquito vector of human malaria in Asia. We further find that An. stephensi females are preferentially attracted to dead and dying caterpillars infected with B. bassiana, landing on them and subsequently becoming infected with the fungus. Females are also preferentially attracted to cloth sprayed with oil-formulated B. bassiana spores, with 95% of the attracted females becoming infected after a one-minute visit on the cloth. This is the first report of an insect being attracted to a lethal fungal pathogen. The exact mechanisms involved in this behavior remain unclear. Nonetheless, our results indicate that biopesticidal formulations comprising B. bassiana spores will be conducive to attraction and on-source visitation by malaria vectors.

Potential for sublethal insecticide exposure to impact vector competence of Aedes albopictus (Diptera: Culicidae for dengue and Zika viruses

Directory of Open Access Journals (Sweden)

Richards SL

2017-05-01

Full Text Available Stephanie L Richards, Avian V White, Jo Anne G Balanay Department of Health Education and Promotion, College of Health and Human Performance, East Carolina University, Greenville, NC, USA Abstract: Chikungunya, dengue, and Zika viruses (CHIKV, family Togaviridae, genus Alphavirus; DENV and ZIKV, family Flaviviridae, genus Flavivirus are arboviruses that cause human epidemics. Due to the lack of vaccines for many mosquito-borne diseases, there is a need for mosquito control. In the US and other regions, residual barrier insecticide sprays are applied to foliage where female mosquitoes rest and/or sugar feed between blood meals. Residual sprays are an important control method for anthropogenic day-active sylvan mosquitoes such as Aedes albopictus (vector of CHIKV, DENV, and ZIKV that are difficult to control using ultralow-volume sprays applied only at dusk or dawn when these mosquitoes are not active. In this exploratory study, we analyzed the extent to which ingestion of a sublethal dose of the active ingredient bifenthrin affected vector competence (i.e., infection, dissemination, and transmission of Ae. albopictus for DENV and ZIKV. Two incubation periods (IPs; 7 and 14 d were tested at 28°C for insecticide-fed and sugar-fed mosquitoes. We show that mosquitoes that were fed bifenthrin (0.128 µg/mL mixed with sucrose solution exhibited significantly lower DENV infection rates and body titers after a 14-d IP. During the 7-d IP, one mosquito (sugar group transmitted ZIKV. During the 14-d IP, 100% of mosquitoes showed body and leg ZIKV infections, and one mosquito (sugar+bifenthrin group transmitted ZIKV. This is a preliminary communication, and more studies will be required to further investigate these findings. We expect the findings of this small-scale study to spur larger-scale investigations of the impacts of insecticides on mechanisms regulating vector competence, and exposure to other active ingredients, and aid in development of new

Quantifying impact of mosquitoes on quality of life

Science.gov (United States)

New Jersey, like many eastern states, has a persistent problem of the Asian tiger mosquito. This and other mosquitoes reduce residents’ quality of life from discomfort and possible risk of disease. To guide a comprehensive area-wide pest management project to control Aedes albopictus in two counties...

Biological Control Strategies for Mosquito Vectors of Arboviruses

Directory of Open Access Journals (Sweden)

Yan-Jang S. Huang

2017-02-01

Full Text Available Historically, biological control utilizes predatory species and pathogenic microorganisms to reduce the population of mosquitoes as disease vectors. This is particularly important for the control of mosquito-borne arboviruses, which normally do not have specific antiviral therapies available. Although development of resistance is likely, the advantages of biological control are that the resources used are typically biodegradable and ecologically friendly. Over the past decade, the advancement of molecular biology has enabled optimization by the manipulation of genetic materials associated with biological control agents. Two significant advancements are the discovery of cytoplasmic incompatibility induced by Wolbachia bacteria, which has enhanced replacement programs, and the introduction of dominant lethal genes into local mosquito populations through the release of genetically modified mosquitoes. As various arboviruses continue to be significant public health threats, biological control strategies have evolved to be more diverse and become critical tools to reduce the disease burden of arboviruses.

Review of refractory ceramic fiber (RCF) toxicity, epidemiology and occupational exposure.

Science.gov (United States)

Maxim, L Daniel; Utell, Mark J

2018-02-01

This literature review on refractory ceramic fibers (RCF) summarizes relevant information on manufacturing, processing, applications, occupational exposure, toxicology and epidemiology studies. Rodent toxicology studies conducted in the 1980s showed that RCF caused fibrosis, lung cancer and mesothelioma. Interpretation of these studies was difficult for various reasons (e.g. overload in chronic inhalation bioassays), but spurred the development of a comprehensive product stewardship program under EPA and later OSHA oversight. Epidemiology studies (both morbidity and mortality) were undertaken to learn more about possible health effects resulting from occupational exposure. No chronic animal bioassay studies on RCF have been conducted since the 1980s. The results of the ongoing epidemiology studies confirm that occupational exposure to RCF is associated with the development of pleural plaques and minor decrements in lung function, but no interstitial fibrosis or incremental lung cancer. Evidence supporting a finding that urinary tumors are associated with RCF exposure remains, but is weaker. One reported, but unconfirmed, mesothelioma was found in an individual with prior occupational asbestos exposure. An elevated SMR for leukemia was found, but was absent in the highly exposed group and has not been observed in studies of other mineral fibers. The industry will continue the product stewardship program including the mortality study.

Composition of human skin microbiota affects attractiveness to malaria mosquitoes.

Directory of Open Access Journals (Sweden)

Niels O Verhulst

Full Text Available The African malaria mosquito Anopheles gambiae sensu stricto continues to play an important role in malaria transmission, which is aggravated by its high degree of anthropophily, making it among the foremost vectors of this disease. In the current study we set out to unravel the strong association between this mosquito species and human beings, as it is determined by odorant cues derived from the human skin. Microbial communities on the skin play key roles in the production of human body odour. We demonstrate that the composition of the skin microbiota affects the degree of attractiveness of human beings to this mosquito species. Bacterial plate counts and 16S rRNA sequencing revealed that individuals that are highly attractive to An. gambiae s.s. have a significantly higher abundance, but lower diversity of bacteria on their skin than individuals that are poorly attractive. Bacterial genera that are correlated with the relative degree of attractiveness to mosquitoes were identified. The discovery of the connection between skin microbial populations and attractiveness to mosquitoes may lead to the development of new mosquito attractants and personalized methods for protection against vectors of malaria and other infectious diseases.

Mosquitoes and other aquatic insects in fallow field biotopes and rice paddy fields.

Science.gov (United States)

Ohba, S Y; Matsuo, T; Takagi, M

2013-03-01

Fallow field biotopes that develop from abandoned rice fields are man-made wetlands that provide new habitats for various aquatic animals. Although consideration of such biotopes generally focuses on their positive aspects, this study evaluated the negative aspects of establishing fallow field biotopes with regard to mosquito breeding sites. To determine whether fallow field biotopes become breeding habitats for vector mosquitoes, we evaluated mosquito fauna in fallow field biotopes and adjacent rice fields. We found larvae of Anopheles lesteri, Anopheles sinensis and Culex tritaeniorhynchus (all: Diptera: Culicidae) in the biotopes. Although abundances of mosquito larvae in the biotopes and rice fields were statistically similar, mosquito abundances in rice fields increased dramatically in August when the water level reduced after the rainy season. The abundance and variety of the mosquitoes' natural predators were greater in biotopes than in rice fields because the former are a permanent and stable aquatic environment. A generalized linear mixed model showed a negative effect of predator diversity on mosquito larvae abundance in both habitats. Although fallow field biotopes become breeding habitats for vector mosquitoes, establishing biotopes from fallow fields in order to protect various aquatic animals, including mosquito insect predators, may help to control mosquito breeding. © 2012 The Royal Entomological Society.

Comparative susceptibility to permethrin of two Anopheles gambiae s.l. populations from Southern Benin, regarding mosquito sex, physiological status, and mosquito age

Directory of Open Access Journals (Sweden)

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.

In vitro bioassays to evaluate complex chemical mixtures in recycled water.

Science.gov (United States)

Jia, Ai; Escher, Beate I; Leusch, Frederic D L; Tang, Janet Y M; Prochazka, Erik; Dong, Bingfeng; Snyder, Erin M; Snyder, Shane A

2015-09-01

With burgeoning population and diminishing availability of freshwater resources, the world continues to expand the use of alternative water resources for drinking, and the quality of these sources has been a great concern for the public as well as public health professionals. In vitro bioassays are increasingly being used to enable rapid, relatively inexpensive toxicity screening that can be used in conjunction with analytical chemistry data to evaluate water quality and the effectiveness of water treatment. In this study, a comprehensive bioassay battery consisting of 36 bioassays covering 18 biological endpoints was applied to screen the bioactivity of waters of varying qualities with parallel treatments. Samples include wastewater effluent, ultraviolet light (UV) and/or ozone advanced oxidation processed (AOP) recycled water, and infiltrated recycled groundwater. Based on assay sensitivity and detection frequency in the samples, several endpoints were highlighted in the battery, including assays for genotoxicity, mutagenicity, estrogenic activity, glucocorticoid activity, arylhydrocarbon receptor activity, oxidative stress response, and cytotoxicity. Attenuation of bioactivity was found to be dependent on the treatment process and bioassay endpoint. For instance, ozone technology significantly removed oxidative stress activity, while UV based technologies were most efficient for the attenuation of glucocorticoid activity. Chlorination partially attenuated genotoxicity and greatly decreased herbicidal activity, while groundwater infiltration efficiently attenuated most of the evaluated bioactivity with the exception of genotoxicity. In some cases, bioactivity (e.g., mutagenicity, genotoxicity, and arylhydrocarbon receptor) increased following water treatment, indicating that transformation products of water treatment may be a concern. Furthermore, several types of bioassays with the same endpoint were compared in this study, which could help guide the selection

Wolbachia enhances West Nile virus (WNV infection in the mosquito Culex tarsalis.

Directory of Open Access Journals (Sweden)

Brittany L Dodson

2014-07-01

Full Text Available Novel strategies are required to control mosquitoes and the pathogens they transmit. One attractive approach involves maternally inherited endosymbiotic Wolbachia bacteria. After artificial infection with Wolbachia, many mosquitoes become refractory to infection and transmission of diverse pathogens. We evaluated the effects of Wolbachia (wAlbB strain on infection, dissemination and transmission of West Nile virus (WNV in the naturally uninfected mosquito Culex tarsalis, which is an important WNV vector in North America. After inoculation into adult female mosquitoes, Wolbachia reached high titers and disseminated widely to numerous tissues including the head, thoracic flight muscles, fat body and ovarian follicles. Contrary to other systems, Wolbachia did not inhibit WNV in this mosquito. Rather, WNV infection rate was significantly higher in Wolbachia-infected mosquitoes compared to controls. Quantitative PCR of selected innate immune genes indicated that REL1 (the activator of the antiviral Toll immune pathway was down regulated in Wolbachia-infected relative to control mosquitoes. This is the first observation of Wolbachia-induced enhancement of a human pathogen in mosquitoes, suggesting that caution should be applied before releasing Wolbachia-infected insects as part of a vector-borne disease control program.

Relative abundance of mosquito species in Katsina Metropolis ...

African Journals Online (AJOL)

A study was conducted on the relative abundance of mosquito species, around selected areas of Katsina metropolis, Katsina State, Nigeria during the months of January, February, April and June 2010. Mosquitoes were collected from five sampling sites: Kofar Durbi, Kofar Kaura, Kofar Marusa, GRA and Layout. These were ...

The immune strategies of mosquito Aedes aegypti against microbial infection.

Science.gov (United States)

Wang, Yan-Hong; Chang, Meng-Meng; Wang, Xue-Li; Zheng, Ai-Hua; Zou, Zhen

2018-06-01

Yellow fever mosquito Aedes aegypti transmits many devastating arthropod-borne viruses (arboviruses), such as dengue virus, yellow fever virus, Chikungunya virus, and Zika virus, which cause great concern to human health. Mosquito control is an effective method to block the spread of infectious diseases. Ae. aegypti uses its innate immune system to fight against arboviruses, parasites, and fungi. In this review, we briefly summarize the recent findings in the immune response of Ae. aegypti against arboviral and entomopathogenic infections. This review enriches our understanding of the mosquito immune system and provides evidence to support the development of novel mosquito control strategies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simplified models of vector control impact upon malaria transmission by zoophagic mosquitoes.

Directory of Open Access Journals (Sweden)

Samson S Kiware

interventions using three field-measurable parameters; the proportion of human exposure to mosquitoes occurring when an intervention can be practically used, its protective efficacy when used, and the proportion of people using it.

Filarial worms reduce Plasmodium infectivity in mosquitoes.

Directory of Open Access Journals (Sweden)

Matthew T Aliota

2011-02-01

Full Text Available Co-occurrence of malaria and filarial worm parasites has been reported, but little is known about the interaction between filarial worm and malaria parasites with the same Anopheles vector. Herein, we present data evaluating the interaction between Wuchereria bancrofti and Anopheles punctulatus in Papua New Guinea (PNG. Our field studies in PNG demonstrated that An. punctulatus utilizes the melanization immune response as a natural mechanism of filarial worm resistance against invading W. bancrofti microfilariae. We then conducted laboratory studies utilizing the mosquitoes Armigeres subalbatus and Aedes aegypti and the parasites Brugia malayi, Brugia pahangi, Dirofilaria immitis, and Plasmodium gallinaceum to evaluate the hypothesis that immune activation and/or development by filarial worms negatively impact Plasmodium development in co-infected mosquitoes. Ar. subalbatus used in this study are natural vectors of P. gallinaceum and B. pahangi and they are naturally refractory to B. malayi (melanization-based refractoriness.Mosquitoes were dissected and Plasmodium development was analyzed six days after blood feeding on either P. gallinaceum alone or after taking a bloodmeal containing both P. gallinaceum and B. malayi or a bloodmeal containing both P. gallinaceum and B. pahangi. There was a significant reduction in the prevalence and mean intensity of Plasmodium infections in two species of mosquito that had dual infections as compared to those mosquitoes that were infected with Plasmodium alone, and was independent of whether the mosquito had a melanization immune response to the filarial worm or not. However, there was no reduction in Plasmodium development when filarial worms were present in the bloodmeal (D. immitis but midgut penetration was absent, suggesting that factors associated with penetration of the midgut by filarial worms likely are responsible for the observed reduction in malaria parasite infections.These results could have an

The temporal spectrum of adult mosquito population fluctuations: conceptual and modeling implications.

Directory of Open Access Journals (Sweden)

Yun Jian

Full Text Available An improved understanding of mosquito population dynamics under natural environmental forcing requires adequate field observations spanning the full range of temporal scales over which mosquito abundance fluctuates in natural conditions. Here we analyze a 9-year daily time series of uninterrupted observations of adult mosquito abundance for multiple mosquito species in North Carolina to identify characteristic scales of temporal variability, the processes generating them, and the representativeness of observations at different sampling resolutions. We focus in particular on Aedes vexans and Culiseta melanura and, using a combination of spectral analysis and modeling, we find significant population fluctuations with characteristic periodicity between 2 days and several years. Population dynamical modelling suggests that the observed fast fluctuations scales (2 days-weeks are importantly affected by a varying mosquito activity in response to rapid changes in meteorological conditions, a process neglected in most representations of mosquito population dynamics. We further suggest that the range of time scales over which adult mosquito population variability takes place can be divided into three main parts. At small time scales (indicatively 2 days-1 month observed population fluctuations are mainly driven by behavioral responses to rapid changes in weather conditions. At intermediate scales (1 to several month environmentally-forced fluctuations in generation times, mortality rates, and density dependence determine the population characteristic response times. At longer scales (annual to multi-annual mosquito populations follow seasonal and inter-annual environmental changes. We conclude that observations of adult mosquito populations should be based on a sub-weekly sampling frequency and that predictive models of mosquito abundance must include behavioral dynamics to separate the effects of a varying mosquito activity from actual changes in the

Benchmarking organic micropollutants in wastewater, recycled water and drinking water with in vitro bioassays.

Science.gov (United States)

Escher, Beate I; Allinson, Mayumi; Altenburger, Rolf; Bain, Peter A; Balaguer, Patrick; Busch, Wibke; Crago, Jordan; Denslow, Nancy D; Dopp, Elke; Hilscherova, Klara; Humpage, Andrew R; Kumar, Anu; Grimaldi, Marina; Jayasinghe, B Sumith; Jarosova, Barbora; Jia, Ai; Makarov, Sergei; Maruya, Keith A; Medvedev, Alex; Mehinto, Alvine C; Mendez, Jamie E; Poulsen, Anita; Prochazka, Erik; Richard, Jessica; Schifferli, Andrea; Schlenk, Daniel; Scholz, Stefan; Shiraishi, Fujio; Snyder, Shane; Su, Guanyong; Tang, Janet Y M; van der Burg, Bart; van der Linden, Sander C; Werner, Inge; Westerheide, Sandy D; Wong, Chris K C; Yang, Min; Yeung, Bonnie H Y; Zhang, Xiaowei; Leusch, Frederic D L

2014-01-01

Thousands of organic micropollutants and their transformation products occur in water. Although often present at low concentrations, individual compounds contribute to mixture effects. Cell-based bioassays that target health-relevant biological endpoints may therefore complement chemical analysis for water quality assessment. The objective of this study was to evaluate cell-based bioassays for their suitability to benchmark water quality and to assess efficacy of water treatment processes. The selected bioassays cover relevant steps in the toxicity pathways including induction of xenobiotic metabolism, specific and reactive modes of toxic action, activation of adaptive stress response pathways and system responses. Twenty laboratories applied 103 unique in vitro bioassays to a common set of 10 water samples collected in Australia, including wastewater treatment plant effluent, two types of recycled water (reverse osmosis and ozonation/activated carbon filtration), stormwater, surface water, and drinking water. Sixty-five bioassays (63%) showed positive results in at least one sample, typically in wastewater treatment plant effluent, and only five (5%) were positive in the control (ultrapure water). Each water type had a characteristic bioanalytical profile with particular groups of toxicity pathways either consistently responsive or not responsive across test systems. The most responsive health-relevant endpoints were related to xenobiotic metabolism (pregnane X and aryl hydrocarbon receptors), hormone-mediated modes of action (mainly related to the estrogen, glucocorticoid, and antiandrogen activities), reactive modes of action (genotoxicity) and adaptive stress response pathway (oxidative stress response). This study has demonstrated that selected cell-based bioassays are suitable to benchmark water quality and it is recommended to use a purpose-tailored panel of bioassays for routine monitoring.

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

Directory of Open Access Journals (Sweden)

Marta Ferreira Maia

Full Text Available 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.

A versatile electrowetting-based digital microfluidic platform for quantitative homogeneous and heterogeneous bio-assays

Science.gov (United States)

Vergauwe, Nicolas; Witters, Daan; Ceyssens, Frederik; Vermeir, Steven; Verbruggen, Bert; Puers, Robert; Lammertyn, Jeroen

2011-05-01

Electrowetting-on-dielectric (EWOD) lab-on-a-chip systems have already proven their potential within a broad range of bio-assays. Nevertheless, research on the analytical performance of those systems is limited, yet crucial for a further breakthrough in the diagnostic field. Therefore, this paper presents the intrinsic possibilities of an EWOD lab-on-a-chip as a versatile platform for homogeneous and heterogeneous bio-assays with high analytical performance. Both droplet dispensing and splitting cause variations in droplet size, thereby directly influencing the assay's performance. The extent to which they influence the performance is assessed by a theoretical sensitivity analysis, which allows the definition of a basic framework for the reduction of droplet size variability. Taking advantage of the optimized droplet manipulations, both homogeneous and heterogeneous bio-assays are implemented in the EWOD lab-on-a-chip to demonstrate the analytical capabilities and versatility of the device. A fully on-chip enzymatic assay is realized with high analytical performance. It demonstrates the promising capabilities of an EWOD lab-on-a-chip in food-related and medical applications, such as nutritional and blood analyses. Further, a magnetic bio-assay for IgE detection using superparamagnetic nanoparticles is presented whereby the nanoparticles are used as solid carriers during the bio-assay. Crucial elements are the precise manipulation of the superparamagnetic nanoparticles with respect to dispensing and separation. Although the principle of using nano-carriers is demonstrated for protein detection, it can be easily extended to a broader range of bio-related applications like DNA sensing. In heterogeneous bio-assays the chip surface is actively involved during the execution of the bio-assay. Through immobilization of specific biological compounds like DNA, proteins and cells a reactive chip surface is realized, which enhances the bio-assay performance. To demonstrate

Aedes-Borne Virus-Mosquito Interactions: Mass Spectrometry Strategies and Findings.

Science.gov (United States)

Pando-Robles, Victoria; Batista, Cesar V

2017-06-01

Aedes-borne viruses are responsible for high-impact neglected tropical diseases and unpredictable outbreaks such as the ongoing Zika epidemics. Aedes mosquitoes spread different arboviruses such as Dengue virus (DENV), Chikungunya virus (CHIKV), and Zika virus, among others, and are responsible for the continuous emergence and reemergence of these pathogens. These viruses have complex transmission cycles that include two hosts, namely the Aedes mosquito as a vector and susceptible vertebrate hosts. Human infection with arboviruses causes diseases that range from subclinical or mild to febrile diseases, encephalitis, and hemorrhagic fever. Infected mosquitoes do not show detectable signs of disease, even though the virus maintains a lifelong persistent infection. The infection of the Aedes mosquito by viruses involves a molecular crosstalk between cell and viral proteins. An understanding of how mosquito vectors and viruses interact is of fundamental interest, and it also offers novel perspectives for disease control. In recent years, mass spectrometry (MS)-based strategies in combination with bioinformatics have been successfully applied to identify and quantify global changes in cellular proteins, lipids, peptides, and metabolites in response to viral infection. Although the information about proteomics in the Aedes mosquito is limited, the information that has been reported can set up the basis for future studies. This review reflects how MS-based approaches have extended our understanding of Aedes mosquito biology and the development of DENV and CHIKV infection in the vector. Finally, this review discusses future challenges in the field.

Improving global laboratory capabilities for emergency radionuclide bioassay

International Nuclear Information System (INIS)

Li, C.; Jourdain, J.; Kramer, G. H.

2012-01-01

During a radiological or nuclear emergency, first-responders and the general public may be internally contaminated with the radionuclide(s) involved. A timely radionuclide bioassay provides important information about contamination, for subsequent dose assessment and medical management. Both technical and operational gaps are discussed in this paper. As many people may need to be assessed in a short period of time, any single laboratory may find its capabilities insufficient. Laboratories from other regions or other countries may be called upon for assistance. This paper proposes a road-map to improve global capabilities in emergency radionuclide bioassay, suggesting a phased approach for establishing a global laboratory network. Existing international collaboration platforms could provide the base on which to build such a network. (authors)

Biodiversity and ecosystem risks arising from using guppies to control mosquitoes

Science.gov (United States)

Rana W. El-Sabaawi; Therese C. Frauendorf; Piata S. Marques; Richard A. Mackenzie; Luisa R. Manna; Rosana Mazzoni; Dawn A. T. Phillip; Misha L. Warbanski; Eugenia Zandon

2016-01-01

Deploying mosquito predators such as the guppy (Poecilia reticulata) into bodies of water where mosquitoes breed is a common strategy for limiting the spread of disease-carrying mosquitoes. Here, we draw on studies from epidemiology, conservation, ecology and evolution to show that the evidence for the effectiveness of guppies in controlling...

Free boundary models for mosquito range movement driven by climate warming.

Science.gov (United States)

Bao, Wendi; Du, Yihong; Lin, Zhigui; Zhu, Huaiping

2018-03-01

As vectors, mosquitoes transmit numerous mosquito-borne diseases. Among the many factors affecting the distribution and density of mosquitoes, climate change and warming have been increasingly recognized as major ones. In this paper, we make use of three diffusive logistic models with free boundary in one space dimension to explore the impact of climate warming on the movement of mosquito range. First, a general model incorporating temperature change with location and time is introduced. In order to gain insights of the model, a simplified version of the model with the change of temperature depending only on location is analyzed theoretically, for which the dynamical behavior is completely determined and presented. The general model can be modified into a more realistic one of seasonal succession type, to take into account of the seasonal changes of mosquito movements during each year, where the general model applies only for the time period of the warm seasons of the year, and during the cold season, the mosquito range is fixed and the population is assumed to be in a hibernating status. For both the general model and the seasonal succession model, our numerical simulations indicate that the long-time dynamical behavior is qualitatively similar to the simplified model, and the effect of climate warming on the movement of mosquitoes can be easily captured. Moreover, our analysis reveals that hibernating enhances the chances of survival and successful spreading of the mosquitoes, but it slows down the spreading speed.

Using green fluorescent malaria parasites to screen for permissive vector mosquitoes

Directory of Open Access Journals (Sweden)

Martin Beatrice

2006-03-01

Full Text Available Abstract Background The Plasmodium species that infect rodents, particularly Plasmodium berghei and Plasmodium yoelii, are useful to investigate host-parasite interactions. The mosquito species that act as vectors of human plasmodia in South East Asia, Africa and South America show different susceptibilities to infection by rodent Plasmodium species. P. berghei and P. yoelii infect both Anopheles gambiae and Anopheles stephensi, which are found mainly in Africa and Asia, respectively. However, it was reported that P. yoelii can infect the South American mosquito, Anopheles albimanus, while P. berghei cannot. Methods P. berghei lines that express the green fluorescent protein were used to screen for mosquitoes that are susceptible to infection by P. berghei. Live mosquitoes were examined and screened for the presence of a fluorescent signal in the abdomen. Infected mosquitoes were then examined by time-lapse microscopy to reveal the dynamic behaviour of sporozoites in haemolymph and extracted salivary glands. Results A single fluorescent oocyst can be detected in live mosquitoes and P. berghei can infect A. albimanus. As in other mosquitoes, P. berghei sporozoites can float through the haemolymph and invade A. albimanus salivary glands and they are infectious in mice after subcutaneous injection. Conclusion Fluorescent Plasmodium parasites can be used to rapidly screen susceptible mosquitoes. These results open the way to develop a laboratory model in countries where importation of A. gambiae and A. stephensi is not allowed.

West Nile Virus in Mosquitoes of Iranian Wetlands.

Science.gov (United States)

Bagheri, Masoomeh; Terenius, Olle; Oshaghi, Mohammad Ali; Motazakker, Morteza; Asgari, Sassan; Dabiri, Farrokh; Vatandoost, Hassan; Mohammadi Bavani, Mulood; Chavshin, Ali Reza

2015-12-01

The West Nile virus (WNV) transmission cycle includes a wide range of migratory wetland birds as reservoirs, mosquitoes as biological vectors, and equines and humans as dead-end hosts. Despite the presence of potential vector species, there is no information about the existence of WNV in mosquito vectors in Iran. The Iranian West Azerbaijan Province is located in the northwestern part of Iran and has borders with Turkey, Iraq, Armenia, and the Republic of Azerbaijan. The current study was conducted to identify the wetland mosquitoes of the West Azerbaijan Province and their infection with WNV. In this study, 2143 specimens were collected, comprising 1541 adults and 602 larvae. Six species belonging to four genera were collected and identified: Anopheles maculipennis sensu lato (s.l.), Culex (Cx.) hortensis, Cx. pipiens s.l., Cx. theileri, Culiseta longiareolata, and Aedes (Ae.) (Ochlerotatus) caspius. In total, 45 pools of mosquitoes were examined. Two of the adult pools collected from the same location showed the presence of WNV in Ae. (Och.) caspius, from Sangar, Makoo County, as confirmed by PCR and sequencing. Due to the discovery of WNV in the mosquito population of the region, and the presence of wetlands and significant populations of migratory birds, the health sector should carefully monitor the factors involved in the cycle of this disease.

Toxicity of a plant based mosquito repellent/killer

Science.gov (United States)

Singh, Prakash Raj; Mohanty, Manoj Kumar

2012-01-01

The mission to make humans less attractive to mosquitoes has fuelled decades of scientific research on mosquito behaviour and control. The search for the perfect topical insect repellent/killer continues. This analysis was conducted to review and explore the scientific information on toxicity produced by the ingredients/contents of a herbal product. In this process of systemic review the following methodology was applied. By doing a MEDLINE search with key words of selected plants, plant based insect repellents/killers pertinent articles published in journals and authentic books were reviewed. The World Wide Web and the Extension Toxicity Network database (IPCS-ITOX) were also searched for toxicology data and other pertinent information. Repellents do not all share a single mode of action and surprisingly little is known about how repellents act on their target insects. Moreover, different mosquito species may react differently to the same repellent. After analysis of available data and information on the ingredient, of the product in relation to medicinal uses, acute and chronic toxicity of the selected medicinal plants, it can be concluded that the ingredients included in the herbal product can be used as active agents against mosquitoes. If the product which contains the powder of the above said plants is applied with care and safety, it is suitable fo use as a mosquito repellent/killer. PMID:23554562

Variation in Aedes aegypti Mosquito Competence for Zika Virus Transmission.

Science.gov (United States)

Roundy, Christopher M; Azar, Sasha R; Rossi, Shannan L; Huang, Jing H; Leal, Grace; Yun, Ruimei; Fernandez-Salas, Ildefonso; Vitek, Christopher J; Paploski, Igor A D; Kitron, Uriel; Ribeiro, Guilherme S; Hanley, Kathryn A; Weaver, Scott C; Vasilakis, Nikos

2017-04-01

To test whether Zika virus has adapted for more efficient transmission by Aedes aegypti mosquitoes, leading to recent urban outbreaks, we fed mosquitoes from Brazil, the Dominican Republic, and the United States artificial blood meals containing 1 of 3 Zika virus strains (Senegal, Cambodia, Mexico) and monitored infection, dissemination, and virus in saliva. Contrary to our hypothesis, Cambodia and Mexica strains were less infectious than the Senegal strain. Only mosquitoes from the Dominican Republic transmitted the Cambodia and Mexica strains. However, blood meals from viremic mice were more infectious than artificial blood meals of comparable doses; the Cambodia strain was not transmitted by mosquitoes from Brazil after artificial blood meals, whereas 61% transmission occurred after a murine blood meal (saliva titers up to 4 log 10 infectious units/collection). Although regional origins of vector populations and virus strain influence transmission efficiency, Ae. aegypti mosquitoes appear to be competent vectors of Zika virus in several regions of the Americas.

Zika virus emergence in mosquitoes in southeastern Senegal, 2011.

Directory of Open Access Journals (Sweden)

Diawo Diallo

Full Text Available Zika virus (ZIKV; genus Flavivirus, family Flaviviridae is maintained in a zoonotic cycle between arboreal Aedes spp. mosquitoes and nonhuman primates in African and Asian forests. Spillover into humans has been documented in both regions and the virus is currently responsible for a large outbreak in French Polynesia. ZIKV amplifications are frequent in southeastern Senegal but little is known about their seasonal and spatial dynamics. The aim of this paper is to describe the spatio-temporal patterns of the 2011 ZIKV amplification in southeastern Senegal.Mosquitoes were collected monthly from April to December 2011 except during July. Each evening from 18:00 to 21:00 hrs landing collections were performed by teams of 3 persons working simultaneously in forest (canopy and ground, savannah, agriculture, village (indoor and outdoor and barren land cover sites. Mosquitoes were tested for virus infection by virus isolation and RT-PCR. ZIKV was detected in 31 of the 1,700 mosquito pools (11,247 mosquitoes tested: Ae. furcifer (5, Ae. luteocephalus (5, Ae. africanus (5, Ae. vittatus (3, Ae. taylori, Ae. dalzieli, Ae. hirsutus and Ae. metallicus (2 each and Ae. aegypti, Ae. unilinaetus, Ma. uniformis, Cx. perfuscus and An. coustani (1 pool each collected in June (3, September (10, October (11, November (6 and December (1. ZIKV was detected from mosquitoes collected in all land cover classes except indoor locations within villages. The virus was detected in only one of the ten villages investigated.This ZIKV amplification was widespread in the Kédougou area, involved several mosquito species as probable vectors, and encompassed all investigated land cover classes except indoor locations within villages. Aedes furcifer males and Aedes vittatus were found infected within a village, thus these species are probably involved in the transmission of Zika virus to humans in this environment.

[Birds, mosquitoes and West Nile virus: little risk of West Nile fever in the Netherlands].

Science.gov (United States)

Duijster, Janneke W; Stroo, C J Arjan; Braks, Marieta A H

2016-01-01

Due to increased incidence of West Nile fever (WNF) in Europe and the rapid spread of West Nile virus (WNV) in the US, it is commonly thought that it will only be a matter of time before WNV reaches the Netherlands. However, assessing whether WNV is really a threat to the Dutch population is challenging, due to the numerous factors affecting transmission of the virus. Some of these factors are known to limit the risk of WNF in the Netherlands. This risk is determined by the interaction between the pathogen (WNV), the vectors (Culex mosquitoes), the reservoirs (birds) and the exposure of humans to infected mosquitoes. In this paper, we discuss the factors influencing introduction, establishment and spread of WNV in the Netherlands. The probability that each of these three phases will occur in the Netherlands is currently relatively small, as is the risk of WNF infection in humans in the Netherlands.

Sample preparation for combined chemical analysis and bioassay application in water quality assessment

NARCIS (Netherlands)

Kolkman, A.; Schriks, M.; Brand, W; Bäuerlein, P.S.; van der Kooi, M.M.E.; van Doorn, R.H.; Emke, E.; Reus, A.; van der Linden, S.; de Voogt, P.; Heringa, M.B.

2013-01-01

The combination of in vitro bioassays and chemical screening can provide a powerful toolbox to determine biologically relevant compounds in water extracts. In this study, a sample preparation method is evaluated for the suitability for both chemical analysis and in vitro bioassays. A set of 39

The CALUX bioassay: current status of its application to screening food and feed

NARCIS (Netherlands)

Hoogenboom, L.A.P.; Goeyens, L.; Carbonnelle, S.; Loco, van J.; Beernaert, H.; Baeyens, W.; Traag, W.A.; Bovee, T.F.H.; Jacobs, G.; Schoeters, G.

2006-01-01

The CALUX bioassay is at present the best screening method for dioxins and dioxin-like (dl) polychlorinated biphenyls (PCBs) in food and feed, and the only assay used in routine monitoring and during larger incidents. Furthermore, the use of bioassays in addition to chemical reference methods allows

Analysis of a malaria model with mosquito-dependent transmission ...

Indian Academy of Sciences (India)

model for the spread of malaria in human and mosquito population. ... tures, high humidity and water bodies allow mosquito and parasites to reproduce. The ... understand the main parameters in the transmission of the disease and to develop ...

Assessment of acrylamide toxicity using a battery of standardised bioassays.

Science.gov (United States)

Zovko, Mira; Vidaković-Cifrek, Željka; Cvetković, Želimira; Bošnir, Jasna; Šikić, Sandra

2015-12-01

Acrylamide is a monomer widely used as an intermediate in the production of organic chemicals, e.g. polyacrylamides (PAMs). Since PAMs are low cost chemicals with applications in various industries and waste- and drinking water treatment, a certain amount of non-polymerised acrylamide is expected to end up in waterways. PAMs are non-toxic but acrylamide induces neurotoxic effects in humans and genotoxic, reproductive, and carcinogenic effects in laboratory animals. In order to evaluate the effect of acrylamide on freshwater organisms, bioassays were conducted on four species: algae Desmodesmus subspicatus and Pseudokirchneriella subcapitata, duckweed Lemna minor and water flea Daphnia magna according to ISO (International Organization for Standardisation) standardised methods. This approach ensures the evaluation of acrylamide toxicity on organisms with different levels of organisation and the comparability of results, and it examines the value of using a battery of low-cost standardised bioassays in the monitoring of pollution and contamination of aquatic ecosystems. These results showed that EC50 values were lower for Desmodesmus subspicatus and Pseudokirchneriella subcapitata than for Daphnia magna and Lemna minor, which suggests an increased sensitivity of algae to acrylamide. According to the toxic unit approach, the values estimated by the Lemna minor and Daphnia magna bioassays, classify acrylamide as slightly toxic (TU=0-1; Class 1). The results obtained from algal bioassays (Desmodesmus subspicatus and Pseudokirchneriella subcapitata) revealed the toxic effect of acrylamide (TU=1-10; Class 2) on these organisms.

Transmission of Rift Valley fever virus from European-breed lambs to Culex pipiens mosquitoes.

Directory of Open Access Journals (Sweden)

Rianka P M Vloet

2017-12-01

Full Text Available Rift Valley fever virus (RVFV is a mosquito-borne bunyavirus of the genus Phlebovirus that is highly pathogenic to ruminants and humans. The disease is currently confined to Africa and the Arabian Peninsula, but globalization and climate change may facilitate introductions of the virus into currently unaffected areas via infected animals or mosquitoes. The consequences of such an introduction will depend on environmental factors, the availability of susceptible ruminants and the capacity of local mosquitoes to transmit the virus. We have previously demonstrated that lambs native to the Netherlands are highly susceptible to RVFV and we here report the vector competence of Culex (Cx. pipiens, the most abundant and widespread mosquito species in the country. Vector competence was first determined after artificial blood feeding of laboratory-reared mosquitoes using the attenuated Clone 13 strain. Subsequently, experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs were performed. Finally, the transmission of RVFV from viremic lambs to mosquitoes was studied.Artificial feeding experiments using Clone 13 demonstrated that indigenous, laboratory-reared Cx. pipiens mosquitoes are susceptible to RVFV and that the virus can be transmitted via their saliva. Experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs confirmed the vector competence of Cx. pipiens mosquitoes from the Netherlands. To subsequently investigate transmission of the virus under more natural conditions, mosquitoes were allowed to feed on RVFV-infected lambs during the viremic period. We found that RVFV is efficiently transmitted from lambs to mosquitoes, although transmission was restricted to peak viremia. Interestingly, in the mosquito-exposed skin samples, replication of RVFV was detected in previously unrecognized target cells.We here report the vector competence of Cx. pipiens mosquitoes from the Netherlands for RVFV. Both

Driven to extinction? The ethics of eradicating mosquitoes with gene-drive technologies.

Science.gov (United States)

Pugh, Jonathan

2016-09-01

Mosquito-borne diseases represent a significant global disease burden, and recent outbreaks of such diseases have led to calls to reduce mosquito populations. Furthermore, advances in 'gene-drive' technology have raised the prospect of eradicating certain species of mosquito via genetic modification. This technology has attracted a great deal of media attention, and the idea of using gene-drive technology to eradicate mosquitoes has been met with criticism in the public domain. In this paper, I shall dispel two moral objections that have been raised in the public domain against the use of gene-drive technologies to eradicate mosquitoes. The first objection invokes the concept of the 'sanctity of life' in order to claim that we should not drive an animal to extinction. In response, I follow Peter Singer in raising doubts about general appeals to the sanctity of life, and argue that neither individual mosquitoes nor mosquitoes species considered holistically are appropriately described as bearing a significant degree of moral status. The second objection claims that seeking to eradicate mosquitoes amounts to displaying unacceptable degrees of hubris. Although I argue that this objection also fails, I conclude by claiming that it raises the important point that we need to acquire more empirical data about, inter alia, the likely effects of mosquito eradication on the ecosystem, and the likelihood of gene-drive technology successfully eradicating the intended mosquito species, in order to adequately inform our moral analysis of gene-drive technologies in this context. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Linking in situ bioassays and population dynamics of macroinvertebrates to assess agricultural contamination in streams of the Argentine pampa.

Science.gov (United States)

Jergentz, S; Pessacq, P; Mugni, H; Bonetto, C; Schulz, R

2004-10-01

The two local crustacean species Hyalella curvispina and Macrobrachium borelli were chosen for assessment of agricultural contamination in two streams (Horqueta and Maguire) in the Argentine pampa. In parallel with in situ bioassays of both species, the population dynamics and the organismic drift of H. curvispina were investigated throughout the main period of insecticide application, from December 2001 to March 2002. In Maguire none of the current-use insecticides (chlorpyrifos, alpha-cypermethrin, and endosulfan) in question were detected throughout the sampling period. During 1-week intervals with no contamination by insecticides the survival rate of H. curvispina varied between 77 +/- 6% (+/- SE, n = 4) and 85 +/- 3%. In Horqueta during a week with a peak insecticide contamination of 64 microg/kg chlorpyrifos in the suspended particles, a mortality of 100% was observed in the in situ bioassays for both species, H. curvispina and M. borelli. At the same time, in Maguire H. curvispina showed reduced survival rates of 23 +/- 5% and 25 +/- 18% at the two sites, while the survival rate of M. borelli was 60 +/- 11% upstream and 93 +/- 5% downstream, below a wetland. During the period with 100% mortality of H. curvispina in Horqueta, the population density of this species decreased correspondingly, from 106 +/- 26 to 0 individuals/m(2). We conclude that in situ bioassays can be successfully linked to in-stream population dynamics for the same species and that this link is very useful for interpreting causal exposure-effect relationships.

Reciprocal Trophic Interactions and Transmission of Blood Parasites between Mosquitoes and Frogs

Directory of Open Access Journals (Sweden)

Todd G. Smith

2012-04-01

Full Text Available The relationship between mosquitoes and their amphibian hosts is a unique, reciprocal trophic interaction. Instead of a one-way, predator-prey relationship, there is a cyclical dance of avoidance and attraction. This has prompted spatial and temporal synchrony between organisms, reflected in emergence time of mosquitoes in the spring and choice of habitat for oviposition. Frog-feeding mosquitoes also possess different sensory apparatuses than do their mammal-feeding counterparts. The reciprocal nature of this relationship is exploited by various blood parasites that use mechanical, salivary or trophic transmission to pass from mosquitoes to frogs. It is important to investigate the involvement of mosquitoes, frogs and parasites in this interaction in order to understand the consequences of anthropogenic actions, such as implementing biocontrol efforts against mosquitoes, and to determine potential causes of the global decline of amphibian species.

Host reproductive phenology drives seasonal patterns of host use in mosquitoes.

Directory of Open Access Journals (Sweden)

Nathan D Burkett-Cadena

2011-03-01

Full Text Available Seasonal shifts in host use by mosquitoes from birds to mammals drive the timing and intensity of annual epidemics of mosquito-borne viruses, such as West Nile virus, in North America. The biological mechanism underlying these shifts has been a matter of debate, with hypotheses falling into two camps: (1 the shift is driven by changes in host abundance, or (2 the shift is driven by seasonal changes in the foraging behavior of mosquitoes. Here we explored the idea that seasonal changes in host use by mosquitoes are driven by temporal patterns of host reproduction. We investigated the relationship between seasonal patterns of host use by mosquitoes and host reproductive phenology by examining a seven-year dataset of blood meal identifications from a site in Tuskegee National Forest, Alabama USA and data on reproduction from the most commonly utilized endothermic (white-tailed deer, great blue heron, yellow-crowned night heron and ectothermic (frogs hosts. Our analysis revealed that feeding on each host peaked during periods of reproductive activity. Specifically, mosquitoes utilized herons in the spring and early summer, during periods of peak nest occupancy, whereas deer were fed upon most during the late summer and fall, the period corresponding to the peak in births for deer. For frogs, however, feeding on early- and late-season breeders paralleled peaks in male vocalization. We demonstrate for the first time that seasonal patterns of host use by mosquitoes track the reproductive phenology of the hosts. Peaks in relative mosquito feeding on each host during reproductive phases are likely the result of increased tolerance and decreased vigilance to attacking mosquitoes by nestlings and brooding adults (avian hosts, quiescent young (avian and mammalian hosts, and mate-seeking males (frogs.

A review of mixed malaria species infections in anopheline mosquitoes

Directory of Open Access Journals (Sweden)

Day Nicholas PJ

2011-08-01

Full Text Available Abstract Background In patients with malaria mixed species infections are common and under reported. In PCR studies conducted in Asia mixed infection rates often exceed 20%. In South-East Asia, approximately one third of patients treated for falciparum malaria experience a subsequent Plasmodium vivax infection with a time interval suggesting relapse. It is uncertain whether the two infections are acquired simultaneously or separately. To determine whether mixed species infections in humans are derived from mainly from simultaneous or separate mosquito inoculations the literature on malaria species infection in wild captured anopheline mosquitoes was reviewed. Methods The biomedical literature was searched for studies of malaria infection and species identification in trapped wild mosquitoes and artificially infected mosquitoes. The study location and year, collection methods, mosquito species, number of specimens, parasite stage examined (oocysts or sporozoites, and the methods of parasite detection and speciation were tabulated. The entomological results in South East Asia were compared with mixed infection rates documented in patients in clinical studies. Results In total 63 studies were identified. Individual anopheline mosquitoes were examined for different malaria species in 28 of these. There were 14 studies from Africa; four with species evaluations in individual captured mosquitoes (SEICM. One study, from Ghana, identified a single mixed infection. No mixed infections were identified in Central and South America (seven studies, two SEICM. 42 studies were conducted in Asia and Oceania (11 from Thailand; 27 SEICM. The proportion of anophelines infected with Plasmodium falciparum parasites only was 0.51% (95% CI: 0.44 to 0.57%, for P. vivax only was 0.26% (95% CI: 0.21 to 0.30%, and for mixed P. falciparum and P. vivax infections was 0.036% (95% CI: 0.016 to 0.056%. The proportion of mixed infections in mosquitoes was significantly higher

EPA Registers the Wolbachia ZAP Strain in Live Male Asian Tiger Mosquitoes

Science.gov (United States)

EPA registered a new mosquito biopesticide – ZAP Males® - that can reduce local populations of the type of mosquito (Aedes albopictus, or Asian Tiger Mosquitoes) that can spread numerous diseases of significant human health concern, including the Zika viru

Midgut of the non-hematophagous mosquito Toxorhynchites theobaldi (Diptera, Culicidae)

OpenAIRE

Godoy, Raquel S. M.; Fernandes, Kenner M.; Martins, Gustavo F.

2015-01-01

In most mosquito species, the females require a blood-feeding for complete egg development. However, in Toxorhynchites mosquitoes, the eggs develop without blood-feeding, and both females and males exclusively feed on sugary diets. The midgut is a well-understood organ in blood-feeding mosquitoes, but little is known about it in non-blood-feeding ones. In the present study, the detailed morphology of the midgut of Toxorhynchites theobaldi were investigated using histochemical and ultrastructu...

Comparison of solid-phase bioassays and ecoscores to evaluate the toxicity of contaminated soils

Energy Technology Data Exchange (ETDEWEB)

Lors, Christine [Universite Lille Nord de France, 1bis rue Georges Lefevre, 59044 Lille Cedex (France); Ecole des Mines de Douai, MPE-GCE, 941 rue Charles-Bourseul, 59500 Douai (France); Centre National de Recherche sur les Sites et Sols Pollues, 930 Boulevard Lahure, BP 537, 59505 Douai Cedex (France); Ponge, Jean-Francois, E-mail: ponge@mnhn.f [Museum National d' Histoire Naturelle, CNRS UMR 7179, 4 Avenue du Petit-Chateau, 91800 Brunoy (France); Martinez Aldaya, Maite [Museum National d' Histoire Naturelle, CNRS UMR 7179, 4 Avenue du Petit-Chateau, 91800 Brunoy (France); Damidot, Denis [Universite Lille Nord de France, 1bis rue Georges Lefevre, 59044 Lille Cedex (France); Ecole des Mines de Douai, MPE-GCE, 941 rue Charles-Bourseul, 59500 Douai (France)

2010-08-15

Five bioassays (inhibition of lettuce germination and growth, earthworm mortality, inhibition of springtail population growth, avoidance by springtails) were compared, using four coke factory soils contaminated by PAHs and trace elements, before and after biotreatment. For each bioassay, several endpoints were combined in an 'ecoscore', a measure of test sensitivity. Ecoscores pooled over all tested bioassays revealed that most organisms were highly sensitive to the concentration of 3-ring PAHs. When four soils were combined, behavioural tests using the springtail Folsomia candida showed higher ecoscores, i.e. they were most sensitive to soil contamination. However, despite overall higher sensitivity of behavioural tests, which could be used for cheap and rapid assessment of soil toxicity, especially at low levels of contamination, some test endpoints were more sensitive than others, and this may differ from a soil to another, pointing to the need for a battery of bioassays when more itemized results are expected. - The avoidance test using the soil springtail Folsomia candida is globally more sensitive to PAH contamination than acute and chronic toxicity bioassays using plants and animals but a battery of tests could reveal better in detail.

Comparison of solid-phase bioassays and ecoscores to evaluate the toxicity of contaminated soils

International Nuclear Information System (INIS)

Lors, Christine; Ponge, Jean-Francois; Martinez Aldaya, Maite; Damidot, Denis

2010-01-01

Five bioassays (inhibition of lettuce germination and growth, earthworm mortality, inhibition of springtail population growth, avoidance by springtails) were compared, using four coke factory soils contaminated by PAHs and trace elements, before and after biotreatment. For each bioassay, several endpoints were combined in an 'ecoscore', a measure of test sensitivity. Ecoscores pooled over all tested bioassays revealed that most organisms were highly sensitive to the concentration of 3-ring PAHs. When four soils were combined, behavioural tests using the springtail Folsomia candida showed higher ecoscores, i.e. they were most sensitive to soil contamination. However, despite overall higher sensitivity of behavioural tests, which could be used for cheap and rapid assessment of soil toxicity, especially at low levels of contamination, some test endpoints were more sensitive than others, and this may differ from a soil to another, pointing to the need for a battery of bioassays when more itemized results are expected. - The avoidance test using the soil springtail Folsomia candida is globally more sensitive to PAH contamination than acute and chronic toxicity bioassays using plants and animals but a battery of tests could reveal better in detail.

Periodic dynamic systems for infected hosts and mosquitoes

Directory of Open Access Journals (Sweden)

Oliva W. M.

1996-01-01

Full Text Available A mathematical model for the purpose of analysing the dynamic of the populations of infected hosts anf infected mosquitoes when the populations of mosquitoes are periodic in time is here presented. By the computation of a parameter lambda (the spectral radius of a certain monodromy matrix one can state that either the infection peters out naturally (lambda 1 the infection becomes endemic. The model generalizes previous models for malaria by considering the case of periodic coefficients; it is also a variation of that for gonorrhea. The main motivation for the consideration of this present model was the recent studies on mosquitoes at an experimental rice irrigation system, in the South-Eastern region of Brazil.

Periodic dynamic systems for infected hosts and mosquitoes

Directory of Open Access Journals (Sweden)

W. M. Oliva

1996-06-01

Full Text Available A mathematical model for the purpose of analysing the dynamic of the populations of infected hosts anf infected mosquitoes when the populations of mosquitoes are periodic in time is here presented. By the computation of a parameter lambda (the spectral radius of a certain monodromy matrix one can state that either the infection peters out naturally (lambda 1 the infection becomes endemic. The model generalizes previous models for malaria by considering the case of periodic coefficients; it is also a variation of that for gonorrhea. The main motivation for the consideration of this present model was the recent studies on mosquitoes at an experimental rice irrigation system, in the South-Eastern region of Brazil.

Nature, nurture and evolution of intra-species variation in mosquito arbovirus transmission competence.

Science.gov (United States)

Tabachnick, Walter J

2013-01-11

Mosquitoes vary in their competence or ability to transmit arthropod-borne viruses (arboviruses). Many arboviruses cause disease in humans and animals. Identifying the environmental and genetic causes of variation in mosquito competence for arboviruses is one of the great challenges in public health. Progress identifying genetic (nature) and environmental (nurture) factors influencing mosquito competence for arboviruses is reviewed. There is great complexity in the various traits that comprise mosquito competence. The complex interactions between environmental and genetic factors controlling these traits and the factors shaping variation in Nature are largely unknown. The norms of reaction of specific genes influencing competence, their distributions in natural populations and the effects of genetic polymorphism on phenotypic variation need to be determined. Mechanisms influencing competence are not likely due to natural selection because of the direct effects of the arbovirus on mosquito fitness. More likely the traits for mosquito competence for arboviruses are the effects of adaptations for other functions of these competence mechanisms. Determining these other functions is essential to understand the evolution and distributions of competence for arboviruses. This information is needed to assess risk from mosquito-borne disease, predict new mosquito-arbovirus systems, and provide novel strategies to mitigate mosquito-borne arbovirus transmission.

Nature, Nurture and Evolution of Intra-Species Variation in Mosquito Arbovirus Transmission Competence

Directory of Open Access Journals (Sweden)

Walter J. Tabachnick

2013-01-01

Full Text Available Mosquitoes vary in their competence or ability to transmit arthropod-borne viruses (arboviruses. Many arboviruses cause disease in humans and animals. Identifying the environmental and genetic causes of variation in mosquito competence for arboviruses is one of the great challenges in public health. Progress identifying genetic (nature and environmental (nurture factors influencing mosquito competence for arboviruses is reviewed. There is great complexity in the various traits that comprise mosquito competence. The complex interactions between environmental and genetic factors controlling these traits and the factors shaping variation in Nature are largely unknown. The norms of reaction of specific genes influencing competence, their distributions in natural populations and the effects of genetic polymorphism on phenotypic variation need to be determined. Mechanisms influencing competence are not likely due to natural selection because of the direct effects of the arbovirus on mosquito fitness. More likely the traits for mosquito competence for arboviruses are the effects of adaptations for other functions of these competence mechanisms. Determining these other functions is essential to understand the evolution and distributions of competence for arboviruses. This information is needed to assess risk from mosquito-borne disease, predict new mosquito-arbovirus systems, and provide novel strategies to mitigate mosquito-borne arbovirus transmission.

Nature, Nurture and Evolution of Intra-Species Variation in Mosquito Arbovirus Transmission Competence

Science.gov (United States)

Tabachnick, Walter J.

2013-01-01

Mosquitoes vary in their competence or ability to transmit arthropod-borne viruses (arboviruses). Many arboviruses cause disease in humans and animals. Identifying the environmental and genetic causes of variation in mosquito competence for arboviruses is one of the great challenges in public health. Progress identifying genetic (nature) and environmental (nurture) factors influencing mosquito competence for arboviruses is reviewed. There is great complexity in the various traits that comprise mosquito competence. The complex interactions between environmental and genetic factors controlling these traits and the factors shaping variation in Nature are largely unknown. The norms of reaction of specific genes influencing competence, their distributions in natural populations and the effects of genetic polymorphism on phenotypic variation need to be determined. Mechanisms influencing competence are not likely due to natural selection because of the direct effects of the arbovirus on mosquito fitness. More likely the traits for mosquito competence for arboviruses are the effects of adaptations for other functions of these competence mechanisms. Determining these other functions is essential to understand the evolution and distributions of competence for arboviruses. This information is needed to assess risk from mosquito-borne disease, predict new mosquito-arbovirus systems, and provide novel strategies to mitigate mosquito-borne arbovirus transmission. PMID:23343982

Mass mosquito trapping for malaria control in western Kenya

NARCIS (Netherlands)

Hiscox, Alexandra; Homan, Tobias; Mweresa, Collins K.; Maire, Nicolas; Pasquale, Di Aurelio; Masiga, Daniel; Oria, Prisca A.; Alaii, Jane; Leeuwis, Cees; Mukabana, Wolfgang R.; Takken, Willem; Smith, Thomas A.

2016-01-01

Background: Increasing levels of insecticide resistance as well as outdoor, residual transmission of malaria threaten the efficacy of existing vector control tools used against malaria mosquitoes. The development of odour-baited mosquito traps has led to the possibility of controlling malaria

Experience with NQA-1 quality assurance standards applied to in vitro bioassay

International Nuclear Information System (INIS)

Bihl, D.E.; MacLellan, J.A.

1991-10-01

On June 1, 1990, the large (about 4000 samples per year) excreta bioassay program at the Hanford Site ceased abruptly when the contract with the bioassay laboratory was terminated. An intense, high-priority effort was begun to replace the services on an interim basis until a new contract could be procured. Despite the urgency to get the excreta bioassay program going again, the Hanford Internal Dosimetry Program was constrained to use only labs that could meet stringent quality assurance (QA) requirements, even during the interim period. The QA requirements were based on NQA-1 with selected additions from the Environmental Protection Agency's QAMS 005/80 (EPA 1983) and the American Society for Testing and Materials' C 1009-83 (ASTM 1984). This constraint was driven both by legal reasons and by the Hanford Site contractors and workers not wanting the quality of the data to be sacrificed. Finding labs that could (1) handle the large throughput, (2) meet the technical requirements, and (3) pass the QA audit proved more difficult than first anticipated. This presentation focuses on the QA requirements that the labs had to meet and how those very broad requirements were applied specifically to excreta bioassay. 5 refs

Experience with NQA-1 quality assurance standards applied to in vitro bioassay

International Nuclear Information System (INIS)

Bihl, D.E.; MacLellan, J.A.

1991-01-01

On June 1, 1990, the large (about 4,000 samples per year) excreta bioassay program at the Hanford Site ceased abruptly when the contract with the bioassay laboratory was terminated. An intense, high-priority effort was begun to replace the services on an interim basis until a new contract could be procured. Despite the urgency to get the excreta bioassay program going again, the Hanford Internal Dosimetry Program was constrained to use only labs that could meet stringent quality assurance (QA) requirements, even during the interim period. The QA requirements were based on NQA-1 with selected additions from the Environmental Protection Agency's QAMS 005/80 (EPA 1983) and the American Society for Testing and Materials' C 1009-83 (ASTM 1984). This constraint was driven both by legal reasons and by the Hanford Site contractors and workers not wanting the quality of the data to be sacrificed. Finding labs that could (1) handle the large throughput, (2) meet the technical requirements, and (3) pass the QA audit proved more difficult than first anticipated. This presentation focuses on the QA requirements that the labs had to meet and how those very broad requirements were applied specifically to excreta bioassay

Uncovering the Repertoire of Endogenous Flaviviral Elements in Aedes Mosquito Genomes.

Science.gov (United States)

Suzuki, Yasutsugu; Frangeul, Lionel; Dickson, Laura B; Blanc, Hervé; Verdier, Yann; Vinh, Joelle; Lambrechts, Louis; Saleh, Maria-Carla

2017-08-01

Endogenous viral elements derived from nonretroviral RNA viruses have been described in various animal genomes. Whether they have a biological function, such as host immune protection against related viruses, is a field of intense study. Here, we investigated the repertoire of endogenous flaviviral elements (EFVEs) in Aedes mosquitoes, the vectors of arboviruses such as dengue and chikungunya viruses. Previous studies identified three EFVEs from Aedes albopictus cell lines and one from Aedes aegypti cell lines. However, an in-depth characterization of EFVEs in wild-type mosquito populations and individual mosquitoes in vivo has not been performed. We detected the full-length DNA sequence of the previously described EFVEs and their respective transcripts in several A. albopictus and A. aegypti populations from geographically distinct areas. However, EFVE-derived proteins were not detected by mass spectrometry. Using deep sequencing, we detected the production of PIWI-interacting RNA-like small RNAs, in an antisense orientation, targeting the EFVEs and their flanking regions in vivo The EFVEs were integrated in repetitive regions of the mosquito genomes, and their flanking sequences varied among mosquito populations. We bioinformatically predicted several new EFVEs from a Vietnamese A. albopictus population and observed variation in the occurrence of those elements among mosquitoes. Phylogenetic analysis of an A. aegypti EFVE suggested that it integrated prior to the global expansion of the species and subsequently diverged among and within populations. The findings of this study together reveal the substantial structural and nucleotide diversity of flaviviral integrations in Aedes genomes. Unraveling this diversity will help to elucidate the potential biological function of these EFVEs. IMPORTANCE Endogenous viral elements (EVEs) are whole or partial viral sequences integrated in host genomes. Interestingly, some EVEs have important functions for host fitness and

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 nanoparticles containing essential oil are a promising source of eco-friendly mosquito larvicidal products.

Temporal Coordination of Carbohydrate Metabolism during Mosquito Reproduction.

Directory of Open Access Journals (Sweden)

Yuan Hou

2015-07-01

Full Text Available Hematophagous mosquitoes serve as vectors of multiple devastating human diseases, and many unique physiological features contribute to the incredible evolutionary success of these insects. These functions place high-energy demands on a reproducing female mosquito, and carbohydrate metabolism (CM must be synchronized with these needs. Functional analysis of metabolic gene profiling showed that major CM pathways, including glycolysis, glycogen and sugar metabolism, and citrate cycle, are dramatically repressed at post eclosion (PE stage in mosquito fat body followed by a sharply increase at post-blood meal (PBM stage, which were also verified by Real-time RT-PCR. Consistent to the change of transcript and protein level of CM genes, the level of glycogen, glucose and trehalose and other secondary metabolites are also periodically accumulated and degraded during the reproductive cycle respectively. Levels of triacylglycerols (TAG, which represent another important energy storage form in the mosquito fat body, followed a similar tendency. On the other hand, ATP, which is generated by catabolism of these secondary metabolites, showed an opposite trend. Additionally, we used RNA interference studies for the juvenile hormone and ecdysone receptors, Met and EcR, coupled with transcriptomics and metabolomics analyses to show that these hormone receptors function as major regulatory switches coordinating CM with the differing energy requirements of the female mosquito throughout its reproductive cycle. Our study demonstrates how, by metabolic reprogramming, a multicellular organism adapts to drastic and rapid functional changes.

Play the Mosquito Game

Science.gov (United States)

... and Work Teachers' Questionnaire Malaria Play the Mosquito Game Play the Parasite Game About the games Malaria is one of the world's most common ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

The 10th Annual Bioassays and Bioanalytical Method Development Conference.

Science.gov (United States)

Ma, Mark; Tudan, Christopher; Koltchev, Dolly

2015-01-01

The 10th Annual Bioassays and Bioanalytical Method Development Conference was hosted in Boston, MA, USA on 20-22 October 2014. This meeting brought together scientists from the biopharmaceutical and life sciences industries, the regulatory agency and academia to share and discuss current trends in cell-based assays and bioanalysis, challenges and ideas for the future of the bioassays and bioanalytical method development. The experiences associated with new and innovative technologies were evaluated as well as their impact on the current bioassays methodologies and bioanalysis workflow, including quality, feasibility, outsourcing strategies and challenges, productivity and compliance. Several presentations were also provided by members of the US FDA, sharing both scientific and regulatory paradigms including a most recent update on the position of the FDA with specific aspects of the draft Bioanalytical Method Validation guidance following its review of the industry's responses. The meeting was jointly coincided with the 15th Annual Immunogenicity for Biotherapeutics meeting, allowing for attendees to also familiarize themselves with new and emerging approaches to overcome the effect of immunogenicity, in addition to investigative strategies.

Mosquito (Diptera: Culicidae Habitat Surveillance by Android Mobile Devices in Guangzhou, China

Directory of Open Access Journals (Sweden)

Tai-Ping Wu

2016-12-01

Full Text Available In 2014, Guangzhou City, South China, suffered from its worst outbreak of dengue fever in decades. Larval mosquito habitat surveillance was carried out by using android mobile devices in four study sites in May 2015. The habitats with larval mosquitoes were recorded as photo waypoints in OruxMaps or in videos. The total number of potential mosquito habitats was 342, of which 166 (49% were found to have mosquito larvae or pupae. Small containers were the most abundant potential habitats, accounting for 26% of the total number. More mosquito larvae and pupae, were found in small containers than in other objects holding water, for example, potted or hydroponic plants (p < 0.05. Mosquito larvae were collected from all plastic road barriers, used tires, and underground water. Aedes albopictus larvae were found from small and large containers, stumps, among others. The overall route index (RI was 11.3, which was 14.2 times higher than the grade C criteria of the National Patriotic Health Campaign Committee (NPHCC, China. The higher RIs were found from the bird and flower markets, schools, and underground parking lots. The results indicated that Android mobile devices are a convenient and useful tool for surveillance of mosquito habitats, and the enhancement of source reduction may benefit the prevention and control of dengue vector mosquitoes.

Altered vector competence in an experimental mosquito-mouse transmission model of Zika infection.

Directory of Open Access Journals (Sweden)

Ryuta Uraki

2018-03-01

Full Text Available Few animal models of Zika virus (ZIKV infection have incorporated arthropod-borne transmission. Here, we establish an Aedes aegypti mosquito model of ZIKV infection of mice, and demonstrate altered vector competency among three strains, (Orlando, ORL, Ho Chi Minh, HCM, and Patilas, PAT. All strains acquired ZIKV in their midguts after a blood meal from infected mice, but ZIKV transmission only occurred in mice fed upon by HCM, and to a lesser extent PAT, but not ORL, mosquitoes. This defect in transmission from ORL or PAT mosquitoes was overcome by intrathoracic injection of ZIKV into mosquito. Genetic analysis revealed significant diversity among these strains, suggesting a genetic basis for differences in ability for mosquito strains to transmit ZIKV. The intrathoracic injection mosquito-mouse transmission model is critical to understanding the influence of mosquitoes on ZIKV transmission, infectivity and pathogenesis in the vertebrate host, and represents a natural transmission route for testing vaccines and therapeutics.

Bioassay data and a retention-excretion model for systemic plutonium

International Nuclear Information System (INIS)

Leggett, R.W.

1984-05-01

The estimation of systemic burdens from urinalyses has been the most common and useful method of quantifying occupational exposures to plutonium. Problems arise in using this technique, however, because of inadequate modeling of human retention, translocation, and excretion of this element. Present methods for estimating the systemic burden from urinalyses were derived to a large extent from patterns observed in the first few months after exposure, but there is now evidence that these same patterns do not persist over long periods. In this report we collect and discuss data needed for the interpretation of bioassay results for Pu. These data are used to develop a model that describes the movement, retention, and excretion of systemic Pu in the human body in terms of explicitly identified anatomical compartments. This model may be used in conjunction with existing models and/or case-specific information concerning the translocation of Pu from the respiratory or gastrointestinal tract or from wounds to the bloodstream. Attention is restricted to the behavior of Pu after it has gained access to the bloodstream. There remain significant uncertainties concerning some aspects of the movement of Pu, particularly its translocation from the liver. An attempt has been made to construct the model in such a way as to elucidate those areas needing further attention. 98 references, 18 figures, 16 tables

Competence of Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus Mosquitoes as Zika Virus Vectors, China

Science.gov (United States)

Liu, Zhuanzhuan; Zhou, Tengfei; Lai, Zetian; Zhang, Zhenhong; Jia, Zhirong; Zhou, Guofa; Williams, Tricia; Xu, Jiabao; Gu, Jinbao; Zhou, Xiaohong; Lin, Lifeng; Yan, Guiyun

2017-01-01

In China, the prevention and control of Zika virus disease has been a public health threat since the first imported case was reported in February 2016. To determine the vector competence of potential vector mosquito species, we experimentally infected Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus mosquitoes and determined infection rates, dissemination rates, and transmission rates. We found the highest vector competence for the imported Zika virus in Ae. aegypti mosquitoes, some susceptibility of Ae. albopictus mosquitoes, but no transmission ability for Cx. quinquefasciatus mosquitoes. Considering that, in China, Ae. albopictus mosquitoes are widely distributed but Ae. aegypti mosquito distribution is limited, Ae. albopictus mosquitoes are a potential primary vector for Zika virus and should be targeted in vector control strategies. PMID:28430562

Competence of Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus Mosquitoes as Zika Virus Vectors, China.

Science.gov (United States)

Liu, Zhuanzhuan; Zhou, Tengfei; Lai, Zetian; Zhang, Zhenhong; Jia, Zhirong; Zhou, Guofa; Williams, Tricia; Xu, Jiabao; Gu, Jinbao; Zhou, Xiaohong; Lin, Lifeng; Yan, Guiyun; Chen, Xiao-Guang

2017-07-01

In China, the prevention and control of Zika virus disease has been a public health threat since the first imported case was reported in February 2016. To determine the vector competence of potential vector mosquito species, we experimentally infected Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus mosquitoes and determined infection rates, dissemination rates, and transmission rates. We found the highest vector competence for the imported Zika virus in Ae. aegypti mosquitoes, some susceptibility of Ae. albopictus mosquitoes, but no transmission ability for Cx. quinquefasciatus mosquitoes. Considering that, in China, Ae. albopictus mosquitoes are widely distributed but Ae. aegypti mosquito distribution is limited, Ae. albopictus mosquitoes are a potential primary vector for Zika virus and should be targeted in vector control strategies.

Long lasting persistence of Bacillus thuringiensis Subsp. israelensis (Bti in mosquito natural habitats.

Directory of Open Access Journals (Sweden)

Mathieu Tilquin

Full Text Available BACKGROUND: The detrimental effects of chemical insecticides on the environment and human health have lead to the call for biological alternatives. Today, one of the most promising solutions is the use of spray formulations based on Bacillus thuringiensis subsp. israelensis (Bti in insect control programs. As a result, the amounts of Bti spread in the environment are expected to increase worldwide, whilst the common belief that commercial Bti is easily cleared from the ecosystem has not yet been clearly established. METHODOLOGY/MAIN FINDINGS: In this study, we aimed to determine the nature and origin of the high toxicity toward mosquito larvae found in decaying leaf litter collected in several natural mosquito breeding sites in the Rhône-Alpes region. From the toxic fraction of the leaf litter, we isolated B. cereus-like bacteria that were further characterized as B. thuringiensis subsp. israelensis using PCR amplification of specific toxin genes. Immunological analysis of these Bti strains showed that they belong to the H14 group. We finally used amplified length polymorphism (AFLP markers to show that the strains isolated from the leaf litter were closely related to those present in the commercial insecticide used for field application, and differed from natural worldwide genotypes. CONCLUSIONS/SIGNIFICANCE: Our results raise the issue of the persistence, potential proliferation and environmental accumulation of human-spread Bti in natural mosquito habitats. Such Bti environmental persistence may lengthen the exposure time of insects to this bio-insecticide, thereby increasing the risk of resistance acquisition in target insects, and of a negative impact on non-target insects.

9 CFR 147.16 - Procedure for the evaluation of mycoplasma reactors by in vivo bio-assay (enrichment).

Science.gov (United States)

2010-01-01

... mycoplasma reactors by in vivo bio-assay (enrichment). 147.16 Section 147.16 Animals and Animal Products... the evaluation of mycoplasma reactors by in vivo bio-assay (enrichment). This procedure has been shown... publications: (a) Bigland, C. H. and A. J. DaMassa, “A Bio-Assay for Mycoplasma Gallisepticum.” In: United...

GLOBE Observer Mosquito Habitat Mapper: Geoscience and Public Health Connections

Science.gov (United States)

Low, R.; Boger, R. A.

2017-12-01

The global health crisis posed by vector-borne diseases is so great in scope that it is clearly insurmountable without the active help of tens-or hundreds- of thousands of individuals, working to identify and eradicate risk in communities around the world. Mobile devices equipped with data collection capabilities and visualization opportunities are lowering the barrier for participation in data collection efforts. The GLOBE Observer Mosquito Habitat Mapper (MHM) provides citizen scientists with an easy to use mobile platform to identify and locate mosquito breeding sites in their community. The app also supports the identification of vector taxa in the larvae development phase via a built-in key, which provides important information for scientists and public health officials tracking the rate of range expansion of invasive vector species and associated health threats. GO Mosquito is actively working with other citizen scientist programs across the world to ensure interoperability of data through standardization of metadata fields specific to vector monitoring, and through the development of APIs that allow for data exchange and shared data display through a UN-sponsored proof of concept project, Global Mosquito Alert. Avenues of application for mosquito vector data-both directly, by public health entities, and by modelers who employ remotely sensed environmental data to project mosquito population dynamics and epidemic disease will be featured.

Converting Mosquito Surveillance to Arbovirus Surveillance with Honey-Baited Nucleic Acid Preservation Cards.

Science.gov (United States)

Flies, Emily J; Toi, Cheryl; Weinstein, Philip; Doggett, Stephen L; Williams, Craig R

2015-07-01

Spatially and temporally accurate information about infectious mosquito distribution allows for pre-emptive public health interventions that can reduce the burden of mosquito-borne infections on human populations. However, the labile nature of arboviruses, the low prevalence of infection in mosquitoes, the expensive labor costs for mosquito identification and sorting, and the specialized equipment required for arbovirus testing can obstruct arbovirus surveillance efforts. The recently developed techniques of testing mosquito expectorate using honey-baited nucleic acid preservation cards or sugar bait stations allows a sensitive method of testing for infectious, rather than infected, mosquito vectors. Here we report the results from the first large-scale incorporation of honey-baited cards into an existing mosquito surveillance program. During 4 months of the peak virus season (January-April, 2014) for a total of 577 trap nights, we set CO2-baited encephalitis vector survey (EVS) light traps at 88 locations in South Australia. The collection container for the EVS trap was modified to allow for the placement of a honey-baited nucleic acid preservation card (FTA™ card) inside. After collection, mosquitoes were maintained in a humid environment and allowed access to the cards for 1 week. Cards were then analyzed for common endemic Australian arboviruses using a nested RT-PCR. Eighteen virus detections, including 11 Ross River virus, four Barmah Forest virus, and three Stratford virus (not previously reported from South Australia) were obtained. Our findings suggest that adding FTA cards to an existing mosquito surveillance program is a rapid and efficient way of detecting infectious mosquitoes with high spatial resolution.

Probability of Transmission of Malaria from Mosquito to Human Is Regulated by Mosquito Parasite Density in Naïve and Vaccinated Hosts.

Directory of Open Access Journals (Sweden)

Thomas S Churcher

2017-01-01

Full Text Available Over a century since Ronald Ross discovered that malaria is caused by the bite of an infectious mosquito it is still unclear how the number of parasites injected influences disease transmission. Currently it is assumed that all mosquitoes with salivary gland sporozoites are equally infectious irrespective of the number of parasites they harbour, though this has never been rigorously tested. Here we analyse >1000 experimental infections of humans and mice and demonstrate a dose-dependency for probability of infection and the length of the host pre-patent period. Mosquitoes with a higher numbers of sporozoites in their salivary glands following blood-feeding are more likely to have caused infection (and have done so quicker than mosquitoes with fewer parasites. A similar dose response for the probability of infection was seen for humans given a pre-erythrocytic vaccine candidate targeting circumsporozoite protein (CSP, and in mice with and without transfusion of anti-CSP antibodies. These interventions prevented infection more efficiently from bites made by mosquitoes with fewer parasites. The importance of parasite number has widespread implications across malariology, ranging from our basic understanding of the parasite, how vaccines are evaluated and the way in which transmission should be measured in the field. It also provides direct evidence for why the only registered malaria vaccine RTS,S was partially effective in recent clinical trials.

Behavioral Response of Aedes aegypti Mosquito towards Essential Oils Using Olfactometer

Science.gov (United States)

Uniyal, Ashish; Tikar, Sachin N; Mendki, Murlidhar J; Singh, Ram; Shukla, Shakti V; Agrawal, Om P; Veer, Vijay; Sukumaran, Devanathan

2016-01-01

Background: Aedes aegypti mosquito is responsible for transmitting human diseases like dengue and chikungunya. Personal or space protection with insect repellents is a practical approach to reducing human mosquito contact, thereby minimizing disease transmission. Essential oils are natural volatile substances from plants used as protective measure against blood-sucking mosquitoes. Methods: Twenty-three essential oils were evaluated for their repellent effect against Ae. aegypti female mosquito in laboratory conditions using Y-tube olfactometer. Results: The essential oils exhibited varying degree of repellency. Litsea oil showed 50.31%, 60.2 %, and 77.26% effective mean repellency at 1 ppm, 10 ppm and 100 ppm respectively, while DEET exhibited 59.63%, 68.63%, 85.48% and DEPA showed 57.97%, 65.43%, and 80.62% repellency at respective above concentrations. Statistical analysis revealed that among the tested essential oils, litsea oil had effective repellency in comparison with DEET and DEPA against Ae. aegypti mosquito at all concentration. Essential oils, DEET and DEPA showed significant repellence against Ae. aegypti (Poil exhibited effective percentage repellency similar to DEET and DEPA. The essential oils are natural plant products that may be useful for developing safer and newer herbal based effective mosquito repellents. PMID:27308295

Hypersensitivity to mosquito bite manifested as Skeeter syndrome

Directory of Open Access Journals (Sweden)

Rafael Pérez-Vanzzini

2015-02-01

Full Text Available The reactions to mosquito bites are immunological reactions with involvement of IgE, IgG and T cells mediated hypersensitivity. These reactions are common and range from small local reactions, large local reactions to systemic allergic reactions. Skeeter syndrome is defined as a large local induced inflammatory reaction to mosquito bite and sometimes accompanied by systemic symptoms such as fever and vomiting. Diagnosis is based on clinical history and physical examination, supported by the identification of specific IgE by skin testing. Treatment includes prevention, antihistamines and steroids in some cases. Specific immunotherapy still requires further study. This paper reports two cases of patients with hypersensitivity reactions to mosquito bites, which were evaluated in our center presenting positive skin tests.

Landscape Effects on the Presence, Abundance and Diversity of Mosquitoes in Mediterranean Wetlands.

Directory of Open Access Journals (Sweden)

David Roiz

Full Text Available Environment determines the distribution of mosquito-borne diseases in that it influences the vector-host-pathogen transmission cycle, including vector distribution, abundance and diversity. In this study, we analyse the relationship between environmental variables estimated by remote sensing and the spatial distribution (presence, abundance and diversity of seven mosquito species vectors of West Nile and other pathogens (Usutu, avian malaria and dirofilariasis in the Doñana Natural Park, Spain. Traps were distributed over an area of 54,984 ha divided into six ecological units: marshland, sand dunes, scrubland, ricefields, crops and fishponds. We collected mosquitoes once a month from up to 112 locations using BG-Sentinel traps baited with BG-lure and CO2 during March-November 2010. Hydroperiod, NDVI and Inundation surface were estimated at several resolution scales (100, 250, 500, 1000 and 2000 metres from corrected and normalized Landsat Images. We sampled 972,346 female mosquitoes, the most abundant species being Culex theileri, Ochlerotatus caspius, Culex modestus, Culex perexiguus, Culex pipiens, Anopheles atroparvus and Ochlerotatus detritus. Our results suggest that: (1 hydroperiod, inundation surface and NDVI are strongly related to the spatial distribution of mosquitoes; (2 the spatial scales used to measure these variables affected quantification of these relationships, the larger scale being more informative; (3 these relationships are species-specific; (4 hydroperiod is negatively related to mosquito presence and richness; (5 Culex abundance is positively related to hydroperiod; (6 NDVI is positively related to mosquito diversity, presence and abundance, except in the case of the two salt marsh species (Oc. caspius and Oc. detritus; and (7 inundation surfaces positively condition the abundance and richness of most species except the salt marsh mosquitoes. Remote sensing data provided reliable information for monitoring mosquito

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.

Mosquito Bites are Bad!

Centers for Disease Control (CDC) Podcasts

2016-08-11

In this podcast for kids, the Kidtastics talk about the dangers of mosquito bites and how to prevent getting them.  Created: 8/11/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/11/2016.

Controle de mosquitos com base em larvicidas no Estado do Rio Grande do Sul, Brasil: a escolha do agente de controle Mosquito control based on larvicides in the State of Rio Grande do Sul, Brazil: choice of the control agent

Directory of Open Access Journals (Sweden)

Antônio L. Ruas-Neto

1994-06-01

Full Text Available Desenvolveu-se neste estudo uma comparação entre larvicidas químicos e biológicos usados em programas de controle de mosquitos no Rio Grande do Sul. Em bioensaios de laboratório contra Culex quinquefasciatus constatou-se que as formulações biológicas líquidas Vectobac 12 AS e Teknar 3000 (Bacillus thuringiensis israelensis, ABG 6262 líquido e em pó (B. sphaericus 2362, foram altamente eficazes. Também as formulações experimentais de B. thuringiensis israelensis produzidas em laboratórios brasileiros foram consideradas adequadas. Entre as formulações químicas, os compostos piretróides Pirisa e K-Othrine produziram resultados melhores do que os organo-fosforados Lebaycid e Abate. Estes últimos produziram respostas dez vezes mais fracas do que o previsto em outros estudos. Em condições de campo, a dose de 1250 mg/m² para as formulações biológicas foi considerada adequada para a rotina das aplicações, porque permite superar as influências físicas do meio sobre os resultados. Somente as formulações de B. sphaericus produziram interrupções nas reinfestações dos focos de culicídeos observados. Períodos de até 39 semanas sem reinfestações foram observados em focos naturais e de um mês sem sobrevivência foi observado em tanques, onde procedia-se a reinfestação artificial. Este estudo sugere que as alternativas biológicas devem ser consideradas em programas de controle de mosquitos. Elas podem superar os problemas de resistência e eliminação, bem como da ausência de efeito residual nas aplicações de larvicidas.A comparison between chemical and biological larvicides in routine operations against mosquitoes in Rio Grande do Sul State was carried out in this study. In laboratory bioassays against Culex quinquefasciatus, biological formulations Vectobac 12 AS and Teknar 3000 (Bacillus thuringiensis israelensis as well as ABG 6262 (B. sphaericus 2362, both in liquid and powder form, were highly effective

A rapid and inexpensive bioassay to evaluate the decontamination of organophosphates.

Science.gov (United States)

Claborn, David M; Martin-Brown, Skylar A; Sagar, Sanjay Gupta; Durham, Paul

2012-01-01

An inexpensive and rapid bioassay using adult red flour beetles was developed for use in assessing the decontamination of environments containing organophosphates and related chemicals. A decontamination protocol was developed which demonstrated that 2 to 3 applications of 5% bleach solution were required to obtain nearly complete decontamination of malathion. The bioassay was also used to screen common household cleaners as potential decontaminating agents, but only 5% bleach was effective at improving survival of insects on steel plates treated with 25% malathion. A toxic degradation product (malaoxon) was detected using gas chromatography/mass spectrophotometry; this toxin affected the decontamination efficacy and resulted in continued toxicity to the beetles until subsequent decontaminations. The bioassay provides evidence to support the use of red flour beetles as a sensitive, less expensive method for determining safety levels of environments contaminated with malathion and other toxins, and may have application in the study of chemical warfare agents.

Comparative genomic analysis of Drosophila melanogaster and vector mosquito developmental genes.

Directory of Open Access Journals (Sweden)

Susanta K Behura

Full Text Available Genome sequencing projects have presented the opportunity for analysis of developmental genes in three vector mosquito species: Aedes aegypti, Culex quinquefasciatus, and Anopheles gambiae. A comparative genomic analysis of developmental genes in Drosophila melanogaster and these three important vectors of human disease was performed in this investigation. While the study was comprehensive, special emphasis centered on genes that 1 are components of developmental signaling pathways, 2 regulate fundamental developmental processes, 3 are critical for the development of tissues of vector importance, 4 function in developmental processes known to have diverged within insects, and 5 encode microRNAs (miRNAs that regulate developmental transcripts in Drosophila. While most fruit fly developmental genes are conserved in the three vector mosquito species, several genes known to be critical for Drosophila development were not identified in one or more mosquito genomes. In other cases, mosquito lineage-specific gene gains with respect to D. melanogaster were noted. Sequence analyses also revealed that numerous repetitive sequences are a common structural feature of Drosophila and mosquito developmental genes. Finally, analysis of predicted miRNA binding sites in fruit fly and mosquito developmental genes suggests that the repertoire of developmental genes targeted by miRNAs is species-specific. The results of this study provide insight into the evolution of developmental genes and processes in dipterans and other arthropods, serve as a resource for those pursuing analysis of mosquito development, and will promote the design and refinement of functional analysis experiments.