Larvicidal Activity of Nerium oleander against Larvae West Nile Vector Mosquito Culex pipiens (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Fouad El-Akhal

2015-01-01

Full Text Available Background. Outbreaks of the West Nile virus infection were reported in Morocco in 1996, 2003, and 2010. Culex pipiens was strongly suspected as the vector responsible for transmission. In the North center of Morocco, this species has developed resistance to synthetic insecticides. There is an urgent need to find alternatives to the insecticides as natural biocides. Objective. In this work, the insecticidal activity of the extract of the local plant Nerium oleander, which has never been tested before in the North center of Morocco, was studied on larval stages 3 and 4 of Culex pipiens. Methods. Biological tests were realized according to a methodology inspired from standard World Health Organization protocol. The mortality values were determined after 24 h of exposure and LC50 and LC90 values were calculated. Results. The extract had toxic effects on the larvae of culicid mosquitoes. The ethanolic extract of Nerium oleander applied against the larvae of Culex pipiens has given the lethal concentrations LC50 and LC90 in the order of 57.57 mg/mL and 166.35 mg/mL, respectively. Conclusion. This investigation indicates that N. oleander could serve as a potential larvicidal, effective natural biocide against mosquito larvae, particularly Culex pipiens.

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.

Single-step biosynthesis and characterization of silver nanoparticles using Zornia diphylla leaves: A potent eco-friendly tool against malaria and arbovirus vectors.

Science.gov (United States)

Govindarajan, Marimuthu; Rajeswary, Mohan; Muthukumaran, Udaiyan; Hoti, S L; Khater, Hanem F; Benelli, Giovanni

2016-08-01

Mosquitoes (Diptera: Culicidae) are vectors of important pathogens and parasites, including malaria, dengue, chikungunya, Japanese encephalitis, lymphatic filariasis and Zika virus. The application of synthetic insecticides causes development of resistance, biological magnification of toxic substances through the food chain, and adverse effects on the environment and human health. In this scenario, eco-friendly control tools of mosquito vectors are a priority. Here single-step fabrication of silver nanoparticles (AgNP) using a cheap aqueous leaf extract of Zornia diphylla as reducing and capping agent pf Ag(+) ions has been carried out. Biosynthesized AgNP were characterized by UV-visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction analysis (XRD). The acute toxicity of Z. diphylla leaf extract and biosynthesized AgNP was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Both the Z. diphylla leaf extract and Ag NP showed dose dependent larvicidal effect against all tested mosquito species. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 values of 12.53, 13.42 and 14.61μg/ml, respectively. Biosynthesized Ag NP were found safer to non-target organisms Chironomus circumdatus, Anisops bouvieri and Gambusia affinis, with the respective LC50 values ranging from 613.11 to 6903.93μg/ml, if compared to target mosquitoes. Overall, our results highlight that Z. diphylla-fabricated Ag NP are a promising and eco-friendly tool against larval populations of mosquito vectors of medical and veterinary importance, with negligible toxicity against other non-target organisms. Copyright © 2016 Elsevier B

Monthly prevalence and diversity of mosquitoes (Diptera: Culicidae in Fars Province, Southern Iran

Directory of Open Access Journals (Sweden)

Davood Keshavarzi

2017-02-01

Full Text Available Objective: To get new data about the ecology of mosquitoes, which would be valuable to develop programs for future provision of mosquito controls in the study area. Methods: During April to September 2012, larvae of mosquitoes were collected from six counties in south of Fars Province using dipping method. Characteristics of larval breeding places were considered based on water conditions. Species diversity was examined in terms of alpha and beta measures, with the intent of comparing mosquito diversity according to the typology of regions. Results: During this investigation, totally, 5 057 larvae of mosquitoes belonging to 5 genera and 17 different mosquito species were recognized, namely, Anopheles dthali, Anopheles fluviatilis, Anopheles stephensi, Anopheles superpictus, Culex quinquefasciatus (Cx. quinquefasciatus, Culex mimeticus, Culex perexiguus, Culex pipiens (Cx. pipiens, Culex tritaeniorhynchus, Culex theileri (Cx. theileri, Culex tritaeniorhynchus, Culex sinaiticus, Culex torrentium, Culex modestus, Ochlerotatus caspius, Culiseta longiareolata and Aedes vexans (Ae. vexans. This is the first record of Ae. vexans, Culex perexiguus and Culex modestus in the Province. Cx. pipiens (27.3%, Cx. theileri (15.9% and Cx. quinquefasciatus (9.4% were the most abundant species found respectively. Cx. pipiens reached the highest density in August and July, while Cx. theileri, Cx. quinquefasciatus and Ae. vexans were found in high numbers in June. Diversity analysis indicated the highest species diversity in the Mohr County (Margalef index of 1.41 and Shannon index of 1.7 and the lowest species diversity in the Lamerd County (Margalef index of 0.33 and Shannon index of 0.38. Conclusions: Regarding to this research, there are some potential vectors of medical and veterinary importance in Fars Province. Results of the present study may serve as a basis for risk assessment of emerging mosquito-borne diseases.

Larvicidal potentiality, longevity and fecundity inhibitory activities of Bacillus sphaericus (Bs G3-IV on vector mosquitoes, Aedes aegypti and Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

Arjunan Nareshkumar

2012-12-01

Full Text Available Intervention measures to control the transmission of vector-borne diseases include control of the vector population. In mosquito control, synthetic insecticides used against both the larvae (larvicides and adults (adulticides create numerous problems, such as environmental pollution, insecticide resistance and toxic hazards to humans. In the present study, a bacterial pesticide, Bacillus sphaericus (Bs G3-IV, was used to control the dengue and filarial vectors, Aedes aegypti and Culex quinquefasciatus. Bacillus sphaericus (Bs G3-IV was very effective against Aedes aegypti and Culex quinquefasciatus, showing significant larval mortality. Evaluated lethal concentrations (LC50 and LC90 were age-dependent, with early instars requiring a lower concentration compared with later stages of mosquitoes. Culex quinquefasciatus was more susceptible to Bacillus sphaericus (Bs G3-IV than was Aedes aegypti. Fecundity rate was highly reduced after treatment with different concentrations of Bacillus sphaericus (Bs G3-IV. Larval and pupal longevity both decreased after treatment with Bacillus sphaericus (Bs G3-IV, total number of days was lower in the B. sphaericus treatments compared with the control. Our results show the bacterial pesticide Bacillus sphaericus (Bs G3-IV to be an effective mosquito control agent that can be used for more integrated pest management programs.

Environmental and biological factors influencing Culex pipiens quinquefasciatus (Diptera: Culicidae) vector competence for West Nile Virus.

Science.gov (United States)

Richards, Stephanie L; Lord, Cynthia C; Pesko, Kendra N; Tabachnick, Walter J

2010-07-01

Interactions between environmental and biological factors affect the vector competence of Culex pipiens quinquefasciatus for West Nile virus. Three age cohorts from two Cx. p. quinquefasciatus colonies were fed blood containing a low- or high-virus dose, and each group was held at two different extrinsic incubation temperatures (EIT) for 13 days. The colonies differed in the way that they responded to the effects of the environment on vector competence. The effects of mosquito age on aspects of vector competence were dependent on the EIT and dose, and they changed depending on the colony. Complex interactions must be considered in laboratory studies of vector competence, because the extent of the genetic and environmental variation controlling vector competence in nature is largely unknown. Differences in the environmental (EIT and dose) and biological (mosquito age and colony) effects from previous studies of Cx. p. quinquefasciatus vector competence for St. Louis encephalitis virus are discussed.

Vector competence of Culex quinquefasciatus say from different regions of Brazil to Dirofilaria immitis

Directory of Open Access Journals (Sweden)

Ahid Silvia Maria Mendes

2000-01-01

Full Text Available The vector competence of Culex quinquefasciatus from five localities in Brazil to Dirofilaria immitis was evaluated experimentally. Females from each locality were fed on an infected dog (~ 6 microfilariae/µl blood. A sample of blood fed mosquitoes were dissected approximately 1 h after blood meal. These results demonstrated that all had ingested microfilariae (mean, 4.8 to 24.6 microfilariae/mosquito. Fifteen days after the infected blood meal, the infection and infective rates were low in all populations of Cx. quinquefasciatus. The mean number of infective larvae detected in the head and proboscis of these mosquitoes was 1-1.5. The vector efficiency, the number of microfilariae ingested/number of infective larvae, was low for all populations of Cx. quinquefasciatus. However, the survival rate for all populations was high (range 50-75%. The survival rate of Aedes aegypti assayed simultaneously for comparison was low (24.7%, while the vector efficiency was much higher than for Cx. quinquefasciatus. These data suggest that the vector competence of all assayed populations of Cx. quinquefasciatus to D. immitis in Brazil is similar and that this species is a secondary vector due to its low susceptibility. Nevertheless, vector capacity may vary between populations due to differences in biting frequency on dogs that has been reported in Brazil.

Larvicidal Activity of Cassia occidentalis (Linn. against the Larvae of Bancroftian Filariasis Vector Mosquito Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

Deepak Kumar

2014-01-01

Full Text Available Background & Objectives. The plan of this work was to study the larvicidal activity of Cassia occidentalis (Linn. against the larvae of Culex quinquefasciatus. These larvae are the most significant vectors. They transmit the parasites and pathogens which cause a deadly disease like filariasis, dengue, yellow fever, malaria, Japanese encephalitis, chikungunya, and so forth, which are considered harmful towards the population in tropic and subtropical regions. Methods. The preliminary laboratory trail was undertaken to determine the efficacy of petroleum ether and N-butanol extract of dried whole plant of Cassia occidentalis (Linn. belonging to the family Caesalpiniaceae at various concentrations against the late third instar larvae of Culex quinquefasciatus by following the WHO guidelines. Results. The results suggest that 100% mortality effect of petroleum ether and N-butanol extract of Cassia occidentalis (Linn. was observed at 200 and 300 ppm (parts per million. The results obviously showed use of plants in insect control as an alternative method for minimizing the noxious effect of some pesticide compounds on the environment. Thus the extract of Cassia occidentalis (Linn. is claimed as more selective and biodegradable agent. Conclusion. This study justified that plant Cassia occidentalis (Linn. has a realistic mortality result for larvae of filarial vector. This is safe to individual and communities against mosquitoes. It is a natural weapon for mosquito control.

Larvicidal Activity of Cassia occidentalis (Linn.) against the Larvae of Bancroftian Filariasis Vector Mosquito Culex quinquefasciatus.

Science.gov (United States)

Kumar, Deepak; Chawla, Rakesh; Dhamodaram, P; Balakrishnan, N

2014-01-01

Background & Objectives. The plan of this work was to study the larvicidal activity of Cassia occidentalis (Linn.) against the larvae of Culex quinquefasciatus. These larvae are the most significant vectors. They transmit the parasites and pathogens which cause a deadly disease like filariasis, dengue, yellow fever, malaria, Japanese encephalitis, chikungunya, and so forth, which are considered harmful towards the population in tropic and subtropical regions. Methods. The preliminary laboratory trail was undertaken to determine the efficacy of petroleum ether and N-butanol extract of dried whole plant of Cassia occidentalis (Linn.) belonging to the family Caesalpiniaceae at various concentrations against the late third instar larvae of Culex quinquefasciatus by following the WHO guidelines. Results. The results suggest that 100% mortality effect of petroleum ether and N-butanol extract of Cassia occidentalis (Linn.) was observed at 200 and 300 ppm (parts per million). The results obviously showed use of plants in insect control as an alternative method for minimizing the noxious effect of some pesticide compounds on the environment. Thus the extract of Cassia occidentalis (Linn.) is claimed as more selective and biodegradable agent. Conclusion. This study justified that plant Cassia occidentalis (Linn.) has a realistic mortality result for larvae of filarial vector. This is safe to individual and communities against mosquitoes. It is a natural weapon for mosquito control.

SURVAI VECTOR DAN RESERVOIR PENYAKIT ZOONOTIK YANG DITULARKAN OLEH ARTHROPODA DI DESA BASI, KECAMATAN DONDO KABUPATEN BUOL — TOLITOLI, SULAWESI TENGAH, INDONESIA

Directory of Open Access Journals (Sweden)

Tuti R. Hadi

2012-09-01

Full Text Available An ecological survey was conducted in Central Sulawesi to obtain information on the distri­bution of reservoir hosts and vectors of arthropod-borne zoonotic diseases. Serological test were done from human sera collected in the area against arboviral and rickettsial antigens. Three species of Culex mosquitoes known as potential vectors of arbovirosis: Cx. bitaeni-orhynchus, Cx. gelidus and Cx. tritaeniorhynchus, were found in the area surveyed. A known vector of scrub typhus, Leptotrombidium (L. deliensis, was also found in that area. Suspected reservoirs of arthropod-borne zoonosis in the area surveyed were chickens, ducks, cows, horses, monkeys and rats. The prevalence of antibodies against arbovirus group A antigens ( Chikungunya, Getah and Sindbis was 34,06%, 28,5% and 4,39%, against arbovirus group B antigen (Japanese Encepha­litis was 93,4% and none against Rickettsia tsutsugamushi and Rickettsia typhy antigens, out of 91 human sera examined. Antibodies were found in animal sera examined against arbovirus group A and arbovirus group B antigens in a variation of 11,8% — 100%. The prevalence of antibodies against R. tsutsugamushi antigen was 22,7% out of 22 rat sera examined.

Spatial variation in host feeding patterns of Culex tarsalis and the Culex pipiens complex (Diptera: Culicidae) in California.

Science.gov (United States)

Thiemann, T C; Lemenager, D A; Kluh, S; Carroll, B D; Lothrop, H D; Reisen, W K

2012-07-01

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) is now endemic in California across a variety of ecological regions that support a wide diversity of potential avian and mammalian host species. Because different avian hosts have varying competence for WNV, determining the blood-feeding patterns of Culex (Diptera: Culicidae) vectors is a key component in understanding the maintenance and amplification of the virus as well as tangential transmission to humans and horses. We investigated the blood-feeding patterns of Culex tarsalis Coquillett and members of the Culex pipiens L. complex from southern to northern California. Nearly 100 different host species were identified from 1,487 bloodmeals, by using the mitochondrial gene cytochrome c oxidase I (COI). Cx. tarsalis fed on a higher diversity of hosts and more frequently on nonhuman mammals than did the Cx. pipiens complex. Several WNV-competent host species, including house finch and house sparrow, were common bloodmeal sources for both vector species across several biomes and could account for WNV maintenance and amplification in these areas. Highly competent American crow, western scrub-jay and yellow-billed magpie also were fed upon often when available and are likely important as amplifying hosts for WNV in some areas. Neither species fed frequently on humans (Cx. pipiens complex [0.4%], Cx. tarsalis [0.2%]), but with high abundance, both species could serve as both enzootic and bridge vectors for WNV.

Host-feeding patterns of Culex pipiens and other potential mosquito vectors (Diptera: Culicidae) of West Nile virus (Flaviviridae) collected in Portugal.

Science.gov (United States)

Osório, Hugo Costa; Zé-Zé, Líbia; Alves, Maria João

2012-05-01

The host blood-feeding patterns of mosquito vectors affects the likelihood of human exposure to zoonotic pathogens, including West Nile Virus (family Flaviviridae, genus Flavivirus, WNV). In Portugal, data are unavailable regarding the blood-feeding habits of common mosquito species, including Culex pipiens L., considered the primary vector of WNV to humans. The sources of bloodmeals in 203 blood-fed mosquitoes of nine species collected from June 2007 to November 2010 in 34 Portuguese counties were analyzed by sequencing cytochrome-b partial fragments. Cx. pipiens was the most common species collected and successfully analyzed (n = 135/78). In addition, blood-fed females of the following species were analyzed: Ochlerotatus caspius Pallas (n = 20), Culex theileri Theobald (n = 16), Anopheles maculipennis s.l. Meigen (n = 10), Culiseta longiareolata Macquart (n = 7), Aedes aegypti L. (n = 6), Culex perexiguus Theobald (n = 3), Culiseta annulata Schrank (n = 3), and Ochlerotatus detritus Haliday (n = 3). The Cx. pipiens mosquitoes fed predominantly on birds (n = 55/78, 70.5%), with a high diversity of avian species used as hosts, although human blood was identified in 18 specimens (18/78, 23.1%). No significant differences were found between the host-feeding patterns of blood-fed Cx. pipiens collected in residential and nonresidential habitats. The occurrence of human derived blood meals and the presence of a mix avian-human bloodmeal accordingly suggest this species as a potential vector of WNV. Therefore, in Portugal, Cx. pipiens may play a role both in the avian-to-avian enzootic WNV cycle and in the avian-to-mammal transmission. In this context, the identity of Cx. pipiens (considering the forms molestus and pipiens) and the potential consequence on feeding behavior and WNV transmission are discussed.

Development of lymphatic filarial parasite Wuchereria bancrofti (Spirurida: Onchocercidae) in mosquito species (Diptera: Culicidae) fed artificially on microfilaremic blood.

Science.gov (United States)

Paily, K P; Hoti, S L; Balaraman, K

2006-11-01

The efficiency of laboratory colonies of mosquitoes such as Anopheles stephensi Liston, Aedes aegypti (L.) Liverpool strain, Ae. aegypti wild type, Aedes albopictus (Skuse), Culex tritaeniorhynchus Giles, Culex sitiens Wiedemann, and Armigeres subalbatus Coquillett in supporting the development of Wuchereria bancrofti (Cobbold) (Spirurida: Onchocercidae) microfilariae to infective larvae was investigated. The mosquitoes were fed on heparinized microfilaremic human blood by using a membrane-feeding unit with Parafilm as membrane. The rate of infection, parasite development, and parasite burden were compared with that in the known vector mosquito Culex quinquefasciatus Say. Cx. quinquefasciatus showed the highest percentage of infection, followed by Ae. aegypti Liverpool strain and An. stephensi. The rate of development of the parasite was more or less similar in all the three species, and infective larvae were found on day 13. When the larvae were harvested on day 17, Cx. quinquefasciatus yielded the highest numbers, followed by Ae. aegypti Liverpool strain and An. stephensi. The percentage of infection was low, and the development was slow in Cx. tritaeniorhynchus compared with the other susceptible species. The parasite developed to second-stage larvae only by day 22 and to infective larvae by day 28. When 2-wk-old Cx. tritaeniorhynchus were fed on microfilaremic blood, they could develop the parasite to infective larvae by day 13 postfeeding. All other species of mosquitoes tested were found to be refractory to parasite development. It is shown that Cx. quinquefasciatus is the most suitable mosquito host for the production of infective larvae. However, Ae. aegypti Liverpool strain, which is commonly used for Brugia malayi filarial parasite, also can be used for generation of W. bancrofti infective larvae to circumvent the problem of maintaining two mosquito species.

Studies on mosquitoes (Diptera: Culicidae and anthropic environment: 10- survey of adult behaviour of Culex nigripalpus and other species of Culex (Culex in South-Eastern Brazil

Directory of Open Access Journals (Sweden)

Oswaldo Paulo Forattini

1995-08-01

Full Text Available A survey of adult behaviour of Culex (Culex species was carried out from August 1992 through December 1993 in a human modified (anthropic environment in the Ribeira Valley, S.Paulo State, Brazil. Culex nigripalpus dominated the catches at several sites and it's tendency to increase in the anthropic environment became quite clear. Nevertheless no high level of synanthropy was demonstrated. So it seems that the mosquito may have a restricted role in natural arbovirus cycles. Nonetheless, Cx. nigripalpus must be considered a potential vector of arboviruses, especially St. Louis encephalitis virus outside dwellings.São relatados os resultados obtidos mediante coletas regulares de adultos de Culex (Culex em ambientes antrópico do Vale do Ribeira, SP, Brasil, no período de agosto de 1992 a dezembro de 1993. Pôde-se evidenciar a dominancia de Culex nigripalpus nas várias coletas efetuadas. Revelou-se claramente a preferência por parte desse mosquito em aumentar sua densidade no ambiente antrópico. Todavia, sua freqüência ao domicílio mostrou-se baixa, revelando fraco grau de sinantropia. Assim sendo, seu papel vetor de arbovirus parece restringir-se à participação no ciclo natural desses agentes infecciosos. Contudo, pode-se considerá-lo como vetor potencial no meio extradomiciliar. Nesse particular, seu papel pode não ser negligenciável, especialmente no que tange à possibilidade de transmissão de encefalite de S.Luís, cujo agente já foi assinalado na região.

Haematophageous vector monitoring in Djibouti city from 2008 to 2009: first records of Culex pipiens ssp. torridus (IGLISCH), and Anopheles sergentii (theobald).

Science.gov (United States)

Faulde, Michael K; Ahmed, Ammar A

2010-08-01

The Horn of Africa represents a region formerly known to be highly susceptible to mosquito-borne infectious diseases. In order to monitor and analyze the current presence and threat of vector mosquitoes, continuous and standardized trapping using CDC light traps without an additional CO2-generator has been carried out at six selected monitoring sites located in Djibouti City, from August 2008 until December 2009. An overall of 620 haematophageous Diptera were trapped, 603 (97.3%) were mosquitoes, 10 (1.6%) were sand flies, and 7 (1.1%) were biting midges, respectively. Genus distribution of mosquitoes revealed that 600 (99.5%) were Culex spp., 2 (0.3%) were Anopheles sergentii, and 1 (0.2%) was Aedes aegypti. Culex species were represented by Cx. quinquefasciatus (78.5%), and Cx. pipiens ssp. torridus (21.5%). The later species was first detected focally in early December 2009 showing a strongly increasing population density resulting in a maximum trap rate of 25 mosquitoes per trap night. Sand flies were all Sergentomyia antennata, and biting midges of the genus Culicoides were represented by C. nubeculosus (71.4%) and C. vexans (28.6 %). The findings included the first records for Cx. pipiens ssp. torridus and An. sergentii in Djibouti. However, none of the captured female Culex spp, the known vector for West Nile Virus, showed positive results for viral nucleic acids using WNV RT-real time PCR system. Also, females An. sergentii were Plasmodium falciparum and P. vivax circumsporozoite protein negative.

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

Directory of Open Access Journals (Sweden)

Domingo Montada Dorta

1993-12-01

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

Species composition, co-occurrence, association and affinity indices of mosquito larvae (Diptera: Culicidae) in Mazandaran Province, northern Iran.

Science.gov (United States)

Nikookar, Seyed Hassan; Azari-Hamidian, Shahyad; Fazeli-Dinan, Mahmoud; Nasab, Seyed Nouraddin Mousavi; Aarabi, Mohsen; Ziapour, Seyyed Payman; Enayati, Ahmadali

2016-05-01

Although considerable progress has been made in the past years in management of mosquito borne diseases such as malaria, dengue, yellow fever and West Nile fever through research in biology and ecology of the vectors, these diseases are still major threats to human health. Therefore, more research is required for better management of the diseases. This investigation provides information on the composition, co-occurrence, association and affinity indices of mosquito larvae in Mazandaran Province, northern Iran. In a large scale field study, mosquito larvae were collected from 120 sentinel sites in 16 counties in Mazandaran Province, using standard 350 ml dipper. Sampling took place monthly from May to December 2014. Collected larvae were mounted on glass slides using de Faure's medium and were diagnosed using morphological characters. Totally, 19,840 larvae were collected including three genera and 16 species from 120 larval habitats, as follows: Anopheles claviger, Anopheles hyrcanus, Anopheles maculipennis s.l., Anopheles marteri, Anopheles plumbeus, Anopheles pseudopictus, Culex pipiens, Culex tritaeniorhynchus, Culex torrentium, Culex perexiguus, Culex territans, Culex mimeticus, Culex hortensis, Culiseta annulata, Culiseta longiareolata, and Culiseta morsitans. Predominant species were Cx. pipiens and An. maculipennis s.l. which show the highest co-occurrence. The pair of species An. hyrcanus/An. pseudopictus showed significant affinity and association. High co-occurrence of the predominant species Cx. pipiens and An. maculipennis s.l. in the study area is of considerable importance in terms of vector ecology. It was also revealed that An. pseudopictus/An. hyrcanus often occur sympatrically indicating their common habitat requirements. The information may be equally important when vector control measures are considered. Copyright © 2016 Elsevier B.V. All rights reserved.

Culex pipiens and Stegomyia albopicta (= Aedes albopictus) populations as vectors for lineage 1 and 2 West Nile virus in Europe.

Science.gov (United States)

Brustolin, M; Talavera, S; Santamaría, C; Rivas, R; Pujol, N; Aranda, C; Marquès, E; Valle, M; Verdún, M; Pagès, N; Busquets, N

2016-06-01

The emerging disease West Nile fever is caused by West Nile virus (WNV), one of the most widespread arboviruses. This study represents the first test of the vectorial competence of European Culex pipiens Linnaeus 1758 and Stegomyia albopicta (= Aedes albopictus) (both: Diptera: Culicidae) populations for lineage 1 and 2 WNV isolated in Europe. Culex pipiens and S. albopicta populations were susceptible to WNV infection, had disseminated infection, and were capable of transmitting both WNV lineages. This is the first WNV competence assay to maintain mosquito specimens under environmental conditions mimicking the field (day/night) conditions associated with the period of maximum expected WNV activity. The importance of environmental conditions is discussed and the issue of how previous experiments conducted in fixed high temperatures may have overestimated WNV vector competence results with respect to natural environmental conditions is analysed. The information presented should be useful to policymakers and public health authorities for establishing effective WNV surveillance and vector control programmes. This would improve preparedness to prevent future outbreaks. © 2016 The Authors. Medical and Veterinary Entomology published by John Wiley & Sons Ltd on behalf of Royal Entomological Society.

Protection against mosquito vectors Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus using a novel insect repellent, ethyl anthranilate.

Science.gov (United States)

Islam, Johirul; Zaman, Kamaruz; Tyagi, Varun; Duarah, Sanjukta; Dhiman, Sunil; Chattopadhyay, Pronobesh

2017-10-01

Growing concern on the application of synthetic mosquito repellents in the recent years has instigated the identification and development of better alternatives to control different mosquito-borne diseases. In view of above, present investigation evaluates the repellent activity of ethyl anthranilate (EA), a non-toxic, FDA approved volatile food additive against three known mosquito vectors namely, Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus under laboratory conditions following standard protocols. Three concentration levels (2%, 5% and 10% w/v) of EA were tested against all the three selected mosquito species employing K & D module and arm-in-cage method to determine the effective dose (ED 50 ) and complete protection time (CPT), respectively. The repellent activity of EA was further investigated by modified arm-in-cage method to determine the protection over extended spatial ranges against all mosquito species. All behavioural situations were compared with the well-documented repellent N,N-diethylphenyl acetamide (DEPA) as a positive control. The findings demonstrated that EA exhibited significant repellent activity against all the three mosquitoes species. The ED 50 values of EA, against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus were found to be 0.96%, 5.4% and 3.6% w/v, respectively. At the concentration of 10% w/v, it provided CPTs of 60, 60 and 30min, respectively, against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes. Again in spatial repellency evaluation, EA was found to be extremely effective in repelling all the three tested species of mosquitoes. Ethyl anthranilate provided comparable results to standard repellent DEPA during the study. Results have concluded that the currently evaluated chemical, EA has potential repellent activity against some well established mosquito vectors. The study emphasizes that repellent activity of EA could be exploited for developing effective, eco

Ecological characterization and molecular differentiation of Culex pipiens complex taxa and Culex torrentium in eastern Austria.

Science.gov (United States)

Zittra, Carina; Flechl, Eva; Kothmayer, Michael; Vitecek, Simon; Rossiter, Heidemarie; Zechmeister, Thomas; Fuehrer, Hans-Peter

2016-04-11

Culex pipiens complex taxa differ in behaviour, ecophysiology and epidemiologic importance. Despite their epidemiologic significance, information on genetic diversity, occurrence and seasonal and spatial distribution patterns of the Cx. pipiens complex is still insufficient. Assessment of seasonal and spatial distribution patterns of Culex pipiens forms and their congener Cx. torrentium is crucial for the understanding of their vector-pathogen dynamics. Female mosquitoes were trapped from April-October 2014 twice a month for a 24-h time period with BG-sentinel traps at 24 sampling sites in eastern Austria, using carbon dioxide as attractant. Ecological forms of Cx. pipiens s.l. and their hybrids were differentiated using the CQ11 locus, and Cx. pipiens forms and their congener Cx. torrentium using the ACE-2 gene. Differential exploitation of ecological niches by Cx. pipiens forms and Cx. torrentium was analysed using likelihood ratio tests. Possible effects of environmental parameters on these taxa were tested using PERMANOVA based on distance matrices and, if significant, were modelled in nMDS ordination space to estimate non-linear relationships. For this study, 1476 Culex spp. were sampled. Culex pipiens f. pipiens representing 87.33 % of the total catch was most abundant, followed by hybrids of both forms (5.62 %), Cx. torrentium (3.79 %) and Cx. pipiens f. molestus (3.25 %). Differences in proportional abundances were found between land cover classes. Ecological parameters affecting seasonal and spatial distribution of these taxa in eastern Austria are precipitation duration, air temperature, sunlight and the interaction term of precipitation amount and the Danube water level, which can be interpreted as a proxy for breeding habitat availability. The Cx. pipiens complex of eastern Austria comprises both ecologically different forms, the mainly ornithophilic form pipiens and the mainly mammalophilic and anthropophilic form molestus. Heterogeneous agricultural

Baseline Susceptibility of Filarial Vector Culex quinquefasciatus (Diptera: Cu-licidae to Five Insecticides with Different Modes of Action in Southeast of Iran

Directory of Open Access Journals (Sweden)

Yaser Salim-Abadi

2017-12-01

Full Text Available Background: Culex quinquefasciatus (Diptera: Culicidae is an important vector for many human diseases. The aim of this study was to evaluate the susceptibility level of larval and adult stages of Cu. quinquefasciatus to different groups of WHO recommended insecticides for vector control.Methods: Larval stages of the Culex mosquitoes were collected from their natural habitats in Rafsanjan County at Kerman Province, southeast of Iran in 2016. Insecticide susceptibility status of adult female Cx. quinquefasciatus against DDT (4%, deltamethrin (0.05%, malathion 5%, and bendiocarb (0.1% were determined using WHO stand­ard insecticide susceptibility test. Additional test was carried out to determine the susceptibility status of larvae of Cx. quinquefasciatus to temephos. Bioassay data were analyzed by Probit program.Results: Cx. quinquefasciatus adults showed resistance to all four groups of the tested insecticides according to the WHO criteria for resistance evaluation. The lethal concentrations for 50% mortality (LC50 and 90% mortality (LC90 of temephos against Cx. quinquefasciatus larvae were 0.18mg/l and 0.78mg/l, respectively. This finding also con­firms resistance to temephos based on the WHO recommended instructions for resistance evaluation.Conclusion: Resistance to all groups of the tested insecticides should be considered for future vector control investi­gations in the study area.

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

The abundance and host-seeking behavior of culicine species (Diptera: Culicidae and Anopheles sinensis in Yongcheng city, people's Republic of China

Directory of Open Access Journals (Sweden)

Liu Xiao-Bo

2011-11-01

Full Text Available Abstract Background The knowledge of mosquito species diversity and the level of anthropophily exhibited by each species in a region are of great importance to the integrated vector control. Culicine species are the primary vectors of Japanese encephalitis (JE virus and filariasis in China. Anopheles sinensis plays a major role in the maintenance of Plasmodium vivax malaria transmission in China. The goal of this study was to compare the abundance and host-seeking behavior of culicine species and An. sinensis in Yongcheng city, a representative region of P. vivax malaria. Specifically, we wished to determine the relative attractiveness of different animal baits versus human bait to culicine species and An. sinensis. Results Culex tritaeniorhynchus was the most prevalent mosquito species and An. sinensis was the sole potential vector of P. vivax malaria in Yongcheng city. There were significant differences (P An. sinensis and Cx. tritaeniorhynchus collected in distinct baited traps. The relative attractiveness of animal versus human bait was similar towards both An. sinensis and Cx. tritaeniorhynchus. The ranking derived from the mean number of mosquitoes per bait indicated that pigs, goats and calves frequently attracted more mosquitoes than the other hosts tested (dogs, humans, and chickens. These trends were similar across all capture nights at three distinct villages. The human blood index (HBI of female An. sinensis was 2.94% when computed with mixed meals while 3.70% computed with only the single meal. 19:00~21:00 was the primary peak of host-seeking female An. sinensis while 4:00~5:00 was the smaller peak at night. There was significant correlation between the density of female An. sinensis and the average relative humidity (P Conclusions Pigs, goats and calves were more attractive to An. sinensis and Cx. tritaeniorhynchus than dogs, humans, and chickens. Female An. sinensis host-seeking activity mainly occurred from 19:00 to 21:00. Thus

Increased presence of the thermophilic mosquitoes and potential vectors Anopheles hyrcanus (Pallas, 1771) and Culex modestus Ficalbi 1889 in Central Europe’s lower Dyje River basin (South Moravia, Czech Republic)

Czech Academy of Sciences Publication Activity Database

Šebesta, O.; Gelbič, Ivan

2015-01-01

Roč. 51, č. 3 (2015), s. 272-280 ISSN 0037-9271 Institutional support: RVO:60077344 Keywords : Anopheles hyrcanus * Culex modestus * vector Subject RIV: EH - Ecology, Behaviour Impact factor: 0.575, year: 2015

Role of Culex and Anopheles mosquito species as potential vectors of rift valley fever virus in Sudan outbreak, 2007

Directory of Open Access Journals (Sweden)

Galal Fatma H

2010-03-01

Full Text Available Abstract Background Rift Valley fever (RVF is an acute febrile arthropod-borne viral disease of man and animals caused by a member of the Phlebovirus genus, one of the five genera in the family Bunyaviridae. RVF virus (RVFV is transmitted between animals and human by mosquitoes, particularly those belonging to the Culex, Anopheles and Aedes genera. Methods Experiments were designed during RVF outbreak, 2007 in Sudan to provide an answer about many raised questions about the estimated role of vector in RVFV epidemiology. During this study, adult and immature mosquito species were collected from Khartoum and White Nile states, identified and species abundance was calculated. All samples were frozen individually for further virus detection. Total RNA was extracted from individual insects and RVF virus was detected from Culex, Anopheles and Aedes species using RT-PCR. In addition, data were collected about human cases up to November 24th, 2007 to asses the situation of the disease in affected states. Furthermore, a historical background of the RVF outbreaks was discussed in relation to global climatic anomalies and incriminated vector species. Results A total of 978 mosquitoes, belonging to 3 genera and 7 species, were collected during Sudan outbreak, 2007. Anopheles gambiae arabiensis was the most frequent species (80.7% in White Nile state. Meanwhile, Cx. pipiens complex was the most abundant species (91.2% in Khartoum state. RT-PCR was used and successfully amplified 551 bp within the M segment of the tripartite negative-sense single stranded RNA genome of RVFV. The virus was detected in female, male and larval stages of Culex and Anopheles species. The most affected human age interval was 15-29 years old followed by ≥ 45 years old, 30-44 years old, and then 5-14 years old. Regarding to the profession, housewives followed by farmers, students, shepherd, workers and the free were more vulnerable to the infection. Furthermore, connection between

Larvicidal potential of Cyathea species against Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

Johnson Marimuthu alias Antonysamy

2017-05-01

Full Text Available Resistance to insecticides has persuaded researchers to find new methods to control Culex quinquefasciatus proliferation. Plants may be a source of alternative agents for mosquito control due to ever-growing insecticide resistance in mosquito vectors and environmental imbalance caused by synthetic insecticides. The present study was intended to study the larvicidal activity of selected Cyathea species against the filarial vector Culex quinquefasciatus. Larvicidal potential of different extracts were evaluated and larval mortality were recorded. The larvae were more sensitive to ethanolic extracts of studied three Cyathea species when compared to other extracts. Acetone, chloroform and petroleum ether extracts were considered to be less effective. The LC50 values of different extracts ranged from 320.72 to 657.03 µg/ml. The results exhibited that the tested three Cyathea species showed concentration dependent potential larvicidal effects and also provide an indication of possible bioactive properties.

Environmental and biological factors influencing Culex pipiens quinquefasciatus Say (Diptera: Culicidae) vector competence for Saint Louis encephalitis virus.

Science.gov (United States)

Richards, Stephanie L; Lord, Cynthia C; Pesko, Kendra; Tabachnick, Walter J

2009-08-01

Complex interactions between environmental and biological factors influence the susceptibility of Culex pipiens quinquefasciatus to St. Louis encephalitis virus and could affect the epidemiology of virus transmission. Similar interactions could have epidemiologic implications for other vector-virus systems. We conducted an experiment to examine four such factors in combination: mosquito age, extrinsic incubation temperature (EIT), virus dose, and colony. The proportion of mosquitoes with body infections or disseminated infections varied between colonies, and was dependant on age, EIT, and dose. We also show that the probability of a body or leg infection interacted in complex ways between colonies, ages, EITs, and doses. The complex interactive effects of environmental and biological factors must be taken into account for studies of vector competence and epidemiology, especially when laboratory studies are used to generalize to natural transmission dynamics where the extent of variation is largely unknown.

Preliminary findings on Bagaza virus (Flavivirus: Flaviviridae growth kinetics, transmission potential & transovarial transmission in three species of mosquitoes

Directory of Open Access Journals (Sweden)

A B Sudeep

2013-01-01

Full Text Available Background & objectives: Bagaza virus (BAGV, a flavivirus synonymous with Israel turkey meningoencephalitis virus, has been found to circulate in India. BAGV has recently been held responsible for inducing febrile illness in humans and causing unusually high mortality to wild birds in Spain. A study was therefore, undertaken to determine its replication kinetics in certain mosquitoes and to determine vector competence and potential of the mosquitoes to transmit BAGV experimentally. Methods: Aedes aegypti, Culex tritaeniorhynchus and Cx quinquefasciatus mosquitoes were inoculated with BAGV; samples were harvested every day and titrated in BHK-21 cell line. Vector competence and experimental transmission were determined by examining the saliva of infected mosquitoes for virus and induction of sickness in suckling mice, respectively. Results: Cx. tritaeniorhynchus and Ae. aegypti mosquitoes yielded 5 log 10 and 4.67 log 10 TCID 50 /ml of virus on day 3 post-infection (PI, respectively while Cx. quinquefasciatus yielded a titre of 4 log 10 TCID 50 /ml on day 4 PI. BAGV was detected in saliva of all the infected mosquitoes demonstrating their vector competence. Experimental transmission of BAGV to infant mice as well as transovarial transmission was demonstrated by Cx. tritaeniorhynchus but not by Ae. aegypti and Cx. quinquefasciatus mosquitoes. Interpretation & conclusions: Replication of BAGV to high titres and dissemination to saliva in three most prevalent mosquitoes in India is of immense public health importance. Though no major outbreak involving man has been reported yet, BAGV has a potential to cause outbreaks in future.

"Bird biting" mosquitoes and human disease: a review of the role of Culex pipiens complex mosquitoes in epidemiology.

Science.gov (United States)

Farajollahi, Ary; Fonseca, Dina M; Kramer, Laura D; Marm Kilpatrick, A

2011-10-01

The transmission of vector-borne pathogens is greatly influenced by the ecology of their vector, which is in turn shaped by genetic ancestry, the environment, and the hosts that are fed on. One group of vectors, the mosquitoes in the Culex pipiens complex, play key roles in the transmission of a range of pathogens including several viruses such as West Nile and St. Louis encephalitis viruses, avian malaria (Plasmodium spp.), and filarial worms. The Cx. pipiens complex includes Culex pipiens pipiens with two forms, pipiens and molestus, Culex pipiens pallens, Culex quinquefasciatus, Culex australicus, and Culex globocoxitus. While several members of the complex have limited geographic distributions, Cx. pipienspipiens and Cx. quinquefasciatus are found in all known urban and sub-urban temperate and tropical regions, respectively, across the world, where they are often principal disease vectors. In addition, hybrids are common in areas of overlap. Although gaps in our knowledge still remain, the advent of genetic tools has greatly enhanced our understanding of the history of speciation, domestication, dispersal, and hybridization. We review the taxonomy, genetics, evolution, behavior, and ecology of members of the Cx. pipiens complex and their role in the transmission of medically important pathogens. The adaptation of Cx. pipiens complex mosquitoes to human-altered environments led to their global distribution through dispersal via humans and, combined with their mixed feeding patterns on birds and mammals (including humans), increased the transmission of several avian pathogens to humans. We highlight several unanswered questions that will increase our ability to control diseases transmitted by these mosquitoes. Copyright © 2011 Elsevier B.V. All rights reserved.

An Ecological Survey of Mosquitoes and the Distribution of Japanese Encephalitis Virus in Ishikawa Prefecture, Japan, between 2010 and 2014.

Science.gov (United States)

Murakami, Manabu; Hori, Kiyoe; Kitagawa, Yoko; Oikawa, Yosaburo; Kamimura, Kiyoshi; Takegami, Tsutomu

2017-07-24

Japanese encephalitis virus (JEV) is a flavivirus, responsible for over 30,000 annual cases of encephalitis worldwide, with a mortality rate of approximately 30%. Therefore, it is important to examine the distribution of mosquitos carrying JEV in the fields, even though recently, the number of Japanese encephalitis cases has been approximately 5 per year in Japan. We report the seasonal dynamics of mosquitoes between 2010 and 2014 in Ishikawa Prefecture, Japan. We collected 39,308 female adult mosquitoes, 98.2% of which were classified as Culex tritaeniorhynchus Giles. We identified JEV genomic RNA belonging to genotype 1 from the homogenate of Cx. tritaeniorhynchus, collected during our study using reverse transcription-PCR and nucleotide sequencing techniques. Our results indicate that mosquito vectors for JEV are distributed not only in areas in Ishikawa, but also throughout Japan, and the results suggest that we must be careful regarding JEV outbreaks in Japan in the future.

Toxicity of seaweed-synthesized silver nanoparticles against the filariasis vector Culex quinquefasciatus and its impact on predation efficiency of the cyclopoid crustacean Mesocyclops longisetus.

Science.gov (United States)

Murugan, Kadarkarai; Benelli, Giovanni; Ayyappan, Suganya; Dinesh, Devakumar; Panneerselvam, Chellasamy; Nicoletti, Marcello; Hwang, Jiang-Shiou; Kumar, Palanisamy Mahesh; Subramaniam, Jayapal; Suresh, Udaiyan

2015-06-01

Nearly 1.4 billion people in 73 countries worldwide are threatened by lymphatic filariasis, a parasitic infection that leads to a disease commonly known as elephantiasis. Filariasis is vectored by mosquitoes, with special reference to the genus Culex. The main control tool against mosquito larvae is represented by treatments with organophosphates and insect growth regulators, with negative effects on human health and the environment. Recently, green-synthesized nanoparticles have been proposed as highly effective larvicidals against mosquito vectors. In this research, we attempted a reply to the following question: do green-synthesized nanoparticles affect predation rates of copepods against mosquito larvae? We proposed a novel method of seaweed-mediated synthesis of silver nanoparticles using the frond extract of Caulerpa scalpelliformis. The toxicity of the seaweed extract and silver nanoparticles was assessed against the filarial vector Culex quinquefasciatus. Then, we evaluated the predatory efficiency of the cyclopoid crustacean Mesocyclops longisetus against larval instars of C. quinquefasciatus in a nanoparticle-contaminated water environment. Green-synthesized silver nanoparticles were characterized by UV-vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In mosquitocidal assays, the LC₅₀ values of the C. scalpelliformis extract against C. quinquefasciatus were 31.38 ppm (I), 46.49 ppm (II), 75.79 ppm (III), 102.26 ppm (IV), and 138.89 ppm (pupa), while LC₅₀ of silver nanoparticles were 3.08 ppm, (I), 3.49 ppm (II), 4.64 ppm (III), 5.86 ppm (IV), and 7.33 ppm (pupa). The predatory efficiency of the copepod M. longisetus in the control treatment was 78 and 59% against I and II instar larvae of C. quinquefasciatus. In a nanoparticle-contaminated environment, predation efficiency was 84 and 63%, respectively. Predation was higher against first instar larvae over other instars

Spatio-Temporal Distribution of Vector-Host Contact (VHC) Ratios and Ecological Niche Modeling of the West Nile Virus Mosquito Vector, Culex quinquefasciatus, in the City of New Orleans, LA, USA.

Science.gov (United States)

Sallam, Mohamed F; Michaels, Sarah R; Riegel, Claudia; Pereira, Roberto M; Zipperer, Wayne; Lockaby, B Graeme; Koehler, Philip G

2017-08-08

The consistent sporadic transmission of West Nile Virus (WNV) in the city of New Orleans justifies the need for distribution risk maps highlighting human risk of mosquito bites. We modeled the influence of biophysical and socioeconomic metrics on the spatio-temporal distributions of presence/vector-host contact (VHC) ratios of WNV vector, Culex quinquefasciatus , within their flight range . Biophysical and socioeconomic data were extracted within 5-km buffer radii around sampling localities of gravid female Culex quinquefasciatus . The spatio-temporal correlations between VHC data and 33 variables, including climate, land use-land cover (LULC), socioeconomic, and land surface terrain were analyzed using stepwise linear regression models (RM). Using MaxEnt, we developed a distribution model using the correlated predicting variables. Only 12 factors showed significant correlations with spatial distribution of VHC ratios ( R ² = 81.62, p < 0.01). Non-forested wetland (NFWL), tree density (TD) and residential-urban (RU) settings demonstrated the strongest relationship. The VHC ratios showed monthly environmental resilience in terms of number and type of influential factors. The highest prediction power of RU and other urban and built up land (OUBL), was demonstrated during May-August. This association was positively correlated with the onset of the mosquito WNV infection rate during June. These findings were confirmed by the Jackknife analysis in MaxEnt and independently collected field validation points. The spatial and temporal correlations of VHC ratios and their response to the predicting variables are discussed.

Mapping of zones potentially occupied by Aedes vexans and Culex poicilipes mosquitoes, the main vectors of Rift Valley fever in Senegal

Directory of Open Access Journals (Sweden)

Yves M. Tourre

2008-11-01

Full Text Available A necessary condition for Rift Valley fever (RVF emergence is the presence of Aedes (Aedimorphus vexans and Culex (Culex poicilipes mosquitoes carrying the arbovirus and responsible for the infection. This paper presents a detailed mapping in the Sahelian region of Senegal of zones potentially occupied by these mosquitoes (ZPOMs whose population density is directly linked to ecozones in the vicinity of small ponds. The vectors habitats and breeding sites have been characterized through an integrated approach combining remote sensing technology, geographical information systems, geographical positioning systems and field observations for proper geo-referencing. From five SPOT-5 images (~10 m spatial resolution with appropriate channels, a meridional composite transect of 290 x 60 km was first constructed at the height of the summer monsoon. Subsequent ZPOMs covered major ecozones from north to south with different hydrological environments and different patterns pond distributions. It was found that an overall area of 12,817 ha ± 10% (about 0.8% of the transect is occupied by ponds with an average ZPOM 17 times larger than this (212,813 ha ± 10% or about 14% of the transect. By comparing the very humid year of 2003 with 2006 which had just below normal rainfall, the ZPOMs inter-annual variability was analyzed in a sandy-clayey ecozone with an important hydrofossil riverbed within the Ferlo region of Senegal. Very probably contributing to an increased abundance of vectors by the end of August 2003, it was shown that the aggregate pond area was already about 22 times larger than in August 2006, corresponding to an approximately five times larger total ZPOM. The results show the importance of pin-pointing small ponds (sizes down to 0.1 ha and their geographical distribution in order to assess animal exposure to the RVF vectors.

Bionomics of Culex quinquefasciatus within urban areas of Rio de Janeiro, Southeastern Brazil

Directory of Open Access Journals (Sweden)

Mariana Rocha David

2012-10-01

Full Text Available OBJECTIVE: To evaluate density, parity rates, daily survival and longevity of natural populations of Culex quinquefasciatus in three neighborhoods with distinct socio-economic and infrastructure profiles. METHODS: Mosquito collections of the Culex quinquefasciatus species were performed weekly during two four month periods, from August to November 2008 (spring and March to June 2009 (fall, in a favela (slum, a suburban area and a middle class area of Rio de Janeiro, Southeastern Brazil. Collections were performed with backpack aspirators, in 20 randomly selected houses in each area per week, during 15-20 minutes per house. Ovaries were removed from captured females and classified as initial, intermediary or final stage. Furthermore, females were dissected for determination of parity based on the condition of the tracheal system. Mosquito survival rate and longevity were estimated on a per month basis for each neighborhood. RESULTS: We collected a total of 2,062 Culex quinquefasciatus, but monthly vector density was not correlated with temperature and rainfall. We dissected the ovaries of 625 Culex quinquefasciatus, and overall, there was a higher proportion of nulliparous females during the dryer months, while gravid females were more frequent in rainy months. In the middle class neighborhood, the parity rate reached up to 93.75% with survivorship of 0.979. Lower parity and survival rates were obtained in the suburban area (as low as 36.4% parity and 0.711 daily survival. Up to 84.7% of Culex quinquefasciatus females could survive the eight day period needed to complete West Nile Virus incubation. CONCLUSIONS: The survival rate of Culex quinquefasciatus varied significantly between the neighborhoods. This suggests that vectorial capacity and disease transmission risk may vary greatly between different urban areas, which is potentially useful information for vector control programs.

Larvicidal activity of Lawsonia inermis and Murraya exotica leaves extract on filarial vector, Culex quinquefasciatus.

Directory of Open Access Journals (Sweden)

K. Dass

2014-06-01

Full Text Available Extensive use of synthetic and chemical insecticides to control mosquitoes result in environment hazards and development of resistance in vector species. This research work is about an alternative mosquito control method that is considered as safe to environment and non-target species and also bio-degradable. Hence an attempt was made to study the larvicidal effect of the extract of Lawsonia inermis and Murraya exotica leaves on III and IV instar larva and pupa of Culex quinquefasciatus. The LC50 value of Murraya exotica for III and IV instar larvae and pupae is 135.539 ppm, 154.361 ppm and 178.571 ppm respectively. Likewise for Lawsonia inermis it is 139.057 for III instar, 163.630 for IV instar and 188.151 for the pupa. Of these, two plants Murraya exotica plant extract is more effective than the Lawsonia inermis.

Exploring genetic variation in haplotypes of the filariasis vector Culex quinquefasciatus (Diptera: Culicidae) through DNA barcoding.

Science.gov (United States)

Vadivalagan, Chithravel; Karthika, Pushparaj; Murugan, Kadarkarai; Panneerselvam, Chellasamy; Del Serrone, Paola; Benelli, Giovanni

2017-05-01

Culex quinquefasciatus (Diptera: Culicidae) is a vector of many pathogens and parasites of humans, as well as domestic and wild animals. In urban and semi-urban Asian countries, Cx. quinquefasciatus is a main vector of nematodes causing lymphatic filariasis. In the African region, it vectors the Rift Valley fever virus, while in the USA it transmits West Nile, St. Louis encephalitis and Western equine encephalitis virus. In this study, DNA barcoding was used to explore the genetic variation of Cx. quinquefasciatus populations from 88 geographical regions. We presented a comprehensive approach analyzing the effectiveness of two gene markers, i.e. CO1 and 16S rRNA. The high threshold genetic divergence of CO1 (0.47%) gene was reported as an ideal marker for molecular identification of this mosquito vector. Furthermore, null substitutions were lower in CO1 if compared to 16S rRNA, which influenced its differentiating potential among Indian haplotypes. NJ tree was well supported with high branch values for CO1 gene than 16S rRNA, indicating ideal genetic differentiation among haplotypes. TCS haplotype network revealed 14 distinct clusters. The intra- and inter-population polymorphism were calculated among the global and Indian Cx. quinquefasciatus lineages. The genetic diversity index Tajima' D showed negative values for all the 4 intra-population clusters (G2-4, G10). Fu's FS showed negative value for G10 cluster, which was significant and indicated recent population expansion. However, the G2-G4 (i.e. Indian lineages) had positive values, suggesting a bottleneck effect. Overall, our research firstly shed light on the genetic differences among the haplotypes of Cx. quinquefasciatus species complex, adding basic knowledge to the molecular ecology of this important mosquito vector. Copyright © 2017 Elsevier B.V. All rights reserved.

Loss of genetic diversity in Culex quinquefasciatus targeted by a lymphatic filariasis vector control program in Recife, Brazil.

Science.gov (United States)

Cartaxo, Marina F S; Ayres, Constância F J; Weetman, David

2011-09-01

Recife is one of the largest cities in north-eastern Brazil and is endemic for lymphatic filariasis transmitted by Culex quinquefasciatus. Since 2003 a control program has targeted mosquito larvae by elimination of breeding sites and bimonthly application of Bacillus sphaericus. To assess the impact of this program on the local vector population we monitored the genetic diversity and differentiation of Cx. quinquefasciatus using microsatellites and a B. sphaericus-resistance associated mutation (cqm1(REC)) over a 3-year period. We detected a significant but gradual decline in allelic diversity, which, coupled with subtle temporal genetic structure, suggests a major impact of the control program on the vector population. Selection on cqm1(REC) does not appear to be involved with loss of neutral diversity from the population, with no temporal trend in resistant allele frequency and no correlation with microsatellite differentiation. The evidence for short-term genetic drift we detected suggests a low ratio of effective population size: census population size for Cx. quinquefasciatus, perhaps coupled with strong geographically-restricted population structure. Spatial definition of populations will be an important step for success of an expanded vector control program. Copyright © 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

European Aedes albopictus and Culex pipiens Are Competent Vectors for Japanese Encephalitis Virus.

Directory of Open Access Journals (Sweden)

Mélissanne de Wispelaere

2017-01-01

Full Text Available Japanese encephalitis virus (JEV is the causative agent of Japanese encephalitis, the leading cause of viral encephalitis in Asia. JEV transmission cycle involves mosquitoes and vertebrate hosts. The detection of JEV RNA in a pool of Culex pipiens caught in 2010 in Italy raised the concern of a putative emergence of the virus in Europe. We aimed to study the vector competence of European mosquito populations, such as Cx. pipiens and Aedes albopictus for JEV genotypes 3 and 5.After oral feeding on an infectious blood meal, mosquitoes were dissected at various times post-virus exposure. We found that the peak for JEV infection and transmission was between 11 and 13 days post-virus exposure. We observed a faster dissemination of both JEV genotypes in Ae. albopictus mosquitoes, when compared with Cx. pipiens mosquitoes. We also dissected salivary glands and collected saliva from infected mosquitoes and showed that Ae. albopictus mosquitoes transmitted JEV earlier than Cx. pipiens. The virus collected from Ae. albopictus and Cx. pipiens saliva was competent at causing pathogenesis in a mouse model for JEV infection. Using this model, we found that mosquito saliva or salivary glands did not enhance the severity of the disease.In this study, we demonstrated that European populations of Ae. albopictus and Cx. pipiens were efficient vectors for JEV transmission. Susceptible vertebrate species that develop high viremia are an obligatory part of the JEV transmission cycle. This study highlights the need to investigate the susceptibility of potential JEV reservoir hosts in Europe, notably amongst swine populations and local water birds.

Discovery of Novel Viruses in Mosquitoes from the Zambezi Valley of Mozambique.

Directory of Open Access Journals (Sweden)

Harindranath Cholleti

Full Text Available Mosquitoes carry a wide variety of viruses that can cause vector-borne infectious diseases and affect both human and veterinary public health. Although Mozambique can be considered a hot spot for emerging infectious diseases due to factors such as a rich vector population and a close vector/human/wildlife interface, the viral flora in mosquitoes have not previously been investigated. In this study, viral metagenomics was employed to analyze the viral communities in Culex and Mansonia mosquitoes in the Zambezia province of Mozambique. Among the 1.7 and 2.6 million sequences produced from the Culex and Mansonia samples, respectively, 3269 and 983 reads were classified as viral sequences. Viruses belonging to the Flaviviridae, Rhabdoviridae and Iflaviridae families were detected, and different unclassified single- and double-stranded RNA viruses were also identified. A near complete genome of a flavivirus, tentatively named Cuacua virus, was obtained from the Mansonia mosquitoes. Phylogenetic analysis of this flavivirus, using the NS5 amino acid sequence, showed that it grouped with 'insect-specific' viruses and was most closely related to Nakiwogo virus previously identified in Uganda. Both mosquito genera had viral sequences related to Rhabdoviruses, and these were most closely related to Culex tritaeniorhynchus rhabdovirus (CTRV. The results from this study suggest that several viruses specific for insects belonging to, for example, the Flaviviridae and Rhabdoviridae families, as well as a number of unclassified RNA viruses, are present in mosquitoes in Mozambique.

Influence of Bloodmeal Source on Reproductive Output of the Potential West Nile Vector, Culex theileri (Diptera: Culicidae).

Science.gov (United States)

Demirci, Berna; Durmaz, Esra; Alten, Bulent

2014-11-01

Culex theileri Theobald (Diptera: Culicidae) has a wide Afrotropical, southern Palaearctic, northern Oriental, and European distribution. It is mainly considered as a mammophilic mosquito and also feeds on birds and serves as a vector for various zoonotic diseases including West Nile virus. Despite its broad distribution and evidence indicating that Cx. theileri is a competent vector of human and domestic animal pathogens, basic biological and ecological features of this species have not been well investigated. We evaluated the impact of bloodmeal source (human, chicken, cow, and a double bloodmeal such as human and cow or chicken and cow and mixed bloodmeals [cow, chicken, and human] via artificial feeding) on fecundity, hatching rates, developmental times, and viability from egg to adult for laboratory colonized Cx. theileri. Fecundity in mosquitoes that took a chicken bloodmeal, a double bloodmeal and mixed bloodmeals was significantly higher than in females fed on a single cow or single human blood. This is the first study about the bloodmeal sources effect on laboratory-reared Cx. theileri populations and these findings contribute to our understanding of the impact of bloodmeal source on reproduction in Cx. theileri. As it is known that Cx. theileri is a vector for West Nile virus, the potential impacts of bloodmeal source on virus transmission are discussed. © 2014 Entomological Society of America.

How often do they meet? Genetic similarity between European populations of a potential disease vector Culex pipiens.

Science.gov (United States)

Lõhmus, Mare; Lindström, Anders; Björklund, Mats

2012-01-01

Species in the Culex pipiens complex are common almost all over the world and represent important vectors for many serious zoonotic diseases. Even if, at the moment, many of the pathogens potentially transmitted by Cx. pipiens are not a problem in northern Europe, they may, with increasing temperatures and changing ecosystems caused by climate change, move northward in the future. Therefore, the question whether or not the Cx. pipiens populations in northern Europe will be competent vectors for them is of high importance. One way to estimate the similarity and the rate of contact between European Cx. pipiens populations is to look at the gene exchange between these populations. To test the genetic diversity and degree of differentiation between European Cx. pipiens populations, we used eight microsatellite markers in 10 mosquito populations originating from northern, central, and southern Europe. We found that three of the analyzed populations were very different from the rest of the populations and they also greatly differed from each other. When these three populations were removed, the variance among the rest of the populations was low, suggesting an extensive historic gene flow between many European Cx. pipiens populations. This suggests that infectious diseases spread by this species may not be associated with a certain vector genotype but rather with suitable environmental conditions. Consequently, we would expect these pathogens to disperse northward with favorable climatic parameters.

Novel synthesis of silver nanoparticles using Bauhinia variegata: a recent eco-friendly approach for mosquito control.

Science.gov (United States)

Govindarajan, Marimuthu; Rajeswary, Mohan; Veerakumar, Kaliyan; Muthukumaran, Udaiyan; Hoti, S L; Mehlhorn, Heinz; Barnard, Donald R; Benelli, Giovanni

2016-02-01

Mosquito vectors are responsible for transmitting diseases such as malaria, dengue, chikungunya, Japanese encephalitis, dengue, and lymphatic filariasis. The use of synthetic insecticides to control mosquito vectors has caused physiological resistance and adverse environmental effects, in addition to high operational cost. Biosynthesis of silver nanoparticles has been proposed as an alternative to traditional control tools. In the present study, green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Bauhinia variegata by reduction of Ag(+) ions from silver nitrate solution has been investigated. The bioreduced silver nanoparticles were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD). Leaf extract and synthesized AgNPs were evaluated against the larvae of Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Compared to aqueous extract, synthesized AgNPs showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 and LC90 values of 41.96, 46.16, and 51.92 μg/mL and 82.93, 89.42, and 97.12 μg/mL, respectively. Overall, this study proves that B. variegata is a potential bioresource for stable, reproducible nanoparticle synthesis and may be proposed as an efficient mosquito control agent.

Multiple insecticide resistances in the disease vector Culex p. quinquefasciatus from Western Indian Ocean.

Science.gov (United States)

Pocquet, Nicolas; Milesi, Pascal; Makoundou, Patrick; Unal, Sandra; Zumbo, Betty; Atyame, Célestine; Darriet, Frédéric; Dehecq, Jean-Sébastien; Thiria, Julien; Bheecarry, Ambicadutt; Iyaloo, Diana P; Weill, Mylène; Chandre, Fabrice; Labbé, Pierrick

2013-01-01

Several mosquito-borne diseases affect the Western Indian Ocean islands. Culex pipiens quinquefasciatus is one of these vectors and transmits filariasis, Rift Valley and West Nile viruses and the Japanese encephalitis. To limit the impact of these diseases on public health, considerable vector control efforts have been implemented since the 50s, mainly through the use of neurotoxic insecticides belonging to Organochlorines (OC), Organophosphates (OP) and pyrethroids (PYR) families. However, mosquito control failures have been reported on site, and they were probably due to the selection of resistant individuals in response to insecticide exposure. In this study, we used different approaches to establish a first regional assessment of the levels and mechanisms of resistance to various insecticides. Bioassays were used to evaluate resistance to various insecticides, enzyme activity was measured to assess the presence of metabolic resistances through elevated detoxification, and molecular identification of known resistance alleles was investigated to determine the frequency of target-site mutations. These complementary approaches showed that resistance to the most used insecticides families (OC, OP and PYR) is widespread at a regional scale. However, the distribution of the different resistance genes is quite heterogeneous among the islands, some being found at high frequencies everywhere, others being frequent in some islands and absent in others. Moreover, two resistance alleles displayed clinal distributions in Mayotte and La Réunion, probably as a result of a heterogeneous selection due to local treatment practices. These widespread and diverse resistance mechanisms reduce the capacity of resistance management through classical strategies (e.g. insecticide rotation). In case of a disease outbreak, it could undermine the efforts of the vector control services, as only few compounds could be used. It thus becomes urgent to find alternatives to control populations

Multiple insecticide resistances in the disease vector Culex p. quinquefasciatus from Western Indian Ocean.

Directory of Open Access Journals (Sweden)

Nicolas Pocquet

Full Text Available Several mosquito-borne diseases affect the Western Indian Ocean islands. Culex pipiens quinquefasciatus is one of these vectors and transmits filariasis, Rift Valley and West Nile viruses and the Japanese encephalitis. To limit the impact of these diseases on public health, considerable vector control efforts have been implemented since the 50s, mainly through the use of neurotoxic insecticides belonging to Organochlorines (OC, Organophosphates (OP and pyrethroids (PYR families. However, mosquito control failures have been reported on site, and they were probably due to the selection of resistant individuals in response to insecticide exposure. In this study, we used different approaches to establish a first regional assessment of the levels and mechanisms of resistance to various insecticides. Bioassays were used to evaluate resistance to various insecticides, enzyme activity was measured to assess the presence of metabolic resistances through elevated detoxification, and molecular identification of known resistance alleles was investigated to determine the frequency of target-site mutations. These complementary approaches showed that resistance to the most used insecticides families (OC, OP and PYR is widespread at a regional scale. However, the distribution of the different resistance genes is quite heterogeneous among the islands, some being found at high frequencies everywhere, others being frequent in some islands and absent in others. Moreover, two resistance alleles displayed clinal distributions in Mayotte and La Réunion, probably as a result of a heterogeneous selection due to local treatment practices. These widespread and diverse resistance mechanisms reduce the capacity of resistance management through classical strategies (e.g. insecticide rotation. In case of a disease outbreak, it could undermine the efforts of the vector control services, as only few compounds could be used. It thus becomes urgent to find alternatives to

Culex quinquefasciatus (Diptera: Culicidae as a potential West Nile virus vector in Tucson, Arizona: Blood meal analysis indicates feeding on both humans and birds

Directory of Open Access Journals (Sweden)

Margaret Zinser

2004-06-01

Full Text Available Most reports from the United States suggest Culex quinquefasciatus mosquitoes feed minimally on humans. Given the abundance of C. quinquefasciatus in residential Tucson and parts of metropolitan Phoenix, and the arrival of West Nile virus to this area, discovering the blood meal hosts of the local population is important. Using a sandwich ELISA technique, the local C. quinquefasciatus were found to feed on both humans and birds. This suggests they should be considered potential West Nile virus vectors.

Human Blood Feeding Activity of Female Hybrids between Culex pipiens pipiens and Culex pipiens quinquefasciatus（Diptera: Culicidae）

OpenAIRE

Yoshii, Manabu; Mine, Mariko; Kurokawa, Kenji; Oda, Tsutomu; Kato, Katsutomo; Ogawa, Yasunori; Eshita, Yuuki; Uchida, Keikichi

2007-01-01

Human blood feeding activity was examined in females of hybrids between Culex pipiens pipiens and Culex pipiens quinquefasciatus during long photoperiod at 25℃. Blood feeding rates of hybrids were lower than in Culex pipiens quinquefasciatus and Culex pipiens pallens, and higher than in Culex pipiens pipiens, because no females fed on human blood in Culex pipiens pipiens.

Larvicidal activity of Nerium oleander L. (Apocynaceae flower extracts against Culex quinquefasciatus Say (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

R. Raveen

2014-03-01

Full Text Available Culex quinquefasciatus is the vector responsible for serious disease filariasis among human beings. Plant derived products have received increased attention from scientists as they serve as a rich source for novel natural substances possessing insecticidal properties which are safe to human and ecosystem. During the last decade, various studies on natural plant products against vector mosquito indicate them as possible alternatives to chemical and synthetic insecticides for mosquito control. In the present study, the crude hexane and aqueous extract of Nerium oleander flowers were reported for larvicidal activity against the filarial vector, Culex quinquefasciatus. Mortality was observed for 24 and 48 hours. Hexane flower extract exhibited highest larvicidal activity with a LC50 value of 102.54 ppm and 61.11ppm after 24 and 48 hours respectively. Further investigations are needed to elucidate this activity against a wide range of all stages of mosquito species and also the active ingredient(s of the extract responsible for larvicidal activity should be identified.

Natural infection of Culex theileri (Diptera: Culicidae) with Dirofilaria immitis (Nematoda: Filarioidea) on Madeira Island, Portugal.

Science.gov (United States)

Santa-Ana, Marta; Khadem, Manhaz; Capela, Ruben

2006-01-01

Field and laboratory studies were performed to verify whether Culex theileri Theobald functions as a natural vector of Dirofilaria immitis (Leidy) on Madeira Island, Portugal. CO2-baited light traps (EVS traps) were use to sample mosquitoes monthly basis between February 2002 and February 2003 in the area of Quebradas (Funchal). Three mosquito species were captured, including 58 Culex pipiens L., 790 Cx. theileri, and three Culiseta longiareolata (Macquart). Only C. theileri tested positive for D. immitis. The presence of this filarial worm was detected by direct observation, infectivity assay dissection technique, and polymerase chain reaction methods. Infected mosquitoes were recovered in October and December 2002 and January 2003. These data provide evidence that Cx. theileri could be the main vector of D. immitis in Funchal, Madeira.

Culex coronator in coastal Georgia and South Carolina.

Science.gov (United States)

Moulis, Robert A; Russell, Jennifer D; Lewandowski, Henry B; Thompson, Pamela S; Heusel, Jeffrey L

2008-12-01

In 2007, adult Culex coronator were collected in Chatham County, Georgia, and Jasper County, South Carolina, during nuisance and disease vector surveillance efforts. A total of 75 specimens of this species were collected at 8 widely separated locations in Chatham County, Georgia, and 4 closely situated sites in Jasper County, South Carolina. These represent the first Atlantic coastal records of this species in Georgia and the first confirmed records of Cx. coronator in South Carolina.

Host-Feeding Patterns of Culex stigmatosoma (Diptera: Culicidae) in Southern California.

Science.gov (United States)

McPhatter, Lee P; Su, Tianyun; Williams, Greg; Cheng, Min-Lee; Dhillon, Major; Gerry, Alec C

2017-11-07

Knowledge of the blood-feeding patterns exhibited by arthropod vectors is essential for understanding the complex dynamics of vector-borne disease transmission. Some species of mosquitoes belonging to the genus Culex have been implicated as having major roles in the transmission of arboviruses such as West Nile virus, Saint Louis encephalitis virus, and Western equine encephalitis virus. Although the host-feeding patterns for many of these Culex species are well studied, the host-feeding patterns of Culex stigmatosoma Dyar are relatively poorly studied, even though this species is suspected to be an important maintenance vector for West Nile virus and other arboviruses. In the current study, bloodmeals from 976 blood-engorged Cx. stigmatosoma, collected from 30 sites in southern California from 2009-2012, were processed for vertebrate host identification by nucleotide sequencing following polymerase chain reaction to amplify portions of the cytochrome oxidase I and cytochrome b genes of vertebrate animals. Vertebrate DNA was amplified, sequenced, and identified from a total of 647 Cx. stigmatosoma bloodmeals, revealing that 98.6% of bloodmeals were from birds, 1.2% from three mammal species, and a single bloodmeal was from a reptile species. In total, 40 different host species were identified. The greatest number of bloodmeals identified was from domestic chicken (Gallus gallus domesticus L.) (38% of bloodmeals), house sparrow (Passer domesticus L.) (23%), house finch (Haemorhous mexicanus Müller) (17%), American crow (Corvus brachyrhynchos L.) (4%), and mourning dove (Zenaida macroura L.) (3%). However, chicken bloodmeals were identified almost entirely from a single site where mosquito collection devices were placed in the near vicinity of confined domestic chickens. The strongly ornithophilic feeding behavior shown in this study for Cx. stigmatosoma supports the hypothesis that this mosquito species may be an important maintenance (or endemic) vector for

Mosquitoes of the genus Culex in the Suez Canal Governorates.

Science.gov (United States)

Morsy, T A; el Okbi, L M; Kamal, A M; Ahmed, M M; Boshara, E F

1990-06-01

Mosquitoes are among the most annoying and important vectors of human and animal diseases as malaria, filariasis, yellow fever, rift valley fever...etc. In this paper, it was aimed to study the present status of species of genus Culex in the Suez Canal Governorates after the reconstruction and developmental projects. Five species of Culex were identified: C. pipiens, C. univittatus, C. antennatus, C. poicilipes and C. pusillus. The latter species was represented by two specimens. C. pipiens was the commonest species both indoors and outdoors. C. antennatus and C. poicilipes were found only outdoors. C. pipiens was found all the year round particularly in Spring. Other species were found in Spring and Autumn, except C. antennatus which was found in Summer as well. The results were discussed on the light of work done before.

Transmission of West Nile virus by Culex quinquefasciatus say infected with Culex Flavivirus Izabal.

Directory of Open Access Journals (Sweden)

Rebekah J Kent

Full Text Available BACKGROUND: The natural history and potential impact of mosquito-specific flaviviruses on the transmission efficiency of West Nile virus (WNV is unknown. The objective of this study was to determine whether or not prior infection with Culex flavivirus (CxFV Izabal altered the vector competence of Cx. quinquefasciatus Say for transmission of a co-circulating strain of West Nile virus (WNV from Guatemala. METHODS AND FINDINGS: CxFV-negative Culex quinquefasciatus and those infected with CxFV Izabal by intrathoracic inoculation were administered WNV-infectious blood meals. Infection, dissemination, and transmission of WNV were measured by plaque titration on Vero cells of individual mosquito bodies, legs, or saliva, respectively, two weeks following WNV exposure. Additional groups of Cx. quinquefasciatus were intrathoracically inoculated with WNV alone or WNV+CxFV Izabal simultaneously, and saliva collected nine days post inoculation. Growth of WNV in Aedes albopictus C6/36 cells or Cx. quinquefasciatus was not inhibited by prior infection with CxFV Izabal. There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05. However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014. Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva. CONCLUSIONS: In the sequential infection experiments, prior infection with CxFV Izabal had no significant impact on WNV replication, infection, dissemination, or transmission by Cx. quinquefasciatus, however WNV transmission was enhanced in the Honduras colony when mosquitoes were inoculated simultaneously with

Laboratory evaluation of lactic acid on attraction of Culex spp. (Diptera: Culicidae).

Science.gov (United States)

Allan, Sandra A; Bernier, Ulrich R; Kline, Daniel L

2010-12-01

The role of lactic acid was evaluated for attraction of Culex nigripalpus, Culex quinquefasciatus, Culex tarsalis, and Aedes aegypti in the laboratory using a dual-port olfactometer. When lactic acid was combined with chicken odor, attraction was increased for Cx. quinquefasciatus compared to chicken odor alone but not for Cx. nigripalpus, Cx. tarsalis, and Ae. aegypti. Lactic acid combined with hand odor did not change attraction of Cx. tarsalis and Ae. aegypti but decreased attraction of Cx. nigripalpus and Cx. quinquefasciatus. The addition of lactic acid to CO(2) increased attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis. Use of commercial lactic acid baits with CO(2) resulted in a similar trend except for Cx. nigripalpus which showed no difference. A blend of lactic acid, acetone, and dimethyl disulfide was attractive to Ae. aegypti (63.4%) but elicited low responses by all Culex spp. (1.3-26.8%). Addition of the blend to CO(2) increased attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis. The mixture of compounds plus CO(2) was as attractive as a hand for Cx. quinquefasciatus, Cx. tarsalis, and Ae. aegypti. © 2010 The Society for Vector Ecology.

Impact of West Nile virus dose and incubation period on vector competence of Culex nigripalpus (Diptera: Culicidae).

Science.gov (United States)

Richards, Stephanie L; Anderson, Sheri L; Lord, Cynthia C; Tabachnick, Walter J

2011-11-01

Female Culex nigripalpus were fed blood containing a low dose (6.3±0.01 logs plaque-forming units (PFU)/mL) or high dose (7.3±0.1 logs PFU/mL) of West Nile virus (WNV) and maintained at 28°C for incubation periods (IPs) of 6 or 12 days. Vector competence was measured using rates of infection (% with WNV-positive bodies), dissemination (% infected with WNV-positive legs), and transmission (% infected with WNV-positive saliva). Infection rates were not influenced by dose or IP. Dissemination rates were significantly higher at the high dose, and this was dependent on IP. Despite 100% infection and 90% dissemination in the most permissive treatment of high dose and 12 days, only 11% transmission was observed. Virus titers in body and leg tissues were significantly lower at the low dose and the titers were not influenced by IP. We show that not all mosquitoes with infections and/or disseminated infections transmit WNV under the conditions of this test. Therefore, characterizing the transmission ability of a vector population using infection or dissemination as indicators of transmission may provide inaccurate information. The complex relationships between infection, dissemination, and transmission must be evaluated under a variety of biological and environmental conditions to begin to assess the epidemiological risk of natural mosquito populations.

Role of the repartition of wetland breeding sites on the spatial distribution of Anopheles and Culex, human disease vectors in Southern France

Directory of Open Access Journals (Sweden)

Fontenille Didier

2011-05-01

Full Text Available Abstract Background In this study, carried out in the Camargue region (France, we combined entomological data with geomatic and modelling tools to assess whether the location of breeding sites may explain the spatial distribution of adult mosquitoes. The species studied are important and competent disease vectors in Europe: Culex modestus Ficalbi and Cx. pipiens Linnaeus (West Nile virus, Anopheles atroparvus Van Thiel, a former Plasmodium vector, and An. melanoon Hackett, competent to transmit Plasmodium. Using a logistic regression model, we first evaluated which land cover variables determined the presence of Culex and Anopheles larva. The resulting probability map of larval presence then was used to project the average probability of finding adults in a buffer area. This was compared to the actual number of adults collected, providing a quantitative assessment of adult dispersal ability for each species. Results The distribution of Cx. modestus and An. melanoon is mainly driven by the repartition of irrigated farm fields and reed beds, their specific breeding habitats. The presence of breeding sites explained the distribution of adults of both species. The buffer size, reflecting the adult dispersal ability, was 700 m for Cx. modestus and 1000 m for An. melanoon. The comparatively stronger correlation observed for Cx. modestus suggested that other factors may affect the distribution of adult An. melanoon. We did not find any association between Cx. pipiens larval presence and the biotope due to the species' ubiquist character. Conclusion By applying the same method to different species, we highlighted different strengths of association between land cover (irrigated farm fields and reed beds, larval presence and adult population distribution. This paper demonstrates the power of geomatic tools to quantify the spatial organization of mosquito populations, and allows a better understanding of links between landcover, breeding habitats, presence

Larvacidal Effect of Imperata Cylindrical Root Decoction against Culex sp. Larvae

Directory of Open Access Journals (Sweden)

Afini Tiara Resi

2014-08-01

Full Text Available Background: Filariasis is one of the neglected tropical diseases. About 337 of 401 districts in Indonesia are endemic areas for filariasis, especially in Sumatera, Kalimantan, and Papua. Culex sp. is one of the lymphatic filariasis vectors which can be controlled by insecticide, including larvacide. This study was conducted to determine the larvacidal effect of Imperata cylindrical root decoction against Culex sp. larvae. Methods: This study was conducted at the Laboratory of Parasitology, Faculty of Medicine, Universitas Padjadjaran during the period of September to November 2012. The study object was Culex sp. larvae III/IV instars. The design of this study was experimental laboratory using true experimental approach. The larvae were divided into three groups: negative control (distilled water, reference (Abate®, and decoction. The number of larvae in each group was 25 larvae, and the effects were evaluated by the total number of dead larvae in 48 hours under observation. The data were then analyzed by Mann-Whitney test and Probit test. Results: The result of the Mann-Whitney test to compare Imperata cylindrica root decoction treatment to distilled water as control was significant (p<0.05. However, Abate® gave a better result. The Probit test resultwas LC50: 63% and LC90: 489%. Conclusions: Imperata cylindrical root decoction has a larvacidal effect against Culex sp. larvae.

Comparative analysis of gut microbiota of Culex restuans (Diptera: Culicidae) females from different parents

Science.gov (United States)

The potential for gut microbiota to impede or enhance pathogen transmission is well-documented but the factors that shape this microbiota in mosquito vectors are poorly understood. We characterized and compared the gut microbiota of adult females of Culex restuans Theobald from different parents. Cu...

Slow release formulations of Bacillus thuringiensis israelensis (AM 65-52 and spinosyns: effectiveness against the West Nile vector Culex pipiens in Saudi Arabia

Directory of Open Access Journals (Sweden)

Alaa Sulaiman Alsobhi

2016-07-01

Full Text Available Objective: To investigate the effectiveness of slow release formulations of Bacillus thuringiensis israelensis (AM 65-52 (B. thuringiensis israelensis and spinosyns against the West Nile vector Culex pipiens (Cx. pipiens in Saudi Arabia. Methods: We tested slow release insecticide formulations of Natular DT, Tap 60 and VectoBac granule against II instars of Cx. pipiens larvae in 50 L laboratory arenas. Results: Slow release formulations of B. thuringiensis israelensis and spinosyns gave continuous control against Cx. pipiens for several weeks. Natular DT was more effective over Tap 60 and VectoBac granule of about 1.3 and 5.8 times, respectively. Variations in the durations of effective control among the tested slow release formulations may reflect differences in their active ingredients and the mode of action. Conclusions: Our results highlighted the effectiveness of B. thuringiensis israelensis and spinosyns against an important West Nile vector, providing baseline data to develop ecofriendly mosquito control programs in Saudi Arabia.

Mosquitoes of the rice agroecosystem of Malaysia: species composition and their abundance in relation to rice farming

International Nuclear Information System (INIS)

Abu Hassan Ahmad; Che Salmah Md Rawi

2002-01-01

Mosquito abundance in relation to rice farming was studied in the Muda and the Kerian Irrigation Schemes. Mosquito larvae were collected using dippers for several growing seasons. Adult mosquitoes were collected by using human bait and cow bait and net trap at nights. Culex, Mansonia and Anopheles were the three genera of mosquito found in the rice agroecosystem. Four species of Mansonia were found biting on human bait. Culex mosquitoes were caught biting on human and cow baits. Culex tritaeniorhynchus, C pseudovishnui, C vishnui, C gelidus and C bitaeniorhynchus were the most common Culex mosquitoes found. Anoheles sinensis and A. peditaeniatus were the most dominant panopheline mosquitoes. High abundance of larvae and adult mosquitoes were observed during ploughing, planting, and tillering stages of rice farming. (Author)

Mosquito Surveys Carried out On Green Island, Orchid Island, and Penghu Island, Taiwan, in 2003

Directory of Open Access Journals (Sweden)

Hwa-Jen Teng

2005-02-01

Full Text Available Field surveys of mosquitoes were carried out on Green, Orchid, and Penghu Islands in 2003 to ascertain the status of mosquito vectors. Eighteen species of mosquitoes were collected, including three species of Anopheles, four species of Aedes, eight species of Culex, two species of Armigeres, and one species of Malaya. Seventeen previously recorded species were not collected in this study but 11 species collected had not previously been recorded. Ten newly recorded species, An. maculatus, An. takasagoensis, Ae. alcasidi, Ae. lineatopennis, Ae. vexans vexans, Ar. omissus, Cx. vishnui, Cx. halifaxii, Cx. hayashii, and Cx. neomimulus, were collected on Green Island and one previously unrecorded species, Ar. subalbatus, was collected on Orchid Island. Potential vectors An. maculatus and An. sinensis, malaria vectors in Korea and Mainland China, Ae. albopictus, a vector of dengue in Taiwan and West Nile virus in the USA, Cx. vishnui and Cx. tritaeniorhynchus, Japanese encephalitis vectors in Taiwan, Ae. vexans vexans, an eastern equine encephalitis vector in the USA, and Cx. quinquefasciatus, a vector of filariasis in Taiwan and West Nile virus in the USA, were among the mosquito species collected.

Evaluation of mosquito larvicidal activity of fruit extracts of Acacia auriculiformis against the Japanese encephalitis vector Culex vishnui.

Science.gov (United States)

Barik, Mousumi; Rawani, Anjali; Laskar, Subrata; Chandra, Goutam

2018-02-19

The larvicidal potentiality of crude and ethyl acetate extracts of fruits of Acacia auriculiformis was investigated against all the larval instars of JE vector Culex vishnui. The crude extracts showed good results against all the larval instars with highest mortality at 0.09%. Highest mortality was found at 300 ppm of ethyl acetate extract. Lowest LC 50 value was obtained at 72 h for third instar larvae. Non target organisms tested, showed no to very less mortality to ethyl acetate solvent extract. Presence of N-H stretching, a C=O stretching, C=C and C-N stretching vibrations of secondary amide or amine group were confirmed from IR analysis. GC-MS analysis revealed the presence of three compounds namely Ethane 2-chloro-1,1-dimethoxy, Acetic acid, 1-methyl ether ester and [4-[1-[3,5-Dimethyl-4[(trimethylsilyl)oxy)phenyl]-1,3-dimethylbutyl)-2,6dimethylphenoxy)(trimethyl) silane, responsible for mosquito larval death.

Ovicidal, larvicidal and adulticidal properties of Asparagus racemosus (Willd.) (Family: Asparagaceae) root extracts against filariasis (Culex quinquefasciatus), dengue (Aedes aegypti) and malaria (Anopheles stephensi) vector mosquitoes (Diptera: Culicidae).

Science.gov (United States)

Govindarajan, Marimuthu; Sivakumar, Rajamohan

2014-04-01

Several diseases are associated to the mosquito-human interaction. Mosquitoes are the carriers of severe and well-known illnesses such as malaria, arboviral encephalitis, dengue fever, chikungunya fever, West Nile virus and yellow fever. These diseases produce significant morbidity and mortality in humans and livestock around the world. The present investigation was undertaken to study the ovicidal, larvicidal and adulticidal activities of crude hexane, ethyl acetate, benzene, chloroform and methanol extracts of root of Asparagus racemosus were assayed for their toxicity against three important vector mosquitoes, viz., Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi (Diptera: Culicidae). The mean percent hatchability of the eggs was observed after 48 h post-treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. All the five solvent extracts showed moderate ovicidal activity; however, the methanol extract showed the highest ovicidal activity. The methanol extract of Asparagus racemosus against Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi exerted 100% mortality (zero hatchability) at 375, 300 and 225 ppm, respectively. Control eggs showed 99-100% hatchability. The larval mortality was observed after 24 h of exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in methanol extract of root of Asparagus racemosus against the larvae of Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi with the LC50 and LC90 values were 115.13, 97.71 and 90.97 ppm and 210.96, 179.92, and 168.82 ppm, respectively. The adult mortality was observed after 24 h recovery period. The plant crude extracts showed dose-dependent mortality. At higher concentrations, the adult showed restless movement for some times with abnormal wagging and then died. Among the extracts tested, the highest adulticidal activity was observed in

Predicting distribution of Aedes aegypti and Culex pipiens complex, potential vectors of Rift Valley fever virus in relation to disease epidemics in East Africa

Directory of Open Access Journals (Sweden)

Clement Nyamunura Mweya

2013-10-01

Full Text Available Background: The East African region has experienced several Rift Valley fever (RVF outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. Methods: Diverse ecological niche modelling techniques have been developed for this purpose: we present a maximum entropy (Maxent approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Results: Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Conclusion: Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods.

Predicting distribution of Aedes aegypti and Culex pipiens complex, potential vectors of Rift Valley fever virus in relation to disease epidemics in East Africa.

Science.gov (United States)

Mweya, Clement Nyamunura; Kimera, Sharadhuli Iddi; Kija, John Bukombe; Mboera, Leonard E G

2013-01-01

The East African region has experienced several Rift Valley fever (RVF) outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. DIVERSE ECOLOGICAL NICHE MODELLING TECHNIQUES HAVE BEEN DEVELOPED FOR THIS PURPOSE: we present a maximum entropy (Maxent) approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex) responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods.

BIOLARVASIDA EKSTRAK ETANOL KULIT NANAS (Ananas comosus L. Merr TERHADAP LARVA NYAMUK Culex Sp.

Directory of Open Access Journals (Sweden)

Siti Juariah

2017-10-01

Full Text Available ABSTRAK   Nanas merupakan salah satu komoditi asal Provinsi Riau. Setiap tahun nanas mengalami peningkatan dengan semakin meningkatnya produksi nanas maka limbah yang dihasilkan akan semakin meningkat. Pada limbah kulit nanas diduga terdapat senyawa alkaloid yang dapat membunuh larva nyamuk Culex Sp. Nyamuk yang termasuk dalam genus Culex dikenal sebagai vektor penular arbovirus, demam kaki gajah, dan malaria pada unggas. Pengendalian serangga umumnya dilakukan menggunakan pestisida sintetik. Penggunaan senyawa kimia yang bersifat sintetik sangat berbahaya bagi pengguna yang terpajan. Tujuan dari penelitian ini adalah untuk menentukan efektifitas ekstrak etanol kulit nanas dan mengetahui jumlah larva yang mati dengan menentukan konsentrasi terbaik dari ekstrak etanol kulit nanas (AnanascomosusL. terhadap larva nyamuk culex Sp. Penelitian ini bersifat Eksperimen Laboratory, yaitu meneliti tentang uji mortalitas larva nyamuk Culex Sp setelah pemberian ekstrak etanol kulit nanas (AnanascomosusL.. Hasil penelitian yang didapatkan bahwa ekstrak etanol kulit nanas dapat dibuktikan pada tingkat konsentrasi 1% angka kematian larva nyamuk telah mencapai 72,5%. Sedangkan pada konsentrasi 4% telah mampu membunuh larva sebesar 97,5%. Kata Kunci        : Ekstraketanol, Kulit nanas, Culex Sp.   ABSTRACT                Pineapple is one of the commodities origin of Riau Province. Each year the pineapple increases with the increasing production of pineapple so the waste generated will increase. In pineapple leaf waste is suspected of alkaloid compounds that can kill the mosquito larvae Culex Sp. The mosquitoes belonging to the genus Culex are known as arbovirus-transmitting vectors, elephant leg fever, and malaria in poultry. Insect control is generally done using synthetic pesticides. The use of synthetic chemicals is very dangerous for exposed users. The purpose of this study was to determine the effectiveness of pineapple ethanol

First report of L1014F-kdr mutation in Culex pipiens complex from Morocco.

Science.gov (United States)

Bkhache, Meriem; Tmimi, Fatim-Zohra; Charafeddine, Omar; Faraj, Chafika; Failloux, Anna-Bella; Sarih, M'hammed

2016-12-16

Mosquitoes of the Culex pipiens complex, competent vectors for West Nile virus (WNV) and Rift Valley fever virus (RVFV) are widely targeted by insecticide treatments. The intensive application of chemical insecticides led to the development of resistance in many insects including Culex pipiens mosquitoes. The absence of data on resistance mechanisms in Morocco allow us to assess the levels of lambda-cyhalothrin resistance and the frequency of the mutated gene L1014F kdr in different forms of Cx. pipiens complex from three regions of Morocco. Mosquito adults were reared from immature stages collected in three different regions in Morocco (Tangier, Casablanca and Marrakech). Standard WHO insecticide susceptibility tests were conducted on adults emerged from collected larvae. Specimens were identified as belonging to the Culex pipiens complex using a multiplex PCR assay with diagnostic primers designed from the flanking region of microsatellite CQ11. Identified mosquitoes were then tested for the presence of the L1014F kdr mutation using PCR assay. Our results showed that 21% of the tested population has a resistance to lambda-cyhalothrin. The molecular identification of survivors shows that 43% belonged to the Cx. pipiens pipiens and only 9.5% to the Cx. pipiens molestus form. On the other hand, 416 specimens were screened for the L1014F kdr mutation. L1014F mutation was detected in different forms of Cx. pipiens in different sites. The frequency of L1014F mutation was similar between the Cx. pipiens pipiens form and hybrid form, while it was lower in the Cx. pipiens molestus form. The presence of the L1014F kdr allele was significantly associated with resistance to lambda-cyhalothrin in Cx. pipiens pipiens (P Morocco. These findings will provide important information to propose more adapted vector control measures towards this mosquito species, potential vector of arboviruses.

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.

Evaluation of larvicidal activity of Acalypha alnifolia Klein ex Willd. (Euphorbiaceae) leaf extract against the malarial vector, Anopheles stephensi, dengue vector, Aedes aegypti and Bancroftian filariasis vector, Culex quinquefasciatus (Diptera: Culicidae).

Science.gov (United States)

Kovendan, Kalimuthu; Murugan, Kadarkarai; Vincent, Savariar

2012-02-01

The leaf extract of Acalypha alnifolia with different solvents - hexane, chloroform, ethyl acetate, acetone and methanol - were tested for larvicidal activity against three important mosquitoes such as malarial vector, Anopheles stephensi, dengue vector, Aedes aegypti and Bancroftian filariasis vector, Culex quinquefasciatus. The medicinal plants were collected from the area around Kallar Hills near the Western Ghats, Coimbatore, India. A. alnifolia plant was washed with tap water and shade dried at room temperature. The dried leaves were powdered mechanically using commercial electrical stainless steel blender. The powder 800 g of the leaf material was extract with 2.5 litre of various each organic solvents such as hexane, chloroform, ethyl acetate, acetone, methanol for 8 h using Soxhlet apparatus, and filtered. The crude plant extracts were evaporated to dryness in a rotary vacuum evaporator. The yield of extracts was hexane (8.64 g), chloroform (10.74 g), ethyl acetate (9.14 g), acetone (10.02 g), and methanol (11.43 g). One gram of the each plant residue was dissolved separately in 100 ml of acetone (stock solution) from which different concentrations, i.e., 50, 150, 250, 350 and 450 ppm, was prepared. The hexane, chloroform, ethyl acetate, acetone was moderate considerable mortality; however, the highest larval mortality was methanolic extract observed in three mosquito vectors. The larval mortality was observed after 24 h exposure. No mortality was observed in the control. The early fourth-instar larvae of A. stephensi had values of LC(50) = 197.37, 178.75, 164.34, 149.90 and 125.73 ppm and LC(90) = 477.60, 459.21, 435.07, 416.20 and 395.50 ppm, respectively. The A. aegypti had values of LC(50) = 202.15, 182.58, 160.35, 146.07 and 128.55 ppm and LC(90) = 476.57, 460.83, 440.78, 415.38 and 381.67 ppm, respectively. The C. quinquefasciatus had values of LC(50) = 198.79, 172.48, 151.06, 140.69 and 127.98 ppm and LC(90) = 458.73, 430

Effects of virus dose and extrinsic incubation temperature on vector competence of Culex nigripalpus (Diptera: Culicidae) for St. Louis encephalitis virus.

Science.gov (United States)

Richards, Stephanie L; Anderson, Sheri L; Lord, Cynthia C; Tabachnick, Walter J

2012-11-01

Culex nigripalpus Theobald is a primary vector of St. Louis encephalitis virus in the southeastern United States. Cx. nigripalpus females were fed blood containing a low (4.0 +/- 0.01 log10 plaque-forming unit equivalents (PFUeq) /ml) or high (4.7 +/- 0.1 log10 PFUeq/ml) St. Louis encephalitis virus dose and maintained at extrinsic incubation temperatures (EIT) of 25 or 28 degrees C for 12 d. Vector competence was measured via quantitative real-time reverse transcriptase polymerase chain reaction to estimate PFUeq using rates of infection, dissemination, and transmission. There were no differences in infection rates between the two EITs at either dose. The low dose had higher infection rates at both EITs. Dissemination rates were significantly higher at 28 degrees C compared with 25 degrees C at both doses. Virus transmission was observed (<7%) only at 28 degrees C for both doses. The virus titer in body tissues was greater at 28 degrees C compared with 25 degrees C at both doses. The difference between the EITs was greater at the low dose, resulting in a higher titer for the low dose than the high dose at 28 degrees C. Virus titers in leg tissues were greater in mosquitoes fed the high versus low dose, but were not influenced by EIT. Further investigations using a variety of environmental and biological factors would be useful in exploring the complexity of vector competence.

Impact of climate change on filarial vector, Culex quinquefasciatus and control using bacterial pesticide, spinosad

Directory of Open Access Journals (Sweden)

Nareshkumar Arjunan

2014-02-01

Full Text Available Objective: To show the effect of temperature on the biology of Culex quinquefasciatus and also to show the effect of the bacterial pesticide, spinosad on developmental stages of the filarial vector. Methods: A laboratory colony of mosquito larvae was used for the larvicidal activity of temperature and spinosad. Twenty-five numbers of first, second, third, fourth instar larvae were introduced into the 500 mL glass beaker containing 250 mL of de-chlorinated water with desired temperatures (16 °C, 20 °C, 24 °C, 28 °C, 32 °C, 36 °C, similarly spinosad, at different concentrations. The development was observed for every 24 h. Results: The results showed that the rise in temperature acts as a growth inhibiting factor for mosquitoes. And no development was found in the temperature below 16 °C and above 36 °C. The hatchability was increased as the temperature was increased up to 32 °C, after which eclosion rates dropped gradually. Conclusions: 32 °C was obtained as the maximum sustainable temperature and after which the developmental rate was gradually reduced. The optimal temperature for development was lower than the temperatures at which development was quickest. The bacterial pesticide spinosad showed that it is an effective mosquito control agent and can be used for further integrated pest management programmes.

SYBR green-based one step quantitative real-time polymerase chain reaction assay for the detection of Zika virus in field-caught mosquitoes.

Science.gov (United States)

Tien, Wei-Ping; Lim, Gareth; Yeo, Gladys; Chiang, Suzanna Nicole; Chong, Chee-Seng; Ng, Lee-Ching; Hapuarachchi, Hapuarachchige Chanditha

2017-09-19

The monitoring of vectors is one of the key surveillance measures to assess the risk of arbovirus transmission and the success of control strategies in endemic regions. The recent re-emergence of Zika virus (ZIKV) in the tropics, including Singapore, emphasizes the need to develop cost-effective, rapid and accurate assays to monitor the virus spread by mosquitoes. As ZIKV infections largely remain asymptomatic, early detection of ZIKV in the field-caught mosquitoes enables timely implementation of appropriate mosquito control measures. We developed a rapid, sensitive and specific real-time reverse transcription polymerase chain reaction (rRT-PCR) assay for the detection of ZIKV in field-caught mosquitoes. The primers and PCR cycling conditions were optimized to minimize non-specific amplification due to cross-reactivity with the genomic material of Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, Culex tritaeniorhynchus, Culex sitiens and Anopheles sinensis, as well as accompanying microbiota. The performance of the assay was further evaluated with a panel of flaviviruses and alphaviruses as well as in field-caught Ae. aegypti mosquitoes confirmed to be positive for ZIKV. As compared to a probe-based assay, the newly developed assay demonstrated 100% specificity and comparable detection sensitivity for ZIKV in mosquitoes. Being a SYBR Green-based method, the newly-developed assay is cost-effective and easy to adapt, thus is applicable to large-scale vector surveillance activities in endemic countries, including those with limited resources and expertise. The amplicon size (119 bp) also allows sequencing to confirm the virus type. The primers flank relatively conserved regions of ZIKV genome, so that, the assay is able to detect genetically diverse ZIKV strains. Our findings, therefore, testify the potential use of the newly-developed assay in vector surveillance programmes for ZIKV in endemic regions.

Mosquito repellent properties of Delonix elata (L. gamble (Family: Fabaceae against filariasis vector, Culex quinquefasciatus Say. (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Marimuthu Govindarajan

2014-02-01

Full Text Available Objective: To determine the repellent activity of hexane, ethyl acetate, benzene, chloroform and methanol extract of Delonix elata (D. elata leaf and seed against Culex quinquefasciatus (Cx. quinquefasciatus. Methods: Evaluation was carried out in a net cage (45 cm伊30 cm伊25 cm containing 100 blood starved female mosquitoes of Cx. quinquefasciatus. Repellent activity was carried out in the laboratory conditions according to the WHO 2009 protocol. Plant crude extracts of D. elata were applied at 1.0, 2.5, and 5.0 mg/cm2 separately in the exposed fore arm of study subjects. Ethanol was used as the sole control. Results: In this study, the applied plant crude extracts were observed to protect against mosquito bites. There were no allergic reactions experienced by the study subjects. The repellent activity of the extract was dependent on the strength of the extract. Among the tested solvents, the leaf and seed methanol extract showed the maximum efficacy. The highest concentration of 5.0 mg/cm2 provided over 150 min and 120 min protection, respectively. Conclusions: Crude extracts of D. elata exhibit the potential for controlling Cx. quinquefasciatus, the mosquito vector of filariasis.

The efficacy of repellents against Aedes, Anopheles, Culex and Ixodes spp. - a literature review.

Science.gov (United States)

Lupi, Eleonora; Hatz, Christoph; Schlagenhauf, Patricia

2013-01-01

Travellers are confronted with a variety of vector-borne threats. Is one type of repellent effective against all biting vectors? The aim of this review is to examine the literature, up to December 31st, 2012, regarding repellent efficacy. We searched PubMed for relevant papers. Repellents of interest were DEET, Icaridin as well as other piperidine-derived products (SS220), Insect Repellent (IR) 3535 (ethyl-butylacetyl-amino-propionat, EBAAP) and plant-derived products, including Citriodora (para-menthane-3,8-diol). As vectors, we considered the mosquito species Anopheles, Aedes and Culex as well as the tick species Ixodes. We selected only studies evaluating the protective efficacy of repellents on human skin. We reviewed a total of 102 publications. Repellents were evaluated regarding complete protection time or as percentage efficacy [%] in a time interval. We found no standardized study for tick bite prevention. Regarding Aedes, DEET at concentration of 20% or more, showed the best efficacy providing up to 10 h protection. Citriodora repellency against this mosquito genus was lower compared to the other products. Also between subspecies a difference could be observed: Ae. aegypti proved more difficult to repel than Ae. Albopictus. Fewer studies have been conducted on mosquito species Anopheles and Culex. The repellency profile against Anopheles species was similar for the four principal repellents of interest, providing on average 4-10 h of protection. Culex mosquitoes are easier to repel and all four repellents provided good protection. Few studies have been conducted on the tick species Ixodes. According to our results, the longest protection against Ixodes scapularis was provided by repellents containing IR3535, while DEET and commercial products containing Icaridin or PMD showed a better response than IR3535 against Ixodes ricinus. Many plant-based repellents provide only short duration protection. Adding vanillin 5% to plant-based repellents and to DEET

Larval habitat for the avian malaria vector culex quinquefasciatus (Diptera: Culicidae) in altered mid-elevation mesic-dry forests in Hawai'i

Science.gov (United States)

Reiter, M.E.; Lapointe, D.A.

2009-01-01

Effective management of avian malaria (Plasmodium relictum) in Hawai'i's endemic honeycreepers (Drepanidinae) requires the identification and subsequent reduction or treatment of larval habitat for the mosquito vector, Culex quinquefasciatus (Diptera: Culicidae). We conducted ground surveys, treehole surveys, and helicopter aerial surveys from 20012003 to identify all potential larval mosquito habitat within two 100+ ha mesic-dry forest study sites in Hawai'i Volcanoes National Park, Hawai'i; 'Ainahou Ranch and Mauna Loa Strip Road. At 'Ainahou Ranch, anthropogenic sites (43%) were more likely to contain mosquitoes than naturally occurring (8%) sites. Larvae of Cx. quinquefasciatus were predominately found in anthropogenic sites while Aedes albopictus larvae occurred less frequently in both anthropogenic sites and naturally-occurring sites. Additionally, moderate-size (???20-22,000 liters) anthropogenic potential larval habitat had >50% probability of mosquito presence compared to larger- and smaller-volume habitat (malaria, may be controlled by larval habitat reduction in the mesic-dry landscapes of Hawai'i where anthropogenic sources predominate.

Pengaruh Pengasapan (Thermal Fogging Insektisida Piretroid (Malation 95% Terhadap Nyamuk Aedes aegypti dan Culex quinquefasciatus di Pemukiman

Directory of Open Access Journals (Sweden)

Hasan Boesri

2013-02-01

Full Text Available Abstracts. The evaluation of piretroid insecticide (active ingredient Malation 95% was con­ducted in Sub district Tengarang, Semarang Segency, Central Java Province. The insecti­cide was applied using thermal fogging method for dosages of 125, 250, 375, 500 and 625 ml/ha (diluted in diesel to 10 litters. The evaluation of the efficacy was conducted against two mosquito species, Aedes aegypti (the main dengue haemorrhagic fever and Culex quinquefasciatus (the urban lymphatic fil­ariasis vector. Result of the evaluation was revealed that dosages of 500 and 625 ml/ha were effective against both tested mosquito species indoor and outdoor.Key Word: Aedes aegypti, Culex quinquefasciatus, insecticide Piretroid (Malation 95%, thermal fogging.

Ecology of Malaria Vectors in a Rainforest Suburban Community of ...

African Journals Online (AJOL)

User

2011-04-19

Apr 19, 2011 ... Key words: Malaria, Mosquito, Vectors, Ecology, Suburban, Community. ... including host bloodmeal preferences, time and place of biting and resting .... Five species of mosquitoes namely Aedes albopictus, Culex tigripes,.

Development of the immature stages of Culex (Culex saltanensis Dyar (Diptera, Culicidae under laboratory conditions

Directory of Open Access Journals (Sweden)

João Antonio C. Zequi

2012-03-01

Full Text Available Development of the immature stages of Culex (Culex saltanensis Dyar (Diptera, Culicidae under laboratory conditions. Culex (Culex saltanensis Dyar, 1928 is becoming frequent and abundant in natural and artificial breeding sites in urban and rural areas of Brazil. This study contributes to the knowledge of the biology of a Brazilian strain of C. saltanensis. The development of specimens reared individually or grouped was observed. The study was conducted at a constant temperature of 27 ± 2°C, 14L:10D photoperiod and 80 ± 5% relative humidity. The immature stages were observed every 6 hours until adult emergence, which occurred in 12.29 days among individually reared specimens and in 13.12 days among group-reared specimens. Egg rafts for the experiment were obtained from the laboratory and field. Eggs hatched at a rate of 97.48 ± 2.32%. More eggs per egg raft were obtained from the field than from the laboratory. Males from individually reared specimens emerged in 12.29 ± 1.11 days and females in 13.12 ± 1.58 days. The male-female ratio was 1:1. Larval survival rate was higher than 85% for larvae reared isolated and higher than 95% for group-reared larvae. The Culex saltanensis life cycle was completed within 12 to 14 days, where larval instars I and IV took the most time to develop and the pupae, the shortest.

Abrigos de mosquitos Culex (Culex em zona rural (Diptera: Culicidae Resting places of mosquitoes Culex (Culex in rural zones (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Almério de Castro Gomes

1990-10-01

Full Text Available As atividades antrópicas levadas a cabo em zona rural têm afetado o comportamento de mosquitos Culex (Culex, motivo pelo qual foi realizada investigação para observar seus abrigos naturais em área de pastagem, margem e interior de matas primitivas ou residuais. Foram escolhidas três localidades com características mesológicas diferenciadas pelo tipo de atividade humana, todas situadas na região do Vale do Ribeira, Estado de São Paulo, Brasil. As espécies mais abundantes foram Cx. mollis (28,0%, Cx. declarator (25,0%, Cx. lygrus (13,0% e Cx. coronator (9,6%. O conjunto Cx. Bidens + Cx. dolosus + Cx. chidesteri, de hábito mais urbanizado, foi capturado em número muito reduzido. Com relação aos ambientes pesquisados, a mata contribuiu com 2.281 indivíduos (71,4%, sugerindo ser local de abrigo preferido pelo grupo, exceto para Cx. quinquefasciatus. Avaliou-se o potencial de domiciliação de cada espécie e suas conseqüências para a população humana.The human activities carried out in rural zones have been affeecting the behavior of mosquitoes of the Culex (Culex subgenera, which was the reason for undertaking this investigation with a view to registering data on the natural resting places in pastures and on the edge of or within primitive and residual forest areas. Three localities with different mesological conditions, as to type of human activity, all them situated in the Ribeira Valley region of S. Paulo State, Brazil, were chosen. The species most abundantly found were Cx. mollis (28.0%, Cx. declarator (25.0%, Cx. lygrus (13.0% and Cx. coronator (9.6%. The collection of mosquitoes Cx. bidens + Cx. dolosus + Cx. chidesteri, known to be more urban, was much smaller than that of any other species of the group. With reference to outdoor environments, woodland contributed with 2,281 individuals (71.4% suggesting their preference for this resting place, except for Cx. quinquefasciatus. Results are evaluated for the determination

Synthesis and characterization of silver nanoparticles using Bacillus amyloliquefaciens and Bacillus subtilis to control filarial vector Culex pipiens pallens and its antimicrobial activity.

Science.gov (United States)

Fouad, Hatem; Hongjie, Li; Yanmei, Ding; Baoting, Yu; El-Shakh, Ahmed; Abbas, Ghulam; Jianchu, Mo

2017-11-01

Culex pipiens pallens are the most common mosquito's vector in Asia. In order to protect the people from diseases, the anti-mosquito population is necessary that uses safe and new bio-pesticides such as bacteria-AgNPs. In our report, we used two kinds of bacteria to synthesize silver nanoparticles to examine the toxic effect on the larvae and pupae of Cx. pipiens pallens and also used as antimicrobial activity. The biosynthesis of AgNPs and its characterization was carried out by UV-Vis spectrophotometry, FTIR, TEM, SEM, and EDX. The larvicidal and pupicidal assays revealed that the lethal concentration LC 50 values of Bacillus amyloliquefaciens-AgNPs were 0.72 ppm (I), 0.73 ppm (II), 0.69 ppm (III), 1.16 ppm (IV), and 4.18 (Pupae), while LC 50 values of Bacillus subtilis-AgNPs were 0.60 ppm (I), 0.62 ppm (II), 0.21 ppm (III), 0.28 ppm (IV), and 3.46 ppm (Pupae) after 72 h of exposure. Antibacterial activity test of AgNPs reveals better results against rice pathogenic bacteria than bacteria alone. Thus, bacteria-mediated silver nanoparticles have a rapid effect on vector mosquito and microbial pathogen suggesting savings of energy and resources. Hence, bacteria-AgNPs may be used in the future as an effective weapon to control vector mosquito and harmful bacteria.

Observações sobre os mosquitos Culex da cidade de São Paulo, Brasil Observations on Culex mosquitoes of S. Paulo City, Brazil

Directory of Open Access Journals (Sweden)

Oswaldo Paulo Forattini

1973-12-01

Full Text Available São apresentados os resultados obtidos na coleta de mosquitos do gênero Culex na área urbana da cidade de São Paulo, Brasil. Foram empregadas armadilhas luminosas automáticas tipo "New Jersey 50". Os resultados revelaram a presença de outras populações representadas principalmente por Culex chidesteri, C. dolosus e C. bidens as quais, em conjunto, chegaram algumas vezes a sobrepujar a de Culex pipiens fatigans. O maior rendimento foi obtido em áreas com abastecimento de água mas sem rede de esgotos. As coletas intradomiciliares revelaram franca predominância de C. pipiens fatigans.With the use of New Jersey-50 light traps, a survey of Culex mosquitoes was made in the urban área of São Paulo City, Brazil. Beside Culex pipiens fatigans several other species were found, mainly represented by Culex chidesteri, C. dolosus and C. bidens. The combined incidence of these three populations follows nearly the fatigans one and frequently exceeding it. The most high levels of density were found at areas with water treatment but without sewage disposal. Domiciliary collections showed great Culex pipiens fatigans predominancy.

Zika virus replication in the mosquito Culex quinquefasciatus in Brazil.

Science.gov (United States)

Guedes, Duschinka Rd; Paiva, Marcelo Hs; Donato, Mariana Ma; Barbosa, Priscilla P; Krokovsky, Larissa; Rocha, Sura W Dos S; Saraiva, Karina LA; Crespo, Mônica M; Rezende, Tatiana Mt; Wallau, Gabriel L; Barbosa, Rosângela Mr; Oliveira, Cláudia Mf; Melo-Santos, Maria Av; Pena, Lindomar; Cordeiro, Marli T; Franca, Rafael F de O; Oliveira, André Ls de; Peixoto, Christina A; Leal, Walter S; Ayres, Constância Fj

2017-08-09

Zika virus (ZIKV) is a flavivirus that has recently been associated with an increased incidence of neonatal microcephaly and other neurological disorders. The virus is primarily transmitted by mosquito bite, although other routes of infection have been implicated in some cases. The Aedes aegypti mosquito is considered to be the main vector to humans worldwide; however, there is evidence that other mosquito species, including Culex quinquefasciatus, transmit the virus. To test the potential of Cx. quinquefasciatus to transmit ZIKV, we experimentally compared the vector competence of laboratory-reared Ae. aegypti and Cx. quinquefasciatus. Interestingly, we were able to detect the presence of ZIKV in the midgut, salivary glands and saliva of artificially fed Cx. quinquefasciatus. In addition, we collected ZIKV-infected Cx. quinquefasciatus from urban areas with high microcephaly incidence in Recife, Brazil. Corroborating our experimental data from artificially fed mosquitoes, ZIKV was isolated from field-caught Cx. quinquefasciatus, and its genome was partially sequenced. Collectively, these findings indicate that there may be a wider range of ZIKV vectors than anticipated.

Mosquito diversity in Keeriparai and Mundanthurai hill ranges of the Western Ghats, southern India

Directory of Open Access Journals (Sweden)

A. Munirathinam

2015-07-01

Full Text Available After a gap of 25 years the Centre for Research in Medical Entomology (CRME surveyed the mosquito biodiversity in the tail-end hill ranges of the Western Ghats, viz., Kanyakumari (Keeriparai and Tirunelveli districts (Kalakkad-Mundanthurai Tiger Reserve (KMTR and Courtallam of Tamil Nadu between July 2010 and June 2013.  The altitude of the hills ranged from 100–950 m covered by evergreen forests.  A major emphasis was given to collect the immature stages of mosquitoes, from various breeding habitats, viz., slow flowing streams, spring pool, rocky pool, leaf axils, latex cup, tree hole, bamboo stumps, etc.  Altogether 4602 immature individuals were collected, reared individually to be identified at the adult stage.  A total of 3583 specimens belonging to 50 species classified under 21 genera and 18 subgenera were recorded.  The major vector species found in these hill ranges were Stegomyia aegypti, S. albopicta (Dengue and Chikungunya, Culex bitaeniorhynchus, C. tritaeniorhynchus (Japanese encephalitis, Downsiomyia nivea (diurnally subperiodic filariasis and Anopheles mirans (Simian malaria vectors were recorded. 

Fauna, Ecological Characteristics, and Checklist of the Mosquitoes in Mazandaran Province, Northern Iran.

Science.gov (United States)

Nikookar, Seyed Hassan; Fazeli-Dinan, Mahmoud; Azari-Hamidian, Shahyad; Nasab, Seyed Nouraddin Mousavi; Aarabi, Mohsen; Ziapour, Seyyed Payman; Enayati, Ahmadali; Hemingway, Janet

2018-05-04

Mosquitoes are important vectors of human and animal diseases. This study updates current knowledge on fauna, dominance, and distribution of mosquitoes in Mazandaran Province, Northern Iran, to inform disease control effort. Larval collections, using standard dippers or droppers, and adult collections, using total catches, shelter pits, CDC light traps, and human landing catches, were performed monthly in 30 villages across 16 counties, from May to December 2014. Ovitraps, baited with hay infusion as oviposition attractants or stimulants for Aedes (Stegomyia) mosquitoes, were installed in each village and inspected weekly for eggs. Lactophenol and Berlese media were used for preserving and mounting specimens. Overall, 36,024 mosquito specimens (19,840 larvae and 16,184 adults) belonging to 4 genera and 20 species were morphologically identified. The dominance and distribution indices showed that Culex pipiens s.s. was the eudominant species with a constant distribution of larvae (D = 69.07%, C = 100%) and adults (D = 31.86%, C = 100%), followed by Cx tritaeniorhynchus (D = 38.14%, C = 100%) and Anopheles maculipennis s.l. (D = 11.05%, C = 100%) as adults. Aedes vexans was the dominant (7.85%) species, but it had a sporadic (20%) distribution. Culex torrentium and Culiseta morsitans were added as the new species to the checklist of mosquitoes in Mazandaran Province. Due to the potential role, Cx. pipiens s.s. as a vector of various pathogens, further ecological studies are recommended.

Mosquito larvicidal and ovicidal properties of Pithecellobium dulce (Roxb.) Benth. (Fabaceae) against Culex quinquefasciatus Say (Diptera: Culicidae)

OpenAIRE

Govindarajan Marimuthu; Rajeswary Mohan

2014-01-01

Objective: To assess the larvicidal and ovicidal potential of the crude hexane, benzene, chloroform, ethyl acetate and methanol solvent extracts from the medicinal plant, Pithecellobium dulce (P. dulce) against filariasis vector mosquito, Culex quinquefasciatus (Cx. quinquefasciatus). Methods: Twenty five early third instar larvae of Cx. quinquefasciatus were exposed to various concentrations and were assayed in the laboratory by using the protocol of WHO (2005). The larval mor...

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.

Ecological differentiation of members of the Culex pipiens complex, potential vectors of West Nile virus and Rift Valley fever virus in Algeria.

Science.gov (United States)

Amara Korba, Raouf; Alayat, Moufida Saoucen; Bouiba, Lazhari; Boudrissa, Abdelkarim; Bouslama, Zihad; Boukraa, Slimane; Francis, Frederic; Failloux, Anna-Bella; Boubidi, Saïd Chaouki

2016-08-17

We investigated the ecological differentiation of two members of the Culex pipiens complex, Cx. p. pipiens form pipiens and Cx. p. pipiens form molestus in three sites, El-Kala, M'Sila and Tinerkouk in Algeria. These two forms are the most widespread mosquito vectors in temperate regions exhibiting important behavioural and physiological differences. Nevertheless, this group of potential vectors has been poorly studied, particularly in North Africa. Ten larval populations of Cx. p. pipiens were sampled from various above- and underground habitats in three zones representing the three bioclimatic regions in Algeria. The reproduction characteristics were also investigated in the laboratory to define the rates of autogeny and stenogamy. Identification of Cx. p. pipiens members present in Algeria was achieved using a molecular analysis with the microsatellite CQ11 locus. We detected larvae of Cx. p. pipiens in all areas suggesting that the species is a ubiquitous mosquito well adapted to various environments. To our knowledge, this study provides the first molecular evidence of the presence of the Cx. p. pipiens form molestus and hybrids (molestus/pipiens) in Algeria with a high proportion of molestus form (48.3 %) in comparison with hybrids (36.8 %) and pipiens form (14.9 %). Some unexpected correlations between the proportion of forms pipiens, molestus and hybrids, and mosquito biological characteristics were observed suggesting some epigenetic effects controlling Cx. p. pipiens mating and reproduction. Consequences for pathogen transmission are discussed.

Rift Valley fever vector diversity and impact of meteorological and environmental factors on Culex pipiens dynamics in the Okavango Delta, Botswana.

Science.gov (United States)

Pachka, Hammami; Annelise, Tran; Alan, Kemp; Power, Tshikae; Patrick, Kgori; Véronique, Chevalier; Janusz, Paweska; Ferran, Jori

2016-08-08

In Northern Botswana, rural communities, livestock, wildlife and large numbers of mosquitoes cohabitate around permanent waters of the Okavango Delta. As in other regions of sub-Saharan Africa, Rift Valley Fever (RVF) virus is known to circulate in that area among wild and domestic animals. However, the diversity and composition of potential RVF mosquito vectors in that area are unknown as well as the climatic and ecological drivers susceptible to affect their population dynamics. Using net traps baited with carbon dioxide, monthly mosquito catches were implemented over four sites surrounding cattle corrals at the northwestern border of the Okavango Delta between 2011 and 2012. The collected mosquito species were identified and analysed for the presence of RVF virus by molecular methods. In addition, a mechanistic model was developed to assess the qualitative influence of meteorological and environmental factors such as temperature, rainfall and flooding levels, on the population dynamics of the most abundant species detected (Culex pipiens). More than 25,000 mosquitoes from 32 different species were captured with an overabundance of Cx. pipiens (69,39 %), followed by Mansonia uniformis (20,67 %) and a very low detection of Aedes spp. (0.51 %). No RVF virus was detected in our mosquito pooled samples. The model fitted well the Cx. pipiens catching results (ρ = 0.94, P = 0.017). The spatial distribution of its abundance was well represented when using local rainfall and flooding measures (ρ = 1, P = 0.083). The global population dynamics were mainly influenced by temperature, but both rainfall and flooding presented a significant influence. The best and worst suitable periods for mosquito abundance were around March to May and June to October, respectively. Our study provides the first available data on the presence of potential RVF vectors that could contribute to the maintenance and dissemination of RVF virus in the Okavango Delta. Our model allowed us to

Seasonal abundance and potential of Japanese encephalitis virus infection in mosquitoes at the nesting colony of ardeid birds, Thailand.

Science.gov (United States)

Changbunjong, Tanasak; Weluwanarak, Thekhawet; Taowan, Namaoy; Suksai, Parut; Chamsai, Tatiyanuch; Sedwisai, Poonyapat

2013-03-01

To investigate the abundance and seasonal dynamics of mosquitoes, and to detect Japanese encephalitis virus (JEV) in these mosquitoes at the nesting colony of ardeid birds. Mosquitoes were collected bimonthly from July 2009 to May 2010 by Centers for Disease Control. Light traps and dry ice, as a source of CO2, were employed to attract mosquitoes. Mosquitoes were first identified, pooled into groups of upto 50 mosquitoes by species, and tested for JEV infection by viral isolation and reverse transcriptase polymerase chain reaction. A total of 20 370 mosquitoes comprising 14 species in five genera were collected. The five most abundant mosquito species collected were Culex tritaeniorhynchus (95.46%), Culex vishnui (2.68%), Culex gelidus (0.72%), Anopheles peditaeniatus (0.58%) and Culex quinquefasciatus (0.22%). Mosquito peak densities were observed in July. All of 416 mosquito pools were negative for JEV. This study provides new information about mosquito species and status of JEV infection in mosquitoes in Thailand. Further study should be done to continue a close survey for the presence of this virus in the ardeid birds.

Effects of West Nile virus dose and extrinsic incubation temperature on temporal progression of vector competence in Culex pipiens quinquefasciatus.

Science.gov (United States)

Anderson, Sheri L; Richards, Stephanie L; Tabachnick, Walter J; Smartt, Chelsea T

2010-03-01

Culex pipiens quinquefasciatus were fed blood containing either 7.0 +/- 0.1 logs plaque-forming units (pfu)/ml (high dose) or 5.9 +/- 0.1 logs pfu/ml (low dose) of West Nile virus and held at extrinsic incubation temperatures (EIT) of 28 degrees C or 25 degrees C. Approximately 20 mosquitoes per dose were collected after incubation periods (IP) of 4, 6, 8, and 12 days postinfection (dpi). Infection rates were influenced by EIT and virus dose but not by IP. Body titer was significantly higher for mosquitoes fed the high dose and held at 28 degrees C at the later IPs (6, 8, and 12 dpi). However, leg titer was significantly higher for mosquitoes at the later IPs but did not differ between EITs or doses. Because infection rates varied with EIT and dose, there is likely a midgut infection barrier influenced by these factors that is not influenced by IP. Dissemination rates were influenced by all 3 factors consistent with the presence of a midgut escape barrier. Dissemination rate, body titer, and leg titer were dependent on IP, indicating the need to investigate multiple time points in vector competence studies to elucidate critical events in infection and dissemination.

Ecological niche modelling of Rift Valley fever virus vectors in Baringo, Kenya

Directory of Open Access Journals (Sweden)

Alfred O. Ochieng

2016-11-01

Full Text Available Background: Rift Valley fever (RVF is a vector-borne zoonotic disease that has an impact on human health and animal productivity. Here, we explore the use of vector presence modelling to predict the distribution of RVF vector species under climate change scenario to demonstrate the potential for geographic spread of Rift Valley fever virus (RVFV. Objectives: To evaluate the effect of climate change on RVF vector distribution in Baringo County, Kenya, with an aim of developing a risk map for spatial prediction of RVF outbreaks. Methodology: The study used data on vector presence and ecological niche modelling (MaxEnt algorithm to predict the effect of climatic change on habitat suitability and the spatial distribution of RVF vectors in Baringo County. Data on species occurrence were obtained from longitudinal sampling of adult mosquitoes and larvae in the study area. We used present (2000 and future (2050 Bioclim climate databases to model the vector distribution. Results: Model results predicted potential suitable areas with high success rates for Culex quinquefasciatus, Culex univitattus, Mansonia africana, and Mansonia uniformis. Under the present climatic conditions, the lowlands were found to be highly suitable for all the species. Future climatic conditions indicate an increase in the spatial distribution of Cx. quinquefasciatus and M. africana. Model performance was statistically significant. Conclusion: Soil types, precipitation in the driest quarter, precipitation seasonality, and isothermality showed the highest predictive potential for the four species.

An impossible journey? The development of Plasmodium falciparum NF54 in Culex quinquefasciatus.

Directory of Open Access Journals (Sweden)

Julia Knöckel

Full Text Available Although Anopheles mosquitoes are the vectors for human Plasmodium spp., there are also other mosquito species-among them culicines (Culex spp., Aedes spp.-present in malaria-endemic areas. Culicine mosquitoes transmit arboviruses and filarial worms to humans and are vectors for avian Plasmodium spp., but have never been observed to transmit human Plasmodium spp. When ingested by a culicine mosquito, parasites could either face an environment that does not allow development due to biologic incompatibility or be actively killed by the mosquito's immune system. In the latter case, the molecular mechanism of killing must be sufficiently powerful that Plasmodium is not able to overcome it. To investigate how human malaria parasites develop in culicine mosquitoes, we infected Culex quinquefasciatus with Plasmodium falciparum NF54 and monitored development of parasites in the blood bolus and midgut epithelium at different time points. Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3. After 30 hours, parasites have invaded the midgut and can be observed on the basal side of the midgut epithelium by confocal and transmission electron microscopy. Very few of the parasites in C. quinquefasciatus are alive, most of them are lysed. Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus. Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.

Effect of photoperiod on blood feeding activity of female hybrids between Culex pipiens pipiens and Culex pipiens quinquefasciatus (Diptera: Culicidae)

OpenAIRE

Kurokawa, Kenji; Yoshii, Manabu; Oda, Tsutomu; Kato, Katsutomo; Uchida, Keikichi; Eshita, Yuki; Tahara, Hiroyuki; Mine, Mariko; Ogawa, Yasunori

2004-01-01

Blood feeding activity was examined in females of hybrids (F1) between Culex pipiens pipiens and Culex pipiens quinquefasciatus in long and short photoperiods at 2l℃ to examine the effect of photoperiod on blood feeding rate. Blood feeding rates (F1) were lower in short photoperiods than in long photoperiods. From this, it seems that the hybrids show diapause.

Transgenerational interactions between pesticide exposure and warming in a vector mosquito

DEFF Research Database (Denmark)

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

2018-01-01

of single and combined exposure to warming (4°C increase) and the pesticide chlorpyrifos on life history traits of the vector mosquito Culex pipiens. Parental exposure to a single stressor, either warming or the pesticide, had negative effects on the offspring: both parental exposure to warming...

A first note on Japanese encephalitis virus isolation from Culex quinquefasciatus Say in Northern West Bengal.

OpenAIRE

V. Thenmozhi; T. Mariappan; R. Krishnamoorthy; R. Krishnamoorthi; T. Balaji; B. K. Tyagi; V. Thenmozhi

2014-01-01

Japanese encephalitis (JE) is endemic in many parts of India including the state of West Bengal. In West Bengal, the first major outbreaks of JE occurred in the districts of Bankura and Burdwan in 1973. The Culex vishnui subgroup of mosquitoes has been implicated as major vectors of JE. However in India, JE virus (JEV) has been isolated from 16 species of mosquitoes. During September 2011, JE cases were reported from four districts -Jalpaiguri, Darjeeling, Dinajpur and Cooch Behar of West Ben...

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

Asymmetric effects of native and exotic invasive shrubs on ecology of the West Nile virus vector Culex pipiens (Diptera: Culicidae).

Science.gov (United States)

Gardner, Allison M; Allan, Brian F; Frisbie, Lauren A; Muturi, Ephantus J

2015-06-16

Exotic invasive plants alter the structure and function of native ecosystems and may influence the distribution and abundance of arthropod disease vectors by modifying habitat quality. This study investigated how invasive plants alter the ecology of Culex pipiens, an important vector of West Nile virus (WNV) in northeastern and midwestern regions of the United States. Field and laboratory experiments were conducted to test the hypothesis that three native leaf species (Rubus allegheniensis, blackberry; Sambucus canadensis, elderberry; and Amelanchier laevis, serviceberry), and three exotic invasive leaf species (Lonicera maackii, Amur honeysuckle; Elaeagnus umbellata, autumn olive; and Rosa multiflora, multiflora rose) alter Cx. pipiens oviposition site selection, emergence rates, development time, and adult body size. The relative abundance of seven bacterial phyla in infusions of the six leaf species also was determined using quantitative real-time polymerase chain reaction to test the hypothesis that variation in emergence, development, and oviposition site selection is correlated to differences in the diversity and abundance of bacteria associated with different leaf species, important determinants of nutrient quality and availability for mosquito larvae. Leaf detritus from invasive honeysuckle and autumn olive yielded significantly higher adult emergence rates compared to detritus from the remaining leaf species and honeysuckle alleviated the negative effects of intraspecific competition on adult emergence. Conversely, leaves of native blackberry acted as an ecological trap, generating high oviposition but low emergence rates. Variation in bacterial flora associated with different leaf species may explain this asymmetrical production of mosquitoes: emergence rates and oviposition rates were positively correlated to bacterial abundance and diversity, respectively. We conclude that the displacement of native understory plant species by certain invasive shrubs

Culex quinquefasciatus from Rio de Janeiro Is Not Competent to Transmit the Local Zika Virus.

Directory of Open Access Journals (Sweden)

Rosilainy Surubi Fernandes

2016-09-01

Full Text Available The Americas have suffered a dramatic epidemic of Zika since May in 2015, when Zika virus (ZIKV was first detected in Brazil. Mosquitoes belonging to subgenus Stegomyia of Aedes, particularly Aedes aegypti, are considered the primary vectors of ZIKV. However, the rapid spread of the virus across the continent raised several concerns about the transmission dynamics, especially about potential mosquito vectors. The purpose of this work was to assess the vector competence of the house mosquito Culex quinquefasciatus from an epidemic Zika area, Rio de Janeiro, Brazil, for local circulating ZIKV isolates.Culex quinquefasciatus and Ae. aegypti (positive control of ZIKV infection from Rio de Janeiro were orally exposed to two ZIKV strains isolated from human cases from Rio de Janeiro (Rio-U1 and Rio-S1. Fully engorged mosquitoes were held in incubators at 26 ± 1°C, 12 h:12 h light:dark cycle and 70 ± 10% humidity. For each combination mosquito population-ZIKV strain, 30 specimens were examined for infection, dissemination and transmission rates, at 7, 14 and 21 days after virus exposure by analyzing body (thorax plus abdomen, head and saliva respectively. Infection rates were minimal to completely absent in all Cx. quinquefasciatus-virus combinations and were significantly high for Ae. aegypti. Moreover, dissemination and transmission were not detected in any Cx. quinquefasciatus mosquitoes whatever the incubation period and the ZIKV isolate. In contrast, Ae. aegypti ensured high viral dissemination and moderate to very high transmission.The southern house mosquito Cx. quinquefasciatus from Rio de Janeiro was not competent to transmit local strains of ZIKV. Thus, there is no experimental evidence that Cx. quinquefasciatus likely plays a role in the ZIKV transmission. Consequently, at least in Rio, mosquito control to reduce ZIKV transmission should remain focused on Ae. aegypti.

Quantifying seasonal and diel variation in Anopheline and Culex human biting rates in Southern Ecuador.

Science.gov (United States)

Ryan, Sadie J; Lippi, Catherine A; Boersch-Supan, Philipp H; Heydari, Naveed; Silva, Mercy; Adrian, Jefferson; Noblecilla, Leonardo F; Ayala, Efraín B; Encalada, Mayling D; Larsen, David A; Krisher, Jesse T; Krisher, Lyndsay; Fregosi, Lauren; Stewart-Ibarra, Anna M

2017-11-22

Quantifying mosquito biting rates for specific locations enables estimation of mosquito-borne disease risk, and can inform intervention efforts. Measuring biting itself is fraught with ethical concerns, so the landing rate of mosquitoes on humans is often used as a proxy measure. Southern coastal Ecuador was historically endemic for malaria (Plasmodium falciparum and Plasmodium vivax), although successful control efforts in the 2000s eliminated autochthonous transmission (since 2011). This study presents an analysis of data collected during the elimination period. Human landing catch (HLC) data for three mosquito taxa: two malaria vectors, Anopheles albimanus and Anopheles punctimacula, and grouped Culex spp. were examined for this study. These data were collected by the National Vector Control Service of the Ministry of Health over a 5-year time span (2007-2012) in five cities in southern coastal Ecuador, at multiple households, in all months of the year, during dusk-dawn (18:00-6:00) hours, often at both indoor and outdoor locations. Hurdle models were used to determine if biting activity was fundamentally different for the three taxa, and to identify spatial and temporal factors influencing bite rate. Due to the many different approaches to studying and quantifying bite rates in the literature, a glossary of terms was created, to facilitate comparative studies in the future. Biting trends varied significantly with species and time. All taxa exhibited exophagic feeding behavior, and outdoor locations increased both the odds and incidence of bites across taxa. Anopheles albimanus was most frequently observed biting, with an average of 4.7 bites/h. The highest and lowest respective months for significant biting activity were March and July for An. albimanus, July and August for An. punctimacula, and February and July for Culex spp. Fine-scale differences in endophagy and exophagy, and temporal differences among months and hours exist in biting patterns among

Comparison of sampling techniques for Rift Valley Fever virus potential vectors, Aedes aegypti and Culex pipiens complex, in Ngorongoro District in northern Tanzania.

Science.gov (United States)

Mweya, Clement N; Kimera, Sharadhuli I; Karimuribo, Esron D; Mboera, Leonard E G

2013-07-01

We investigated mosquito sampling techniques with two types of traps and attractants at different time for trapping potential vectors for Rift Valley Fever virus. The study was conducted in six villages in Ngorongoro district in Tanzania from September to October 2012. A total of 1814 mosquitoes were collected, of which 738 were collected by CDC light traps and 1076 by Mosquito Magnet trapping technique. Of the collected mosquitoes, 12.46% (N = 226) were Aedes aegypti and 87.54% (N = 1588) were Culex pipiens complex. More mosquitoes were collected outdoors using Mosquito Magnets baited with octenol attractant, 36.38% (N =660) followed by indoor trapping using CDC light traps without attractant, 29.60% (N = 537). Most of Ae. aegypti mosquitoes were collected outdoor using Mosquito Magnets, 95% (N = 214) whereas Cx. pipiens complex were trapped both indoor using CDC light traps without attractant and outdoors using both CDC light traps baited with carbon dioxide (CO2) sachets and Mosquito Magnets. Analysis on the differences in abundance of mosquitoes trapped by different techniques using Generalized Linear Models was statistically significance at p-value < 0.05 for both species. Three hours mosquito collections show differing patterns in activity, most Ae. aegypti species were collected primarily during the first and last quarters of the day. Cx pipiens complex was active throughout the night, early evening and early morning then decreased markedly during the day time. The results presented in this paper emphasize the possibility of using Mosquito Magnets in order to efficiently capture these potential RVF vectors.

Transgenerational interactions between a pesticide and warming in a vector mosquito

DEFF Research Database (Denmark)

Tran, T.; Dinh, Khuong Van; Stoks, R.

may change in a polluted environment. We set up a full-factorial transgenerational experiment where Culex pipiens vector mosquitoes were reared at two temperatures (20°C vs 24°C) and, when they reached the final larval stage, exposed to one of two chlorpyrifos treatments (absent vs present). We...

Culex pipiens, an experimental efficient vector of West Nile and Rift Valley fever viruses in the Maghreb region.

Directory of Open Access Journals (Sweden)

Fadila Amraoui

Full Text Available West Nile fever (WNF and Rift Valley fever (RVF are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 10(7.8 and 10(8.5 plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14-21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology.

St. Louis Encephalitis virus mosquito vectors dynamics in three different environments in relation to remotely sensed environmental conditions.

Science.gov (United States)

Batallán, Gonzalo P; Estallo, Elizabet L; Flores, Fernando S; Sartor, Paolo; Contigiani, Marta S; Almirón, Walter R

2015-06-01

In Argentina the St. Louis Encephalitis virus (SLEV) is an endemic and widely distributed pathogen transmitted by the cosmopolitan mosquito Culex quinquefasciatus. During two outbreaks in Córdoba city, in 2005 and 2010, Culex interfor was also found infected, but its role as vector of SLEV is poorly known. This mosquito species is distributed from central Argentina to southern Brazil. The primary aim of this study was to analyze the population dynamic of Cx. interfor and Cx. quinquefasciatus in three different environments (urban, suburban and non-urban) in relation to remotely sensed environmental data for vegetation (NDVI and NDWI) and temperature (brightness temperature). Cx. quinquefasciatus and Cx. interfor were found at the three sampled sites, being both the most abundant Culex species, with peaks in early and midsummer. Temporal distribution patterns of both mosquito species were highly correlated in a non-urban area of high SLEV risk transmission. Cx. quinquefasciatus and Cx. interfor were associated with the most urbanized site and the non-urban environment, respectively; high significant correlations were detected between vegetation indices and abundance of both mosquito species confirming these associations. These data provide a foundation for building density maps of these two SLEV mosquito vectors using remotely sensed data to help inform vector control programs. Copyright © 2015 Elsevier B.V. All rights reserved.

Data-driven identification of potential Zika virus vectors

Science.gov (United States)

Evans, Michelle V; Dallas, Tad A; Han, Barbara A; Murdock, Courtney C; Drake, John M

2017-01-01

Zika is an emerging virus whose rapid spread is of great public health concern. Knowledge about transmission remains incomplete, especially concerning potential transmission in geographic areas in which it has not yet been introduced. To identify unknown vectors of Zika, we developed a data-driven model linking vector species and the Zika virus via vector-virus trait combinations that confer a propensity toward associations in an ecological network connecting flaviviruses and their mosquito vectors. Our model predicts that thirty-five species may be able to transmit the virus, seven of which are found in the continental United States, including Culex quinquefasciatus and Cx. pipiens. We suggest that empirical studies prioritize these species to confirm predictions of vector competence, enabling the correct identification of populations at risk for transmission within the United States. DOI: http://dx.doi.org/10.7554/eLife.22053.001 PMID:28244371

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.

Distribuição sazonal de Culex (Culex eduardoi Casal & Garcia (Diptera, Culicidae em criadouros antrópicos introduzidos em mata residual degradada, área urbana de Curitiba, Paraná,Brasil Seazonal distribution of Culex (Culex eduardoi Casal & Garcia (Diptera, Culicidae in artificial receptacles in disturbed patch of forest degraded inurban area of Curitiba, Paraná, Brazil

Directory of Open Access Journals (Sweden)

Magda Clara Vieira da Costa Ribeiro

2002-07-01

Full Text Available The utilization of artificial receptacles to oviposition by mosquitoes in forest environment may indicate a sinantropic tendency or behaviour. Our data revealed that tires were as the most acceptable breeding for Culex (Culex eduardoi Casal & Garcia 1968.The population density of this species was higher and summer seasons.

Genetic and anatomic determinants of enzootic Venezuelan equine encephalitis virus infection of Culex (Melanoconion taeniopus.

Directory of Open Access Journals (Sweden)

Joan L Kenney

Full Text Available Venezuelan equine encephalitis (VEE is a re-emerging, mosquito-borne viral disease with the potential to cause fatal encephalitis in both humans and equids. Recently, detection of endemic VEE caused by enzootic strains has escalated in Mexico, Peru, Bolivia, Colombia and Ecuador, emphasizing the importance of understanding the enzootic transmission cycle of the etiologic agent, VEE virus (VEEV. The majority of work examining the viral determinants of vector infection has been performed in the epizootic mosquito vector, Aedes (Ochlerotatus taeniorhynchus. Based on the fundamental differences between the epizootic and enzootic cycles, we hypothesized that the virus-vector interaction of the enzootic cycle is fundamentally different from that of the epizootic model. We therefore examined the determinants for VEEV IE infection in the enzootic vector, Culex (Melanoconion taeniopus, and determined the number and susceptibility of midgut epithelial cells initially infected and their distribution compared to the epizootic virus-vector interaction. Using chimeric viruses, we demonstrated that the determinants of infection for the enzootic vector are different than those observed for the epizootic vector. Similarly, we showed that, unlike A. taeniorhynchus infection with subtype IC VEEV, C. taeniopus does not have a limited subpopulation of midgut cells susceptible to subtype IE VEEV. These findings support the hypothesis that the enzootic VEEV relationship with C. taeniopus differs from the epizootic virus-vector interaction in that the determinants appear to be found in both the nonstructural and structural regions, and initial midgut infection is not limited to a small population of susceptible cells.

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.

Differential effect of human ivermectin treatment on blood feeding Anopheles gambiae and Culex quinquefasciatus

DEFF Research Database (Denmark)

Derua, Yahya A.; Kisinza, William N.; Simonsen, Paul Erik

2015-01-01

BACKGROUND: Widespread and large scale use of ivermectin in humans and domestic animals can have unexpected effects on non-target organisms. As a search for a possible explanation for an observed longitudinal decline in density of anopheline vector mosquitoes, but not in Culex quinquefasciatus...... to receive either ivermectin or placebo. Twenty four hours after treatment, one volunteer from each group was concurrently exposed to 50 laboratory reared An. gambiae on one arm and 50 laboratory reared Cx. quinquefasciatus on the other arm for 15-30 minutes. Engorged mosquitoes were maintained on 10...

Ovicidal and larvicidal effects of garlic and asafoetida essential oils against West Nile virus vectors

Science.gov (United States)

We examined the chemical composition of garlic and asafoetida essential oils and their individual and combined toxicity against larvae of two West Nile virus vectors, Culex pipiens pipiens and Cx. restuans. The effect of the two essential oils on egg hatch was also examined. Ten and twelve compounds...

Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA

Directory of Open Access Journals (Sweden)

Haramis Linn

2010-03-01

Full Text Available Abstract Background Models of the effects of environmental factors on West Nile virus disease risk have yielded conflicting outcomes. The role of precipitation has been especially difficult to discern from existing studies, due in part to habitat and behavior characteristics of specific vector species and because of differences in the temporal and spatial scales of the published studies. We used spatial and statistical modeling techniques to analyze and forecast fine scale spatial (2000 m grid and temporal (weekly patterns of West Nile virus mosquito infection relative to changing weather conditions in the urban landscape of the greater Chicago, Illinois, region for the years from 2004 to 2008. Results Increased air temperature was the strongest temporal predictor of increased infection in Culex pipiens and Culex restuans mosquitoes, with cumulative high temperature differences being a key factor distinguishing years with higher mosquito infection and higher human illness rates from those with lower rates. Drier conditions in the spring followed by wetter conditions just prior to an increase in infection were factors in some but not all years. Overall, 80% of the weekly variation in mosquito infection was explained by prior weather conditions. Spatially, lower precipitation was the most important variable predicting stronger mosquito infection; precipitation and temperature alone could explain the pattern of spatial variability better than could other environmental variables (79% explained in the best model. Variables related to impervious surfaces and elevation differences were of modest importance in the spatial model. Conclusion Finely grained temporal and spatial patterns of precipitation and air temperature have a consistent and significant impact on the timing and location of increased mosquito infection in the northeastern Illinois study area. The use of local weather data at multiple monitoring locations and the integration of mosquito

Pengaruh Pengasapan (Thermal Fogging Insektisida Piretroid (Malation 95% Terhadap Nyamuk Aedes aegypti dan Culex quinquefasciatus di Pemukiman

Directory of Open Access Journals (Sweden)

Hasan Boesri

2009-12-01

Full Text Available The evaluation of piretroid insecticide (active ingredient Malation 95% was con-ducted in Sub district Tengarang, Semarang Segency, Central Java Province. The insecti-cide was applied using thermal fogging method for dosages of 125, 250, 375, 500 and 625 ml/ha (diluted in diesel to 10 litters. The evaluation of the efficacy was conducted against two mosquito species, Aedes aegypti (the main dengue haemorrhagic fever and Culex quinquefasciatus (the urban lymphatic fil-ariasis vector. Result of the evaluation was revealed that dosages of 500 and 625 ml/ha were effective against both tested mosquito species indoor and outdoor.

Long-term pathogenic response to Plasmodium relictum infection in Culex pipiens mosquito.

Science.gov (United States)

Pigeault, Romain; Villa, Manon

2018-01-01

The transmission of Plasmodium within a vertebrate host population is strongly associated with the life history traits of its vector. Therefore the effect of malaria infection on mosquito fecundity and longevity has traditionally received a lot of attention. Several species of malaria parasites reduce mosquito fecundity, nevertheless almost all of the studies have focused only on the first gonotrophic cycle. Yet, during their lifetime, female mosquitoes go through several gonotrophic cycles, which raises the question of whether they are able to compensate the fecundity costs induced by the parasite. The impact of Plasmodium infection on female longevity is not so clear and has produced conflicting results. Here we measured the impact of Plasmodium relictum on its vector's longevity and fecundity during three consecutive gonotrophic cycles. In accordance with previous studies, we observed a negative impact of Plasmodium infection on mosquito (Culex pipiens) fecundity in the first gonotrophic cycle. Interestingly, despite having taken two subsequent uninfected blood meals, the negative impact of malaria parasite persisted. Nevertheless no impact of infection on mosquito longevity was observed. Our results are not in line with the hypothesis that the reduction of fecundity observed in infected mosquitoes is an adaptive strategy of Plasmodium to increase the longevity of its vector. We discuss the different underlying mechanisms that may explain our results.

Darker eggs of mosquitoes resist more to dry conditions: Melanin enhances serosal cuticle contribution in egg resistance to desiccation in Aedes, Anopheles and Culex vectors.

Science.gov (United States)

Farnesi, Luana C; Vargas, Helena C M; Valle, Denise; Rezende, Gustavo L

2017-10-01

Mosquito vectors lay their white eggs in the aquatic milieu. During early embryogenesis water passes freely through the transparent eggshell, which at this moment is composed of exochorion and endochorion. Within two hours the endochorion darkens via melanization but even so eggs shrink and perish if removed from moisture. However, during mid-embryogenesis, cells of the extraembryonic serosa secrete the serosal cuticle, localized right below the endochorion, becoming the third and innermost eggshell layer. Serosal cuticle formation greatly reduces water flow and allows egg survival outside the water. The degree of egg resistance to desiccation (ERD) at late embryogenesis varies among different species: Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus eggs can survive in a dry environment for ≥ 72, 24 and 5 hours, respectively. In some adult insects, darker-body individuals show greater resistance to desiccation than lighter ones. We asked if egg melanization enhances mosquito serosal cuticle-dependent ERD. Species with higher ERD at late embryogenesis exhibit more melanized eggshells. The melanization-ERD hypothesis was confirmed employing two Anopheles quadrimaculatus strains, the wild type and the mutant GORO, with a dark-brown and a golden eggshell, respectively. In all cases, serosal cuticle formation is fundamental for the establishment of an efficient ERD but egg viability outside the water is much higher in mosquitoes with darker eggshells than in those with lighter ones. The finding that pigmentation influences egg water balance is relevant to understand the evolutionary history of insect egg coloration. Since eggshell and adult cuticle pigmentation ensure insect survivorship in some cases, they should be considered regarding species fitness and novel approaches for vector or pest insects control.

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.

Effects of time after infection, mosquito genotype, and infectious viral dose on the dynamics of Culex tarsalis vector competence for western equine encephalomyelitis virus.

Science.gov (United States)

Mahmood, Farida; Chiles, Robert E; Fang, Ying; Green, Emily N; Reisen, William K

2006-06-01

The vector competence of Culex tarsalis Coquillett for the BFS 1703 strain of western equine encephalomyelitis virus (WEEV) changed significantly as a function of time after infection, mosquito genotype, and infectious virus dose. After ingesting a high virus dose (5 log10 plaque-forming units [PFU]/0.1 ml), female of the susceptible high virus producer (HVP) strain rapidly amplified the virus, developed a disseminated infection, and efficiently transmitted WEEV by 4 days postinfection (dpi). The quantity of virus expectorated peaked at 4 dpi (mean 3.4 log10 PFU), and the percentage of females transmitting per os peaked at 7 dpi (80%); both measures of transmission subsequently decreased to low levels throughout the remainder of infected life. HVP females imbibing a low virus dose (3 log10 PFU/0.1 ml) were infected less frequently and took longer to amplify virus to levels recorded for the high virus dose group and did not transmit virus efficiently, thereby indicating midgut infection and escape barriers were dose and time dependent. These data emphasized the importance of elevated avian viremias in Cx. tarsalis vector competence. Females from the WEEV-resistant (WR) strain and two wild-type strains from Kern and Riverside counties were significantly less susceptible to infection at both high and low doses than was the HVP strain. Overall, females with a high virus titer more frequently had a disseminated infection, but there did not seem to be a distinct threshold demarcating this relationship. In marked contrast, all infected females transmitting virus had body titers >4.3 log10 PFU, and most had titers >4.8 log10 PFU. These data indicated that not all females with a disseminated infection transmitted virus because of the presence of one or more salivary gland barriers.

Distribution of Brugia malayi larvae and DNA in vector and non-vector mosquitoes: implications for molecular diagnostics

Directory of Open Access Journals (Sweden)

Christensen Bruce M

2009-11-01

Full Text Available Abstract Background The purpose of this study was to extend prior studies of molecular detection of Brugia malayi DNA in vector (Aedes aegypti- Liverpool and non-vector (Culex pipiens mosquitoes at different times after ingestion of infected blood. Results Parasite DNA was detected over a two week time course in 96% of pooled thoraces of vector mosquitoes. In contrast, parasite DNA was detected in only 24% of thorax pools from non-vectors; parasite DNA was detected in 56% of midgut pools and 47% of abdomen pools from non-vectors. Parasite DNA was detected in vectors in the head immediately after the blood meal and after 14 days. Parasite DNA was also detected in feces and excreta of the vector and non-vector mosquitoes which could potentially confound results obtained with field samples. However, co-housing experiments failed to demonstrate transfer of parasite DNA from infected to non-infected mosquitoes. Parasites were also visualized in mosquito tissues by immunohistololgy using an antibody to the recombinant filarial antigen Bm14. Parasite larvae were detected consistently after mf ingestion in Ae. aegypti- Liverpool. Infectious L3s were seen in the head, thorax and abdomen of vector mosquitoes 14 days after Mf ingestion. In contrast, parasites were only detected by histology shortly after the blood meal in Cx. pipiens, and these were not labeled by the antibody. Conclusion This study provides new information on the distribution of filarial parasites and parasite DNA in vector and non-vector mosquitoes. This information should be useful for those involved in designing and interpreting molecular xenomonitoring studies.

Experimental infection of Hawai'i 'Amakihi (hemignathus virens) with West Nile virus and competence of a co-occurring vector, culex quinquefasciatus: potential impacts on endemic Hawaiian avifauna.

Science.gov (United States)

Lapointe, Dennis; Hofmeister, Erik K.; Atkinson, C.T.; Porter, R.E.; Dusek, Robert J.

2009-01-01

Introduced mosquito-borne avian disease is a major limiting factor in the recovery and restoration of native Hawaiian forest birds. Annual epizootics of avian pox (Avipoxvirus) and avian malaria (Plasmodium relictum) likely led to the extinction of some species and continue to impact populations of susceptible Hawaiian honeycreepers (Drepanidinae). The introduction of a novel pathogen, such as West Nile virus (WNV), could result in further population declines and extinctions. During September and October 2004, we infected Hawai'i' Amakihi (Hemignathus virens) with a North American isolate of WNV by needle inoculation and mosquito bite to observe susceptibility, mortality, and illness in this endemic passerine, and to determine the vector competence of the co-occurring, introduced mosquito Culex quinquefasciatus. All experimentally infected Hawai'i ;Amakihi became viremic, with a mean titer >10(5) plaque-forming units (PFU)/ml, and they experienced clinical signs ranging from anorexia and lethargy to ataxia. The fatality rate among needle-inoculated Hawai'i' Amakihi (n=16) was 31.3%, but mortality in free-ranging birds is likely to increase due to predation, starvation, thermal stress, and concomitant infections of avian malaria and pox. Surviving Hawai'i' Amakihi seem to clear WNV from the peripheral blood by 7-10 days postinfection (DPI), and neutralizing antibodies were detected from 9 to 46 DPI. In transmission trials, Hawaiian Cx. quinquefasciatus proved to be a competent vector and Hawai'i Amakihi an adequate amplification host of WNV, suggesting that epizootic WNV could readily become an additional limiting factor of some native Hawaiian bird populations.

Vector Competence of American Mosquitoes for Three Strains of Zika Virus.

Directory of Open Access Journals (Sweden)

James Weger-Lucarelli

2016-10-01

Full Text Available In 2015, Zika virus (ZIKV; Flaviviridae; Flavivirus emerged in the Americas, causing millions of infections in dozens of countries. The rapid spread of the virus and the association with disease outcomes such as Guillain-Barré syndrome and microcephaly make understanding transmission dynamics essential. Currently, there are no reports of vector competence (VC of American mosquitoes for ZIKV isolates from the Americas. Further, it is not clear whether ZIKV strains from other genetic lineages can be transmitted by American Aedes aegypti populations, and whether the scope of the current epidemic is in part facilitated by viral factors such as enhanced replicative fitness or increased vector competence. Therefore, we characterized replication of three ZIKV strains, one from each of the three phylogenetic clades in several cell lines and assessed their abilities to be transmitted by Ae. aegypti mosquitoes. Additionally, laboratory colonies of different Culex spp. were infected with an American outbreak strain of ZIKV to assess VC. Replication rates were variable and depended on virus strain, cell line and MOI. African strains used in this study outcompeted the American strain in vitro in both mammalian and mosquito cell culture. West and East African strains of ZIKV tested here were more efficiently transmitted by Ae. aegypti from Mexico than was the currently circulating American strain of the Asian lineage. Long-established laboratory colonies of Culex mosquitoes were not efficient ZIKV vectors. These data demonstrate the capacity for additional ZIKV strains to infect and replicate in American Aedes mosquitoes and suggest that neither enhanced virus replicative fitness nor virus adaptation to local vector mosquitoes seems likely to explain the extent and intensity of ZIKV transmission in the Americas.

Zika mosquito vectors: the jury is still out [version 1; referees: 5 approved

Directory of Open Access Journals (Sweden)

Walter S. Leal

2016-10-01

Full Text Available After a 40-year hiatus, the International Congress of Entomology (ICE 2016 convened in Orlando, Florida (September 25-30, 2016. One of the symposia at ICE 2016, the Zika Symposium, covered multiple aspects of the Zika epidemic, including epidemiology, sexual transmission, genetic tools for reducing transmission, and particularly vector competence. While there was a consensus among participants that the yellow fever mosquito, Aedes aegypti, is a vector of the Zika virus, there is growing evidence indicating that the range of mosquito vectors might be wider than anticipated. In particular, three independent groups from Canada, China, and Brazil presented and discussed laboratory and field data strongly suggesting that the southern house mosquito, Culex quinquefasciatus, also known as the common mosquito, is highly likely to be a vector in certain environments.

Zika mosquito vectors: the jury is still out [version 2; referees: 5 approved

Directory of Open Access Journals (Sweden)

Walter S. Leal

2016-11-01

Full Text Available After a 40-year hiatus, the International Congress of Entomology (ICE 2016 convened in Orlando, Florida (September 25-30, 2016. One of the symposia at ICE 2016, the Zika Symposium, covered multiple aspects of the Zika epidemic, including epidemiology, sexual transmission, genetic tools for reducing transmission, and particularly vector competence. While there was a consensus among participants that the yellow fever mosquito, Aedes aegypti, is a vector of the Zika virus, there is growing evidence indicating that the range of mosquito vectors might be wider than anticipated. In particular, three independent groups from Canada, China, and Brazil presented and discussed laboratory and field data strongly suggesting that the southern house mosquito, Culex quinquefasciatus, also known as the common mosquito, is highly likely to be a vector in certain environments.

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

Science.gov (United States)

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

2017-10-01

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

Review of climate, landscape, and viral genetics as drivers of the Japanese encephalitis virus ecology.

Directory of Open Access Journals (Sweden)

Guillaume Le Flohic

Full Text Available The Japanese encephalitis virus (JEV, an arthropod-born Flavivirus, is the major cause of viral encephalitis, responsible for 10,000-15,000 deaths each year, yet is a neglected tropical disease. Since the JEV distribution area has been large and continuously extending toward new Asian and Australasian regions, it is considered an emerging and reemerging pathogen. Despite large effective immunization campaigns, Japanese encephalitis remains a disease of global health concern. JEV zoonotic transmission cycles may be either wild or domestic: the first involves wading birds as wild amplifying hosts; the second involves pigs as the main domestic amplifying hosts. Culex mosquito species, especially Cx. tritaeniorhynchus, are the main competent vectors. Although five JEV genotypes circulate, neither clear-cut genotype-phenotype relationship nor clear variations in genotype fitness to hosts or vectors have been identified. Instead, the molecular epidemiology appears highly dependent on vectors, hosts' biology, and on a set of environmental factors. At global scale, climate, land cover, and land use, otherwise strongly dependent on human activities, affect the abundance of JEV vectors, and of wild and domestic hosts. Chiefly, the increase of rice-cultivated surface, intensively used by wading birds, and of pig production in Asia has provided a high availability of resources to mosquito vectors, enhancing the JEV maintenance, amplification, and transmission. At fine scale, the characteristics (density, size, spatial arrangement of three landscape elements (paddy fields, pig farms, human habitations facilitate or impede movement of vectors, then determine how the JEV interacts with hosts and vectors and ultimately the infection risk to humans. If the JEV is introduced in a favorable landscape, either by live infected animals or by vectors, then the virus can emerge and become a major threat for human health. Multidisciplinary research is essential to shed

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.

Temperature, viral genetics, and the transmission of West Nile virus by Culex pipiens mosquitoes.

Directory of Open Access Journals (Sweden)

A Marm Kilpatrick

2008-06-01

Full Text Available The distribution and intensity of transmission of vector-borne pathogens can be strongly influenced by the competence of vectors. Vector competence, in turn, can be influenced by temperature and viral genetics. West Nile virus (WNV was introduced into the United States of America in 1999 and subsequently spread throughout much of the Americas. Previously, we have shown that a novel genotype of WNV, WN02, first detected in 2001, spread across the US and was more efficient than the introduced genotype, NY99, at infecting, disseminating, and being transmitted by Culex mosquitoes. In the current study, we determined the relationship between temperature and time since feeding on the probability of transmitting each genotype of WNV. We found that the advantage of the WN02 genotype increases with the product of time and temperature. Thus, warmer temperatures would have facilitated the invasion of the WN02 genotype. In addition, we found that transmission of WNV accelerated sharply with increasing temperature, T, (best fit by a function of T(4 showing that traditional degree-day models underestimate the impact of temperature on WNV transmission. This laboratory study suggests that both viral evolution and temperature help shape the distribution and intensity of transmission of WNV, and provides a model for predicting the impact of temperature and global warming on WNV transmission.

Aspectos ecológicos de Anopheles cruzii e Culex ribeirensis (Diptera, Culicidae da Mata Atlântica de Morretes, Paraná, Brasil Ecological aspects of Anopheles cruzii and Culex ribeirensis (Diptera, Culicidae in Atlantic Forest of Morretes, Paraná, Brazil

Directory of Open Access Journals (Sweden)

Luiz Gonzaga dos Santos-Neto

2008-01-01

Full Text Available Um estudo foi realizado sobre mosquitos adultos de abril 1995 a março 1996 na Mata Atlântica do município de Morretes, Paraná, Brasil. A investigação foi procedida com auxílio de duas armadilhas luminosas CDC-M instaladas em estratos verticais diferentes. Os mosquitos foram capturados mensalmente durante um ano, com início às 18 horas e término às 6 horas do dia seguinte, totalizando 144 horas de trabalho de campo. Obteve-se 1.408 exemplares de mosquitos (409 na copa e 999 próximo ao solo, pertencentes a 10 gêneros e 31 espécies. Anopheles cruzii e Culex ribeirensis foram predominantes e são objetos do presente estudo. Não foi observada diferença entre as armadilhas para Anopheles cruzii. Mas Culex ribeirensis foi coletado em maior número pela CDC-M/solo. Anopheles cruzii, quanto à freqüência horária, apresentou picos nas primeiras horas da noite, depois a sua atividade decresceu progressivamente até o crepúsculo matutino, sem apresentar um pico secundário. Em referência a distribuição mensal, Anopheles cruzii foi mais freqüente nos meses de abril e maio de 1995 e março de 1996. Não houve correlação do número de exemplares com a temperatura ou precipitações pluviométricas. Culex ribeirensis apresentou maior atividade de vôo de 22h às 4h, mas não houve picos significativos. Nas coletas obtidas por mês, Culex ribeirensis teve picos em dezembro e janeiro. Houve correlação do número de espécimes deste culicíneo com a temperatura e precipitações pluviométricas. Constituem os primeiros registros para o Estado do Paraná: Ochlerotatus rhyacophilus, Culex misionensis, Culex pedroi, Culex ribeirensis e Culex zeteki.A study of adult mosquitoes was performed from April 1995 to March 1996 in the Atlantic Forest near to Morretes city, Paraná, Brazil. The research was carried out by using two CDC-M light traps installed in different vertical stratification levels. Mosquitoes were collected monthly throughout

Correlation between carboxylesterase alleles and insecticide resistance in Culex pipiens complex from China

Directory of Open Access Journals (Sweden)

Liu Yangyang

2011-12-01

Full Text Available Abstract Background In China, large amounts of chemical insecticides are applied in fields or indoors every year, directly or indirectly bringing selection pressure on vector mosquitoes. Culex pipiens complex has evolved to be resistant to all types of chemical insecticides, especially organophosphates, through carboxylesterases. Six resistant carboxylesterase alleles (Ester were recorded previously and sometimes co-existed in one field population, representing a complex situation for the evolution of Ester genes. Results In order to explore the evolutionary scenario, we analyzed the data from an historical record in 2003 and a recent investigation on five Culex pipiens pallens populations sampled from north China in 2010. Insecticide bioassays showed that these five populations had high resistance to pyrethroids, medium resistance to organophosphates, and low resistance to carbamates. Six types of Ester alleles, EsterB1, Ester2, Ester8, Ester9, EsterB10, and Ester11 were identified, and the overall pattern of their frequencies in geographic distribution was consistent with the report seven years prior to this study. Statistical correlation analysis indicated that Ester8 and Ester9 positively correlated with resistance to four insecticides, and EsterB10 to one insecticide. The occurrences of these three alleles were positively correlated, while the occurrence of EsterB1 was negatively correlated with Ester8, indicating an allelic competition. Conclusion Our analysis suggests that one insecticide can select multiple Ester alleles and one Ester allele can work on multiple insecticides. The evolutionary scenario of carboxylesterases under insecticide selection is possibly "one to many".

Genetic diversity of Wolbachia endosymbionts in Culex quinquefasciatus from Hawai`i, Midway Atoll, and Samoa

Science.gov (United States)

Atkinson, Carter T.; Watcher-Weatherwax, William; Lapointe, Dennis

2016-01-01

Incompatible insect techniques are potential methods for controlling Culex quinquefasciatus and avian disease transmission in Hawai‘i without the use of pesticides or genetically modified organisms. The approach is based on naturally occurring sperm-egg incompatibilities within the Culex pipiens complex that are controlled by different strains of the bacterial endosymbiont Wolbachia pipientis (wPip). Incompatibilities can be unidirectional (crosses between males infected with strain A and females infected with strain B are fertile, while reciprocal crosses are not) or bidirectional (reciprocal crosses between sexes with different wPip strains are infertile). The technique depends on release of sufficient numbers of male mosquitoes infected with an incompatible wPip strain to suppress mosquito populations and reduce transmission of introduced avian malaria (Plasmodium relictum) and Avipoxvirus in native forest bird habitats. Both diseases are difficult to manage using more traditional methods based on removal and treatment of larval habitats and coordination of multiple approaches may be needed to control this vector. We characterized the diversity of Wolbachia strains in C. quinquefasciatus from Hawai‘i, Kaua‘i, Midway Atoll, and American Samoa with a variety of genetic markers to identify compatibility groups and their distribution within and between islands. We confirmed the presence of wPip with multilocus sequence typing, tested for local genetic variability using 16 WO prophage genes, and identified similarities to strains from other parts of the world with a transposable element (tr1). We also tested for genetic differences in ankyrin motifs (ank2 and pk1) which have been used to classify wPip strains into five worldwide groups (wPip1–wPip5) that vary in compatibility with each other based on experimental crosses. We found a mixture of both widely distributed and site specific genotypes based on presence or absence of WO prophage and transposable

West Nile Virus lineage-2 in Culex specimens from Iran.

Science.gov (United States)

Shahhosseini, Nariman; Chinikar, Sadegh; Moosa-Kazemi, Seyed Hassan; Sedaghat, Mohammad Mehdi; Kayedi, Mohammad Hassan; Lühken, Renke; Schmidt-Chanasit, Jonas

2017-10-01

Screening of mosquitoes for viruses is an important forecasting tool for emerging and re-emerging arboviruses. Iran has been known to harbour medically important arboviruses such as West Nile virus (WNV) and dengue virus (DENV) based on seroepidemiological data. However, there are no data about the potential mosquito vectors for arboviruses in Iran. This study was performed to provide mosquito and arbovirus data from Iran. A total of 32 317 mosquitos were collected at 16 sites in five provinces of Iran in 2015 and 2016. RT-PCR for detection of flaviviruses was performed. The PCR amplicons were sequenced, and 109 WNV sequences, including one obtained in this study, were used for phylogenetic analyses. The 32 317 mosquito specimens belonging to 25 species were morphologically distinguished and distributed into 1222 pools. Culex pipiens s.l. comprised 56.429%. One mosquito pool (0.08%), containing 46 unfed Cx. pipiens pipiens form pipiens (Cpp) captured in August 2015, was positive for flavivirus RNA. Subsequent sequencing and phylogenetic analyses revealed that the detected Iranian WNV strain belongs to lineage 2 and clusters with a strain recently detected in humans. No flaviviruses other than WNV were detected in the mosquito pools. Cpp could be a vector for WNV in Iran. Our findings indicate recent circulation of WNV lineage-2 strain in Iran and provide a solid base for more targeted arbovirus surveillance programs. © 2017 John Wiley & Sons Ltd.

Environmental and social-demographic predictors of the southern house mosquito Culex quinquefasciatus in New Orleans, Louisiana.

Science.gov (United States)

Moise, Imelda K; Riegel, Claudia; Muturi, Ephantus J

2018-04-17

Understanding the major predictors of disease vectors such as mosquitoes can guide the development of effective and timely strategies for mitigating vector-borne disease outbreaks. This study examined the influence of selected environmental, weather and sociodemographic factors on the spatial and temporal distribution of the southern house mosquito Culex quinquefasciatus Say in New Orleans, Louisiana, USA. Adult mosquitoes were collected over a 4-year period (2006, 2008, 2009 and 2010) using CDC gravid traps. Socio-demographic predictors were obtained from the United States Census Bureau, 2005-2009 American Community Survey and the City of New Orleans Department of Code Enforcement. Linear mixed effects models and ERDAS image processing software were used for statistical analysis and image processing. Only two of the 22 predictors examined were significant predictors of Cx. quinquefasciatus abundance. Mean temperature during the week of mosquito collection was positively associated with Cx. quinquefasciatus abundance while developed high intensity areas were negatively associated with Cx. quinquefasciatus abundance. The findings of this study illustrate the power and utility of integrating biophysical and sociodemographic data using GIS analysis to identify the biophysical and sociodemographic processes that increase the risk of vector mosquito abundance. This knowledge can inform development of accurate predictive models that ensure timely implementation of mosquito control interventions.

A metagenomic survey of viral abundance and diversity in mosquitoes from Hubei province.

Directory of Open Access Journals (Sweden)

Chenyan Shi

Full Text Available Mosquitoes as one of the most common but important vectors have the potential to transmit or acquire a lot of viruses through biting, however viral flora in mosquitoes and its impact on mosquito-borne disease transmission has not been well investigated and evaluated. In this study, the metagenomic techniquehas been successfully employed in analyzing the abundance and diversity of viral community in three mosquito samples from Hubei, China. Among 92,304 reads produced through a run with 454 GS FLX system, 39% have high similarities with viral sequences belonging to identified bacterial, fungal, animal, plant and insect viruses, and 0.02% were classed into unidentified viral sequences, demonstrating high abundance and diversity of viruses in mosquitoes. Furthermore, two novel viruses in subfamily Densovirinae and family Dicistroviridae were identified, and six torque tenosus virus1 in family Anelloviridae, three porcine parvoviruses in subfamily Parvovirinae and a Culex tritaeniorhynchus rhabdovirus in Family Rhabdoviridae were preliminarily characterized. The viral metagenomic analysis offered us a deep insight into the viral population of mosquito which played an important role in viral initiative or passive transmission and evolution during the process.

A Metagenomic Survey of Viral Abundance and Diversity in Mosquitoes from Hubei Province

Science.gov (United States)

Shi, Chenyan; Liu, Yi; Hu, Xiaomin; Xiong, Jinfeng; Zhang, Bo; Yuan, Zhiming

2015-01-01

Mosquitoes as one of the most common but important vectors have the potential to transmit or acquire a lot of viruses through biting, however viral flora in mosquitoes and its impact on mosquito-borne disease transmission has not been well investigated and evaluated. In this study, the metagenomic techniquehas been successfully employed in analyzing the abundance and diversity of viral community in three mosquito samples from Hubei, China. Among 92,304 reads produced through a run with 454 GS FLX system, 39% have high similarities with viral sequences belonging to identified bacterial, fungal, animal, plant and insect viruses, and 0.02% were classed into unidentified viral sequences, demonstrating high abundance and diversity of viruses in mosquitoes. Furthermore, two novel viruses in subfamily Densovirinae and family Dicistroviridae were identified, and six torque tenosus virus1 in family Anelloviridae, three porcine parvoviruses in subfamily Parvovirinae and a Culex tritaeniorhynchus rhabdovirus in Family Rhabdoviridae were preliminarily characterized. The viral metagenomic analysis offered us a deep insight into the viral population of mosquito which played an important role in viral initiative or passive transmission and evolution during the process. PMID:26030271

Acute larvicidal toxicity of five essential oils (Pinus nigra, Hyssopus officinalis, Satureja montana, Aloysia citrodora and Pelargonium graveolens) against the filariasis vector Culex quinquefasciatus: Synergistic and antagonistic effects.

Science.gov (United States)

Benelli, Giovanni; Pavela, Roman; Canale, Angelo; Cianfaglione, Kevin; Ciaschetti, Giampiero; Conti, Fabio; Nicoletti, Marcello; Senthil-Nathan, Sengottayan; Mehlhorn, Heinz; Maggi, Filippo

2017-04-01

Mosquito vector control is facing a number of important and timely challenges, mainly due to the rapid development of pesticide resistance and environmental concerns. In this scenario, screening of botanical resources for their mosquitocidal activity may offer effective and eco-friendly tools against Culicidae vectors. Culex quinquefasciatus Say (Diptera: Culicidae) is a vector of lymphatic filariasis and of dangerous arboviral diseases, such as West Nile and St. Louis encephalitis. In this study, the chemical composition of five essential oils obtained from different plants, namely Pinus nigra J.F. Arnold var. italica (Pinaceae), Hyssopus officinalis L. subsp. aristatus (Lamiaceae), Satureja montana L. subsp. montana (Lamiaceae), Aloysia citriodora Palau (Verbenaceae) and Pelargonium graveolens L'Hér (Geraniaceae), was investigated by GC-MS analysis. Furthermore, it was evaluated their acute toxicity on larvae of C. quinquefasciatus. Then, the most effective oils were selected, in order to focus on the potential synergistic and antagonistic effects, testing them in binary mixtures on C. quinquefasciatus larvae. Results showed that the higher effectiveness was obtained by S. montana subsp. montana essential oil (LC 50 =25.6μL·L -1 ), followed by P. nigra var. italica (LC 50 =49.8μL·L -1 ) and A. citriodora (LC 50 =65.6μL·L -1 ), while the other essential oils showed LC 50 values higher than 90μL·L -1 . The larvicidal effectiveness can be enhanced by preparing simple binary mixtures of essential oils, such as S. montana+A. citriodora (ratio 1:1), which showed higher larvicidal toxicity (LC 50 =18.3μL·L -1 ). On the other hand, testing S. montana+P. nigra (1:1) an antagonistic effect was detected, leading to a LC 50 (72.5μL·L -1 ) higher than the LC 50 values calculated for the two oils tested separately. Overall, our results add useful knowledge to allow the employ of synergistic essential oil blends as effective, cheap and eco-friendly mosquito

Molecular detection and genotyping of Japanese Encephalitis Virus in mosquitoes during a 2010 outbreak in the Republic of Korea

Science.gov (United States)

Seo, Hyun-Ji; Kim, Heung Chul; Klein, Terry A.; Ramey, Andrew M.; Lee, Ji-Hyee; Kyung, Soon-Goo; Park, Jee-Yong; Cho, In-Soo; Yeh, Jung-Yong

2013-01-01

Japanese encephalitis virus (JEV), a mosquito-borne zoonotic pathogen, is one of the major causes of viral encephalitis. To reduce the impact of Japanese encephalitis among children in the Republic of Korea (ROK), the government established a mandatory vaccination program in 1967. Through the efforts of this program only 0-7 (mean 2.1) cases of Japanese encephalitis were reported annually in the ROK during the period of 1984-2009. However, in 2010 there was an outbreak of 26 confirmed cases of Japanese encephalitis, including 7 deaths. This represented a >12-fold increase in the number of confirmed cases of Japanese encephalitis in the ROK as compared to the mean number reported over the last 26 years and a 3.7-fold increase over the highest annual number of cases during this same period (7 cases). Surveillance of adult mosquitoes was conducted during the 2010 outbreak of Japanese encephalitis in the ROK. A total of 6,328 culicine mosquitoes belonging to 12 species from 5 genera were collected at 6 survey sites from June through October 2010 and assayed by reverse-transcription polymerase chain reaction (RT-PCR) for the presence of JEV. A total of 34/371 pooled samples tested positive for JEV (29/121 Culex tritaeniorhynchus, 4/64 Cx. pipiens, and 1/26 Cx. bitaeniorhynchus) as confirmed by sequencing of the pre-membrane and envelope protein coding genes. The maximum likelihood estimates of JEV positive individuals per 1,000 culicine vectors for Cx. tritaeniorhynchus, Cx. pipiens, and Cx. bitaeniorhynchus were 11.8, 5.6, and 2.8, respectively. Sequences of the JEV pre-membrane and envelope protein coding genes amplified from the culicine mosquitoes by RT-PCR were compared with those of JEV genotypes I-V. Phylogenetic analyses support the detection of a single genotype (I) among samples collected from the ROK in 2010.

Inhibition and Larvicidal Activity of Phenylpropanoids from Piper sarmentosum on Acetylcholinesterase against Mosquito Vectors and Their Binding Mode of Interaction.

Directory of Open Access Journals (Sweden)

Arshia Hematpoor

Full Text Available Aedes aegypti, Aedes albopictus and Culex quinquefasciatus are vectors of dengue fever and West Nile virus diseases. This study was conducted to determine the toxicity, mechanism of action and the binding interaction of three active phenylpropanoids from Piper sarmentosum (Piperaceae toward late 3rd or early 4th larvae of above vectors. A bioassay guided-fractionation on the hexane extract from the roots of Piper sarmentosum led to the isolation and identification of three active phenylpropanoids; asaricin 1, isoasarone 2 and trans-asarone 3. The current study involved evaluation of the toxicity and acetylcholinesterase (AChE inhibition of these compounds against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae. Asaricin 1 and isoasarone 2 were highly potent against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae causing up to 100% mortality at ≤ 15 μg/mL concentration. The ovicidal activity of asaricin 1, isoasarone 2 and trans-asarone 3 were evaluated through egg hatching. Asaricin 1 and isoasarone 2 showed potent ovicidal activity. Ovicidal activity for both compounds was up to 95% at 25μg/mL. Asaricin 1 and isoasarone 2 showed strong inhibition on acetylcholinesterase with relative IC50 values of 0.73 to 1.87 μg/mL respectively. These findings coupled with the high AChE inhibition may suggest that asaricin 1 and isoasarone 2 are neuron toxic compounds toward Aedes aegypti, Aedes albopictus and Culex quinquefasciatus. Further computational docking with Autodock Vina elaborates the possible interaction of asaricin 1 and isoasarone 2 with three possible binding sites of AChE which includes catalytic triads (CAS: S238, E367, H480, the peripheral sites (PAS: E72, W271 and anionic binding site (W83. The binding affinity of asaricin 1 and isoasarone 2 were relatively strong with asaricin 1 showed a higher binding affinity in the anionic pocket.

Inhibition and Larvicidal Activity of Phenylpropanoids from Piper sarmentosum on Acetylcholinesterase against Mosquito Vectors and Their Binding Mode of Interaction.

Science.gov (United States)

Hematpoor, Arshia; Liew, Sook Yee; Chong, Wei Lim; Azirun, Mohd Sofian; Lee, Vannajan Sanghiran; Awang, Khalijah

2016-01-01

Aedes aegypti, Aedes albopictus and Culex quinquefasciatus are vectors of dengue fever and West Nile virus diseases. This study was conducted to determine the toxicity, mechanism of action and the binding interaction of three active phenylpropanoids from Piper sarmentosum (Piperaceae) toward late 3rd or early 4th larvae of above vectors. A bioassay guided-fractionation on the hexane extract from the roots of Piper sarmentosum led to the isolation and identification of three active phenylpropanoids; asaricin 1, isoasarone 2 and trans-asarone 3. The current study involved evaluation of the toxicity and acetylcholinesterase (AChE) inhibition of these compounds against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae. Asaricin 1 and isoasarone 2 were highly potent against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae causing up to 100% mortality at ≤ 15 μg/mL concentration. The ovicidal activity of asaricin 1, isoasarone 2 and trans-asarone 3 were evaluated through egg hatching. Asaricin 1 and isoasarone 2 showed potent ovicidal activity. Ovicidal activity for both compounds was up to 95% at 25μg/mL. Asaricin 1 and isoasarone 2 showed strong inhibition on acetylcholinesterase with relative IC50 values of 0.73 to 1.87 μg/mL respectively. These findings coupled with the high AChE inhibition may suggest that asaricin 1 and isoasarone 2 are neuron toxic compounds toward Aedes aegypti, Aedes albopictus and Culex quinquefasciatus. Further computational docking with Autodock Vina elaborates the possible interaction of asaricin 1 and isoasarone 2 with three possible binding sites of AChE which includes catalytic triads (CAS: S238, E367, H480), the peripheral sites (PAS: E72, W271) and anionic binding site (W83). The binding affinity of asaricin 1 and isoasarone 2 were relatively strong with asaricin 1 showed a higher binding affinity in the anionic pocket.

Transcriptomic and phylogenetic analysis of Culex pipiens quinquefasciatus for three detoxification gene families

Directory of Open Access Journals (Sweden)

Yan Liangzhen

2012-11-01

Full Text Available Abstract Background The genomes of three major mosquito vectors of human diseases, Anopheles gambiae, Aedes aegypti, and Culex pipiens quinquefasciatus, have been previously sequenced. C. p. quinquefasciatus has the largest number of predicted protein-coding genes, which partially results from the expansion of three detoxification gene families: cytochrome P450 monooxygenases (P450, glutathione S-transferases (GST, and carboxyl/cholinesterases (CCE. However, unlike An. gambiae and Ae. aegypti, which have large amounts of gene expression data, C. p. quinquefasciatus has limited transcriptomic resources. Knowledge of complete gene expression information is very important for the exploration of the functions of genes involved in specific biological processes. In the present study, the three detoxification gene families of C. p. quinquefasciatus were analyzed for phylogenetic classification and compared with those of three other dipteran insects. Gene expression during various developmental stages and the differential expression responsible for parathion resistance were profiled using the digital gene expression (DGE technique. Results A total of 302 detoxification genes were found in C. p. quinquefasciatus, including 71 CCE, 196 P450, and 35 cytosolic GST genes. Compared with three other dipteran species, gene expansion in Culex mainly occurred in the CCE and P450 families, where the genes of α-esterases, juvenile hormone esterases, and CYP325 of the CYP4 subfamily showed the most pronounced expansion on the genome. For the five DGE libraries, 3.5-3.8 million raw tags were generated and mapped to 13314 reference genes. Among 302 detoxification genes, 225 (75% were detected for expression in at least one DGE library. One fourth of the CCE and P450 genes were detected uniquely in one stage, indicating potential developmentally regulated expression. A total of 1511 genes showed different expression levels between a parathion-resistant and a

The effects of forced-egg retention on the blood-feeding behavior and reproductive potential of Culex pipiens (Diptera: Culicidae).

Science.gov (United States)

Johnson, Brian J; Fonseca, Dina M

2014-07-01

High rates of West Nile virus (WNV) transmission to humans are associated with exceptionally hot and dry summers. This is paradoxical since the eggs of Culex vectors of WNV depend on the persistence of containers with water, which decline during droughts. We examined the effects of forced-egg retention on the reproductive success of female Culex pipiens as well as behavioral responses, such as likelihood of secondary blood meals. As controls we examined the effects of female age and delayed mating. We found that early mating is essential to achieve reproductive success and, consistent with an "all-or-none" ovipositing strategy, C. pipiens females are able to retain considerable reproductive potential while searching for oviposition sites. Specifically, although forced-egg retention resulted in significant decreases in fitness, the decline was moderate for 5 weeks and most can be accounted for by increases in female age. Consequently, no females took blood more than once per gonotrophic cycle, which eliminates the possibility that heightened vectorial capacity due to multiple blood-feedings increases WNV transmission during periods of drought. Instead, our findings suggest that during droughts populations of C. pipiens have time to locate the remaining water holes, which are associated with human populations and WNV-competent bird species. Copyright © 2014. Published by Elsevier Ltd.

The Genus Culex, Subgenus Eumelanomyia Theobald in Southeast Asia and Adjacent Areas

Science.gov (United States)

1972-01-01

Bore1 1930, Mon. Coil. Sot. Path. exot. 3: 365 (d*, ?, L*). Culex macropus Blanchard 1905, Les Moustiques :327. New name for Culex Zongifies Theobald...Spec. Pub. 111, 147 pp. BOREL, E. 1926. Les Moustiques de la Cochinchine et du Sud-Annam. (I), Arch. Inst. Pasteur d’Indochine. 47 pp. 1930. Les... Moustiques de la Cochinchine et du Sud-Annam. Mon. Coll. Sot. Pat. exot. 3, 423 pp. BRAM, R A. 1967. Contributions to the mosquitoes of Southeast Asia

Insecticide resistance in disease vectors from Mayotte: an opportunity for integrated vector management.

Science.gov (United States)

Pocquet, Nicolas; Darriet, Frédéric; Zumbo, Betty; Milesi, Pascal; Thiria, Julien; Bernard, Vincent; Toty, Céline; Labbé, Pierrick; Chandre, Fabrice

2014-07-01

Mayotte, a small island in the Indian Ocean, has been affected for many years by vector-borne diseases. Malaria, Bancroftian filariasis, dengue, chikungunya and Rift Valley fever have circulated or still circulate on the island. They are all transmitted by Culicidae mosquitoes. To limit the impact of these diseases on human health, vector control has been implemented for more than 60 years on Mayotte. In this study, we assessed the resistance levels of four major vector species (Anopheles gambiae, Culex pipiens quinquefasciatus, Aedes aegypti and Aedes albopictus) to two types of insecticides: i) the locally currently-used insecticides (organophosphates, pyrethroids) and ii) alternative molecules that are promising for vector control and come from different insecticide families (bacterial toxins or insect growth regulators). When some resistance was found to one of these insecticides, we characterized the mechanisms involved. Larval and adult bioassays were used to evaluate the level of resistance. When resistance was found, we tested for the presence of metabolic resistance through detoxifying enzyme activity assays, or for target-site mutations through molecular identification of known resistance alleles. Resistance to currently-used insecticides varied greatly between the four vector species. While no resistance to any insecticides was found in the two Aedes species, bioassays confirmed multiple resistance in Cx. p. quinquefasciatus (temephos: ~ 20 fold and deltamethrin: only 10% mortality after 24 hours). In An. gambiae, resistance was scarce: only a moderate resistance to temephos was found (~5 fold). This resistance appears to be due only to carboxyl-esterase overexpression and not to target modification. Finally, and comfortingly, none of the four species showed resistance to any of the new insecticides. The low resistance observed in Mayotte's main disease vectors is particularly interesting, because it leaves a range of tools useable by vector control

Genetic Diversity and Population Genetics of Mosquitoes (Diptera: Culicidae: Culex spp. from the Sonoran Desert of North America

Directory of Open Access Journals (Sweden)

Edward Pfeiler

2013-01-01

Full Text Available The population genetics and phylogenetic relationships of Culex mosquitoes inhabiting the Sonoran Desert region of North America were studied using mitochondrial DNA and microsatellite molecular markers. Phylogenetic analyses of mitochondrial cytochrome c oxidase subunit I (COI from mosquitoes collected over a wide geographic area, including the Baja California peninsula, and mainland localities in southern Arizona, USA and Sonora, Mexico, showed several well-supported partitions corresponding to Cx. quinquefasciatus, Cx. tarsalis, and two unidentified species, Culex sp. 1 and sp. 2. Culex quinquefasciatus was found at all localities and was the most abundant species collected. Culex tarsalis was collected only at Tucson, Arizona and Guaymas, Sonora. The two unidentified species of Culex were most abundant at Navojoa in southern Sonora. Haplotype and nucleotide diversities in the COI gene segment were substantially lower in Cx. quinquefasciatus compared with the other three species. Analysis of molecular variance revealed little structure among seven populations of Cx. quinquefasciatus, whereas significant structure was found between the two populations of Cx. tarsalis. Evidence for an historical population expansion beginning in the Pleistocene was found for Cx. tarsalis. Possible explanations for the large differences in genetic diversity between Cx. quinquefasciatus and the other species of Culex are presented.

Genetic Diversity and Population Genetics of Mosquitoes (Diptera: Culicidae: Culex spp.) from the Sonoran Desert of North America

Science.gov (United States)

Pfeiler, Edward; Flores-López, Carlos A.; Mada-Vélez, Jesús Gerardo; Escalante-Verdugo, Juan; Markow, Therese A.

2013-01-01

The population genetics and phylogenetic relationships of Culex mosquitoes inhabiting the Sonoran Desert region of North America were studied using mitochondrial DNA and microsatellite molecular markers. Phylogenetic analyses of mitochondrial cytochrome c oxidase subunit I (COI) from mosquitoes collected over a wide geographic area, including the Baja California peninsula, and mainland localities in southern Arizona, USA and Sonora, Mexico, showed several well-supported partitions corresponding to Cx. quinquefasciatus, Cx. tarsalis, and two unidentified species, Culex sp. 1 and sp. 2. Culex quinquefasciatus was found at all localities and was the most abundant species collected. Culex tarsalis was collected only at Tucson, Arizona and Guaymas, Sonora. The two unidentified species of Culex were most abundant at Navojoa in southern Sonora. Haplotype and nucleotide diversities in the COI gene segment were substantially lower in Cx. quinquefasciatus compared with the other three species. Analysis of molecular variance revealed little structure among seven populations of Cx. quinquefasciatus, whereas significant structure was found between the two populations of Cx. tarsalis. Evidence for an historical population expansion beginning in the Pleistocene was found for Cx. tarsalis. Possible explanations for the large differences in genetic diversity between Cx. quinquefasciatus and the other species of Culex are presented. PMID:24302868

EVALUATION OF EXTRACTS FROM BAMBOO FOR BIOLOGICAL ACTIVITY AGAINST CULEX PIPIENS PALLENS

Institute of Scientific and Technical Information of China (English)

Hai-qunCao; Yong-deYue; Zhen-huaPeng; Ri-maoHua; FengTang

2004-01-01

The extracts from 7 species of bamboo were tested for larvicidal activity against Culex pipiens pallens. At the tested concentration, the extracts of selected bamboo had different degree of toxic effects on the fourth instar larvae of Culex pipiens pallens. Among them,the extracts of Pleioblastus juxianensis, Brachystachyum albostriatum, Phyllostachys platyglossa and Pleioblastus amarus were found to be effective with LC50values at 24h of 30.65mg/L,53.94mg/L, 41.21 mg/L and 54.49 mg/L respectively, against Culex pipiens pallens larvae. The extract of Pleioblastus juxianensis by Soxhlet method showed stronger activity than the extract obtained by interval-shaking, the LC50 of which were 30.65 mg/L and 48.34 mg/L, respectively.The diethyl ether extract of Pleioblastus juxianensis exhibited better larvicidal activity than the methanol extract and the petroleum ether extract. The results would help to provide the basis for the study of environment acceptable pesticide for mosquito control, and also help to comprehensively utilize the source of bamboo.

Biological control of Anopheles darlingi, Aedes aegypti and Culex quinquefasciatus larvae using shrimps

Directory of Open Access Journals (Sweden)

Willian Marinho Dourado Coelho

2017-08-01

Full Text Available Mosquitoes can act as vectors of important diseases such as malaria, dengue, Zika virus, yellow fever, Chikungunya and Mayaro fever, in addition to filariasis. The use of insecticides, larvicides, bed nets and repellents, besides the use of drugs as chemoprevention and the treatment of the sick are currently the pillars of the control of these vectors. We studied the biological control against of Anopheles darlingi, Aedes aegypti and Culex quinquefasciatus larvae using shrimps of the species M. pantanalense, M. amazonicum, M. brasiliense and M. jelskii. Larvae of mosquitoes were collected from the breeding environment and placed in a 500 and 1000 l tank containing 60 shrimps/m2. The predatory activity was evaluated for 30 days and, in all groups it was observed that 100% of the larvae were consumed in few minutes. In the environment, these same species of crustaceans were released in water bodies with the presence of larvae of these insects. In just 72 h there was a marked reduction of the larvae in the release sites of shrimps. Similarly, there was a reduction in the number of adult mosquitoes caught near the breeding sites, allowing to infer that, in places where the crustaceans were released, the predatory activity on the larvae of mosquitoes was sufficient to reduce the number of adult mosquitoes p ≤ 0,05. This is the first description of the predatory activity of M. pantanalense, M. amazonicum, M. brasiliense and M. jelskii on An. darlingi, A. aegypti and C. quinquefasciatus larvae, constituting an important tool of biological control of these parasites-vectors.

Experimental transmission of West Nile Virus and Rift Valley Fever Virus by Culex pipiens from Lebanon.

Directory of Open Access Journals (Sweden)

Renée Zakhia

2018-01-01

Full Text Available West Nile virus (WNV and Rift Valley fever virus (RVFV are two emerging arboviruses transmitted by Culex pipiens species that includes two biotypes: pipiens and molestus. In Lebanon, human cases caused by WNV and RVFV have never been reported. However, the introduction of these viruses in the country is likely to occur through the migratory birds and animal trades. In this study, we evaluated the ability of Cx. pipiens, a predominant mosquito species in urban and rural regions in Lebanon, to transmit WNV and RVFV. Culex egg rafts were collected in the West Bekaa district, east of Lebanon and adult females of Cx. pipiens were experimentally infected with WNV and RVFV Clone 13 strain at titers of 1.6×108 and 1.33×107 plaque forming units (PFU/mL, respectively. We estimated viral infection, dissemination and transmission at 3, 7, 14 and 19 days post infection (dpi. Results showed that infection was higher for WNV than for RVFV from 3 dpi to 19 dpi. Viral dissemination and transmission started from 3 dpi for WNV; and only from 19 dpi for RVFV. Moreover, Cx. pipiens were able to excrete in saliva a higher number of viral particles of WNV (1028 ± 405 PFU/saliva at 19 dpi than RVFV (42 PFU/saliva at 19 dpi. Cx. pipiens from Lebanon are efficient experimental vectors of WNV and to a lower extent, RVFV. These findings should stimulate local authorities to establish an active entomological surveillance in addition to animal surveys for both viruses in the country.

Effects of blood meal source on the reproduction of Culex pipiens quinquefasciatus (Diptera: Culicidae).

Science.gov (United States)

Richards, Stephanie L; Anderson, Sheri L; Yost, Samantha A

2012-06-01

Culex pipiens quinquefasciatus were fed blood meals from a live chicken (LC), chicken blood in Alsever's (AC) solution, defibrinated bovine blood (DB), or bovine blood in citrate (CB) and incubated at 28° C. The effects of different blood meal sources were evaluated with respect to rates of blood feeding and reproduction (i.e., fecundity and fertility) over two gonotrophic cycles. Mosquitoes that fed on the first blood meal were subjected to a second blood meal as follows (first blood meal / second blood meal): LC/LC, LC/DB, DB/DB, CB/CB, AC/AC. Fecundity and fertility of Cx. p. quinquefasciatus were significantly (P blood; however, fecundity and fertility in different treatment groups varied by gonotrophic cycle. These results contribute to our understanding of the impact of blood meal source on feeding and reproduction in Cx. p. quinquefasciatus. The potential impacts of blood meal source on virus transmission experiments are discussed. © 2012 The Society for Vector Ecology.

Culex quinquefasciatus (Diptera: Culicidae) as a potential West Nile virus vector in Tucson, Arizona: Blood meal analysis indicates feeding on both humans and birds

OpenAIRE

Zinser, Margaret; Ramberg, Frank; Willott, Elizabeth

2004-01-01

Most reports from the United States suggest Culex quinquefasciatus mosquitoes feed minimally on humans. Given the abundance of C. quinquefasciatus in residential Tucson and parts of metropolitan Phoenix, and the arrival of West Nile virus to this area, discovering the blood meal hosts of the local population is important. Using a sandwich ELISA technique, the local C. quinquefasciatus were found to feed on both humans and birds. This suggests they should be considered potential West Nile viru...

Schools as Potential Risk Sites for Vector-Borne Disease Transmission: Mosquito Vectors in Rural Schools in Two Municipalities in Colombia.

Science.gov (United States)

Olano, Víctor Alberto; Matiz, María Inés; Lenhart, Audrey; Cabezas, Laura; Vargas, Sandra Lucía; Jaramillo, Juan Felipe; Sarmiento, Diana; Alexander, Neal; Stenström, Thor Axel; Overgaard, Hans J

2015-09-01

Dengue and other vector-borne diseases are of great public health importance in Colombia. Vector surveillance and control activities are often focused at the household level. Little is known about the importance of nonhousehold sites, including schools, in maintaining vector-borne disease transmission. The objectives of this paper were to determine the mosquito species composition in rural schools in 2 municipalities in Colombia and to assess the potential risk of vector-borne disease transmission in school settings. Entomological surveys were carried out in rural schools during the dry and rainy seasons of 2011. A total of 12 mosquito species were found: Aedes aegypti, Anopheles pseudopunctipennis, Culex coronator, Cx. quinquefasciatus, and Limatus durhamii in both immature and adult forms; Ae. fluviatilis, Cx. nigripalpus, Cx. corniger, and Psorophora ferox in immature forms only; and Ae. angustivittatus, Haemagogus equinus, and Trichoprosopon lampropus in adult forms only. The most common mosquito species was Cx. quinquefasciatus. Classrooms contained the greatest abundance of adult female Ae. aegypti and Cx. quinquefasciatus. The most common Ae. aegypti breeding sites were containers classified as "others" (e.g., cans), followed by containers used for water storage. A high level of Ae. aegypti infestation was found during the wet season. Our results suggest that rural schools are potentially important foci for the transmission of dengue and other mosquito-borne diseases. We propose that public health programs should be implemented in rural schools to prevent vector-borne diseases.

Efficacy of plant-mediated synthesized silver nanoparticles against hematophagous parasites.

Science.gov (United States)

Jayaseelan, Chidambaram; Rahuman, Abdul Abdul; Rajakumar, Govindasamy; Santhoshkumar, Thirunavukkarasu; Kirthi, Arivarasan Vishnu; Marimuthu, Sampath; Bagavan, Asokan; Kamaraj, Chinnaperumal; Zahir, Abdul Abduz; Elango, Gandhi; Velayutham, Kanayairam; Rao, Kokati Venkata Bhaskara; Karthik, Loganathan; Raveendran, Sankariah

2012-08-01

The purpose of the present study was to investigate the acaricidal and larvicidal activity against the larvae of Haemaphysalis bispinosa Neumann (Acarina: Ixodidae) and larvae of hematophagous fly Hippobosca maculata Leach (Diptera: Hippoboscidae) and against the fourth-instar larvae of malaria vector, Anopheles stephensi Liston, Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae) of synthesized silver nanoparticles (AgNPs) utilizing aqueous leaf extract from Musa paradisiaca L. (Musaceae). The color of the extract changed to light brown within an hour, and later it changed to dark brown during the 30-min incubation period. AgNPs results were recorded from UV-vis spectrum at 426 nm; Fourier transform infrared (FTIR) analysis confirmed that the bioreduction of Ag(+) ions to silver nanoparticles are due to the reduction by capping material of plant extract, X-ray diffraction (XRD) patterns clearly illustrates that the nanoparticles formed in the present synthesis are crystalline in nature and scanning electron microscopy (SEM) support the biosynthesis and characterization of AgNPs with rod in shape and size of 60-150 nm. After reaction, the XRD pattern of AgNPs showed diffraction peaks at 2θ = 34.37°, 38.01°, 44.17°, 66.34° and 77.29° assigned to the (100), (111), (102), (110) and (120) planes, respectively, of a faced centre cubic (fcc) lattice of silver were obtained. For electron microscopic studies, a 25 μl sample was sputter-coated on copper stub, and the images of nanoparticles were studied using scanning electron microscopy. The spot EDX analysis showed the complete chemical composition of the synthesized AgNPs. The parasite larvae were exposed to varying concentrations of aqueous extract of M. paradisiaca and synthesized AgNPs for 24 h. In the present study, the percent mortality of aqueous extract of M. paradisiaca were 82, 71, 46, 29, 11 and 78, 66, 38, 31and 16 observed in the concentrations of 50, 40, 30, 20, 10 mg

Influence of Hepatozoon parasites on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens.

Science.gov (United States)

Ferguson, Laura V; Kirk Hillier, N; Smith, Todd G

2013-12-01

Hepatozoon species are heteroxenous parasites that commonly infect the blood of vertebrates and various organs of arthropods. Despite their ubiquity, little is known about how these parasites affect host phenotype, including whether or not these parasites induce changes in hosts to increase transmission success. The objectives of this research were to investigate influences of the frog blood parasite Hepatozoon clamatae and the snake blood parasite Hepatozoon sipedon on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens, respectively. During development of H. sipedon in C. pipiens, significantly fewer infected mosquitoes fed on uninfected snakes compared to uninfected mosquitoes. When H. sipedon was mature in C. pipiens, the number of infected and uninfected C. pipiens that fed on snakes was not significantly different. Higher numbers of mosquitoes fed on naturally infected snakes and frogs compared to laboratory-reared, uninfected control animals. However, experiments using only laboratory-raised frogs revealed that infection did not significantly affect host choice by C. territans. Behaviour of C. pipiens in the presence of H. sipedon may increase transmission success of the parasite and provide the first evidence of phenotypic changes in the invertebrate host of Hepatozoon parasites.

Influence of Hepatozoon parasites on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens☆

Science.gov (United States)

Ferguson, Laura V.; Kirk Hillier, N.; Smith, Todd G.

2012-01-01

Hepatozoon species are heteroxenous parasites that commonly infect the blood of vertebrates and various organs of arthropods. Despite their ubiquity, little is known about how these parasites affect host phenotype, including whether or not these parasites induce changes in hosts to increase transmission success. The objectives of this research were to investigate influences of the frog blood parasite Hepatozoon clamatae and the snake blood parasite Hepatozoon sipedon on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens, respectively. During development of H. sipedon in C. pipiens, significantly fewer infected mosquitoes fed on uninfected snakes compared to uninfected mosquitoes. When H. sipedon was mature in C. pipiens, the number of infected and uninfected C. pipiens that fed on snakes was not significantly different. Higher numbers of mosquitoes fed on naturally infected snakes and frogs compared to laboratory-reared, uninfected control animals. However, experiments using only laboratory-raised frogs revealed that infection did not significantly affect host choice by C. territans. Behaviour of C. pipiens in the presence of H. sipedon may increase transmission success of the parasite and provide the first evidence of phenotypic changes in the invertebrate host of Hepatozoon parasites. PMID:24533317

Evaluation in vitro de l'efficacité du fipronil sur Culex pipiens pipiens

OpenAIRE

Toral y Caro, Muriel

2005-01-01

Les moustiques sont responsables de nuisances directes et indirectes, chez l'homme et chez l'animal. C'est pourquoi il est intéressant de tester l'efficacité de nouvelles molécules sur ces insectes. Ce travail expérimental vise à tester l'efficacité potentielle du fipronil sur les moustiques appartenant au complexe Culex pipiens au moyen d'un nouveau test mis en place au laboratoire. Une première partie de ce travail est consacrée à l'étude bibliographique des caractéristiques de Culex ...

Mosquito Vector Diversity across Habitats in Central Thailand Endemic for Dengue and Other Arthropod-Borne Diseases

Science.gov (United States)

Thongsripong, Panpim; Green, Amy; Kittayapong, Pattamaporn; Kapan, Durrell; Wilcox, Bruce; Bennett, Shannon

2013-01-01

Recent years have seen the greatest ecological disturbances of our times, with global human expansion, species and habitat loss, climate change, and the emergence of new and previously-known infectious diseases. Biodiversity loss affects infectious disease risk by disrupting normal relationships between hosts and pathogens. Mosquito-borne pathogens respond to changing dynamics on multiple transmission levels and appear to increase in disturbed systems, yet current knowledge of mosquito diversity and the relative abundance of vectors as a function of habitat change is limited. We characterize mosquito communities across habitats with differing levels of anthropogenic ecological disturbance in central Thailand. During the 2008 rainy season, adult mosquito collections from 24 sites, representing 6 habitat types ranging from forest to urban, yielded 62,126 intact female mosquitoes (83,325 total mosquitoes) that were assigned to 109 taxa. Female mosquito abundance was highest in rice fields and lowest in forests. Diversity indices and rarefied species richness estimates indicate the mosquito fauna was more diverse in rural and less diverse in rice field habitats, while extrapolated estimates of true richness (Chao1 and ACE) indicated higher diversity in the forest and fragmented forest habitats and lower diversity in the urban. Culex sp. (Vishnui subgroup) was the most common taxon found overall and the most frequent in fragmented forest, rice field, rural, and suburban habitats. The distributions of species of medical importance differed significantly across habitat types and were always lowest in the intact, forest habitat. The relative abundance of key vector species, Aedes aegypti and Culex quinquefasciatus, was negatively correlated with diversity, suggesting that direct species interactions and/or habitat-mediated factors differentially affecting invasive disease vectors may be important mechanisms linking biodiversity loss to human health. Our results are an

Seasonal and Topographical Factors Affecting Breeding Sites of Culex Larvae in Nakhon Si Thammarat, Thailand

OpenAIRE

Warabhorn PREECHAPORN; Mullica JAROENSUTASINEE; Krisanadej JAROENSUTASINEE; Jirawat SAETON

2007-01-01

This study investigated how the seasons affect the key breeding sites of Culex larvae in three topographical areas: mangrove, rice paddy and mountainous areas. We examined how the number of Culex larvae varied in different types of water containers. Water containers were categorised into the following groups: indoor/outdoor containers, artificial/natural containers, earthen/plastic containers, containers with/without lids and dark/light coloured containers. Samples were collected from 300 hou...

Vertebrate hosts and phylogenetic relationships of amphibian trypanosomes from a potential invertebrate vector, Culex territans Walker (Diptera: Culicidae).

Science.gov (United States)

Bartlett-Healy, Kristen; Crans, Wayne; Gaugler, Randy

2009-04-01

The blood meals of field-collected female Culex territans (Diptera: Culicidae) were concurrently assayed for the presence of trypanosomes and for vertebrate host identification. We amplified vertebrate DNA in 42 of 119 females and made positive identification to the host species level in 29 of those samples. Of the 119 field-collected Cx. territans females, 24 were infected with trypanosomes. Phylogenetic analysis placed the trypanosomes in the amphibian portion of the aquatic clade of the Trypanosomatidae. These trypanosomes were isolated from Cx. territans females that had fed on the frog species Rana clamitans, R. catesbeiana, R. virgatipes, and Rana spp. Results support a potential new lineage of dipteran-transmitted amphibian trypanosomes may occur within the aquatic clade. The frequency in which female Cx. territans acquire trypanosomes, through diverse feeding habits, indicates a new relationship between amphibian trypanosomes and mosquitoes that has not been examined previously. Combining Trypanosoma species, invertebrate, and vertebrate hosts to existing phylogenies can elucidate trypanosome and host relationships.

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

Comparative insecticidal efficacy of a new pyrethroid, metofluthrin, against colonies of Asian Culex quinquefasciatus and Culex pipiens pallens

OpenAIRE

Argueta, Tamara Belzabel Obispo; Kawada, Hitoshi; Shimabukuro, Kozue; Kubota, Shunichi; Shono, Yoshinori; Tsushima, Kazunori; Takagi, Masahiro

2004-01-01

Comparative insecticidal efficacy of metofluthrin, a newly synthesized pyrethroid, and other pyrethroids against several colonies of Asian Culex quinquefas-ciatus (from Indonesia, Thailand, Vietnam and Malaysia) was evaluated by topical application. Metofluthrin was the most effective against the four colonies of Cx. quinquefasciatus. The LD50-based relative effective ratio of metofluthrin against d-allethrin was higher in Cx. quinquefasciatus (33.3 to 78.8) than in Cx. pipiens pallens (27.8)...

Species\\' identification of Anopheles and Culex mosquitoes and its ...

African Journals Online (AJOL)

Indoor and outdoor bites' collections of gravid Anopheles and Culex mosquitoes were made with plastic aspirator from residential areas within Jimeta-Yola metropolis for three years (between March and May; August and October 2003 to 2005). They were identified using standard morphological keys and polymerase chain ...

Susceptibilidade larval de populações de Aedes aegypti e Culex quinquefasciatus a inseticidas químicos Larval susceptibility of Aedes aegypti and Culex quinquefasciatus populations to chemical insecticides

Directory of Open Access Journals (Sweden)

Jairo Campos

2003-08-01

Full Text Available OBJETIVO: Avaliar a susceptibilidade a inseticidas químicos de larvas de Culex quinquefasciatus e Aedes aegypti, provenientes de áreas sujeitas ou não a tratamentos de controle. MÉTODOS: Foram coletadas larvas de mosquitos em uma área não sujeita a tratamentos com inseticidas (Campinas, SP e em áreas sujeitas a esses tratamentos (Campo Grande, MS e Cuiabá, MT. Foram usados bioensaios com concentrações diagnóstico e concentrações múltipla de inseticidas organofosforados e piretróides, segundo padrão da Organização Mundial de Saúde, para avaliar a susceptibilidade dessas larvas. RESULTADOS: Ensaios com larvas de Culex quinquefasciatus de Campinas, SP, permitiram a suspeita de resistência à cipermetrina e evidenciaram resistência à ciflutrina. Larvas dessa espécie coletadas em Campo Grande, MS, e Campinas, SP, apresentaram resistência ao temephos. Para a colônia campineira desta espécie, foram estabelecidas as razões de resistência: RR50=6,36 e RR95=4,94, com base em linhagem susceptível padrão. Adicionalmente, os testes com Aedes aegypti mostraram susceptibilidade similar ao temephos em uma população de campo (Cuiabá, MT e uma de laboratório. CONCLUSÕES: Os resultados indicam resistência a organofosforado e piretróides em Culex quinquefasciatus, evidenciando a necessidade de avaliações e monitoramento da efetividade dos inseticidas a serem usados nos programas de controle de mosquitos.OBJECTIVE: To evaluate the susceptibility to chemical insecticides of Culex quinquefasciatus and Aedes aegypt larvae from areas subjected to control treatments or not. METHODS: Bioassays for diagnostic concentration and multiple concentration were performed for organophosphate and pyrethroid insecticides according to World Health Organization parameters. The susceptibility was assessed for mosquito larvae collected from an area not subjected to chemical control (Campinas, State of São Paulo, SP and from other areas (Campo

Potential topical natural repellent against Ae. aegypti, Culex sp. and Anopheles sp. mosquitoes

Directory of Open Access Journals (Sweden)

Dewi Nur Hodijah

2014-08-01

Full Text Available AbstrakLatar belakang:Minyak atsiri daun sirih diketahui mempunyai daya proteksi. Dibuatkan losion berdasarkan pengantar sediaan farmasi yang ditambahkan minyak atsiri daun nilam. Sediaan losion dipilih agar dapat menempel lebih lama di permukaan kulit. Tujuan penelitian ini untuk membandingkan daya proteksi antara losion dengan penambahan minyak nilam dan losion tanpa penambahan minyak nilam dibandingkan daya proteksi dengan DEET. Metode: Penelitian ini merupakan penelitian eksperimental laboratorium. Semua nyamuk uji berasal dari insektarium laboratorium penelitian kesehatan Loka litbang P2B2 Ciamis. Konsentrasi minyak atsiri daun sirih dalam losion adalah 4%; konsentrasi minyak nilam sebagai zat pengikat adalah 0,4%. Formula yang digunakan yaitu formula dasar yang ada pada pengantar sediaan farmasi. Uji repelensi dilakukan dengan menggunakan metoda yang direkomendasikan oleh Komisi pestisida.Hasil: Dihasilkan formulasi losion yang stabil dan masih memenuhi standar formulasi sediaan. Berdasarkan hasil, diperoleh data bahwa DEET dan losion hasil modifikasi memiliki rata-rata daya proteksi di atas 90% selama 6 jam terhadap nyamuk Ae.aegypti dan Culex sp. Kesimpulan: Penambahan minyak nilam pada losion sirih dapat meningkatkan daya proteksi terhadap hinggapan nyamuk Ae. aegypti dan Culex sp. (Health Science Indones 2014;1:44-8Kata kunci:repelen alamiah, minyak atsiri, daun sirih, daun nilam, Ae. aegypti, Culex sp.AbstractBackground: Betel leaf essential oil lotion has been known to have insect repellent properties. A lotion was made based on a pharmaceutical formula from a monograph where patchouli leaf essential oil was added. A lotion preparation was intended to enhance adherence of the formula on the surface of the skin. The purpose of this study was to compare protection percentage of lotion with patchouli oil and without patchouli oil lotion compared to DEET.Methods: This study is an experimental laboratory-based research. All mosquitoes

Identification of environmental covariates of West Nile virus vector mosquito population abundance.

Science.gov (United States)

Trawinski, Patricia R; Mackay, D Scott

2010-06-01

The rapid spread of West Nile virus (WNv) in North America is a major public health concern. Culex pipiens-restuans is the principle mosquito vector of WNv in the northeastern United States while Aedes vexans is an important bridge vector of the virus in this region. Vector mosquito abundance is directly dependent on physical environmental factors that provide mosquito habitats. The objective of this research is to determine landscape elements that explain the population abundance and distribution of WNv vector mosquitoes using stepwise linear regression. We developed a novel approach for examining a large set of landscape variables based on a land use and land cover classification by selecting variables in stages to minimize multicollinearity. We also investigated the distance at which landscape elements influence abundance of vector populations using buffer distances of 200, 400, and 1000 m. Results show landscape effects have a significant impact on Cx. pipiens-estuans population distribution while the effects of landscape features are less important for prediction of Ae. vexans population distributions. Cx. pipiens-restuans population abundance is positively correlated with human population density, housing unit density, and urban land use and land cover classes and negatively correlated with age of dwellings and amount of forested land.

Detection, isolation, and genetic characterization of Rift Valley fever virus from Anopheles (Anopheles) coustani, Anopheles (Anopheles) squamosus, and Culex (Culex) antennatus of the Haute Matsiatra region, Madagascar.

Science.gov (United States)

Ratovonjato, Jocelyn; Olive, Marie-Marie; Tantely, Luciano Michael; Andrianaivolambo, Lala; Tata, Etienne; Razainirina, Josette; Jeanmaire, Elisabeth; Reynes, Jean-Marc; Elissa, Nohal

2011-06-01

Following veterinary alerts of Rift Valley fever (RVF) in the districts of Fianarantsoa I and II in November 2008 and in the district of Ambalavao in April 2009, entomological and virological investigations were carried out to identify the mosquito species that could act as RVF virus (RVFV) vectors in the region. A total of 12,785 adult mosquitoes belonging to 5 genera and 21 species were collected. After identification, mosquitoes were pooled by species, sex, and female status (fed or unfed) and then stored at -80°C. Of 319 pools of unfed monospecific female mosquito tested by real-time RT-polymerase chain reaction, RVFV was detected in 1 pool of Anopheles coustani, 5 pools of An. squamosus, and 2 pools of Culex antennatus mosquitoes. The virus was isolated in mosquito cell lines from two of the five Real Time-RT-polymerase chain reaction (real time-RT-PCR) positive pools of An. squamosus mosquitoes. From the eight RVFV strains detected, partial S, M, and L genome segments sequences were obtained. The phylogenetic analysis of these sequences showed that the strains circulating in mosquitoes were genetically close to those that circulated in livestock and humans during RVF outbreaks in 2008 and 2009. This study, therefore, provides strong evidence that An. squamosus, An. coustani, and Cx. antennatus could play a role as vectors of the RVFV during the disease outbreaks in 2008-2009. Bioecological, genetic, and RVF transmission studies on these three mosquito species are needed to address this question and thus improve prevention and control of future RVF outbreaks in Madagascar, where these species are present.

Culex quinquefasciatus (Diptera: Culicidae From Florida Transmitted Zika Virus

Directory of Open Access Journals (Sweden)

Chelsea T. Smartt

2018-04-01

Full Text Available We report a laboratory colony of Culex quinquefasciatus mosquitoes were experimentally able to salivate Zika virus (ZIKV, Flaviviridae; Flavivirus at 16 days post infection (dpi. ZIKV RNA was detected in bodies and in saliva deposited on filter paper cards with subsequent studies demonstrating the presence of live ZIKV in saliva.

How Diverse Detrital Environments Influence Nutrient Stoichiometry between Males and Females of the Co-Occurring Container Mosquitoes Aedes albopictus, Ae. aegypti, and Culex quinquefasciatus.

Science.gov (United States)

Yee, Donald A; Kaufman, Michael G; Ezeakacha, Nnaemeka F

2015-01-01

Allocation patterns of carbon and nitrogen in animals are influenced by food quality and quantity, as well as by inherent metabolic and physiological constraints within organisms. Whole body stoichiometry also may vary between the sexes who differ in development rates and reproductive allocation patterns. In aquatic containers, such as tree holes and tires, detrital inputs, which vary in amounts of carbon and nitrogen, form the basis of the mosquito-dominated food web. Differences in development times and mass between male and female mosquitoes may be the result of different reproductive constraints, which could also influence patterns of nutrient allocation. We examined development time, survival, and adult mass for males and females of three co-occurring species, Aedes albopictus, Ae. aegypti, and Culex quinquefasciatus, across environments with different ratios of animal and leaf detritus. We quantified the contribution of detritus to biomass using stable isotope analysis and measured tissue carbon and nitrogen concentrations among species and between the sexes. Development times were shorter and adults were heavier for Aedes in animal versus leaf-only environments, whereas Culex development times were invariant across detritus types. Aedes displayed similar survival across detritus types whereas C. quinquefasciatus showed decreased survival with increasing leaf detritus. All species had lower values of 15N and 13C in leaf-only detritus compared to animal, however, Aedes generally had lower tissue nitrogen compared to C. quinquefasciatus. There were no differences in the C:N ratio between male and female Aedes, however, Aedes were different than C. quinquefasciatus adults, with male C. quinquefasciatus significantly higher than females. Culex quinquefasciatus was homeostatic across detrital environments. These results allow us to hypothesize an underlying stoichiometric explanation for the variation in performance of different container species under similar

MODELO BIOGEOGRÁFICO DE LOS MOSQUITOS CULEX SPP. (DIPTERA: CULICIDAE EN MÉXICO

Directory of Open Access Journals (Sweden)

Maria Torres Olave

2015-12-01

Full Text Available The mosquitoes distribution and the presence of arboviruses are determined by temperature, rainfall, geographic barriers, and other factors that determine the distribution of Culex spp. and can influence the human arboviral. The objective of this study was to identify potential spatial distribution of Culex spp. The ecological niche modeling was performed using MaxEnt Ecological niche modeling was performed using MaxEnt, bioclimatic variables (WorldClim used for this process are derived from the monthly values of temperature and precipitation to generate biologically significant variables (representing annual trends and limiting factors for the distribution of species. The resulting maps can be interpreted as relative suitability areas, these areas are presented on the east coast of Mexico, mainly in the states of Veracruz and Tabasco. The results show that Bio 2 (mean monthly temperature range, Bio 7 (annual range of temperature and Bio 11 (mean temperature of the coldest quarter, determine the highest percentage range. Distribution modeling Culex spp. It is an approach to identify the most vulnerable areas in Mexico. It is necessary to strengthen and establish multidisciplinary programs for the prevention ofCulexspp transmitted diseases.

A first note on Japanese encephalitis virus isolation from Culex quinquefasciatus Say in Northern West Bengal.

Directory of Open Access Journals (Sweden)

V. Thenmozhi

2014-03-01

Full Text Available Japanese encephalitis (JE is endemic in many parts of India including the state of West Bengal. In West Bengal, the first major outbreaks of JE occurred in the districts of Bankura and Burdwan in 1973. The Culex vishnui subgroup of mosquitoes has been implicated as major vectors of JE. However in India, JE virus (JEV has been isolated from 16 species of mosquitoes. During September 2011, JE cases were reported from four districts -Jalpaiguri, Darjeeling, Dinajpur and Cooch Behar of West Bengal (North. Adult mosquitoes were collected, identified, pooled and screened for JEV using antigen capture ELISA. Out of 279 mosquito pools tested, one pool of Cx. pseudovishnui and three pools of Cx. quinquefasciatus were found positive for JEV. The ELISA positive pools were further confirmed as JEV by insect bioassay (Toxo-IFA. Two pools of Cx. quinquefasciatus were confirmed as JEV. This represents the first report of JEV isolation from Cx. quinquefasciatus in West Bengal.

Blood-feeding patterns of the Culex pipiens complex in Sacramento and Yolo Counties, California.

Science.gov (United States)

Montgomery, Matthew J; Thiemann, Tara; Macedo, Paula; Brown, David A; Scott, Thomas W

2011-03-01

Mosquitoes in the Culex pipiens complex are competent vectors of West Nile virus (WNV; family Flaviviridae, genus Flavivirus) in the laboratory, and field-collected mosquitoes have tested positive for the virus in California and elsewhere. A better understanding of Cx. pipiens complex blood-feeding patterns will help define the threat that these mosquitoes pose to human health and their role in WNV amplification in northern California. We collected blood-engorged Cx. pipiens complex mosquitoes from resting sites near and away from human habitation in Sacramento and Yolo Counties. Cytochrome c oxidase 1 gene sequences were used to identify the vertebrate species from which blood meals were taken. Of 330 engorged mosquitoes collected at 28 sites from June through August 2007 and May through August 2008, >99% fed on an avian host. Three mosquitoes contained bovine blood and none had fed on a human. American Robins (Turdus migratorius) were bitten most often, and the proportion of American Robin blood meals increased significantly over the summer. Other important avian hosts included House Finches (Carpodacus mexicanus), Barn Swallows (Hirundo rustica), Western Meadowlarks (Sturnella neglecta), and Mourning Doves (Zenaida macroura). In rural areas, Barn Swallows, Brewer's Blackbirds (Euphagus cyanocephalus), and House Sparrows (Passer domesticus) were frequent hosts. In settings near human habitation, Mourning Doves and Western Meadowlarks were common hosts. Our data indicate that in north central California mosquitoes in the Cx. pipiens complex may be more important as epiornitic than epidemic vectors of WNV.

Entomopathogenic fungus generated Nanoparticles for enhancement of efficacy in Culex quinquefasciatus and Anopheles stephensi

Directory of Open Access Journals (Sweden)

N. SONI, S. PRAKASH

2012-05-01

Full Text Available Objective: To evaluate to efficacy of silver and gold generated larvicide with the help of entomopathogenic fungus Chrysosporium tropicum against the Culex quinquefasciatus and Anopheles stephensi larvae. Methods: The silver and gold nanoparticles were quantified and observed by the Micro-scan reader and X-ray diffraction technique. The micrographs of silver and gold nanoparticles were obtained by the Transmission electron microscope and Scanning electron microscope. The larvicidal efficacy was then performed at six different log concentrations by the probit analysis. Results: The characterization study confirmed the spherical shaped and sized (20-50 and 2-15 nm of silver and gold nanoparticles. The all larval stages of Cx. quinquefasciatus were found more susceptible to the synthesized silver nanoparticles. Whereas, the larvae of An. stephensi were found more susceptible to larvicide synthesized with gold nanoparticles. Conclusions: The results suggested that the silver and gold nanoparticles generated by the entomopathogenic fungus C. tropicum is an environmentally safer and greener approach for mosquito control and new possibility in vector control strategy.

The Morphological Variations of Culex pipiens Larvae (Diptera: Culicidae in Yazd Province, Central Iran

Directory of Open Access Journals (Sweden)

H Dehghan

2010-12-01

Full Text Available "nAbstract "nBackground: Culex pipiens complex shows variations in morphological and biological characters including differ­ent biological forms and has medical and veterinary importance. Because of having morphological variations, some­times it is not easy to separate this species from Cx. quinquefasciatus and Cx. torrentium. The aim of this study was to  identify the  Culex pipiens complex species in order to use in control programs in the future. "nMethods: This study was carried out in two randomly selected rural villages in Yazd County, eastern Iran using dip­ping technique from April to October 2009. The data were analyzed using SPSS software version 16. "nResults: Average of siphon index in fourth-instrar larvae was 3.86±0.03, the minimum and maximum were calculated 2.43 and 5.14, respectively. Siphon/Saddle index was measured as average, minimum and maximum 3.2±0.2, 2.78, and 4.42 respectively. In our study, only 4 specimens had single seta 1 on segments III and VI (2.5% and the remaining beard double seta (97.5%. The maximum 3-6 branches seta 1a-S and 1b-S (95% were observed on siphon. "nConclusion: More populations of Culex pipiens from different areas of Iran need to be studied to gain complete informa­tion about the taxonomy and ecology of the species in the country. "n  "nKeywords: Culex pipiens complex, larvae, taxonomy, Iran

Unraveling Host-Vector-Arbovirus Interactions by Two-Gene High Resolution Melting Mosquito Bloodmeal Analysis in a Kenyan Wildlife-Livestock Interface.

Directory of Open Access Journals (Sweden)

David Omondi

Full Text Available The blood-feeding patterns of mosquitoes are directly linked to the spread of pathogens that they transmit. Efficient identification of arthropod vector bloodmeal hosts can identify the diversity of vertebrate species potentially involved in disease transmission cycles. While molecular bloodmeal analyses rely on sequencing of cytochrome b (cyt b or cytochrome oxidase 1 gene PCR products, recently developed bloodmeal host identification based on high resolution melting (HRM analyses of cyt b PCR products is more cost-effective. To resolve the diverse vertebrate hosts that mosquitoes may potentially feed on in sub-Saharan Africa, we utilized HRM profiles of both cyt b and 16S ribosomal RNA genes. Among 445 blood-fed Aedeomyia, Aedes, Anopheles, Culex, Mansonia, and Mimomyia mosquitoes from Kenya's Lake Victoria and Lake Baringo regions where many mosquito-transmitted pathogens are endemic, we identified 33 bloodmeal hosts including humans, eight domestic animal species, six peridomestic animal species and 18 wildlife species. This resolution of vertebrate host species was only possible by comparing profiles of both cyt b and 16S markers, as melting profiles of some pairs of species were similar for either marker but not both. We identified mixed bloodmeals in a Culex pipiens from Mbita that had fed on a goat and a human and in two Mansonia africana mosquitoes from Baringo that each had fed on a rodent (Arvicanthis niloticus in addition to a human or baboon. We further detected Sindbis and Bunyamwera viruses in blood-fed mosquito homogenates by Vero cell culture and RT-PCR in Culex, Aedeomyia, Anopheles and Mansonia mosquitoes from Baringo that had fed on humans and livestock. The observed mosquito feeding on both arbovirus amplifying hosts (including sheep and goats and possible arbovirus reservoirs (birds, porcupine, baboons, rodents informs arbovirus disease epidemiology and vector control strategies.

Adulticidal activity of Pithecellobium dulce (Roxb. Benth. against Culex quinquefasciatus (Say

Directory of Open Access Journals (Sweden)

Govindarajan M

2012-04-01

Full Text Available Objective: To determine the adulticidal efficacy of different solvent leaf and seed extracts of Pithecellobium dulce (P. dulce against Culex quinquefasciatus (Cx. quinquefasciatus. Methods: Sucrose-fed and blood starved mosquitoes were released into the tube, and the mortality effects of the extracts were observed every 10 min for 3 h exposure period. At the end of 1, 2, and 3 h exposure periods, the mosquitoes were placed in the holding tube. Cotton pads soaked in 10% sugar solution with vitamin B complex were placed in the tube during the holding period of 24 h. Mortality of the mosquitoes was recorded after 24 h. Results: Among five solvent extracts tested, the maximum efficacy was observed in the methanol extract of leaves of P. dulce. The LC50 and LC 90 values of P. dulce leaves and seeds against Cx. quinquefasciatus were 234.97, 309.24 ppm and 464.86, 570.80 ppm, respectively. No mortality was observed in controls. The Chi-square values were significant at P<0.05 level. Conclusions: From the results it can be concluded that the crude extract of P. dulce has excellent potential for controlling filariasis vector mosquito, Cx. quinquefasciatus. This is the first report on the mosquito adulticidal activity of the reported P. dulce plant.

Spatio-temporal patterns of distribution of West Nile virus vectors in eastern Piedmont Region, Italy

Directory of Open Access Journals (Sweden)

Bisanzio Donal

2011-12-01

Full Text Available Abstract Background West Nile Virus (WNV transmission in Italy was first reported in 1998 as an equine outbreak near the swamps of Padule di Fucecchio, Tuscany. No other cases were identified during the following decade until 2008, when horse and human outbreaks were reported in Emilia Romagna, North Italy. Since then, WNV outbreaks have occurred annually, spreading from their initial northern foci throughout the country. Following the outbreak in 1998 the Italian public health authority defined a surveillance plan to detect WNV circulation in birds, horses and mosquitoes. By applying spatial statistical analysis (spatial point pattern analysis and models (Bayesian GLMM models to a longitudinal dataset on the abundance of the three putative WNV vectors [Ochlerotatus caspius (Pallas 1771, Culex pipiens (Linnaeus 1758 and Culex modestus (Ficalbi 1890] in eastern Piedmont, we quantified their abundance and distribution in space and time and generated prediction maps outlining the areas with the highest vector productivity and potential for WNV introduction and amplification. Results The highest abundance and significant spatial clusters of Oc. caspius and Cx. modestus were in proximity to rice fields, and for Cx. pipiens, in proximity to highly populated urban areas. The GLMM model showed the importance of weather conditions and environmental factors in predicting mosquito abundance. Distance from the preferential breeding sites and elevation were negatively associated with the number of collected mosquitoes. The Normalized Difference Vegetation Index (NDVI was positively correlated with mosquito abundance in rice fields (Oc. caspius and Cx. modestus. Based on the best models, we developed prediction maps for the year 2010 outlining the areas where high abundance of vectors could favour the introduction and amplification of WNV. Conclusions Our findings provide useful information for surveillance activities aiming to identify locations where the

Mosquito larvicidal properties of silver nanoparticles synthesized using Heliotropium indicum (Boraginaceae) against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus (Diptera: Culicidae).

Science.gov (United States)

Veerakumar, Kaliyan; Govindarajan, Marimuthu; Rajeswary, Mohan; Muthukumaran, Udaiyan

2014-06-01

Mosquitoes transmit dreadful diseases to human beings wherein biological control of these vectors using plant-derived molecules would be an alternative to reduce mosquito population. In the present study activity of aqueous leaf extract and silver nanoparticles (AgNPs) synthesized using Helitropium indicum plant leaves against late third instar larvae of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. The range of varying concentrations of synthesized AgNPs (8, 16, 24, 32, and 40 μg/mL) and aqueous leaf extract (30, 60, 90, 120, and 150 μg/mL) were tested against the larvae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The synthesized AgNPs from H. indicum were highly toxic than crude leaf aqueous extract in three important vector mosquito species. The results were recorded from UV-Vis spectrum, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy analysis, transmission electron microscopy, and histogram. The synthesized AgNPs showed larvicidal effects after 24 h of exposure. Considerable mortality was evident after the treatment of H. indicum for all three important vector mosquitoes. The LC50 and LC90 values of H. indicum aqueous leaf extract appeared to be effective against A. stephensi (LC50, 68.73 μg/mL; LC90, 121.07 μg/mL) followed by A. aegypti (LC50, 72.72 μg/mL; LC90, 126.86 μg/mL) and C. quinquefasciatus (LC50, 78.74 μg/mL; LC90, 134.39 μg/mL). Synthesized AgNPs against the vector mosquitoes of A. stephensi, A. aegypti, and C. quinquefasciatus had the following LC50 and LC90 values: A. stephensi had LC50 and LC90 values of 18.40 and 32.45 μg/mL, A. aegypti had LC50 and LC90 values of 20.10 and 35.97 μg/mL, and C. quinquefasciatus had LC50 and LC90 values of 21.84 and 38.10 μg/mL. No mortality was observed in the control. These results suggest that the leaf aqueous extracts of H. indicum and green synthesis of silver nanoparticles have the

Infection dynamics of western equine encephalomyelitis virus (Togaviridae: Alphavirus in four strains of Culex tarsalis (Diptera: Culicidae: an immunocytochemical study

Directory of Open Access Journals (Sweden)

Neira Oviedo MV

2011-04-01

Full Text Available Marco V Neira Oviedo1,2, William S Romoser1, Calvin BL James1, Farida Mahmood3, William K Reisen31Tropical Disease Institute, Department of Biomedical Sciences, College of Osteopathic Medicine, Ohio University, Athens, OH, USA; 2Oxitec Inc, Oxford, England; 3Center for Vectorborne Diseases, School of Veterinary Medicine, University of California, Davis, CA, USABackground: Vector competence describes the efficiency with which vector arthropods become infected with and transmit pathogens and depends on interactions between pathogen and arthropod genetics as well as environmental factors. For arbovirus transmission, the female mosquito ingests viremic blood, the virus infects and replicates in midgut cells, escapes from the midgut, and disseminates to other tissues, including the salivary glands. Virus-laden saliva is then injected into a new host. For transmission to occur, the virus must overcome several "barriers", including barriers to midgut infection and/or escape and salivary infection and/or escape. By examining the spatial/temporal infection dynamics of Culex tarsalis strains infected with western equine encephalomyelitis virus (WEEV, we identified tissue tropisms and potential tissue barriers, and evaluated the effects of viral dose and time postingestion.Methods: Using immuno-stained paraffin sections, WEEV antigens were tracked in four Cx. tarsalis strains: two recently colonized California field strains – Coachella Valley, Riverside County (COAV and Kern National Wildlife Refuge (KNWR; and two laboratory strains selected for WEEV susceptibility (high viremia producer, HVP, and WEEV resistance (WR.Results and conclusions: Tissues susceptible to WEEV infection included midgut epithelium, neural ganglia, trachea, chorionated eggs, and salivary glands. Neuroendocrine cells in the retrocerebral complex were occasionally infected, indicating the potential for behavioral effects. The HVP and COAV strains vigorously supported viral growth

Seasonal abundance and molecular identification of West Nile virus ...

African Journals Online (AJOL)

Seasonal abundance and molecular identification of West Nile virus vectors, Culex pipens and Culex ... Background: West Nile virus (WNV) infection, is an arbovirus infection with high morbidity and mortality, the vector respon- sible for both human ... Major diseases transmitted are known as Arboviral dis- eases because ...

Ecological study of avian malaria vectors on the island of Minami-Daito, Japan.

Science.gov (United States)

Tsuda, Yoshio; Matsui, Shin; Saito, Atsushi; Akatani, Kana; Sato, Yukita; Takagi, Masaoki; Murata, Koichi

2009-09-01

The seasonal prevalence and spatial distribution of mosquitoes were examined as part of an avian malaria study on the oceanic island of Minami-Daito Island, Japan. Because dry ice was not available in this study, yeast-generated CO2 was used to attract biting mosquitoes. Adult mosquitoes were collected biweekly using battery-operated traps enhanced with yeast-generated CO2 and a gravid trap from March 2006 to February 2007. The CO2-baited traps were distributed in 4 different habitats: sugar cane field, forest and vegetation ring, residential area, and swamp area. At 3 collection sites beside sugar cane fields, traps were fixed at 2 different heights (3 and 6 m above the ground). A total of 1,437 mosquitoes of the following 9 species were collected: Culex quinquefasciatus, Aedes albopictus, Coquillettidia sp., Mansonia uniformis, Culex rubithoracis, Armigeres subalbatus, Lutzia fuscanus, Aedes daitensis, and Aedes togoi. Among them, Cx. quinquefasciatus, Ae. albopictus, and Coquillettidia sp. were dominant. The high density and wide distribution of Cx. quinquefasciatus throughout the island suggested the importance of this species as a principal vector of avian malaria on the island.

The Role of Culex pipiens L. (Diptera: Culicidae in Virus Transmission in Europe

Directory of Open Access Journals (Sweden)

Victor A. Brugman

2018-02-01

Full Text Available Over the past three decades, a range of mosquito-borne viruses that threaten public and veterinary health have emerged or re-emerged in Europe. Mosquito surveillance activities have highlighted the Culex pipiens species complex as being critical for the maintenance of a number of these viruses. This species complex contains morphologically similar forms that exhibit variation in phenotypes that can influence the probability of virus transmission. Critical amongst these is the choice of host on which to feed, with different forms showing different feeding preferences. This influences the ability of the mosquito to vector viruses and facilitate transmission of viruses to humans and domestic animals. Biases towards blood-feeding on avian or mammalian hosts have been demonstrated for different Cx. pipiens ecoforms and emerging evidence of hybrid populations across Europe adds another level of complexity to virus transmission. A range of molecular methods based on DNA have been developed to enable discrimination between morphologically indistinguishable forms, although this remains an active area of research. This review provides a comprehensive overview of developments in the understanding of the ecology, behaviour and genetics of Cx. pipiens in Europe, and how this influences arbovirus transmission.

The Role of Culex pipiens L. (Diptera: Culicidae) in Virus Transmission in Europe

Science.gov (United States)

Hernández-Triana, Luis M.; Medlock, Jolyon M.; Fooks, Anthony R.; Carpenter, Simon; Johnson, Nicholas

2018-01-01

Over the past three decades, a range of mosquito-borne viruses that threaten public and veterinary health have emerged or re-emerged in Europe. Mosquito surveillance activities have highlighted the Culex pipiens species complex as being critical for the maintenance of a number of these viruses. This species complex contains morphologically similar forms that exhibit variation in phenotypes that can influence the probability of virus transmission. Critical amongst these is the choice of host on which to feed, with different forms showing different feeding preferences. This influences the ability of the mosquito to vector viruses and facilitate transmission of viruses to humans and domestic animals. Biases towards blood-feeding on avian or mammalian hosts have been demonstrated for different Cx. pipiens ecoforms and emerging evidence of hybrid populations across Europe adds another level of complexity to virus transmission. A range of molecular methods based on DNA have been developed to enable discrimination between morphologically indistinguishable forms, although this remains an active area of research. This review provides a comprehensive overview of developments in the understanding of the ecology, behaviour and genetics of Cx. pipiens in Europe, and how this influences arbovirus transmission. PMID:29473903

Preliminary screening of plant essential oils against larvae of Culex ...

African Journals Online (AJOL)

Preliminary screenings of 22 plant essential oils were tested for mortality of the mosquito larvae Culex quinquefasciatus under laboratory conditions. Percent (%) mortality of the mosquito larvae were obtained for each essential oil. At different exposure periods, viz. 1, 3, 6, 12 and 24 h among the 22 plant oils tested, eight ...

Larvicidal activity of the methanol extract and fractions of the green fruits of Solanum lycocarpum (Solanaceae against the vector Culex quinquefasciatus (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Thamer Matias Pereira

2014-10-01

Full Text Available Introduction The larvicidal activity of Solanum lycocarpum against Culex quinquefasciatus is unknown. Methods We evaluated the larvicidal activity of extracts of the green fruits of Solanum lycocarpum against third and fourth instar larvae of C. quinquefasciatus. Results Dichloromethane and ethyl acetate fractions showed the greatest larvicidal effect at 200mg/L (83.3% and 86.7%, respectively. The methanol and dichloromethane, ethyl acetate, and hydromethanolic fractions demonstrated larvicidal effects against C. quinquefasciatus, with LC50 values of 126.24, 75.13, 83.15, and 207.05mg/L, respectively. Conclusions Thus, when considering new drugs with larvicidal activity from natural products, S. lycocarpum fruits may be good candidate sources.

Avaliação da sensibilidade de adultos de Culex quinquefasciatus Say a inseticidas químicos de contato Evaluation of the sensitivity of the adult Culex quinquefasciatus Say to chemical insecticides

Directory of Open Access Journals (Sweden)

Carlos Fernando S. de Andrade

1990-08-01

Full Text Available A sensibilidade de adultos do pernilongo doméstico Culex quinquefasciatus a 5 inseticidas químicos foi avaliada sob condições de laboratório pelo critério de Tempo Letal Mediano (TL50. Foram utilizados o organofosforado Malathion e quatro piretróides: Bifenthrin, Deltamethrin, Esfenvalerate e Alfamethrin. Foi sugerida uma técnica simples e eficiente para se avaliar adultos de um dia de idade incluindo 5 repetições para cada tratamento. Os resultados obtidos mostraram ser o método bastante adequado para avaliações rotineiras. Não ocorreu resistência a esses 5 princípios ativos, na população natural de Culex quinquefasciatus estudada.The sensitivity of the adult house mosquito Culex quinquefasciatus to 5 chemical insecticides was evaluated under laboratory condictions, based on the Median Lethal Time (LT50 criterion. The organophosphorous Malathion and four pyrethroids: Bifenthrin, Deltamethrin, Esfenvalerate and Alfamethrin were utilized. An easy and efficient technique was suggested for the testing of one-day-old adults, including five repetitions for each treatment. The results revealed the full adequacy of this method for routine use. Further, no resistance to the 5 chemical compounds was detected among this natural population of Cx. quinquefasciatus.

Larvicidal activity of oils, fatty acids, and methyl esters from ripe and unripe fruit of Solanum lycocarpum (Solanaceae against the vector Culex quinquefasciatus (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Viviane de Cássia Bicalho Silva

2015-10-01

Full Text Available ABSTRACTINTRODUCTION:The larvicidal activity of oils, fatty acids, and methyl esters of Solanum lycocarpum fruit against Culex quinquefasciatus is unknown.METHODS:The larvicidal activity of samples of ripe and unripe fruit from S. lycocarpum was evaluated against third and fourth instar larvae of C. quinquefasciatus .RESULTS:The oils, fatty acids, and methyl esters of S. lycocarpum showed the greatest larvicidal effect (57.1-95.0% at a concentration of 100mg/L (LC 50values between 0.70 and 27.54mg/L.CONCLUSIONS:Solanum lycocarpum fruit may be a good source of new natural products with larvicidal activity.

Iron and iron oxide nanoparticles are highly toxic to Culex quinquefasciatus with little non-target effects on larvivorous fishes.

Science.gov (United States)

Murugan, Kadarkarai; Dinesh, Devakumar; Nataraj, Devaraj; Subramaniam, Jayapal; Amuthavalli, Pandiyan; Madhavan, Jagannathan; Rajasekar, Aruliah; Rajan, Mariappan; Thiruppathi, Kulandhaivel Palani; Kumar, Suresh; Higuchi, Akon; Nicoletti, Marcello; Benelli, Giovanni

2018-04-01

The control of filariasis vectors has been enhanced in several areas, but there are main challenges, including increasing resistance to insecticides and lack of cheap and eco-friendly products. The toxicity of iron (Fe 0 ) and iron oxide (Fe 2 O 3 ) nanoparticles has been scarcely investigated yet. We studied the larvicidal and pupicidal activity of Fe 0 and Fe 2 O 3 nanoparticles against Culex quinquefasciatus. Fe 0 and Fe 2 O 3 nanoparticles produced by green (using a Ficus natalensis aqueous extract) and chemical nanosynthesis, respectively, were analyzed by UV-Vis spectrophotometry, FT-IR spectroscopy, XRD analysis, SEM, and EDX assays. In larvicidal and pupicidal experiments on Cx. quinquefasciatus, LC 50 of Fe 0 nanoparticles ranged from 20.9 (I instar larvae) to 43.7 ppm (pupae) and from 4.5 (I) to 22.1 ppm (pupae) for Fe 2 O 3 nanoparticles synthesized chemically. Furthermore, the predation efficiency of the guppy fish, Poecilia reticulata, after a single treatment with sub-lethal doses of Fe 0 and Fe 2 O 3 nanoparticles was magnified. Overall, this work provides new insights about the toxicity of Fe 0 and Fe 2 O 3 nanoparticles against mosquito vectors; we suggested that green and chemical fabricated nano-iron may be considered to develop novel and effective pesticides.

Trypanosoma avium of raptors (Falconiformes): phylogeny and identification of vectors.

Science.gov (United States)

Votýpka, J; Oborník, M; Volf, P; Svobodová, M; Lukes, J

2002-09-01

Avian trypanosomes are widespread parasites of birds, the transmission of which remains mostly unclear, with various blood-sucking insects mentioned as possible vectors. A search for vectors of trypanosomes of sparrowhawk (Accipiter nisus), buzzard (Buteo buteo), lesser-spotted eagle (Aquila pomarina) and kestrel (Falco tinnunculus) was performed in Czech and Slovak Republics. Black flies (Eusimulium spp.), hippoboscid flies (Ornithomyia avicularia), mosquitoes (Culex pipiens pipiens) and biting midges (Culicoides spp.), trapped while attempting to feed on raptor nestlings, were found to contain trypanosomatids in their intestine. Trypanosomes from the raptors and blood-sucking insects were isolated, and their 18S rRNA sequences were used for species identification and for the inference of intra- and interspecific relationships. Together with the trypanosome isolated from a black fly, the bird trypanosomes formed a well-supported Trypanosoma avium clade. The isolates derived from hippoboscid flies and mosquitoes are most likely also avian trypanosomes infecting birds other than the studied raptors. Analysis of the kinetoplast, that has features characteristic for the avian trypanosomes (minicircle size; dimensions of the kinetoplast disc), provided further evidence for the identification of vectors. It is suggested that all trypanosomes isolated from raptors included in this study belong to the T. avium complex and are transmitted by the ornithophilic simuliids such as Eusimulium securiforme.

A comparative study on larvicidal potential of selected medicinal plants over green synthesized silver nano particles

Directory of Open Access Journals (Sweden)

Syed Zameer Ahmed Khader

2018-03-01

Full Text Available Larvicidal activity was assessed for alcoholic extracts of Phyllanthus amarus, Annona squamosa, Coccinia grandis and Eclipta prostrata extracted using solvents of various polarity. Third instar stage larvae of Dengue-vector, Aedes aegypti and Japanese encephalitis (JE causing mosquito Culex tritaeniorhynchus were subjected to larvicidal bioassay at various concentrations (1000, 500, 250 ppm. The results explored that the phytoconstituents and secondary metabolites present in all the plants elucidated potent larvicidal activity. Among the tested extract ethyl acetate, petroleum ether and hexane extract expressed significant larvicidal activity. Similarly, these plants were subjected to green synthesis of silver nanoparticles, characterized and subjected for its larvicidal activity against Anopheles stephensi causing malaria. The synthesized silver nanoparticles were characterized by UV–VIS spectroscopy, Fourier Transform Infra-Red spectroscopy, Scanning Electron Microscopy respectively. The FTIR analysis strongly supported the capping behaviour of bio-reduced synthesized silver nanoparticles which in turn imparted the high stability of the synthesized silver nanoparticles. The average size of synthesized nanoparticles was less than 1 µm, most spherical in shape with SEM analysis. The findings revealed that Eclipta prostrata and Annona squamosa has effective larvicidal activity, whereas all the synthesised nanoparticles demonstrated dose dependent activity even at very low concentration and the findings reveals that these extracts and nanoparticles can be a better remedy against these mosquitoes.

Enkapsulasi B. bassiana menggunakan maizena dan daya infeksinya terhadap larva Aedes aegypti, Anopheles sp., Culex sp.

Directory of Open Access Journals (Sweden)

Mutiara Widawati

2015-12-01

Full Text Available Abstract. Encapsulation formulae of mycoinsecticide have to be able to maintain fungus viability and pathogenicity. This mycoinsecticide was developed as an alternative way to control mosquito borne disease. The aim of this study was to encapsulate Beauveria bassiana as viable storage and have the capability to kill larvae of Aedes aegypti, Anopheles sp. and Culex sp. Mosquito larvae obtained from laboratory reared at health research laboratory; Loka Litbang P2B2 Ciamis. The treatments made in this study were the formu-lation of cornstarch and controls for comparison. This study showed potential formulation of cornstarch encapsulation as a biolarvacidal. Cornstarch formulations proven to be succeed in maintaining fungus viability, however, the pathogenicity of the microcapsule still not effective to kill Aedes, Culex and Anopheles larvae. Keywords: encapsulation, Beauveria bassiana, Ae.aegypti, Anopheles sp., Culex sp. Abstrak. Pembuatan formula bioinsektisida yang optimal sebagai salah satu alternatif untuk pengen-dalian nyamuk vektor perlu di kembangkan. Sediaan mikoinsektisida yang dibuat harus dapat memper-tahankan viabilitas jamur B. bassiana sehingga masih efektif pada saat penggunaannya. Salah satu cara yang digunakan untuk menjaga kestabilan sediaan mikoinsektisida yang berdampak langsung pada via-bilitas jamur adalah dengan menerapkan metode enkapsulasi. Penelitian ini bertujuan untuk meng-hasilkan sediaan mikokapsul dari Beauvaria bassiana melalui proses enkapsulasi menggunakan maizena yang memiliki kapabilitas tinggi sebagai penyimpan B. bassiana dan efektif dalam membunuh larva dan telur Aedes aegypti, Anopheles sp. dan Culex sp. Semua larva uji berasal dari insektarium laboratorium penelitian kesehatan Loka litbang P2B2 Ciamis. Pembuatan enkapsulasi dimulai dengan kultur dan pema-nenan B. bassiana, uji viabilitas, proses enkapsulasi serta uji larvasida di laboratorium. Uji dilakukan dengan satu perlakuan dan satu kontrol untuk

Assessment of Local Mosquito Species Incriminates Aedes aegypti as the Potential Vector of Zika Virus in Australia.

Directory of Open Access Journals (Sweden)

Sonja Hall-Mendelin

2016-09-01

Full Text Available Within the last 10 years Zika virus (ZIKV has caused unprecedented epidemics of human disease in the nations and territories of the western Pacific and South America, and continues to escalate in both endemic and non-endemic regions. We evaluated the vector competence of Australian mosquitoes for ZIKV to assess their potential role in virus transmission.Mosquitoes were exposed to infectious blood meals containing the prototype African ZIKV strain. After 14 days incubation at 28°C and high relative humidity, infection, dissemination and transmission rates were assessed. Infection in Culex annulirostris and Cx. sitiens could not be detected. 8% of Cx. quinquefasciatus were infected, but the virus did not disseminate in this species. Despite having infection rates > 50%, Aedes notoscriptus and Ae. vigilax did not transmit ZIKV. In contrast, Ae. aegypti had infection and transmission rates of 57% and 27%, respectively. In susceptibility trials, the virus dose required to infect 50% (ID50 of Ae. aegypti was106.4 tissue culture infectious dose50 (TCID50/mL. Additionally, a threshold viral load within the mosquito of at least 105.1 TCID50 equivalents/mL had to be reached before virus transmission occurred.We confirmed Ae. aegypti to be the most likely mosquito vector of ZIKV in Australia, although the restricted distribution of this species will limit the receptive zone to northern Queensland where this species occurs. Importantly, the role in ZIKV transmission of Culex and other Aedes spp. tested will be negligible. Despite being the implicated vector, the relatively high ID50 and need for a high titer disseminated infection in Ae. aegypti suggest that high mosquito population densities will be required to facilitate epidemic ZIKV transmission among the currently immunologically naïve human population in Australia.

Assessment of Local Mosquito Species Incriminates Aedes aegypti as the Potential Vector of Zika Virus in Australia.

Science.gov (United States)

Hall-Mendelin, Sonja; Pyke, Alyssa T; Moore, Peter R; Mackay, Ian M; McMahon, Jamie L; Ritchie, Scott A; Taylor, Carmel T; Moore, Frederick A J; van den Hurk, Andrew F

2016-09-01

Within the last 10 years Zika virus (ZIKV) has caused unprecedented epidemics of human disease in the nations and territories of the western Pacific and South America, and continues to escalate in both endemic and non-endemic regions. We evaluated the vector competence of Australian mosquitoes for ZIKV to assess their potential role in virus transmission. Mosquitoes were exposed to infectious blood meals containing the prototype African ZIKV strain. After 14 days incubation at 28°C and high relative humidity, infection, dissemination and transmission rates were assessed. Infection in Culex annulirostris and Cx. sitiens could not be detected. 8% of Cx. quinquefasciatus were infected, but the virus did not disseminate in this species. Despite having infection rates > 50%, Aedes notoscriptus and Ae. vigilax did not transmit ZIKV. In contrast, Ae. aegypti had infection and transmission rates of 57% and 27%, respectively. In susceptibility trials, the virus dose required to infect 50% (ID50) of Ae. aegypti was106.4 tissue culture infectious dose50 (TCID50)/mL. Additionally, a threshold viral load within the mosquito of at least 105.1 TCID50 equivalents/mL had to be reached before virus transmission occurred. We confirmed Ae. aegypti to be the most likely mosquito vector of ZIKV in Australia, although the restricted distribution of this species will limit the receptive zone to northern Queensland where this species occurs. Importantly, the role in ZIKV transmission of Culex and other Aedes spp. tested will be negligible. Despite being the implicated vector, the relatively high ID50 and need for a high titer disseminated infection in Ae. aegypti suggest that high mosquito population densities will be required to facilitate epidemic ZIKV transmission among the currently immunologically naïve human population in Australia.

Occurrence of avian Plasmodium and West Nile virus in culex species in Wisconsin

Science.gov (United States)

Hughes, T.; Irwin, P.; Hofmeister, E.; Paskewitz, S.M.

2010-01-01

The occurrence of multiple pathogens in mosquitoes and birds could affect the dynamics of disease transmission. We collected adult Culex pipiens and Cx. restuans (Cx. pipiens/restuans hereafter) from sites in Wisconsin and tested them for West Nile virus (WNV) and for avian malaria (Plasmodium). Gravid Cx. pipiens/restuans were tested for WNV using a commercial immunoassay, the RAMP?? WNV test, and positive results were verified by reverse transcriptasepolymerase chain reaction. There were 2 WNV-positive pools of Cx. pipiens/restuans in 2006 and 1 in 2007. Using a bias-corrected maximum likelihood estimation, the WNV infection rate for Cx. pipiens/restuans was 5.48/1,000 mosquitoes in 2006 and 1.08/1,000 mosquitoes in 2007. Gravid Cx. pipiens or Cx. restuans were tested individually for avian Plasmodium by a restriction enzymebased assay. Twelve mosquitoes were positive for avian Plasmodium (10.0), 2 were positive for Haemoproteus, and 3 were positive for Leucocytozoon. There were 4 mixed infections, with mosquitoes positive for >1 of the hemosporidian parasites. This work documents a high rate of hemosporidian infection in Culex spp. and illustrates the potential for co-infections with other arboviruses in bird-feeding mosquitoes and their avian hosts. In addition, hemosporidian infection rates may be a useful tool for investigating the ecological dynamics of Culex/avian interactions. ?? 2010 by The American Mosquito Control Association, Inc.

Efficacy of Bacillus thuringiensis var israelinsis (Bti) on Culex and ...

African Journals Online (AJOL)

dosage that can be used to control Culex mosquito larvae in Zomba after ... exposed to the same dosage of liquid formulation of Bti (0.001ml/L) there ... The objective of this study was to evaluate the efficacy of Bti on mosquito ...... In short Bti whether liquid or granular is very important as it significantly reduces the densities of ...

Evaluation of aqueous and ethanol extract of bioactive medicinal plant, Cassia didymobotrya (Fresenius) Irwin & Barneby against immature stages of filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae).

Science.gov (United States)

Nagappan, Raja

2012-09-01

To evaluate aqueous and ethanol extract of Cassia didymobotrya leaves against immature stages of Culex quinquefasciatus. The mortality rate of immature mosquitoes was tested in wide and narrow range concentration of the plant extract based on WHO standard protocol. The wide range concentration tested in the present study was 10 000, 1 000, 100, 10 and 1 mg/L and narrow range concentration was 50, 100, 150, 200 and 250 mg/L. 2nd instar larvae exposed to 100 mg/L and above concentration of ethanol extract showed 100% mortality. Remaining stages such as 3rd, 4th and pupa, 100% mortality was observed at 1 000 mg/L and above concentration after 24 h exposure period. In aqueous extract all the stages 100% mortality was recorded at 1 000 mg/L and above concentration. In narrow range concentration 2nd instar larvae 100% mortality was observed at 150 mg/L and above concentration of ethanol extract. The remaining stages 100% mortality was recorded at 250 mg/L. In aqueous extract all the tested immature stages 100% mortality was observed at 250 mg/L concentration after 24 h exposure period. The results clearly indicate that the rate of mortality was based dose of the plant extract and stage of the mosquitoes. From this study it is confirmed and concluded that Cassia didymobotrya is having active principle which is responsible for controlling Culex quinquefasciatus. The isolation of bioactive molecules and development of simple formulation technique is important for large scale implementation.

Vector movement underlies avian malaria at upper elevation in Hawaii: implications for transmission of human malaria.

Science.gov (United States)

Freed, Leonard A; Cann, Rebecca L

2013-11-01

With climate warming, malaria in humans and birds at upper elevations is an emerging infectious disease because development of the parasite in the mosquito vector and vector life history are both temperature dependent. An enhanced-mosquito-movement model from climate warming predicts increased transmission of malaria at upper elevation sites that are too cool for parasite development in the mosquito vector. We evaluate this model with avian malaria (Plasmodium relictum) at 1,900-m elevation on the Island of Hawaii, with air temperatures too low for sporogony in the vector (Culex quinquefasciatus). On a well-defined site over a 14-year period, 10 of 14 species of native and introduced birds became infected, several epizootics occurred, and the increase in prevalence was driven more by resident species than by mobile species that could have acquired their infections at lower elevations. Greater movement of infectious mosquitoes from lower elevations now permits avian malaria to spread at 1,900 m in Hawaii, in advance of climate warming at that elevation. The increase in malaria at upper elevations due to dispersal of infectious mosquitoes is a real alternative to temperature for the increased incidence of human malaria in tropical highlands.

High Insecticides Resistance in Culex pipiens (Diptera: Culicidae from Tehran, Capital of Iran

Directory of Open Access Journals (Sweden)

Yaser Salim-Abadi

2016-10-01

Full Text Available Background: During recent years transmission of Dirofilaria immitis (dog heart worm by Culex pipiens and West Nile virus have been reported from Iran. The present study was preformed for evaluating the susceptibility status of Cx. pipiens collected from capital city of Tehran, Iran.Methods: Four Insecticides including: DDT 4%, Lambdacyhalothrin 0.05%, Deltamethrin 0.05% and Cyfluthrin 0.15 % according to WHO standard  methods were used for evaluating the susceptibility status of Cx. pipiens from Tehran moreover  For comparison susceptibility status a Laboratory strain also was used.  Bioassay data were ana­lyzed using Probit program. The lethal time for 50% and 90% mortality (LT50 and LT90 values were calculated from regression line.Results: The susceptibility status of lab strain of Cx. pipiens revealed that it is susceptible to Lambdacyhalothrin, Deltamethrin, Cyfluthrin and resistant to DDT. Moreover cyfluthrin with LT50=36 seconds and DDT with LT50=3005 seconds had the least and most LT50s. Field population was resistance to all tested insecticides and DDT yielded no mortality.Conclusion: Highly resistance level against all WHO recommended imagicides were detected in field populations. We suggest more biochemical and molecular investigations to detect resistance mechanisms in the field population for further decision of vector control.

Laboratory and field evaluation of an oviposition trap for Culex quinquefasciatus(Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Rosângela MR Barbosa

2007-06-01

Full Text Available An ovitrap (BR-OVT based on physical and chemical stimuli for attracting gravid Culex quinquefasciatus (Diptera: Culicidae females was developed and evaluated under laboratory and field conditions. Attractants were assayed using alternative chamber bioassays prior to being used in the BR-OVT oviposition trap. A significant preference of gravid females for sites containing conspecific egg rafts was observed, as a response to the natural oviposition pheromone, as well as for sites treated with the synthetic pheromone erythro-6-acetoxy-5-hexadecanolide. Five- to 20-day old grass infusion was strongly attractive to gravid females for laying eggs. On the other hand, entomopathogenic Bacillus sphaericus (Bs did not influence the choice of an oviposition site when used in combination with grass infusion and can therefore be used as a larvicide in ovitraps. Results from field trials showed that the BR-OVT with grass infusion and with or without Bs works as a preferred oviposition site for Cx. quinquefasciatus. The BR-OVT was more effective for egg collection when placed indoors and comparison with the number of egg rafts laid in cesspits over 40 days indicates that this very simple ovitrap may be a useful tool for monitoring populations of the most important of the vectors of bancroftian filariasis.

Ovicidal and Larvicidal Effects of Garlic and Asafoetida Essential Oils Against West Nile Virus Vectors

Science.gov (United States)

Muturi, Ephantus J; Ramirez, Jose L; Zilkowski, Bruce; Flor-Weiler, Lina B; Rooney, Alejandro P

2018-01-01

Abstract We examined the chemical composition of garlic and asafoetida essential oils and their individual and combined toxicity against larvae of Culex pipiens Linnaeus and Culex restuans Theobald (Diptera: Culicidae). The effect of the two essential oils on egg hatch was also examined. Ten and 12 compounds, respectively, were identified in garlic and asafoetida essential oils. Allyl disulfide (49.13%) and diallyl trisulfide (31.08%) were the most abundant compounds in garlic essential oil accounting for 80.2% of the total oil. In contrast, (E)-sec-butyl propenyl disulfide (30.03%), (Z)-sec-butyl propenyl disulfide (24.32%), and disulfide, methyl 1-(methylthio)propyl (21.87%) were the most abundant compounds in asafoetida essential oil. Allyl disulfide accounted for 7.38% of the total oil in asafoetida essential oil and was one of only three compounds found in both oils. For both mosquito species, garlic essential oil was more toxic than asafoetida essential oil with Cx. restuans (LC50: garlic = 2.7 ppm; asafoetida = 10.1 ppm) being more sensitive than Cx. pipiens (LC50: garlic = 7.5 ppm; asafoetida = 13.5 ppm). When combined, the two essential oils had antagonistic effects. The majority of Culex egg rafts exposed to garlic (73.1%) or asafoetida (55.8%) essential oils failed to hatch and larvae of the few that did hatch mostly died as first instars. Allyl disulfide exhibited strong ovicidal and larvicidal activity suggesting its important contribution to the overall toxicity of the two essential oils. Thus, garlic and asafoetida essential oils are potent mosquito ovicides and larvicides but if used jointly, they could undermine vector control programs. PMID:29718505

Culex annulirostris (Diptera: Culicidae) host feeding patterns and Japanese encephalitis virus ecology in northern Australia.

Science.gov (United States)

Hall-Mendelin, Sonja; Jansen, Cassie C; Cheah, Wai Yuen; Montgomery, Brian L; Hall, Roy A; Ritchie, Scott A; Van den Hurk, Andrew F

2012-03-01

Japanese encephalitis virus (JEV) transmission in northern Australia has, in the past, been facilitated by Culex annulirostris Skuse feeding on domestic pigs, the primary amplifying hosts of the virus. To further characterize mosquito feeding behavior in northern Australia, 1,128 bloodmeals from Cx. annulirostris were analyzed using a double-antibody enzyme-linked immunosorbent assay. Overall, Cx. annulirostris obtained > 94% of blood meals from mammals, comprising marsupials (37%), pigs (20%), dogs (16%), and cows (11%), although the proportion feeding on each of these host types varied between study locations. Where JEV activity was detected, feeding rates on pigs were relatively high. At the location that yielded the first Australian mainland isolate of JEV from mosquitoes, feral pigs (in the absence of domestic pigs) accounted for 82% of bloodmeals identified, representing the first occasion that feeding on feral pigs has been associated with JEV transmission in Australia. Interestingly, blood meals identified, or infected mosquitoes immigrating from areas where domestic pigs are housed, may have contributed to transmission at this location. Because Cx. annulirostris is both an opportunistic feeder and the primary JEV vector in the region, environmental characteristics and host presence can determine JEV transmission dynamics in northern Australia.

Identification of Blood Meals from Potential Arbovirus Mosquito Vectors in the Peruvian Amazon Basin.

Science.gov (United States)

Palermo, Pedro M; Aguilar, Patricia V; Sanchez, Juan F; Zorrilla, Víctor; Flores-Mendoza, Carmen; Huayanay, Anibal; Guevara, Carolina; Lescano, Andrés G; Halsey, Eric S

2016-11-02

The transmission dynamics of many arboviruses in the Amazon Basin region have not been fully elucidated, including the vectors and natural reservoir hosts. Identification of blood meal sources in field-caught mosquitoes could yield information for identifying potential arbovirus vertebrate hosts. We identified blood meal sources in 131 mosquitoes collected from areas endemic for arboviruses in the Peruvian Department of Loreto by sequencing polymerase chain reaction amplicons of the cytochrome b gene. Psorophora (Janthinosoma) albigenu, Psorophora (Grabhamia) cingulata, Mansonia humeralis, Anopheles oswaldoi s.l., and Anopheles benarrochi s.l. had mainly anthropophilic feeding preferences; Aedes (Ochlerotatus) serratus, and Aedes (Ochlerotatus) fulvus had feeding preferences for peridomestic animals; and Culex (Melanoconion) spp. fed on a variety of vertebrates, mainly rodents (spiny rats), birds, and amphibians. On the basis of these feeding preferences, many mosquitoes could be considered as potential enzootic and bridge arbovirus vectors in the Amazon Basin of Peru. © The American Society of Tropical Medicine and Hygiene.

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.

The Ecological Aspects of Culex pipiens (Diptera: Culicidae in Central Iran.

Directory of Open Access Journals (Sweden)

Hossein Dehghan

2014-06-01

Full Text Available The aim was to survey the specific factors, which cause to decrease blood feeding of mosquitoes important to succeed vector control.Larval collection was carried out from fixed and variable breeding places of Yazd County, central Iran in 2009. Autogeny-Anautogeny, Stenogamy-Eurygamy, and blood preference of Culex pipiens were studied using standard mosquito cages blood meal source for Cx. pipiens females considered as the chickens and human and fed females were kept in insectary condition (16:8 L: D, 27±3 °C and 70±10% RH. The data were analyzed using SPSS Ver. 11.5 soft ware.Totally, 96 females' mosquitoes were tested for Stenogamy versus Eurygamy and 122 for blood preference assay. In the small cages (20 × 20 × 20cm and large cage (60 × 40 × 60cm, the ability of mating and insemination rates were 60.0 and 67.0%, respectively. In spite of Cx. pipiens fed from sucrose 5%, none of them laying eggs in 60 × 40 × 60 cages during the study. This finding indicated the Anautogeny behavior of this species. This species was found of low tendency to human blood and almost 4 fold fed on chicken.The occurrence of Steno-Eurygamy, Anautogeny, and Ornithophilic behaviors of Cx. Pipiens was noted. More studies need to be carried out about the bionomics of this species to gain more data about the ecophysiological and behavioral characteristics in other parts of Iran.

[Vector transmitted diseases and climate changes in Europe].

Science.gov (United States)

Rossati, Antonella; Bargiacchi, Olivia; Kroumova, Vesselina; Garavelli, Pietro Luigi

2014-09-01

The increase in temperatures recorded since the mid-nineteenth century is unprecedented in the history of mankind. The consequences of climate changes are numerous and can affect human health through direct (extreme events, natural disasters) or indirect (alteration of the ecosystem) mechanisms. Climate changes have repercussions on ecosystems, agriculture, social conditions, migration, conflicts and the transmission mode of infectious diseases. Vector-borne diseases are infections transmitted by the bite of infected arthropods such as mosquitoes, ticks, triatomines, sand flies and flies. Epidemiological cornerstones of vector-borne diseases are: the ecology and behaviour of the host, the ecology and behaviour of the vector, and the population's degree of immunity. Mosquito vectors related to human diseases mainly belong to the genus Culex, Aedes and Mansonia. Climate changes in Europe have increased the spread of new vectors, such as Aedes albopictus, and in some situations have made it possible to sustain the autochthonous transmission of some diseases (outbreak of Chukungunya virus in northern Italy in 2007, cases of dengue in the South of France and in Croatia). Despite the eradication of malaria from Europe, anopheline carriers are still present, and they may allow the transmission of the disease if the climatic conditions favour the development of the vectors and their contacts with plasmodium carriers. The tick Ixodes ricinus is a vector whose expansion has been documented both in latitude and in altitude in relation to the temperature increase; at the same time the related main viral and bacterial infections have increased. In northern Italy and Germany, the appearance of Leishmaniasis has been associated to climatic conditions that favour the development of the vector Phlebotomus papatasi and the maturation of the parasite within the vector, although the increase of cases of visceral leishmaniasis is also related to host immune factors, particularly

Toxicity of Boswellia dalzielii (Burseraceae) Leaf Fractions Against Immature Stages of Anopheles gambiae (Giles) and Culex quinquefasciatus (Say) (Diptera: Culicidae)

Science.gov (United States)

Younoussa, Lame; Nukenine, Elias Nchiwan; Esimone, Charles Okechukwu

2016-01-01

Mosquitoes are vectors of several human pathogens, and great attention has recently been placed on insecticides from plant-derived products, in search for mosquito control agents. This study, thus, investigated the potency of Boswellia dalzielii methanol leaf extract and its four fractions as mosquito ovicide, larvicide, and pupicide against Anopheles gambiae and Culex quinquefasciatus. The plant products were tested at the following concentrations: 125, 250, 500, 1000, and 2000 ppm on eggs and 312.5, 625, 1250, and 2500 ppm on the larvae and pupae of the mosquitoes. For results, hatchability of A. gambiae eggs was reduced to 5% with n-hexane fraction at 2000 ppm. Among the plant products tested, n-hexane fraction was most toxic against A. gambiae (LC50 = 385.9 ppm) and C. quinquefasciatus (LC50 = 3394.9 ppm). The n-hexane fraction of B. dalzielii might be used as a mosquitocidal agent in the breeding sites of A. gambiae and C. quinquefasciatus. PMID:27279752

Zika virus: An updated review of competent or naturally infected mosquitoes.

Science.gov (United States)

Epelboin, Yanouk; Talaga, Stanislas; Epelboin, Loïc; Dusfour, Isabelle

2017-11-01

Zika virus (ZIKV) is an arthropod-borne virus (arbovirus) that recently caused outbreaks in the Americas. Over the past 60 years, this virus has been observed circulating among African, Asian, and Pacific Island populations, but little attention has been paid by the scientific community until the discovery that large-scale urban ZIKV outbreaks were associated with neurological complications such as microcephaly and several other neurological malformations in fetuses and newborns. This paper is a systematic review intended to list all mosquito species studied for ZIKV infection or for their vector competence. We discuss whether studies on ZIKV vectors have brought enough evidence to formally exclude other mosquitoes than Aedes species (and particularly Aedes aegypti) to be ZIKV vectors. From 1952 to August 15, 2017, ZIKV has been studied in 53 mosquito species, including 6 Anopheles, 26 Aedes, 11 Culex, 2 Lutzia, 3 Coquillettidia, 2 Mansonia, 2 Eretmapodites, and 1 Uranotaenia. Among those, ZIKV was isolated from 16 different Aedes species. The only species other than Aedes genus for which ZIKV was isolated were Anopheles coustani, Anopheles gambiae, Culex perfuscus, and Mansonia uniformis. Vector competence assays were performed on 22 different mosquito species, including 13 Aedes, 7 Culex, and 2 Anopheles species with, as a result, the discovery that A. aegypti and Aedes albopictus were competent for ZIKV, as well as some other Aedes species, and that there was a controversy surrounding Culex quinquefasciatus competence. Although Culex, Anopheles, and most of Aedes species were generally observed to be refractory to ZIKV infection, other potential vectors transmitting ZIKV should be explored.

Zika virus: An updated review of competent or naturally infected mosquitoes

Science.gov (United States)

Talaga, Stanislas; Epelboin, Loïc; Dusfour, Isabelle

2017-01-01

Zika virus (ZIKV) is an arthropod-borne virus (arbovirus) that recently caused outbreaks in the Americas. Over the past 60 years, this virus has been observed circulating among African, Asian, and Pacific Island populations, but little attention has been paid by the scientific community until the discovery that large-scale urban ZIKV outbreaks were associated with neurological complications such as microcephaly and several other neurological malformations in fetuses and newborns. This paper is a systematic review intended to list all mosquito species studied for ZIKV infection or for their vector competence. We discuss whether studies on ZIKV vectors have brought enough evidence to formally exclude other mosquitoes than Aedes species (and particularly Aedes aegypti) to be ZIKV vectors. From 1952 to August 15, 2017, ZIKV has been studied in 53 mosquito species, including 6 Anopheles, 26 Aedes, 11 Culex, 2 Lutzia, 3 Coquillettidia, 2 Mansonia, 2 Eretmapodites, and 1 Uranotaenia. Among those, ZIKV was isolated from 16 different Aedes species. The only species other than Aedes genus for which ZIKV was isolated were Anopheles coustani, Anopheles gambiae, Culex perfuscus, and Mansonia uniformis. Vector competence assays were performed on 22 different mosquito species, including 13 Aedes, 7 Culex, and 2 Anopheles species with, as a result, the discovery that A. aegypti and Aedes albopictus were competent for ZIKV, as well as some other Aedes species, and that there was a controversy surrounding Culex quinquefasciatus competence. Although Culex, Anopheles, and most of Aedes species were generally observed to be refractory to ZIKV infection, other potential vectors transmitting ZIKV should be explored. PMID:29145400

Taxonomic study and redescription of Culex (Melanoconion theobaldi (Lutz, 1904 (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Oswaldo Paulo Forattini

1989-01-01

Full Text Available Based on type examination, Culex (Melanoconion theobaldi (Lutz, 1904 is redescribed. The species Cx. (Mel. chrysonotum Dyar & Knab, 1908, was put back as synonym of theobaldi. Besides, examination of Cx. (Mel. chrysothorax (Newstead & Thomas, 1910 type, leads to retiring as synonym of theobaldi and considered it as "species inquirenda".

Effects of an aqueous extract of Azadirachta indica on the groCulex ...

African Journals Online (AJOL)

The neem tree Azadirachta indica Juss (Meliaceae) is one of the most studied plant species for pest control, including mosquitoes. However, the effect of aqueous neem seed extracts (ANSE) on each of the 4 instars of mosquito Culex quinquefasciatus Say (Diptera: Culicidae) is unknown. In order to determine the effect of ...

Efficacy of agnique (mmf) monomolecular surface film against immature stages of Anopheles arabiensis patton and Culex spp (diptera: culicidae) in Khartoum, Sudan.

Science.gov (United States)

Bashir, Al; Hassan, A Abu; Salmah, M R Che; Rahman, W A

2008-03-01

The efficacy of the larvicidal and pupicidal agent (Agnique) MMF was evaluated against larvae of An. arabiensis and Culex (Diptera: Culicidae) under field conditions in Bahary Locality, Khartoum, Sudan. At an applied dosage of 0.25 ml/m2, MMF resulted in 89.4, 79.8 and 88.2% reductions in L3-L4 instars An. arabiensis and 63.5% in Culex larvae (all stages) 24 to 72 hours post-treatment. Pupae were completely eliminated (100%) within 24 hours posttreatment. The earlier instars (L1-L2) of An. arabiensis were more tolerant with a 62.5% reduction at 72 hours post-treatment compared to (L3-L4) instars and pupae. At 7-days post-treatment Agnique gave a 57.5% reduction in L1-L2 and 92.6% in L3-L4 instar larvae of An. arabiensis and 57.3% and 86.4% in Culex larvae and pupae, respectively. We conclude that Agnique can perform effectively against L3-L4 instars and pupae of An. arabiensis for only 1 week, and 3 to 4 days against L1-L2 instars of Culex spp.

Role of G-protein-coupled receptor-related genes in insecticide resistance of the mosquito, Culex quinquefasciatus.

Science.gov (United States)

Li, Ting; Liu, Lena; Zhang, Lee; Liu, Nannan

2014-09-29

G-protein-coupled receptors regulate signal transduction pathways and play diverse and pivotal roles in the physiology of insects, however, the precise function of GPCRs in insecticide resistance remains unclear. Using quantitative RT-PCR and functional genomic methods, we, for the first time, explored the function of GPCRs and GPCR-related genes in insecticide resistance of mosquitoes, Culex quinquefasciatus. A comparison of the expression of 115 GPCR-related genes at a whole genome level between resistant and susceptible Culex mosquitoes identified one and three GPCR-related genes that were up-regulated in highly resistant Culex mosquito strains, HAmCq(G8) and MAmCq(G6), respectively. To characterize the function of these up-regulated GPCR-related genes in resistance, the up-regulated GPCR-related genes were knockdown in HAmCq(G8) and MAmCq(G6) using RNAi technique. Knockdown of these four GPCR-related genes not only decreased resistance of the mosquitoes to permethrin but also repressed the expression of four insecticide resistance-related P450 genes, suggesting the role of GPCR-related genes in resistance is involved in the regulation of resistance P450 gene expression. This results help in understanding of molecular regulation of resistance development in Cx. quinquefasciatus.

Capacity of the terrestrial entomopathogenic nematode Steinernema rarum (Rhabditida: Steinernematidae to parasite Culex apicinus larvae (Diptera: Culicidae Capacidad del nemátodo terrestre entomopatógeno Steinernema rarum (Rhabditida: Steinernematidae de parasitar larvas de Culex apicinus (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Susana R. Cagnolo

2010-06-01

Full Text Available Entomopathogenic nematodes can be considered effective agents for biocontrol, resulting innocuous for humans. Larvaeof Culex apicinus Philippi were exposed to infective juveniles of Steinernema rarum (OLI strain under laboratory conditions, testing six doses (1:1, 5:1, 10:1, 15:1, 100:1, 400:1. An increasing percentage of mosquito larvae mortality was recorded with an increased dose. The highest percentage of mosquito larvae mortality (75% was obtained with the dose 400:1. This is the first report of parasitism of an isolated of S. rarum from Córdoba against larvae of C. apicinus, with promising results. Therefore, further studies must be carried out to determine if these nematodes would be effective as autochthonous agents for the control of Culex Linnaeus and other mosquitoes of sanitary interest in the country.Los nemátodos entomopatógenos son considerados eficientes agentes de control de insectos plaga e inocuos para los humanos. Larvas de Culex apicinus Philippi fueron expuestas a seis dosis (1:1, 5:1, 10:1, 15:1, 100:1, 400:1 de juveniles infectivos de Steinernema rarum (aislado OLI. Se registró un incremento en la mortalidad de las larvas del mosquito con el aumento de la dosis del nematodo. El mayor porcentaje de mortalidad de larvas del mosquito (75% se obtuvo con la dosis 400:1. Este es el primer reporte de parasitismo de un aislado de S. rarum de Córdoba, en larvas de C. apicinus con resultados promisorios. Por lo tanto, se debería profundizar su estudio para determinar si pueden resultar efectivos como agentes autóctonos para el control biológico de mosquitos Culex Linnaeus, y otros de interés sanitario en el país.

Relationships between infection, dissemination, and transmission of West Nile virus RNA in Culex pipiens quinquefasciatus (Diptera: Culicidae).

Science.gov (United States)

Richards, Stephanie L; Anderson, Sheri L; Lord, Cynthia C; Smartt, Chelsea T; Tabachnick, Walter J

2012-01-01

Culex pipiens quinquefasciatus Say fed blood containing 6.8 +/- 0.3 logs (mean +/- SE) plaque-forming units of West Nile virus (WNV)/ml were maintained at 28 degrees C for incubation periods (IP) of 7, 14, or 21 d. Several attributes of vector competence were determined at each IP using quantitative real-time reverse transcriptase polymerase chain reaction to estimate plaque forming unit equivalents including: infection rate (WNV-positive abdomens), dissemination rate (WNV-positive legs or thoraces), combined dissemination rate (WNV-positive legs and thoraces), transmission rate (WNV-positive saliva), and WNV titers in abdomens, legs, thoraces, and saliva. Each rate increased or was equivalent with increasing IP. Mosquitoes transmitting WNV in saliva also had significantly higher IP-dependent WNV titers in abdomens, legs, and thoraces. Titers of WNV in abdomens were significantly correlated with titers in legs and thoraces, but the degree of association changed with IP. However, titers of abdomens, legs, and thoraces were not correlated with WNV presence or titer in the saliva. The results show that WNV presence or titer in the saliva of infected Cx. p. quinquefasciatus was not directly influenced by processes involved in WNV replication in other tissues. The processes controlling midgut infection and escape are, in part, independent from the infection processes in other tissues. The relationship between infection, dissemination, and transmission varied over time. The infection and replication of WNV in different tissues is likely influenced by different barriers encountered during the extrinsic incubation period. The significance of these observations for understanding vector competence is discussed.

Controlling Aedes albopictus and Culex pipiens pallens using silver nanoparticles synthesized from aqueous extract of Cassia fistula fruit pulp and its mode of action.

Science.gov (United States)

Fouad, Hatem; Hongjie, Li; Hosni, Dawood; Wei, Jiqian; Abbas, Ghulam; Ga'al, Hassan; Jianchu, Mo

2018-05-01

Mosquitoes act as key vector for transmission of devastating parasites and pathogens which affect millions of people globally. In this research, the green synthesis of silver nanoparticles of Cassia fistula fruit pulp as an innovative and operative tool against vector mosquitoes is presented. Silver nanoparticles were characterized by a series of techniques including Fourier transform infrared spectroscopy, Transmission Electron Microscope and confirmed by Scanning Electron Microscope, UV-Vis spectrophotometry and X-ray diffraction. Silver nanoparticles were highly effective against the larvae (I-IV instar) and pupae of Aedes albopictus and Culex pipiens pallens after 24, 48 and 72 h of treatment. Ae. albopictus had LC50 values ranging from 8.3 mg/L (I instar) to 17.3 mg/L (pupae) and LC50 ranging from 1.1 mg/L (I instar) to 19.0 mg/L (pupae) against Cx. pipiens pallens. The systemic effect of AgNPs was further assessed in the fourth instar larvae of Ae. albopictus and Cx. pipiens pallens by measuring the levels of total proteins and activity of two important marker enzymes: Acetylcholinesterase and α- and β-carboxylesterase. Overall, the findings of the study suggest that the use of Cassia fistula-fruit pulp extract mediated synthesis of silver nanoparticles can be used for controlling vector mosquitoes. This is the first report on the mosquito larvicidal and pupicidal activity of AgNPs synthesized by Cassia fistula fruit pulp and its possible mechanism of action.

A MIDGUT DIGESTIVE PHOSPHOLIPASE A2 IN LARVAL MOSQUITOES, AEDES ALBOPICTUS AND CULEX QUINQUEFASCIATUS

Science.gov (United States)

Phospholipase A2 (PLA2) is a secretory digestive enzyme that hydrolyzes ester bond at sn-2 position of dietary phospholipids, creating free fatty acid and lysophopholipid. The free fatty acids (arachidonic acid) are absorbed into midgut cells. Aedes albopictus and Culex quinquefasciatus digestive PL...

Control of pyrethroid-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes with chlorfenapyr in Benin

NARCIS (Netherlands)

N'Guessan, R.; Boko, P.; Odjo, A.; Knols, B.G.J.; Akogbeto, M.; Rowland, M.

2009-01-01

Objective To compare the efficacy of chlorfenapyr applied on mosquito nets and as an indoor residual spray against populations of Anopheles gambiae and Culex quinquefasciatus in an area of Benin that shows problematic levels of pyrethroid resistance. Method Eight-week trial conducted in experimental

PENGARUH VARIASI DOSIS LARUTAN BUAH BELIMBING WULUH (Averrhoa bilimbi L.TERHADAP MORTALITAS LARVA NYAMUK Culex sp. SEBAGAI SUMBER BELAJAR BIOLOGI PADA MATERI INSEKTA

Directory of Open Access Journals (Sweden)

Bagas Rasid Sidik

2015-11-01

Full Text Available Control of larvae of Culex sp. can be done with larvicides. Larvicides used in an attempt to reduce the population of larvae in a breeding place or for termination of the chain of mosquito breeding. Insect repellent effective to kill mosquitoes, but that has not been come mosquito larvae will develop into mosquitoes. Insect repellent made from synthetic chemicals if used excessively will cause adverse effects to humans such as respiratory disorders, digestive, and the environment. The purpose of this study was to determine (1 Whether or not the effect of giving a solution of fruit starfruit (Averrhoa bilimbi, L. against Culex sp. mosquito larvae mortality, (2 determine the most appropriate dosage on mortality of larvae of mosquito Culex sp., (3 Compile the results of the research as a high school biology class X LKPS semester two. This study uses the method of experiment, the draft design used was completely randomized design Variety (CRD with the control (P0 and 4 treatments, namely P1: a dose of1/99 ml, P2: dose2/98 ml, P3: dose3/97 ml, and P4: a dose4/96 ml with 6 replicates each, the number of larvae 150 animals. Larva l sampling and testing conducted at Flores Street No. 19 Ganjar Supreme 14/2 City Metro. The test was analyzed using one-way Anava non-parametric Kruskall-Wallis test. The results of the analysis are obtained as follows: (1 There is a very significant influence on the administration of a solution of fruit starfruit (Averrhoa bilimbi, L. against Culex mosquito larvae mortality due to the α sp 0.05,   at α 0.01 in Chi-square table, (2 the mortality of larvae of Culex for 24 consecutive hour sare from lowest to highest mortality percentage is P0=0%, P1=60%, P2=83.33%, 83.33% =P3, andP4=86,66%. Based on the results of research and discussion we concluded that: (1 There is the effect of star fruit solution on mortality of larvae of Culex sp mosquitoes, with coefficientH=17.73>Chi-square value of7.81at α level of 0.05, 11, 3

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

Genetic diversity based on 28S rDNA sequences among populations of Culex quinquefasciatus collected at different locations in Tamil Nadu, India.

Science.gov (United States)

Sakthivelkumar, S; Ramaraj, P; Veeramani, V; Janarthanan, S

2015-09-01

The basis of the present study was to distinguish the existence of any genetic variability among populations of Culex quinquefasciatus which would be a valuable tool in the management of mosquito control programmes. In the present study, population of Cx. quinquefasciatus collected at different locations in Tamil Nadu were analyzed for their genetic variation based on 28S rDNA D2 region nucleotide sequences. A high degree of genetic polymorphism was detected in the sequences of D2 region of 28S rDNA on the predicted secondary structures in spite of high nucleotide sequence similarity. The findings based on secondary structure using rDNA sequences suggested the existence of a complex genotypic diversity of Cx. quinquefasciatus population collected at different locations of Tamil Nadu, India. This complexity in genetic diversity in a single mosquito population collected at different locations is considered an important issue towards their influence and nature of vector potential of these mosquitoes.

Repellent activity of herbal essential oils against Aedes aegypti (Linn. and Culex quinquefasciatus (Say.

Directory of Open Access Journals (Sweden)

Duangkamon Sritabutra

2013-08-01

Full Text Available Objective: To determine the mosquito repellent activity of herbal essential oils against female Aedes aegypti and Culex quinquefasciatus. Methods: On a volunteer’s forearm, 0.1 mL of each essential oil was applied to 3 cm伊10 cm of exposed skin. The protection time was recorded for 3 min after every 30 min. Results: Essential oil from clove oil in olive oil and in coconut oil gave the longest lasting period of 76.50 min and 96.00 min respectively against Aedes aegypti. The citronella grass oil in olive oil, citronella grass oil in coconut oil and lemongrass oil in coconut oil exhibited protection against Culex quinquefasciatus at 165.00, 105.00, and 112.50 min respectively. Conclusions: The results clearly indicated that clove, citronella and lemongrass oil were the most promising for repellency against mosquito species. These oils could be used to develop a new formulation to control mosquitoes.

Is the expression of autogeny by Culex molestus Forskal (Diptera: Culicidae) influenced by larval nutrition or by adult mating, sugar feeding, or blood feeding?

Science.gov (United States)

Kassim, Nur Faeza A; Webb, Cameron E; Russell, Richard C

2012-06-01

Culex molestus Forskal is suspected to have been introduced into southern Australia during the 1940s. Investigations to determine factors influencing the expression of autogeny, the response of this mosquito to potential blood meals, and the subsequent influence on oviposition were undertaken. Immature mosquitoes raised at five feeding regimes had mortality rates, development rates, wing length, and autogenous egg raft size measured. All surviving female mosquitoes laid autogenous eggs but there was a significant difference between the mean number of eggs per raft. For mosquitoes raised at each of the feeding regimes, there was a significant linear relationship between the number of eggs per autogenous egg raft and wing length. Newly emerged mosquitoes were offered a blood meal (i.e., rodent) daily but no blood feeding occurred until the autogenous egg raft was laid. There was no statistical difference in the rate of autogenous oviposition or post-oviposition blood feeding between control or treatment groups. The results of this study indicate that Cx. molestus is perfectly adapted to subterranean habitats in close association with human habitation, but their preference to delay blood feeding until up to day 8 following emergence may reduce their relative importance as a vector of arboviruses. © 2012 The Society for Vector Ecology.

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...

Experimental transmission of Zika virus by mosquitoes from central Europe.

Science.gov (United States)

Heitmann, Anna; Jansen, Stephanie; Lühken, Renke; Leggewie, Mayke; Badusche, Marlis; Pluskota, Björn; Becker, Norbert; Vapalahti, Olli; Schmidt-Chanasit, Jonas; Tannich, Egbert

2017-01-12

Mosquitoes collected in Germany in 2016, including Culex pipiens pipiens biotype pipiens, Culex torrentium and Aedes albopictus, as well as Culex pipiens pipiens biotype molestus (in colony since 2011) were experimentally infected with Zika virus (ZIKV) at 18 °C or 27 °C. None of the Culex taxa showed vector competence for ZIKV. In contrast, Aedes albopictus were susceptible for ZIKV but only at 27 °C, with transmission rates similar to an Aedes aegypti laboratory colony tested in parallel. This article is copyright of The Authors, 2017.

Repellency and toxicity of aromatic plant extracts against the mosquito Culex pipiens molestus (Diptera: Culicidae).

Science.gov (United States)

Traboulsi, Abdallah F; El-Haj, Samih; Tueni, Marie; Taoubi, Khalil; Nader, Natalie Abi; Mrad, Abir

2005-06-01

The insecticidal activities of essential oil extracts from leaves, flowers and roots of aromatic plants against fourth-instar larvae of the mosquito Culex pipiens molestus Forskal were determined. Extracts of Foeniculum vulgare Mill were the most toxic, followed by those of Ferula hermonis Boiss, Citrus sinensis Osbeck, Pinus pinea L, Laurus nobilis L and Eucalyptus spp with LC50 values of 24.5, 44.0, 60.0, 75.0, 117.0 and 120.0 mg litre(-1), respectively. Combination tests between the LC50 and the maximum sub-lethal concentration (MSLC) were determined. Over 20 major components were identified in extracts from each plant species tested. Five essential oils and nine pure components were studied for their repellency against mosquito bites. Terpineol and 1,8-cineole were the most effective against Culex pipiens molestus bites offering complete protection for 1.6 and 2 h, respectively.

Insecticide resistance and cytochrome-P450 activation in unfed and blood-fed laboratory and field populations of Culex pipiens pallens.

Science.gov (United States)

Chang, Kyu-Sik; Kim, Heung-Chul; Klein, Terry A; Ju, Young Ran

2017-01-01

Understanding the mechanisms of insecticide resistance to vector mosquitoes is critical for the implementation of effective control measures. A nulliparous susceptible Culex pipiens pallens (KSCP) laboratory colony and two field strains from Paju (PAJ) and Jeonju (JEO) Korea were evaluated for susceptibility to five pesticides by microapplication techniques. Unfed PAJ and JEO females demonstrated increased resistance compared to unfed KSCP females, respectively. While blood-fed KSCP females demonstrated resistance compared to unfed PAJ and JEO females, respectively. Unfed and blood-fed groups were assayed for α- and β-esterase, glutathione S -transferases, and cytochrome P-450 (P450) enzyme activity assays. P450 activity was 58.8- and 72.8-fold higher for unfed PAJ and JEO females, respectively, than unfed KSCP females. P450 enzyme activity of KSCP females assayed 1 and 7 days after a blood meal increased by 14.5- and 11.8-fold, respectively, compared to unfed KSCP females, while PAJ and JEO females demonstrated 164.9- and 148.5- and 170.7- and 160.4-fold increased activity, respectively, compared to unfed females of each population. However, other three resistance-related metabolic enzymes showed low activation at P450 acts on elevated insecticide resistance after blood meals in resistant field populations. Our findings might reveal that suppressing of the P450 protein by artificial gene mutation increases insecticidal susceptibility of Cx . pipiens and will promise effective vector mosquito control.

[Twenty-year surveillance of insects relevant to public health during the construction of hydroelectric facilities in Antioquia, Colombia].

Science.gov (United States)

Zuluaga, Walter Alonso; López, Yolanda Lucía; Osorio, Lisardo; Salazar, Luis Fernando; González, Marta Claudia; Ríos, Claudia María; Wolff, Marta Isabel; Escobar, José Pablo

2012-09-01

Entomological studies conducted in large hydroelectric infrastructure projects are a tool for the prevention and control of vector-borne diseases. These diseases emerge as a consequence of changes made to the terrain that often increase the natural and artificial mosquito larval habitats. Many of these insects are of public health importance and population increases result in an increased risk of disease transmission. The culicine (mosquito) and phlebotomine (sand fly) populations were characterized in the area of the Porce II and Porce III hydroelectric projects of Antioquia between 1990 to 2009. Periodical entomological samplings were made in the area of impact, in the workers camps, and construction sites. Adult specimens were captured with nets, Shannon light traps, CDC light traps, and protected human bait. Mosquito larvae of the following species were identified: Culex coronator, Culex nigripalpus, Culex corniger, Culex quinquefasciatus and Limatus durhami. The most frequently identifiers of larval habitats were low tanks, waste cans, tires, and aquatic plants. Aedes aegypti specimens were captured in only two rural locations from two municipalities within the area of influence. Specimens from the following mosquito genera were captured in forest areas: Aedes, Mansonia, Culex, Psorophora, Wyeomyia, Phonyomyia, Uranotaenia, Haemagogus and Sabethes. The most important mosquito found was Haemogogus janthinomis, an efficient yellow fever vector in Colombia. The area has been endemic for leishmaniasis and in the current study, 20 species of Lutzomyia sand flies, potential vectors, were identified. Among malaria vectors, the most important species found in the area were Anopheles nuneztovari and Anopheles pseudopunctipennis. A wide variety of vectors were discovered in the area of the Porce II and Porce III hydroelectric projects, and many of these were relevant for public health. Further monitoring will be necessary to minimize disease transmission risks among the

Immature Aedes mosquitoes colonize Culex quinquefasciatus breeding sites in neighborhoods in the municipality of Olinda, State of Pernambuco

Directory of Open Access Journals (Sweden)

Suzane Alves dos Santos

2014-12-01

Full Text Available Introduction The present study shows the colonization of Aedes mosquitoes in breeding sites specific for Culex quinquefasciatus in neighborhoods in the municipality of Olinda. Methods Samples were collected between May 2011 and June 2012 from breeding sites positive for Cx. quinquefasciatus by using a ladle and manual suction pump. Results Aedes aegypti (0.12%, Aedes albopictus (0.03%, and Cx. quinquefasciatus (99.8% were found across the breeding sites. Conclusions The presence of Aedes ssp. in several Cx. quinquefasciatus breeding sites with a heavy load of organic material demonstrates the need to review the concepts and methods used for treatment, as the use of specific larvicide for breeding sites of Culex.

Molecular Characterization of the Kamese Virus, an Unassigned Rhabdovirus, Isolated from Culex pruina in the Central African Republic.

Science.gov (United States)

Simo Tchetgna, Huguette Dorine; Nakoune, Emmanuel; Selekon, Benjamin; Gessain, Antoine; Manuguerra, Jean-Claude; Kazanji, Mirdad; Berthet, Nicolas

2017-06-01

Rhabdoviridae is one of the most diversified families of RNA viruses whose members infect a wide range of plants, animals, and arthropods. The members of this family are classified into 13 genera and >150 unassigned viruses. Here, we sequenced the complete genome of a rhabdovirus belonging to the Hart Park serogroup, the Kamese virus (KAMV), isolated in 1977 from Culex pruina in the Central African Republic. The genomic sequence showed an organization typical of rhabdoviruses with additional genes in the P-M and G-L intergenic regions, as already reported for the Hart Park serogroup. Our Kamese strain (ArB9074) had 98% and 78.8% nucleotide sequence similarity with the prototypes of the KAMV and Mossuril virus isolated in Uganda and Mozambique in two different Culex species, respectively. Moreover, the protein sequences had 98-100% amino acid similarity with the prototype of the KAMV, except for an additional gene (U3) that showed a divergence of 6%. These molecular data show that our strain of the KAMV is genetically close to the Culex annuliorus strain that was circulating in Uganda in 1967. However, this study suggests the need to improve our knowledge of the KAMV to better understand its behavior, its life cycle, and its potential reservoirs.

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.

Adulticidal activity of Pithecellobium dulce (Roxb.) Benth. against Culex quinquefasciatus (Say)

OpenAIRE

Govindarajan M; Sivakumar R; Rajeswary M; Yogalakshmi K

2012-01-01

Objective: To determine the adulticidal efficacy of different solvent leaf and seed extracts of Pithecellobium dulce (P. dulce) against Culex quinquefasciatus (Cx. quinquefasciatus). Methods: Sucrose-fed and blood starved mosquitoes were released into the tube, and the mortality effects of the extracts were observed every 10 min for 3 h exposure period. At the end of 1, 2, and 3 h exposure periods, the mosquitoes were placed in the holding tube. Cotton pads soaked in 10% sugar ...

Do vegetated rooftops attract more mosquitoes? Monitoring disease vector abundance on urban green roofs.

Science.gov (United States)

Wong, Gwendolyn K L; Jim, C Y

2016-12-15

Green roof, an increasingly common constituent of urban green infrastructure, can provide multiple ecosystem services and mitigate climate-change and urban-heat-island challenges. Its adoption has been beset by a longstanding preconception of attracting urban pests like mosquitoes. As more cities may become vulnerable to emerging and re-emerging mosquito-borne infectious diseases, the knowledge gap needs to be filled. This study gauges the habitat preference of vector mosquitoes for extensive green roofs vis-à-vis positive and negative control sites in an urban setting. Seven sites in a university campus were selected to represent three experimental treatments: green roofs (GR), ground-level blue-green spaces as positive controls (PC), and bare roofs as negative controls (NC). Mosquito-trapping devices were deployed for a year from March 2015 to 2016. Human-biting mosquito species known to transmit infectious diseases in the region were identified and recorded as target species. Generalized linear models evaluated the effects of site type, season, and weather on vector-mosquito abundance. Our model revealed site type as a significant predictor of vector mosquito abundance, with considerably more vector mosquitoes captured in PC than in GR and NC. Vector abundance was higher in NC than in GR, attributed to the occasional presence of water pools in depressions of roofing membrane after rainfall. Our data also demonstrated seasonal differences in abundance. Weather variables were evaluated to assess human-vector contact risks under different weather conditions. Culex quinquefasciatus, a competent vector of diseases including lymphatic filariasis and West Nile fever, could be the most adaptable species. Our analysis demonstrates that green roofs are not particularly preferred by local vector mosquitoes compared to bare roofs and other urban spaces in a humid subtropical setting. The findings call for a better understanding of vector ecology in diverse urban landscapes

Entomologic studies after a St. Louis encephalitis epidemic in Grand Junction, Colorado.

Science.gov (United States)

Tasi, T F; Smith, G C; Ndukwu, M; Jakob, W L; Happ, C M; Kirk, L J; Francy, D B; Lampert, K J

1988-08-01

In 1986, after a St. Louis encephalitis epidemic in Grand Junction, Colorado, in 1985, vector mosquitoes in the city were surveyed to correlate their bionomics and infection rates with the occurrence of human disease. No human cases were reported, but mosquito surveillance disclosed St. Louis encephalitis virus in Culex tarsalis and Culex pipiens pipiens. Mosquitoes were collected with gravid traps designed to attract Cx. p. pipiens and with Centers for Disease Control light traps. Culex p. pipiens was the predominant vector mosquito collected and was captured chiefly in gravid traps. The Culex tarsalis population emerged and expanded approximately one month earlier than did the Cx. p. pipiens population. Consequently, Cx. p. pipiens was the predominant vector species after August. Infection rates throughout the surveillance period (June to September) were severalfold higher in Cx. tarsalis than in Cx. p. pipiens; however, in late summer, diminished numbers of Cx. tarsalis and a persistent population of Cx. p. pipiens resulted in relatively larger numbers of infected Cx. p. pipiens. Thus, the participation of Cx. p. pipiens as a St. Louis encephalitis vector would have been underestimated in previous studies employing light traps alone. These studies provide further evidence that Cx. p. pipiens-associated urban St. Louis encephalitis and rural Cx. tarsalis-associated St. Louis encephalitis cycles may coexist in the West.

Rift Valley fever virus epidemic in Kenya, 2006/2007: the entomologic investigations.

Science.gov (United States)

Sang, Rosemary; Kioko, Elizabeth; Lutomiah, Joel; Warigia, Marion; Ochieng, Caroline; O'Guinn, Monica; Lee, John S; Koka, Hellen; Godsey, Marvin; Hoel, David; Hanafi, Hanafi; Miller, Barry; Schnabel, David; Breiman, Robert F; Richardson, Jason

2010-08-01

In December 2006, Rift Valley fever (RVF) was diagnosed in humans in Garissa Hospital, Kenya and an outbreak reported affecting 11 districts. Entomologic surveillance was performed in four districts to determine the epidemic/epizootic vectors of RVF virus (RVFV). Approximately 297,000 mosquitoes were collected, 164,626 identified to species, 72,058 sorted into 3,003 pools and tested for RVFV by reverse transcription-polymerase chain reaction. Seventy-seven pools representing 10 species tested positive for RVFV, including Aedes mcintoshi/circumluteolus (26 pools), Aedes ochraceus (23 pools), Mansonia uniformis (15 pools); Culex poicilipes, Culex bitaeniorhynchus (3 pools each); Anopheles squamosus, Mansonia africana (2 pools each); Culex quinquefasciatus, Culex univittatus, Aedes pembaensis (1 pool each). Positive Ae. pembaensis, Cx. univittatus, and Cx. bitaeniorhynchus was a first time observation. Species composition, densities, and infection varied among districts supporting hypothesis that different mosquito species serve as epizootic/epidemic vectors of RVFV in diverse ecologies, creating a complex epidemiologic pattern in East Africa.

Laboratory evaluation of ethyl acetate and chloroform: methanol (1:1 v/v extract of Swietenia mahagoni leaf against Japanese Encephalitis vector Culex vishuni group

Directory of Open Access Journals (Sweden)

Utpal Adhikari

2012-12-01

Full Text Available Objective: To study the larvicidal activity of a furniture tree Swietenia mahagoni L. (S. mahagoni against mosquito Culex Vishnui group. Methods: Different concentrations of crude, chloroform: methanol (1:1 v/v and ethyl acetate solvent extracts of S. mahagoni mature leaves were treated against Cx. vishnui group larvae. Results: Five graded concentrations (0.05%, 0.10%, 0.20%, 0.30% and 0.40% of crude extract of mature leaves and five graded concentrations (10 ppm, 20 ppm, 30 ppm, 40 ppm and 50 ppm of chloroform: methanol (1:1 v/v and ethyl acetate solvent extracts showed significant (P<0.05 larval mortalities. LC50, LC90 values were calculated at 24 h, 48 h and 72 h of exposures. Adult Cx. vishnui group mosquitoes exposed to burning coils prepared from S. mahagoni mature leaves showed smoke repellency and toxicity up to 4 h. Conclusions: This study was a pioneer attempt to establish S. mahagoni as an effective mosquito larvicide.

DAYA LARVASIDA EKSTRAK BIJI SRIKAYA (ANNONA SQUAMOSA DENGAN RENTANG WAKTU PENYIMPANAN YANG BERBEDA TERHADAP LARVA CULEX QUINQUEFASCIATUS

Directory of Open Access Journals (Sweden)

Wisnu Satria A.K.

2013-03-01

Full Text Available Abstract. Synthetic insecticide have been used to control Culex quinquefasciatus, but the prolonged usage of synthetic insecticide has a bad impact on the environment and may caused resistance. Sugar apple’s (Annona squamosa seeds which contain alkaloid can be used as an alternative insecticide that was safe for environment. This research aims is to know the effect of sugar apple’s seeds with different length of storage as C. quinquefasciatus larvacide. This research was an experimental study with a randomized controlled trial group design approach. The test material was an extract of sugar apple’s seeds which have been kept for 0, 1, 2, and 3 week with LC50 (0,47 ppm was used. Each treatment used 25 C. quinquefasciatus larvae from third instar larvae stage and replicated five times. After exposed for 24 hours, dead larvae counted. The result confirmed that the extract of sugar apple’s seeds which has been stored in 0, 1, 2, and 3 week did not showed any significant different on larvae mortality. Extract of sugar apple’s seeds which have been stored in 0, 1, 2, and 3 week have an equal activity as Culex quinquefasciatus larvicide. Key Word: Sugar apple (Annona squamosa, seeds, larvicide, Culex quinquefasciatus, length of storage Abstrak. Insektisida sintetik telah banyak digunakan untuk mengontrol Culex quinquefasciatus, tetapi penggunaan insektisida sintetik terus-menerus berdampak buruk terhadap lingkungan dan mengakibatkan resistensi. Fakta ini menjadi alasan biji srikaya (Annona squamosa yang mengandung alkaloid digunakan sebagai insektisida alternatif yang aman bagi lingkungan. Penelitian ini bertujuan untuk mengetahui pengaruh biji srikaya dengan perbedaan lama penyimpanan terhadap larva C. quinquefasciatus. Penelitian ini merupakan penelitian eksperimental dengan desain rancangan acak kelompok. Bahan uji adalah ekstrak biji srikaya yang telah disimpan selama 0, 1, 2, dan 3 minggu. Sampel penelitian ini adalah larva instar ketiga

Feeding patterns of potential West Nile virus vectors in south-west Spain.

Directory of Open Access Journals (Sweden)

Joaquín Muñoz

Full Text Available Mosquito feeding behaviour determines the degree of vector-host contact and may have a serious impact on the risk of West Nile virus (WNV epidemics. Feeding behaviour also interacts with other biotic and abiotic factors that affect virus amplification and transmission.We identified the origin of blood meals in five mosquito species from three different wetlands in SW Spain. All mosquito species analysed fed with different frequencies on birds, mammals and reptiles. Both 'mosquito species' and 'locality' explained a similar amount of variance in the occurrence of avian blood meals. However, 'season of year' was the main factor explaining the presence of human blood meals. The differences in diet resulted in a marked spatial heterogeneity in the estimated WNV transmission risk. Culex perexiguus, Cx. modestus and Cx. pipiens were the main mosquito species involved in WNV enzootic circulation since they feed mainly on birds, were abundant in a number of localities and had high vector competence. Cx. perexiguus may also be important for WNV transmission to horses, as are Cx. pipiens and Cx. theileri in transmission to humans. Estimates of the WNV transmission risk based on mosquito diet, abundance and vector competence matched the results of previous WNV monitoring programs in the area. Our sensitivity analyses suggested that mosquito diet, followed by mosquito abundance and vector competence, are all relevant factors in understanding virus amplification and transmission risk in the studied wild ecosystems. At some of the studied localities, the risk of enzootic circulation of WNV was relatively high, even if the risk of transmission to humans and horses was less.Our results describe for first time the role of five WNV candidate vectors in SW Spain. Interspecific and local differences in mosquito diet composition has an important effect on the potential transmission risk of WNV to birds, horses and humans.

Structural characterization of acetylcholinesterase 1 from the sand fly Lutzomyia longipalpis (Diptera: Psychodidae).

Science.gov (United States)

Coutinho-Abreu, I V; Balbino, V Q; Valenzuela, J G; Sonoda, I V; Ramalho-Ortigão, J M

2007-07-01

Acetylcholinesterase (AChE) plays a key role in cholinergic impulse transmission, and it is the target enzyme for organophosphorus and carbamate insecticides. Two genes, AceI and AceII, have been characterized from different insect species, and point mutations in either gene can lead to significant resistance to these classes of insecticides. In this report, we describe the partial characterization of the AceI gene from Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae), and we show that the possibility exists for the development of a resistant phenotype to organophosphates and carbamates in sand flies. Our results point to the presence of a single AceI gene in L. longipalpis (LlAce1) and that AChE activity is inhibited by organophosphorus at a concentration of 5 x 10(-5) M. Regarding insecticide resistance, analysis of the truncated LlAce1 cDNA suggests that a single missense mutation leading to a glycine-to-serine substitution at amino acid position 119 (G119S) may arise in L. longipalpis, similar to what has been detected in Anopheles gambiae s.s. Another missense mutation involved in resistant phenotypes, F331W, detected in Culex tritaeniorhynchus Giles, is less likely to occur in L. longipalpis, because it faces codon constraint in this sand fly species. Comparison of the three-dimensional structures of the deduced amino acid sequence of the truncated LLAChE1 with that of An. gambiae and Cx. tritaeniorhynchus also suggests that similar structural modifications due to the missense amino acid changes in the active site gorge are detected in all three insects.

Feeding Behavior and Spatial Distribution of Culex Mosquitoes (Diptera: Culicidae) in Wetland Areas of the Czech Republic

Czech Academy of Sciences Publication Activity Database

Rádrová, J.; Šeblová, V.; Votýpka, Jan

2013-01-01

Roč. 50, č. 5 (2013), s. 1097-1104 ISSN 0022-2585 Institutional support: RVO:60077344 Keywords : Culex * spatial distribution * WNV * Rabensburg virus * feeding preference Subject RIV: EG - Zoology Impact factor: 1.815, year: 2013

Field evaluation of the biolarvicide, spinosad 20 per cent emulsifiable concentrate in comparison to its 12 per cent suspension concentrate formulation against Culex quinquefasciatus, the vector of bancroftian filariasis in India.

Science.gov (United States)

Sadanandane, Candasamy; Gunasekaran, Kasinathan; Boopathi Doss, Ponnusamy Sivagnana; Jambulingam, Purushothaman

2018-01-01

Biolarvicides may offer alternatives to chemical larvicides as these are known to be safe to environment and selective against the target species. However, only a limited number of biolarvicides have been approved for mosquito larval control. In the current study, a new formulation of spinosad, 20 per cent emulsifiable concentrate (EC) was tested for its efficacy against Culex quinquefasciatus, in comparison to its 12 per cent suspension concentrate (SC). Spinosad 20 per cent EC was tested against Cx. quinquefasciatus immature at 25, 50, 100 and 150 mg active ingredient (ai)/m [2] in cesspits, drains and abandoned wells in comparison with spinosad 12 per cent SC at the optimum field application dosage of 50 mg ai/m [2] . The 20 per cent EC caused 90-100 per cent reduction of pupal density for 7-14 days in cesspits, 10-17 days in drains and 14-30 days in abandoned wells at all dosages tested. At lower dosages of 25 and 50 mg ai/m [2] , >90 per cent reduction of pupal density was observed for one week in cesspits and street drains and for two weeks in abandoned wells. The effective duration of control provided by the higher dosages, 100 and 150 mg ai/m [2] was 1.4 to 2 times greater than the lower dosages, 25 and 50 mg ai/m [2] . The findings showed that the spinosad 20 per cent EC can be used for larval control against Cx. quinquefasciatus, at the dosage of 25 mg ai/m [2] at weekly interval in cesspits and drains and at fortnightly interval in abandoned wells. Spinosad 20 per cent EC could be one of the options to be considered for larval control under integrated vector management.

Pengaruh ukuran tubuh ikan Poecilia reticulata pada daya pemangsaannya terhadap larva Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

Noer Moehammadi

1999-06-01

Full Text Available The research aimed to know the influence of poecilia reticulata body size, in the feeding capacity on Culex quinquifasciatus larvae. The research was experimental method with Complete Random Design., each treatment with 5 replications. The taken body size of Poecilia reticulata were; 1,50 cm; 2.50 cm; and 3.50 cm. the size of fish €™s body was measured from the tip of snout up to the end of fin (cm. The feeding capacity was determined by subtracting the first amount of larvae which was given the rest of larvae after 24 hours. The result showed that the difference of size of Poecilia reticulate body was significantly different in the feeding capacity on Culex quinquifasciatus larvae. The fish whose body size was 1.50 cm had the lowest feeding capacity by eating 77.2 larvae for average, and the highest one was the fist which body size was 2.50 cm by eating 113.6 larvae for average, subsequently the feeding capacity decrease to the fish which body size was 3.50 cm because of eating 100,6 larvae for 24 hours.

Urban mosquito species (Diptera: Culicidae) of dengue endemic communities in the Greater Puntarenas area, Costa Rica.

Science.gov (United States)

Calderón-Arguedas, Olger; Troyo, Adriana; Solano, Mayra E; Avendaño, Adrián; Beier, John C

2009-12-01

Field studies were conducted to determine the mosquito species richness in the urban area of Greater Puntarenas in Costa Rica. Two cross-sectional entomological surveys were performed in seven localities of Puntarenas: one survey was performed during the wet season and the other during the dry season. The sections evaluated were determined by applying a stratified cluster sampling method using satellite imagery, and a sample of 26 cells (100 x 100m) was selected for the study. The number of cells per locality was proportional to the area of each locality. The presence of mosquito larvae and pupae in water-filled artificial and natural containers was determined in each cell. Infestation was expressed as a diversity index per type of container (Ii). Eight types of larvae were identified (Aedes aegypti, Culex quinquefasciatus, Culex interrogator, Culex nigripalpus, Culex corniger, Culex tarsalis, Limatus durhamii and Toxorhynchites theobaldi) and in two cases it was only possible to identify the genus (Culex sp. and Uranotaenia sp.). A. aegypti was the most common species followed by C. quinquefascitus. Diversity of wet environments can explain the co-occurrence of various culicid species in some localities. Although A. aegypti is the only documented disease vector in the area, C quinquefasciatus, C nigripalpus, and the other species of Culex could be considered potential vectors of other pathogens. The presence and ecology of all mosquito species should be studied to optimize surveillance and prevention of dengue and to prevent the emergence of other mosquito-transmitted diseases.

Daily and seasonal variation in the activity of potential vector mosquitoes

Czech Academy of Sciences Publication Activity Database

Šebesta, Oldřich; Gelbič, Ivan; Peško, Juraj

2011-01-01

Roč. 6, č. 3 (2011), s. 422-430 ISSN 1895-104X R&D Projects: GA MŠk 2B08003 Institutional research plan: CEZ:AV0Z6093917; CEZ:AV0Z50070508 Keywords : South Moravia * Aedes vexans * Ochlerotatus sticticus * Culex modestus * Culex pipiens * West Nile Virus * Ťahyňa virus Subject RIV: EG - Zoology Impact factor: 1.000, year: 2011

Operational Evaluation Of Vectomax® WSP (Bacillus thuringiensis Subsp. israelensis+Bacillus sphaericus) Against Larval Culex pipiens in Septic Tanks (1).

Science.gov (United States)

Cetin, Huseyin; Oz, Emre; Yanikoglu, Atila; Cilek, James E

2015-06-01

The residual effectiveness of VectoMax® WSP (a water-soluble pouch formulation containing a combination of Bacillus thuringiensis subsp. israelensis strain AM65-52 and B. sphaericus strain ABTS 1743) when applied to septic tanks against 3rd- and 4th-stage larvae of Culex pipiens L. was evaluated in this study. This formulation was evaluated at operational application rates of 1 pouch (10 g) and 2 pouches (20 g) per septic tank. Both application rates resulted in >96% control of larvae for 24 days. Operationally, VectoMax WSP has proven to be a useful tool for the nonchemical control of Culex species in septic tank environments.

VECTORS OF MALARIA AND FILARIASIS IN INDONESIA

Directory of Open Access Journals (Sweden)

Hoedojo Hoedojo

2012-09-01

is transmitted by Culex quinquefasciatus, whereas the rural type is transmitted mosdy by Anopheles spp., such as An.aconitus and An.punctulatus complex. The periodic species of Mansonia transmit the subperiodic noctural B.malayi. B.timori which is distributed in the Eastern part of Indonesia (East Nusa Tenggara, is transmitted by An.barbirostris. Some filariasis vectors such as An.aconitus and the An.puctulatus complex may function both as filariasis vector and malaria vector as well.An.barbirostris with is confirmed as a vector of malaria in South Sulawesi, a vector of periodic nocturnal malayan filariasis in Central Sulawesi and as the only vector of timorian filariasis in Timor and Flores, has to be studied further as it has two types of behaviouristic appearance, namely : 1. Anbarbirostris in Java This mosquito is an anthropozophilic species, feeds indoors and outdoors, and rest outdoors. None is found to transmit mosquitoborne disease. 2. Anbarbirostris in Sulawesi and East Nusa Tenggara (outside Java. This mosquito is a zooanthropophilic form, endo and exophagic, and rests outdoors. It is confirmed as a vector of malaria, periodic noctural malayan filariasis and the only vector of timorian filariasis. 

Ecology of potential West Nile virus vectors in southeastern Louisiana: enzootic transmission in the relative absence of Culex quinquefasciatus

Science.gov (United States)

Godsey, Marvin S.; King, Raymond J.; Burkhalter, Kristen; Delorey, Mark; Colton, Leah; Charnetzky, Dawn; Sutherland, Genevieve; Ezenwa, Vanessa O.; Wilson, Lawrence A.; Coffey, Michelle; Milheim, Lesley E.; Taylor, Viki G.; Palmisano, Charles; Wesson, Dawn M.; Guptill, Stephen C.

2013-01-01

A study of West Nile virus (WNV) ecology was conducted in St. Tammany Parish, Louisiana, from 2002 to 2004. Mosquitoes were collected weekly throughout the year using Centers for Disease Control and Prevention (CDC) light traps placed at 1.5 and 6 m above the ground and gravid traps. A total of 379,466 mosquitoes was collected. WNV was identified in 32 pools of mosquitoes comprising four species; 23 positive pools were from Culex nigripalpus collected during 2003. Significantly more positive pools were obtained from Cx. nigripalpus collected in traps placed at 6 m than 1.5 m that year, but abundance did not differ by trap height. In contrast, Cx. nigripalpus abundance was significantly greater in traps placed at 6 m in 2002 and 2004. Annual temporal variation in Cx. nigripalpus peak seasonal abundance has important implications for WNV transmission in Louisiana. One WNV-positive pool, from Cx. erraticus, was collected during the winter of 2004, showing year-round transmission. The potential roles of additional mosquito species in WNV transmission in southeastern Louisiana are discussed. Disclaimer: The opinions expressed in this article are the opinions of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. This article has been peer reviewed and approved for publication consistent with U.S. Geological Survey Fundamental Science Practices (http//pubs.usgs.gov/circ/1367/). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Seasonal blood-feeding behavior of Culex tarsalis (Diptera: Culicidae) in Weld County, Colorado, 2007.

Science.gov (United States)

Kent, Rebekah; Juliusson, Lara; Weissmann, Michael; Evans, Sara; Komar, Nicholas

2009-03-01

Studies on Culex tarsalis Coquillett in Colorado have shown marked seasonal variation in the proportion of blood meals from birds and mammals. However, limitations in the specificity of antibodies used in the precipitin test and lack of vertebrate host availability data warrant revisiting Cx. tarsalis blood feeding behavior in the context of West Nile virus (WNV) transmission. We characterized the host preference of Cx. tarsalis during peak WNV transmission season in eastern Colorado and estimated the relative contribution of different avian species to WNV transmission. Cx. tarsalis preferred birds to mammals each month, although the proportion of blood meals from mammals increased in July and August. The distribution of blood meals differed significantly across months, in part because of changes in the proportion of blood meals from American robins, a preferred host. The estimated proportion of WNV-infectious vectors derived from American robins declined from 60 to 1% between June and August. The majority of avian blood meals came from doves, preferred hosts that contributed 25-40% of the WNV-infectious mosquitoes each month. Active WNV transmission was observed in association with a large house sparrow communal roost. These data show how seasonal patterns in Cx. tarsalis blood feeding behavior relate to WNV transmission in eastern Colorado, with the American robin contributing greatly to early-season virus transmission and a communal roost of sparrows serving as a focus for late-season amplification.

Infection of malaria (Anopheles gambiae s.s.) and filariasis (Culex quinquefasciatus) vectors with the entomopathogenic fungus Metarhizium anisopliae

NARCIS (Netherlands)

Scholte, E.J.; Njiru, B.N.; Smallegange, R.C.; Takken, W.; Knols, B.G.J.

2003-01-01

Background: Current intra-domiciliary vector control depends on the application of residual insecticides and/or repellents. Although biological control agents have been developed against aquatic mosquito stages, none are available for adults. Following successful use of an entomopathogenic fungus

Selected phenotypic features of BR91, a unique spirochaetal strainisolated from the Culex pipiens mosquito

Czech Academy of Sciences Publication Activity Database

Šikutová, Silvie; Buňková, L.; Krejčí, E.; Halouzka, Jiří; Sanogo, Y. O.; Rudolf, Ivo

2014-01-01

Roč. 169, 5-6 (2014), s. 348-352 ISSN 0944-5013 R&D Projects: GA ČR GA206/00/1234; GA ČR GA206/03/0726 Institutional support: RVO:68081766 Keywords : Spirochaete * Culex pipiens * Enzyme activity * SDS-PAGE * FAMEa Subject RIV: EE - Microbiology, Virology Impact factor: 2.561, year: 2014

Field evaluation of picaridin repellents reveals differences in repellent sensitivity between Southeast Asian vectors of malaria and arboviruses.

Directory of Open Access Journals (Sweden)

Karel Van Roey

2014-12-01

Full Text Available Scaling up of insecticide treated nets has contributed to a substantial malaria decline. However, some malaria vectors, and most arbovirus vectors, bite outdoors and in the early evening. Therefore, topically applied insect repellents may provide crucial additional protection against mosquito-borne pathogens. Among topical repellents, DEET is the most commonly used, followed by others such as picaridin. The protective efficacy of two formulated picaridin repellents against mosquito bites, including arbovirus and malaria vectors, was evaluated in a field study in Cambodia. Over a period of two years, human landing collections were performed on repellent treated persons, with rotation to account for the effect of collection place, time and individual collector. Based on a total of 4996 mosquitoes collected on negative control persons, the overall five hour protection rate was 97.4% [95%CI: 97.1-97.8%], not decreasing over time. Picaridin 20% performed equally well as DEET 20% and better than picaridin 10%. Repellents performed better against Mansonia and Culex spp. as compared to aedines and anophelines. A lower performance was observed against Aedes albopictus as compared to Aedes aegypti, and against Anopheles barbirostris as compared to several vector species. Parity rates were higher in vectors collected on repellent treated person as compared to control persons. As such, field evaluation shows that repellents can provide additional personal protection against early and outdoor biting malaria and arbovirus vectors, with excellent protection up to five hours after application. The heterogeneity in repellent sensitivity between mosquito genera and vector species could however impact the efficacy of repellents in public health programs. Considering its excellent performance and potential to protect against early and outdoor biting vectors, as well as its higher acceptability as compared to DEET, picaridin is an appropriate product to evaluate the

Field evaluation of picaridin repellents reveals differences in repellent sensitivity between Southeast Asian vectors of malaria and arboviruses.

Science.gov (United States)

Van Roey, Karel; Sokny, Mao; Denis, Leen; Van den Broeck, Nick; Heng, Somony; Siv, Sovannaroth; Sluydts, Vincent; Sochantha, Tho; Coosemans, Marc; Durnez, Lies

2014-12-01

Scaling up of insecticide treated nets has contributed to a substantial malaria decline. However, some malaria vectors, and most arbovirus vectors, bite outdoors and in the early evening. Therefore, topically applied insect repellents may provide crucial additional protection against mosquito-borne pathogens. Among topical repellents, DEET is the most commonly used, followed by others such as picaridin. The protective efficacy of two formulated picaridin repellents against mosquito bites, including arbovirus and malaria vectors, was evaluated in a field study in Cambodia. Over a period of two years, human landing collections were performed on repellent treated persons, with rotation to account for the effect of collection place, time and individual collector. Based on a total of 4996 mosquitoes collected on negative control persons, the overall five hour protection rate was 97.4% [95%CI: 97.1-97.8%], not decreasing over time. Picaridin 20% performed equally well as DEET 20% and better than picaridin 10%. Repellents performed better against Mansonia and Culex spp. as compared to aedines and anophelines. A lower performance was observed against Aedes albopictus as compared to Aedes aegypti, and against Anopheles barbirostris as compared to several vector species. Parity rates were higher in vectors collected on repellent treated person as compared to control persons. As such, field evaluation shows that repellents can provide additional personal protection against early and outdoor biting malaria and arbovirus vectors, with excellent protection up to five hours after application. The heterogeneity in repellent sensitivity between mosquito genera and vector species could however impact the efficacy of repellents in public health programs. Considering its excellent performance and potential to protect against early and outdoor biting vectors, as well as its higher acceptability as compared to DEET, picaridin is an appropriate product to evaluate the epidemiological

Insecticidal activity of some citrus oils against culex quinquefasciatus

International Nuclear Information System (INIS)

Saeed, H. M. A.

2009-01-01

The present study deals with the larvicidal potency of peel oils of grapefruit (Citrus paradise), sweet orange (Citrus sinensis) and lime (Citrus aurantifolia) on 4''th instar larvae of the mosquito, Culex quinquefasciatus. Orange oil was the most effective followed by grapefruit oil and then lime oil. The toxicity of the oils applied to the 4''th instar larval stage was extended to pupal and adult stages. All oils produced deleterious effects on fecundity of survivors of sublethal doses. By the aid of chemical analysis of oils, the active compound was found to be limonene, a monoterpene compound. The percentages limonene were 97.15%, 92.46% and 32.29% for orange, grapefruit and lime respectively.(Author)

Noncoding Subgenomic Flavivirus RNA Is Processed by the Mosquito RNA Interference Machinery and Determines West Nile Virus Transmission by Culex pipiens Mosquitoes.

Science.gov (United States)

Göertz, G P; Fros, J J; Miesen, P; Vogels, C B F; van der Bent, M L; Geertsema, C; Koenraadt, C J M; van Rij, R P; van Oers, M M; Pijlman, G P

2016-11-15

Flaviviruses, such as Zika virus, yellow fever virus, dengue virus, and West Nile virus (WNV), are a serious concern for human health. Flaviviruses produce an abundant noncoding subgenomic flavivirus RNA (sfRNA) in infected cells. sfRNA results from stalling of the host 5'-3' exoribonuclease XRN1/Pacman on conserved RNA structures in the 3' untranslated region (UTR) of the viral genomic RNA. sfRNA production is conserved in insect-specific, mosquito-borne, and tick-borne flaviviruses and flaviviruses with no known vector, suggesting a pivotal role for sfRNA in the flavivirus life cycle. Here, we investigated the function of sfRNA during WNV infection of Culex pipiens mosquitoes and evaluated its role in determining vector competence. An sfRNA1-deficient WNV was generated that displayed growth kinetics similar to those of wild-type WNV in both RNA interference (RNAi)-competent and -compromised mosquito cell lines. Small-RNA deep sequencing of WNV-infected mosquitoes indicated an active small interfering RNA (siRNA)-based antiviral response for both the wild-type and sfRNA1-deficient viruses. Additionally, we provide the first evidence that sfRNA is an RNAi substrate in vivo Two reproducible small-RNA hot spots within the 3' UTR/sfRNA of the wild-type virus mapped to RNA stem-loops SL-III and 3' SL, which stick out of the three-dimensional (3D) sfRNA structure model. Importantly, we demonstrate that sfRNA-deficient WNV displays significantly decreased infection and transmission rates in vivo when administered via the blood meal. Finally, we show that transmission and infection rates are not affected by sfRNA after intrathoracic injection, thereby identifying sfRNA as a key driver to overcome the mosquito midgut infection barrier. This is the first report to describe a key biological function of sfRNA for flavivirus infection of the arthropod vector, providing an explanation for the strict conservation of sfRNA production. Understanding the flavivirus transmission

Toxic Response of Mosquito Culex Quinquefasciatus (Diptera: Culicidae to some Agricultural Pesticides (Butachlor and Pertilachlor

Directory of Open Access Journals (Sweden)

Aliakbar Hedayati*

2017-06-01

Full Text Available Background: The expansion of herbicide used in aquatic ecosystems as well as in terrestrial if is not properly controlled may produce harmful effects on freshwater fisheries. Residue limits of these agricultural chemicals in tropical fishery waters should be established. The aim of this study was to determine the acute toxicity of butachlor and pertilachlor as potential dangerous herbicides to assess mortality effects of these chemicals to the Mosquito Culex quinquefasciatus. Methods: This study was carried out in Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran at summer 2013. Culex samples were exposed to different concentrations of butachlor and pertilachlor (0-200ppm for butachlor and pertilachlor for 96 h. Results: The low toxicity of LC50s obtained for butachlor (23.81±0.04 and pertilachlor (27.97±0.05 indicate that butachlor and pertilachlor were lowly toxic to Mosquito Cu. quinquefasciatus. Conclusion: Although pretilachlor and butachlor are low toxic but pretilachlor is less toxic in field conditions, these data are useful to potential ecosystem risk assessment.

Deteksi Brugia malayi pada Armigeres subalbatus dan Culex quinquefasciatusyang diinfeksikan darah penderita filariasis dengan metode PCR

Directory of Open Access Journals (Sweden)

Yahya Yahya

2015-01-01

Full Text Available Abstract. Pemayungdistricts, Batanghari regency of Jambi province classified as filariasis endemic areas in Jambi province since the Mf rate reached 1.5% in 2011. A study was conducted to identify Brugia malayi on experimentally infected Ar. subalbatus and Cx. quinquefasciatus. An experimental study was performed with completely randomized design and six repetitions. Standard of treatment in this study was time (hours that selected for mosquitoes to bite the patients with filariasis (experimental infection. Selected time is at 9.00 a.m, 5.00 p.m, 9.00 p.m, and at 1.00 a.m. The results showed that filarial L3 larvae did not found on Ar. subalbatus and Cx. quinquefasciatus mosquitoes during surgery at day 11th to 13th after infection. Density of microfilariae in the blood of humans as a source of infection was 17 microfilariae per 20 micro liter blood. Otherwise, after detection by PCR, our study found positive B.malayi on Cx. quinquefasciatus thorax and proboscis. It indicates that Cx. quinquefasciatusas potential vector of B.malayi filariasis compared to Ar. subalbatus. Keywords: PCR, filariasis, Armigeres subalbatus, Culex quinquefasciatus, Brugia malayi   Abstrak. Kecamatan Pemayung Kabupaten Batanghari Provinsi Jambi merupakan wilayah endemis filariasis di Provinsi Jambi Karena angka Mf rate mencapai 1,5% pada tahun 2011. Penelitian ini untuk mengetahui tingkat kerentanan nyamuk Ar. subalbatus dan Cx. quinquefasciatus terhadap infeksi B. malayi subperiodik nokturna yang dilakukan pada tahun 2013, sehingga dapat dianalisis potensi nyamuk tersebut sebagai vektor filariasis di lokasi penelitian. Desain penelitian adalah eksperimental dengan rancangan acak lengkap dan enam kali pengulangan. Variabel perlakuan dalam penelitian ini adalah waktu (jam yang dipilih untuk menggigitkan nyamuk pada penderita filariasis (infeksi percobaan. Waktu yang dipilih adalah pukul 09.00 WIB, pukul 17.00 WIB, pukul 21.00 WIB dan pukul 01.00 WIB. Hasil penelitian

Evaluación de la actividad insecticida de un producto granulado a base de Bacillus sphaericus sobre larvas de Anopheles albimanus y Culex quinquefasciatus en condiciones experimentales

Directory of Open Access Journals (Sweden)

Estrella Cárdenas

2009-01-01

Full Text Available Culex quinquefasciatus causa alergias por las picaduras y ha sido asociado con la encefalitis equina, mientras que Anopheles albimanus es vector de malaria. El objetivo fue evaluar la toxicidad de un producto granulado a base de Bacillus sphaericus sobre larvas de Culex quinquefasciatus y Anopheles albimanus. El estudio fue realizado sobre larvas de C. quinquefasciatus (Sibaté y Villavicencio y An albimanus (Cartagena y Barranquilla. Las concentraciones ensayadas de B. sphaericus fueron: 20, 40, 60, 80, 100, 120, 140, 160, 180, 200 y 500 ppm para larvas de An. albimanus y para larvas de C. quinquefasciatus fueron: 2, 4, 6, 8, 10, 12, 14 y 16 ppm. Se utilizaron 20 larvas en tres repeticiones por cada concentración del producto y el tiempo de exposición fue de 48 horas. El producto de B. sphaericus mostró alta mortalidad (entre 80 y 100% a bajas concentraciones (8 y 12 ppm para larvas de C. quinquefasciatus; mientras que para larvas de An. albimanus a concentraciones más altas (entre 40 y 200 ppm la mortalidad no superó el 50%. La CL50 Logit fue 176 ppm y la Probit fue 192 ppm de B. sphaericus para larvas de An. albimanus; mientras que para larvas de C. quinquefasciatus la CL50 Logit fue 1, 9 ppm y la Probit fue 2, 2 ppm. Se concluye que las larvas de C. quinquefasciatus fueron más susceptibles a bajas concentraciones (2 a 12 ppm de B. sphaericus, mientras que las larvas de An. albimanus mostraron alta toxicidad a concentraciones de 500 ppm.

Larvicidal effect of aqueous and ethanolic extracts of Senna alata on Anopheles gambiae, Culex quinquefasciatus and Aedes aegypti.

Science.gov (United States)

Edwin, Ubulom Peace Mayen; Nyiutaha, Imandeh Godwin; Essien, Akpabio Eno; Nnamdi, Opara Kenneth; Sunday, Ekanem Mfon

2013-05-01

Senna alata is locally used in South Eastern Nigeria in the treatment of several infections which include ringworm and other parasitic skin diseases.The larvicidal activities of aqueous and ethanolic leaf and stem extracts of S. alata were evaluated in static bioassays, on fourth instar larvae of Anopheles gambiae, Culex quinquefasciatus and Aedes aegypti, at extract concentrations of 0.15, 0.30, 0.45, 0.60 and 0.75% w/v, for 72 hours. Mortality of larvae exposed to the different extracts increased with increase in extract concentration and time of exposure. This study revealed a differential potency of the extracts used and a difference in susceptibility of larvae to the extracts as evident by the 72hLC₅₀ values obtained. The leaf extract proved to be more lethal to the larvae than the stem extract as judged by the 72hLC₅₀ values obtained both for the aqueous as well as the ethanolic extracts assayed. Phytochemical screening of the plant parts investigated revealed the presence of some plant metabolites, which have been reported in separate studies to be lethal to mosquito larvae. Results obtained from this study suggest that the leaf and stem extracts of S. alata possess a promising larvicidal potential which can be exploited in mosquito vector control.

Ultrastructural changes in the flight muscle mitochondria of adult male mosquito Culex Pipiens L I

International Nuclear Information System (INIS)

Abd Elmeguid, A.; Elmoursy, A.A.; Rouchdy, H.; Elzahraa, F.

1995-01-01

Ultrastructural differences between differentiating myoblasts of 1-day old pupae and 2-day old pupae and between well developed flight muscles in newly emerged 1-day old and 2-day old and ageing 21-day old adult male Culex Pipiens were studied. Ageing mosquitoes showed various signs of deterioration, vocalization, fusion and disorientation of cristae. 6 figs

Chemical composition, toxicity and non-target effects of Pinus kesiya essential oil: An eco-friendly and novel larvicide against malaria, dengue and lymphatic filariasis mosquito vectors.

Science.gov (United States)

Govindarajan, Marimuthu; Rajeswary, Mohan; Benelli, Giovanni

2016-07-01

Mosquitoes (Diptera: Culicidae) are vectors of important parasites and pathogens causing death, poverty and social disability worldwide, with special reference to tropical and subtropical countries. 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, the mosquito larvicidal activity of Pinus kesiya leaf essential oil (EO) was evaluated against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the lymphatic filariasis vector Culex quinquefasciatus. The chemical composition of the EO was analyzed by gas chromatography-mass spectroscopy. GC-MS revealed that the P. kesiya EO contained 18 compounds. Major constituents were α-pinene, β-pinene, myrcene and germacrene D. In acute toxicity assays, the EO showed significant toxicity against early third-stage larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus, with LC50 values of 52, 57, and 62µg/ml, respectively. Notably, the EO was safer towards several aquatic non-target organisms Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 values ranging from 4135 to 8390µg/ml. Overall, this research adds basic knowledge to develop newer and safer natural larvicides from Pinaceae plants against malaria, dengue and filariasis mosquito vectors. Copyright © 2016 Elsevier Inc. All rights reserved.

Mosquito blood-meal analysis for avian malaria study in wild bird communities: laboratory verification and application to Culex sasai (Diptera: Culicidae) collected in Tokyo, Japan.

Science.gov (United States)

Kim, Kyeong Soon; Tsuda, Yoshio; Sasaki, Toshinori; Kobayashi, Mutsuo; Hirota, Yoshikazu

2009-10-01

We conducted laboratory experiments to verify molecular techniques of avian malaria parasite detection distinguishing between an infected mosquito (oocysts on midgut wall) and infective mosquito (sporozoites in salivary glands) in parallel with blood-meal identification from individual blood-fed mosquitoes prior to application to field survey for avian malaria. Domestic fowl infected with Plasmodium gallinaceum was exposed to a vector and non-vector mosquito species, Aedes aegypti and Culex pipiens pallens, respectively, to compare the time course of polymerase chain reaction (PCR) detection for parasite between competent and refractory mosquitoes. DNA of the domestic fowl was detectable for at least 3 days after blood feeding. The PCR-based detection of P. gallinaceum from the abdomen and thorax of A. aegypti corresponded to the microscopic observation of oocysts and sporozoites. Therefore, this PCR-based method was considered useful as one of the criteria to assess developmental stages of Plasmodium spp. in mosquito species collected in the field. We applied the same PCR-based method to 21 blood-fed C. sasai mosquitoes collected in Rinshi-no-mori Park in urban Tokyo, Japan. Of 15 blood meals of C. sasai successfully identified, 86.7% were avian-derived, 13.3% were bovine-derived. Plasmodium DNA was amplified from the abdomen of three C. sasai specimens having an avian blood meal from the Great Tit (Parus major), Pale Thrush (Turdus pallidus), and Jungle Crow (Corvus macrorhynchos). This is the first field study on host-feeding habits of C. sasai in relation to the potential role as a vector for avian malaria parasites transmitted in the Japanese wild bird community.

Identification of potential vectors of and detection of antibodies against Rift Valley fever virus in livestock during interepizootic periods.

Science.gov (United States)

Rostal, Melinda K; Evans, Alina L; Sang, Rosemary; Gikundi, Solomon; Wakhule, Lilian; Munyua, Peninah; Macharia, Joseph; Feikin, Daniel R; Breiman, Robert F; Njenga, M Kariuki

2010-05-01

To evaluate the prevalence of Rift Valley fever virus (RVFV) antibodies in livestock and presence of competent mosquito vectors of RVFV during an interepizootic period (IEP) in Kenya. 208 sheep and 84 goats ranging in age from 4 months to 15 years, from 2 breeding herds. Blood specimens were collected from the sheep and goats during the 1999-2006 IEP in Rift Valley Province, and serum was harvested. Serum specimens were tested for IgG and IgM antibodies against RVFV by use of an ELISA. In addition, 7,134 mosquitoes were trapped in Naivasha, Nairobi, and Northeastern Province, and speciation was performed. No animals were seropositive for IgM against RVFV. Of the animals born after the 1997-1998 epizootic, 18% (34/188) of sheep were seropositive for IgG against RVFV, compared with 3% (2/75) of goats. Seventy percent (8,144/11,678) of the mosquitoes collected were of the Culex subgenera; 18% (2,102/11,678) were Aedes spp. Detection of IgG in the sera of sheep and goats born after the 1997-1998 epizootic and before the 2006 epizootic indicated that virus activity existed during the IEP. Detection of Aedes mosquitoes, which are competent vectors of RVFV, suggested that a cryptic vector-to-vertebrate cycle may exist during IEPs.

Genetic Characterization of Spondweni and Zika Viruses and Susceptibility of Geographically Distinct Strains of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus (Diptera: Culicidae) to Spondweni Virus

Science.gov (United States)

2016-10-26

301 policy or position of the U.S. Department of Defense, the Department of the Army, 302 Centers for Disease Control and Prevention, or the Kingdom...Aedes albopicutus (Thailand) 12 0 (0.0) 0 (0.0) Aedes albopicutus ( Venezuela ) 3 0 (0.0) 0 (0.0) Culex quinquefaciatus (Galveston, USA) 24 0 (0.0...albopicutus ( Venezuela ) 24 0 (0.0) 0 (0.0) Culex quinquefaciatus (Galveston, USA) 24 0 (0.0) 0 (0.0) 550 551 552 553 554 555 556 557

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

Directory of Open Access Journals (Sweden)

Howard Annabel FV

2010-09-01

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

Asymmetrical Competition between Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae Coexisting in Breeding Sites

Directory of Open Access Journals (Sweden)

Juan C. Santana-Martínez

2017-10-01

Full Text Available Aedes aegypti and Culex quinquefasciatus are mosquito vectors for several tropical diseases that represent a current public health problem. The ecological requirements for each species are different, however, both species show high biological adaptability, which promotes their coexistence in the same breeding sites. The purpose of this study was to assess the effect of larval association between Ae. aegypti and Cx. quinquefasciatus under different laboratory conditions of food supply and temperature, and under field simulated conditions like peridomestic containers. Our findings showed that under field simulated conditions there was no asymmetrical competition in mixed cultures with the different Cx. quinquefasciatus/Ae. aegypti ratios tested. However, under laboratory conditions in which different doses of food supply were evaluated, it was observed that competition between the two species takes place. Larval coexistence under food scarcity conditions (0.95 mg/larva showed that Ae. aegypti had a greater adult emergence than Cx. quinquefasciatus and was capable of depriving Cx. quinquefasciatus of the food needed to complete metamorphosis. In an intermediate dose of food (1.9 mg/larva, the dry weight of Cx. quinquefasciatus adults decreased, and their larval development time increased when Cx. quinquefasciatus/Ae. aegypti ratio was low. Also, a temperature effect was assessed demonstrating that Cx. quinquefasciatus was more vulnerable to changes in temperature. We suggest that Ae. aegypti is more successful in exploiting microhabitats when food is scarce, due to its scrape active feeding habitats and fast larval development times. Therefore, in conditions of food paucity both species will compete, and Ae. aegypti larvae will prevail.

Mosquitoes (Diptera: Culicidae) and their relevance as disease vectors in the city of Vienna, Austria.

Science.gov (United States)

Lebl, Karin; Zittra, Carina; Silbermayr, Katja; Obwaller, Adelheid; Berer, Dominik; Brugger, Katharina; Walter, Melanie; Pinior, Beate; Fuehrer, Hans-Peter; Rubel, Franz

2015-02-01

Mosquitoes (Diptera: Culicidae) are important vectors for a wide range of pathogenic organisms. As large parts of the human population in developed countries live in cities, the occurrence of vector-borne diseases in urban areas is of particular interest for epidemiologists and public health authorities. In this study, we investigated the mosquito occurrence in the city of Vienna, Austria, in order to estimate the risk of transmission of mosquito-borne diseases. Mosquitoes were captured using different sampling techniques at 17 sites in the city of Vienna. Species belonging to the Culex pipiens complex (78.8 %) were most abundant, followed by Coquillettidia richiardii (10.2 %), Anopheles plumbeus (5.4 %), Aedes vexans (3.8 %), and Ochlerotatus sticticus (0.7 %). Individuals of the Cx. pipiens complex were found at 80.2 % of the trap sites, while 58.8 % of the trap sites were positive for Cq. richiardii and Ae. vexans. Oc. sticticus was captured at 35.3 % of the sites, and An. plumbeus only at 23.5 % of the trap sites. Cx. pipiens complex is known to be a potent vector and pathogens like West Nile virus (WNV), Usutu virus (USUV), Tahyna virus (TAHV), Sindbis virus (SINV), Plasmodium sp., and Dirofilaria repens can be transmitted by this species. Cq. richiardii is a known vector species for Batai virus (BATV), SINV, TAHV, and WNV, while Ae. vexans can transmit TAHV, USUV, WNV, and Dirofilaria repens. An. plumbeus and Oc. sticticus seem to play only a minor role in the transmission of vector-borne diseases in Vienna. WNV, which is already wide-spread in Europe, is likely to be the highest threat in Vienna as it can be transmitted by several of the most common species, has already been shown to pose a higher risk in cities, and has the possibility to cause severe illness.

Genetic variation associated with mammalian feeding in Culex pipiens from a West Nile virus epidemic region in Chicago, Illinois.

Science.gov (United States)

Huang, Shaoming; Hamer, Gabriel L; Molaei, Goudarz; Walker, Edward D; Goldberg, Tony L; Kitron, Uriel D; Andreadis, Theodore G

2009-12-01

Mosquitoes of the Culex pipiens complex are important vectors of West Nile virus in the United States. We examined the genetic variations of Cx. pipiens mosquitoes from Chicago, Illinois that were determined to be principally ornithophilic but exhibited a relatively higher inclination for mammalian hosts including humans. Microsatellite analysis of 10 polymorphic markers was performed on 346 engorged Cx. pipiens specimens with identified avian or mammalian blood meals. Our results indicated that there were no significant differences in allelic richness, the pattern of conformity to Hardy-Weinberg equilibrium, and linkage disequilibrium, nor was there overall genetic differentiation between specimens with avian- and mammalian-derived blood meals. However, Cx. pipiens form pipiens with mammalian- (including human-) derived blood meals had significantly higher ancestry (p 0.05) and the proportion of hybrids (p > 0.05) from Cx. quinquefasciatus (population from Harris Country, Texas). No temporal genetic variation was detected in accordance with the observation that there was no shift in blood feeding from birds to mammals. The results of this study in conjunction with regional host-feeding behavior suggest that the probability of genetic ancestry from Cx. pipiens f. molestus may predispose mosquitoes to feed more readily on mammals; however, the genetic mechanisms are unknown.

Low-cost and eco-friendly green synthesis of silver nanoparticles using Feronia elephantum (Rutaceae) against Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti (Diptera: Culicidae).

Science.gov (United States)

Veerakumar, Kaliyan; Govindarajan, Marimuthu; Rajeswary, Mohan; Muthukumaran, Udaiyan

2014-05-01

Mosquitoes transmit serious human diseases, causing millions of deaths every year. The use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of synthesized natural products for vector control have been a priority in this area. In the present study, the larvicidal activity of silver nanoparticles (AgNPs) synthesized using Feronia elephantum plant leaf extract against late third-instar larvae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus was determined. The range of concentrations of synthesized AgNPs (5, 10, 15, 20, and 25 μg mL(-1)) and aqueous leaf extract (25, 50, 75, 100, and 125 μg mL(-1)) were tested against the larvae of A. stephensi, A. aegypti, and C. quinquefasciatus. Larvae were exposed to varying concentrations of aqueous crude extract and synthesized AgNPs for 24 h. Considerable mortality was evident after the treatment of F. elephantum for all three important vector mosquitoes. The synthesized AgNPs from F. elephantum were highly toxic than crude leaf aqueous extract to three important vector mosquito species. The results were recorded from UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy analysis (EDX). Synthesized AgNPs against the vector mosquitoes A. stephensi, A. aegypti, and C. quinquefasciatus had the following LC50 and LC90 values: A. stephensi had LC50 and LC90 values of 11.56 and 20.56 μg mL(-1); A. aegypti had LC50 and LC90 values of 13.13 and 23.12 μg mL(-1); and C. quinquefasciatus had LC50 and LC90 values of 14.19 and 24.30 μg mL(-1). No mortality was observed in the control. These results suggest that the green synthesis of silver nanoparticles using F. elephantum has the potential to be used as an ideal eco-friendly approach for the control of A. stephensi, A. aegypti, and C

Sampling gravid Culex quinquefasciatus (Diptera: Culicidae) in Tanzania with traps baited with synthetic oviposition pheromone and grass infusions

NARCIS (Netherlands)

Mboera, L.E.G.; Takken, W.; Mdira, K.Y.; Pickett, J.A.

2000-01-01

The effectiveness of traps baited with (5R,6S)-6-acetoxy-5-hexadecanolide (the synthetic oviposition pheromone) and grass infusions in sampling a population of gravid Culex quinquefasciatus Say was conducted in Muheza, Northeast Tanzania. A counterflow geometry (CFG) trap baited with pheromone and

Mosquito larvicidal activity of seaweeds extracts against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

Mohamed Yacoob Syed Ali

2013-06-01

Full Text Available Objective: To identify the larvicidal activity of the seaweed extracts against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus Methods: Seaweed extracts of Ulva lactuca, Caulerpa racemosa (C. racemosa, Sargassum microystum, Caulerpa scalpelliformis, Gracilaria corticata, Turbinaria decurrens, Turbinaria conoides and Caulerpa toxifolia were dissolved in DMSO to prepare a graded series of concentration. The test for the larvicidal effect of seaweeds against mosquitos larvae was conducted in accordance with the WHO standard method. Batches of 25 early 4th instar larvae of three mosquitoes were transferred to 250 mL enamel bowl containing 199 mL of distilled water and 1 mL of plant extracts (10-100 µg. Each experiment was conducted with triplicate with concurrent a control group. Results: Among the seaweeds extract, C. racemosa showed toxicity against 4th instar larvae of Aedes aegypti, Culex quinquefasciatus, Anopheles stephensi with equivalent LC 50 value (0.055 6依0.010 3 µg/mL, (0.067 5依0.136 0 µg/mL and (0.066 1 依0.007 6 µg/mL, respectively. Conclusions: The present study concluded that, the mosquito larvicidal property of C. racemosa might be the prospective alternative source to control the mosquitoes.

Olyset Duo® (a pyriproxyfen and permethrin mixture net: an experimental hut trial against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus in Southern Benin.

Directory of Open Access Journals (Sweden)

Corine Ngufor

Full Text Available Alternative compounds which can complement pyrethroids on long-lasting insecticidal nets (LN in the control of pyrethroid resistant malaria vectors are urgently needed. Pyriproxyfen (PPF, an insect growth regulator, reduces the fecundity and fertility of adult female mosquitoes. LNs containing a mixture of pyriproxyfen and pyrethroid could provide personal protection through the pyrethroid component and reduce vector abundance in the next generation through the sterilizing effect of pyriproxyfen.The efficacy of Olyset Duo, a newly developed mixture LN containing pyriproxyfen and permethrin, was evaluated in experimental huts in southern Benin against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus. Comparison was made with Olyset Net® (permethrin alone and a LN with pyriproxyfen alone (PPF LN. Laboratory tunnel tests were performed to substantiate the findings in the experimental huts.Overall mortality of wild pyrethroid resistant An. gambiae s.s. was significantly higher with Olyset Duo than with Olyset Net (50% vs. 27%, P = 0.01. Olyset DUO was more protective than Olyset Net (71% vs. 3%, P<0.001. The oviposition rate of surviving blood-fed An. gambiae from the control hut was 37% whereas none of those from Olyset Duo and PPF LN huts laid eggs. The tunnel test results were consistent with the experimental hut results. Olyset Duo was more protective than Olyset Net in the huts against wild pyrethroid resistant Cx. quinquefasciatus although mortality rates of this species did not differ significantly between Olyset Net and Olyset Duo. There was no sterilizing effect on surviving blood-fed Cx. quinquefasciatus with the PPF-treated nets.Olyset Duo was superior to Olyset Net in terms of personal protection and killing of pyrethroid resistant An. gambiae, and sterilized surviving blood-fed mosquitoes. Mixing pyrethroid and pyriproxyfen on a LN shows potential for malaria control and management of pyrethroid resistant vectors by

Candidate Vectors and Rodent Hosts of Venezuelan Equine Encephalitis Virus, Chiapas, 2006–2007

Science.gov (United States)

Deardorff, Eleanor R.; Estrada-Franco, Jose G.; Freier, Jerome E.; Navarro-Lopez, Roberto; Da Rosa, Amelia Travassos; Tesh, Robert B.; Weaver, Scott C.

2011-01-01

Enzootic Venezuelan equine encephalitis virus (VEEV) has been known to occur in Mexico since the 1960s. The first natural equine epizootic was recognized in Chiapas in 1993 and since then, numerous studies have characterized the etiologic strains, including reverse genetic studies that incriminated a specific mutation that enhanced infection of epizootic mosquito vectors. The aim of this study was to determine the mosquito and rodent species involved in enzootic maintenance of subtype IE VEEV in coastal Chiapas. A longitudinal study was conducted over a year to discern which species and habitats could be associated with VEEV circulation. Antibody was rarely detected in mammals and virus was not isolated from mosquitoes. Additionally, Culex (Melanoconion) taeniopus populations were found to be spatially related to high levels of human and bovine seroprevalence. These mosquito populations were concentrated in areas that appear to represent foci of stable, enzootic VEEV circulation. PMID:22144461

Larvicidal Activities of Indigenous Bacillus thuringiensis Isolates and Nematode Symbiotic Bacterial Toxins against the Mosquito Vector, Culex pipiens (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Ashraf M Ahmed

2017-06-01

Full Text Available Background: The incidence of mosquito-borne diseases and the resistance of mosquitoes to conventional pesticides have recently caused a panic to the authorities in the endemic countries. This study was conducted to identify native larvicidal biopesticides against Culex pipiens for utilization in the battle against mosquito-borne diseases.Methods: Larvicidal activities of new indigenous Bacillus thuringiensis isolates and crude toxin complexes (TCs of two nematode bacterial-symbionts, Photorhabdus luminescens akhurstii (HRM1 and Ph. luminescens akhurstii (HS1 that tested against Cx. pipiens. B. thuringiensis isolates were recovered from different environmental samples in Saudi Arabia, and the entomopathogenic nematodes, Heterorhabditis indica (HRM1 and He. sp (HS1 were iso­lated from Egypt. Larvicidal activities (LC50 and LC95 of the potentially active B. thuringiensis strains or TCs were then evaluated at 24 and 48h post-treatment.Results: Three B. thuringiensis isolates were almost as active as the reference B. thuringiensis israelensis (Bti-H14, and seven isolates were 1.6–5.4 times more toxic than Bti-H14. On the other hand, the TCs of the bacterial sym­bionts, HRM1 and HS1, showed promising larvicidal activities. HS1 showed LC50 of 2.54 folds that of HRM1 at 24h post-treatment. Moreover, histopathological examinations of the HS1-treated larvae showed deformations in midgut epithelial cells at 24h post-treatment.Conclusion: Synergistic activity and molecular characterization of these potentially active biocontrol agents are currently being investigated. These results may lead to the identification of eco-friend mosquito larvicidal product(s that could contribute to the battle against mosquito-borne diseases.

Biosynthesis, mosquitocidal and antibacterial properties of Toddalia asiatica-synthesized silver nanoparticles: do they impact predation of guppy Poecilia reticulata against the filariasis mosquito Culex quinquefasciatus?

Science.gov (United States)

Murugan, Kadarkarai; Venus, Joseph Selvaraj Eugine; Panneerselvam, Chellasamy; Bedini, Stefano; Conti, Barbara; Nicoletti, Marcello; Sarkar, Santosh Kumar; Hwang, Jiang-Shiou; Subramaniam, Jayapal; Madhiyazhagan, Pari; Kumar, Palanisamy Mahesh; Dinesh, Devakumar; Suresh, Udaiyan; Benelli, Giovanni

2015-11-01

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Furthermore, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. In this study, silver nanoparticles (AgN) were biosynthesized a cheap aqueous extract of T. asiatica leaves as reducing and stabilizing agent. The formation of nanoparticle was confirmed by surface Plasmon resonance band illustrated in UV-vis spectrophotometer. AgN were characterized by FTIR, SEM, EDX, and XRD analyses. AgN were mostly spherical in shape, crystalline in nature, with face-centered cubic geometry, and their mean size was 25-30 nm. T. asiatica aqueous extract and green-synthesized AgN showed excellent larvicidal and pupicidal toxicity against the filariasis vector Culex quinqufasciatus, both in laboratory and field experiments. AgN LC50 ranged from 16.48 (I instar larvae) to 31.83 ppm (pupae). T. asiatica-synthesized were also highly effective in inhibiting growth of Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. Lastly, we evaluated if sublethal doses of nanoparticles affect predation rates of fishes, Poecilia reticulata, against C. quinquefasciatus. In AgN-contaminated environment, predation of guppies against mosquito larvae was slightly higher over normal laboratory conditions. Overall, this study highlighted that T. asiatica-synthesized AgN are easy to produce, stable over time, and may be employed at low dosages to reduce populations of filariasis vectors, without detrimental effects on predation rates of mosquito natural enemies.

Irritability Levels of Field and Laboratory Population of Culex pipiens Complex in Tehran to Different Groups of Insecticides

Directory of Open Access Journals (Sweden)

Sara Rahimi

2016-01-01

Full Text Available Background: The irritant effect of some insecticides can cause a proportion of mosquitoes to leave the sprayed rooms before acquiring a lethal dose, so the repeated contact al sub-lethal dose may lead to extent the resistance.Methods: Larvae and pupae of Culex pipiens complex were collected in mass from open canals of waste water in capital city Tehran and reared to obtain the first generation at laboratory. Sugar-fed 2–3 days female mosquitoes were used for the experiments and compared with laboratory strain. The irritability tests of insecticides impregnated pa­pers were measured in plastic conical exposure chambers placed which implemented at controlled conditions ac­cording  to  the  method  described  by WHO .Number of take-offs were counted during 15  minutes of exposure  time.Results: DDT had the most irritancy effect against field population of Cx. pipiens. DDT, permethrin and deltamethrin was moderately irritable against laboratory strain, whereas, addition to three previous insecticides, malathion, cyfluthrin and propoxur should be also considered as moderately irritable insecticides for field population of. Irritability level of etofenprox, fenithrothion, bendiocarb, and lambdacyhalothrin did not differ from control group.Conclusion: The irritability response of mosquitoes may have a negative impact on control measures. Periodical execution of irritability tests with insecticides that routinely used in vector control program is highly recommended.

Larvicidal Activity of Essential Oils of Five Apiaceae Taxa and Some of Their Main Constituents Against Culex quinquefasciatus.

Science.gov (United States)

Pavela, Roman; Maggi, Filippo; Cianfaglione, Kevin; Bruno, Maurizio; Benelli, Giovanni

2018-01-01

Apiaceae are aromatic herbs producing essential oils which are used on an industrial scale for various purposes. Notably, Apiaceae essential oils may replace synthetic insecticides keeping most of their efficacy and avoiding environmental pollution and human poisoning. In the present work, we explored the insecticidal potential of the essential oils from five Apiaceae taxa, namely Sison amomum, Echinophora spinosa, Heracleum sphondylium subsp. sphondylium, Heracleum sphondylium subsp. ternatum, and Trachyspemum ammi, as well as their major constituents (sabinene, p-cymene, terpinolene, myristicin, and thymol), against the filariasis vector Culex quinquefasciatus. For the purpose, the essential oils were obtained by hydrodistillation and their composition was achieved by gas chromatography/mass spectrometry (GC/MS). Their acute toxicity on third instar larvae of C. quinquefasciatus was determined. The two most active essential oils were those from T. ammi fruits and E. spinosa roots, showing LC 50 below 20 μl/l and LD 90 below 50 μl/l. These oils were dominated by the monoterpene phenol thymol and the phenylpropanoid myristicin, respectively, which showed the strongest larvicidal activity (LC 50 of 15.1 and 16.3 μl/l, respectively) among the pure compounds tested. These results showed that Apiaceae may be useful as source of larvicidal compounds to be used for the development of cheap, effective and eco-friendly insecticidal formulations. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

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

Impact of extrinsic incubation temperature and virus exposure on vector competence of Culex pipiens quinquefasciatus Say (Diptera: Culicidae) for West Nile virus.

Science.gov (United States)

Richards, Stephanie L; Mores, Christopher N; Lord, Cynthia C; Tabachnick, Walter J

2007-01-01

Culex pipiens quinquefasciatus Say mosquitoes from a laboratory colony were exposed to artificial blood meals containing West Nile virus (WNV) and held at incubation temperatures approximating average daily temperatures that occur during Florida arboviral periods. Mosquitoes fed blood meals containing 6.2 logs plaque-forming units (pfu) WNV/mL and held at 25 degrees C, 28 degrees C, or 30 degrees C for 13 days exhibited significantly different rates of infection (30%, 52%, 93%) and dissemination (33%, 22%, 81%) across temperatures. In a separate experiment, Cx. p. quinquefasciatus mosquitoes were provided artificial blood meals with graded doses of WNV from 3.7 to 5.8 logs pfu/mL and maintained at 28 degrees C for 13 days. Rates of infection increased as a function of virus dose, but neither body titers nor dissemination rates were significantly different for mosquitoes that were infected by ingesting different amounts of WNV. Our findings indicate that efficiency of WNV infection and dissemination, and thereby transmission, in Cx. p. quinquefasciatus populations similar to our tested colony may also be diminished when fed blood meals containing less than 5.8 logs pfu WNV/mL and when environmental temperature falls below 30 degrees C. The relationship between the infection rate and dissemination rate changed at different temperatures. This relationship is likely complex and dependent on diverse interactions between factors such as incubation temperature and viremia, which should also be assessed for field populations.

Molecular detection of six (endo-) symbiotic bacteria in Belgian mosquitoes: first step towards the selection of appropriate paratransgenesis candidates.

Science.gov (United States)

Raharimalala, Fara Nantenaina; Boukraa, S; Bawin, T; Boyer, S; Francis, F

2016-04-01

Actually, the use of symbiotic bacteria is one of alternative solution to avoid vector resistance to pesticides. In Belgium, among 31 identified mosquito species, 10 were considered as potential vectors. Given to introduction risks of arbovirosis, the purpose of this study was to investigate the presence of symbiosis bacteria in potential mosquito vectors. Eleven species caught from 12 sites in Belgium were used: Culex pipiens s.l., Culex torrentium, Culex hortensis, Anopheles claviger, Anopheles maculipennis s.l., Anopheles plumbeus, Culiseta annulata, Ochlerotatus geniculatus, Ochlerotatus dorsalis, Aedes albopictus, and Coquillettidia richiardii. Six genera of symbiotic bacteria were screened: Wolbachia sp., Comamonas sp, Delftia sp., Pseudomonas sp., Acinetobacter sp., and Asaia sp. A total of 173 mosquito individuals (144 larvae and 29 adults) were used for the polymerase chain reaction screening. Wolbachia was not found in any Anopheles species nor Cx. torrentium. A total absence of Comamonas and Delftia was observed in all species. Acinetobacter, Pseudomonas, and Asaia were found in most of species with a high prevalence for Pseudomonas. These results were discussed to develop potential strategy and exploit the variable occurrence of symbiotic bacteria to focus on them to propose biological ways of mosquito control.

Sentinel site-enhanced near-real time surveillance documenting West Nile virus circulation in two Culex mosquito species indicating different transmission characteristics, Djibouti City, Djibouti.

Science.gov (United States)

Faulde, Michael K; Spiesberger, Michael; Abbas, Babiker

2012-08-01

The Horn of Africa represents a region formerly known to be highly susceptible to mosquito-borne infectious diseases. In order to investigate whether autochthonous WNV transmission occurs in the Djibouti City area, in how far, and which of, the endemic Culex mosquito species are involved in WNV circulation activity,and whether sentinel site-enhanced near-real time surveillance (SSE-NRTS) may increase WNV detection sensitivity, mosquito vector monitoring was conducted from January 2010 to June 2012. Six monitoring locations, including two identified sentinel sites, considered most probable for potential anthroponotic and zoonotic virus circulation activity, have been continuously employed. Among the 20431 mosquitoes collected, 19069 (93.4%) were Cx. quinquefasciatus, and 1345 (6.6%) Cx. pipiens ssp. torridus. WNV lineage 2 circulation activity was detected between December 20th, 2010 and January 7th, 2011. Overall, 19 WNV RNA-positive mosquito pools were detected. Generally, urban environment-specific WNV-RNA circulation took place in Cx. pipiens ssp. torridus, whereas periurban and rural area-linked circulation was detected only in Cx. quinquefasciatus. Serological investigation data from 10 volunteers employed at the dislocated zoonotic WNV transmission sentinel site suggest that six persons (60%) had an acute, or recent, WNV infection. Results show that WNV should be considered endemic for Djibouti and sentinel site-enhanced near-real time surveillance is an elegant and highly effective epidemiological tool. In Djibouti, the endemicity level, public health impact and transmission modes of vector-borne diseases in concordance with locally optimized monitoring and control regimen deserve further investigation.

Mosquito larvicidal and ovicidal properties of Pithecellobium dulce (Roxb. Benth. (Fabaceae against Culex quinquefasciatus Say (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Govindarajan Marimuthu

2014-04-01

Full Text Available Objective: To assess the larvicidal and ovicidal potential of the crude hexane, benzene, chloroform, ethyl acetate and methanol solvent extracts from the medicinal plant, Pithecellobium dulce (P. dulce against filariasis vector mosquito, Culex quinquefasciatus (Cx. quinquefasciatus. Methods: Twenty five early third instar larvae of Cx. quinquefasciatus were exposed to various concentrations and were assayed in the laboratory by using the protocol of WHO (2005. The larval mortality was observed after 24 h of treatment. The ovicidal activity was determined against Cx. quinquefasciatus mosquito eggs to various concentrations ranging from 100-750 mg/L under the laboratory conditions. Results: The methanol extract of the leaves and seed of P. dulce was the most effective against the larvae with LC 50 and LC90 values 164.12 mg/L, 214.29 mg/L, 289.34 mg/L and 410.18 mg/L being observed after 24 h of exposure. The efficacy of methanol was followed by that of the ethyl acetate, chloroform, benzene and hexane extracts. The mean percent hatchability of the egg rafts were observed after 48 h of treatment. About 100% mortality was observed at 500 mg/L for leaf and 750 mg/L for seed methanol extracts of P. dulce. Conclusions: From the results, it can be concluded that the larvicidal and ovicidal effect of P. dulce against Cx. quinquefasciatus make this plant product promising as an alternative to synthetic insecticide in mosquito control programs.

Effect of gamma radiation on the activity of mosquito culex pipiens

International Nuclear Information System (INIS)

Shoman, A. A.M.

1986-01-01

The present work was carried out to investigate the effects of gamma radiation at three doses; 40,80 and 120 gray on the response of the adult mosquito culex pipiens complex when irradiated in the larval, pupal or adult stage, to the surrounding environmental factors as light, colour and host. The effects on the sexual activity of the mosquito as sex attraction , ability to inseminate and insemination frequency were also studied. Finally, the effect of 3 low dosages; 20,25 and 30 gray, applied in the pupal stage on the adult female capability to transmit filarial larvae, or in other words on the cycle development of the larvae inside the female body, was also investigated

An introduction to vectors, vector operators and vector analysis

CERN Document Server

Joag, Pramod S

2016-01-01

Ideal for undergraduate and graduate students of science and engineering, this book covers fundamental concepts of vectors and their applications in a single volume. The first unit deals with basic formulation, both conceptual and theoretical. It discusses applications of algebraic operations, Levi-Civita notation, and curvilinear coordinate systems like spherical polar and parabolic systems and structures, and analytical geometry of curves and surfaces. The second unit delves into the algebra of operators and their types and also explains the equivalence between the algebra of vector operators and the algebra of matrices. Formulation of eigen vectors and eigen values of a linear vector operator are elaborated using vector algebra. The third unit deals with vector analysis, discussing vector valued functions of a scalar variable and functions of vector argument (both scalar valued and vector valued), thus covering both the scalar vector fields and vector integration.

Green synthesis of silver nanoparticles using Sida acuta (Malvaceae) leaf extract against Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti (Diptera: Culicidae).

Science.gov (United States)

Veerakumar, Kaliyan; Govindarajan, Marimuthu; Rajeswary, Mohan

2013-12-01

Mosquitoes act as a vector for most of the life-threatening diseases like malaria, yellow fever, dengue fever, chikungunya fever, filariasis, encephalitis, West Nile Virus infection, etc. Under the Integrated Mosquito Management, 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 nontarget 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 nontoxic, easily available at affordable prices, biodegradable, and show broad-spectrum target-specific activities against different species of vector mosquitoes. In the present study, the larvicidal activity of silver nanoparticles (AgNPs) synthesized using Sida acuta plant leaf extract against late third instar larvae of Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti was determined. Range of concentrations of synthesized AgNPs (10, 20, 30, 40, and 50 μg/mL) and aqueous leaf extract (50, 100, 150, 200, and 250 μg/mL) were tested against the larvae of C. quinquefasciatus, A. stephensi and A. aegypti. The synthesized AgNPs from S. acuta leaf were highly toxic than crude leaf aqueous extract in three important vector mosquito species. The results were recorded from UV-Vis spectrum, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy analysis. Larvae were exposed to varying concentrations of aqueous crude extract and synthesized AgNPs for 24 h. Considerable mortality was evident after the treatment of S. acuta for all three important vector mosquitoes. The LC50 and LC90 values of S. acuta aqueous leaf extract appeared to be most effective

Blood-feeding patterns of native mosquitoes and insights into their potential role as pathogen vectors in the Thames estuary region of the United Kingdom.

Science.gov (United States)

Brugman, V A; Hernández-Triana, L M; England, M E; Medlock, J M; Mertens, P P C; Logan, J G; Wilson, A J; Fooks, A R; Johnson, N; Carpenter, S

2017-03-27

The range of vertebrate hosts on which species of mosquito blood-feed is an important parameter for identifying potential vectors and in assessing the risk of incursion and establishment of vector-borne pathogens. In the United Kingdom, studies of mosquito host range have collected relatively few specimens and used techniques that could only broadly identify host species. This study conducted intensive collection and analysis of mosquitoes from a grazing marsh environment in southeast England. This site provides extensive wetland habitat for resident and migratory birds and has abundant human nuisance biting mosquitoes. The aim was to identify the blood-feeding patterns of mosquito species present at the site which could contribute to the transmission of pathogens. Twice-weekly collections of mosquitoes were made from Elmley Nature Reserve, Kent, between June and October 2014. Mosquitoes were collected using resting boxes, by aspiration from man-made structures and using a Mosquito Magnet Pro baited with 1-octen-3-ol. Blood-fed specimens were classified according to the degree of blood meal digestion using the Sella scale and vertebrate origin determined using sequencing of a fragment of the mitochondrial cytochrome C oxidase subunit I gene. Mosquitoes that were morphologically cryptic were identified to species level using multiplex PCR and sequencing methods. A total of 20,666 mosquitoes of 11 species were collected, and 2,159 (10.4%) were blood-fed (Sella scale II-VI); of these 1,341 blood-fed specimens were selected for blood meal analysis. Vertebrate origin was successfully identified in 964 specimens (72%). Collections of blood-fed individuals were dominated by Anopheles maculipennis complex (73.5%), Culiseta annulata (21.2%) and Culex pipiens form pipiens (10.4%). Nineteen vertebrate hosts comprising five mammals and 14 birds were identified as hosts for mosquitoes, including two migratory bird species. Feeding on birds by Culex modestus and Anopheles

Experimental investigation of the susceptibility of Italian Culex pipiens mosquitoes to Zika virus infection.

Science.gov (United States)

Boccolini, Daniela; Toma, Luciano; Di Luca, Marco; Severini, Francesco; Romi, R; Remoli, Maria Elena; Sabbatucci, Michela; Venturi, Giulietta; Rezza, Giovanni; Fortuna, Claudia

2016-09-01

We investigated the susceptibility of an Italian population of Culex pipiens mosquitoes to Zika virus (ZIKV) infection, tested in parallel with Aedes aegypti, as a positive control. We analysed mosquitoes at 0, 3, 7, 10, 14, 20 and 24 days after an infectious blood meal. Viral RNA was detected in the body of Cx. pipiens up to three days post-infection, but not at later time points. Our results indicate that Cx. pipiens is not susceptible to ZIKV infection. This article is copyright of The Authors, 2016.

The Influence of Fatty Acid Methyl Esters (FAMEs) in the Biochemistry and the Na(+)/K(+)-ATPase Activity of Culex quinquefasciatus Larvae.

Science.gov (United States)

Silva, Lilian N D; Ribeiro-Neto, José A; Valadares, Jéssica M M; Costa, Mariana M; Lima, Luciana A R S; Grillo, Luciano A M; Cortes, Vanessa F; Santos, Herica L; Alves, Stênio N; Barbosa, Leandro A

2016-08-01

Culex quinquefasciatus is the main vector of lymphatic filariasis and combating this insect is of great importance to public health. There are reports of insects that are resistant to the products currently used to control this vector, and therefore, the search for new products has increased. In the present study, we have evaluated the effects of fatty acid methyl esters (FAMEs) that showed larvicidal activity against C. quinquefasciatus, on glucose, total protein, and triacylglycerol contents and Na(+)/K(+)-ATPase activity in mosquito larvae. The exposure of the fourth instar larvae to the compounds caused a decrease in the total protein content and an increase in the activity of the Na(+)/K(+)-ATPase. Furthermore, the direct effect of FAMEs on cell membrane was assessed on purified pig kidney Na(+)/K(+)-ATPase membranes, erythrocyte ghost membranes, and larvae membrane preparation. No modifications on total phospholipids and cholesterol content were found after FAMEs 20 min treatment on larvae membrane preparation, but only 360 µg/mL FAME 2 was able to decrease total phospholipid of erythrocyte ghost membrane. Moreover, only 60 and 360 µg/mL FAME 3 caused an activation of purified Na(+)/K(+)-ATPase, that was an opposite effect of FAMEs treatment in larvae membrane preparation, and caused an inhibition of the pump activity. These data together suggest that maybe FAMEs can modulate the Na(+)/K(+)-ATPase on intact larvae for such mechanisms and not for a direct effect, one time that the direct effect of FAMEs in membrane preparation decreased the activity of Na(+)/K(+)-ATPase. The biochemical changes caused by the compounds were significant and may negatively influence the development and survival of C. quinquefasciatus larvae.

West Nile virus infection rates in Culex nigripalpus (Diptera: Culicidae) do not reflect transmission rates in Florida.

Science.gov (United States)

Rutledge, C Roxanne; Day, Jonathan F; Lord, Cynthia C; Stark, Lillian M; Tabachnick, Walter J

2003-05-01

We describe the first documented field transmission of West Nile (WN) virus by a North American mosquito. WN was first detected in northern Florida in 2001. An intensive mosquito trapping and surveillance program was conducted in this region for four nights to assess mosquito transmission of WN. Four mosquito traps, each with a single sentinel chicken, were placed at five different locations on each of four nights. A total of 11,948 mosquitoes was collected, and 14 mosquito pools were found to contain WN, giving a minimum infection rate between 1.08 and 7.54 per 1,000. Only one of the 80 sentinel chickens seroconverted to WN, demonstrating a single mosquito transmission event during the study and a mosquito transmission rate of between 0.8 and 1 per 1,000. Culex nigripalpus Theobald was responsible for WN transmission to the sentinel chicken, although both Cx. nigripalpus and Culex quinquefasciatus Say were found infected with WN. Mosquito transmission rates are reported in this study for the first time for a WN outbreak. This information is essential to determine risk of human and animal infection.

Use of Remote Sensing Surveillance to Monitor Environmental Parameters Associated with Mosquito Abundance and Vector-borne Diseases

Science.gov (United States)

1996-01-01

Lymphatic filariasis persists as a major cause of clinical morbidity and a significant impediment to socioeconomic development in various parts of the world including Egypt. In Egypt, filariasis has been endemic since time immemorial. Early epidemiologic studies identified Culex pipiens L. as the main vector of the disease and also showed that the geographic distribution of the disease is highly focal and concentrated in lower Egypt. Between 1950 and 1965, a large scale filariasis control program was carried out by the Egyptian Ministry of Health (EMOH) in the endemic areas. Control efforts led to a steady decrease of the disease in areas of the country previously identified as endemic. However, spot surveys conducted in various parts of the Nile Delta during the 1970's and 1980's revealed that the downward trend of the disease had stopped and that the prevalence and intensity of microfilaraemia had increased.

Feeding patterns of molestus and pipiens forms of Culex pipiens (Diptera: Culicidae) in a region of high hybridization.

Science.gov (United States)

Gomes, Bruno; Sousa, Carla A; Vicente, José L; Pinho, Leonor; Calderón, Isabel; Arez, Eliane; Almeida, António Pg; Donnelly, Martin J; Pinto, João

2013-04-11

Two biological forms of the mosquito Culex pipiens s.s., denoted pipiens and molestus, display behavioural differences that may affect their role as vectors of arboviruses. In this study, the feeding patterns of molestus and pipiens forms were investigated in Comporta (Portugal), where high levels of inter-form admixture have been recorded. Indoor and outdoor mosquito collections were performed in the summer of 2010. Collected Cx. pipiens s.l. females were molecularly identified to species and form by PCR and genotyped for six microsatellites. The source of the blood meal in post-fed females was determined by ELISA and mitochondrial DNA sequencing. The distribution of the forms differed according to the collection method. The molestus form was present only in indoor collections, whereas pipiens and admixed individuals were sampled both indoors and outdoors. In both forms, over 90% of blood meals were made on avian hosts. These included blood meals taken from Passeriformes (Passer domesticus and Turdus merula) by females caught resting inside domestic shelters. Genetic structure and blood meal analyses suggest the presence of a bird biting molestus population in the study area. Both forms were found to rest indoors, mainly in avian shelters, but at least a proportion of females of the pipiens form may bite outdoors in sylvan habitats and then search for anthropogenic resting sites to complete their gonotrophic cycle. This behaviour may potentiate the accidental transmission of arboviruses to humans in the region.

Synthesis of eco-friendly silver nanoparticles from Morinda tinctoria leaf extract and its larvicidal activity against Culex quinquefasciatus.

Science.gov (United States)

Kumar, K Ramesh; Nattuthurai, N; Gopinath, Ponraj; Mariappan, Tirupathi

2015-02-01

Mosquitoes are the major vector for the transmission of malaria, dengue fever, yellow fever, filariasis, chikungunya and Japanese encephalitis, and they accounted for global mortality and morbidity with increased resistance to common insecticides. The aim of this study was to investigate the larvicidal potential of the acetone leaf extracts of Morinda tinctoria and synthesized silver nanoparticles against third instar larvae of Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. Synthesized AgNPs were characterized by ultraviolet-visible (UV-vis) spectroscopy, Atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) analysis. The synthesized silver nanoparticles have also been tested against the third instar larvae of C. quinquefasciatus. The leaf extract and the AgNPs high mortality values were 50 % lethal concentration (LC50) = 8.088 and 1.442 ppm against C. quinquefasciatus, respectively. The results recorded from ultraviolet-visible spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy support the biosynthesis and characterization of silver nanoparticles. These results suggest that the leaf extract of M. tinctoria and synthesis of AgNPs have the potential to be used as an ideal eco-friendly approach for the control of C. quinquefasciatus. By this approach, it is suggestive that this rapid synthesis of nanoparticles would be proper for developing a biological process for mosquito control.

Insects and disease in the 21st century : a wind of change

NARCIS (Netherlands)

Takken, W.

2008-01-01

In recent years, several other vectors have become world news: the sheep tick was discovered to be the vector of Lyme disease in 1980; the mosquito Culex pipiens began transmitting West Nile virus in North America in 1999; in August 2006, bluetongue virus was discovered in Belgium and the

Impact of bifenthrin on honeybees and Culex quinquefasciatus.

Science.gov (United States)

Qualls, Whitney A; Xue, Rui-De; Zhong, He

2010-06-01

The impact of bifenthrin on honeybees, Apis mellifera (Hymenoptera: Apidae) was evaluated in both laboratory and semifield assays. Ten serial dilutions of bifenthrin and an acetone control using the bottle bioassay protocol were used in the laboratory to determine killing time after 15-, 30-, and 60-min honeybee exposure. Both dose and exposure time significantly affected honeybee mortality (df = 6, F = 10.9, P Bifenthrin was applied at 9.7 ml/liter, 19.5 ml/liter, and 29.5 ml/liter of water to common landscape vegetation, Melampodium paludosum Melanie (show star) and Duranta erecta L. (golden dewdrop); a water control was also used. Bee mortality was significantly higher (P < 0.05, df = 2, F = 20.8) at 29.5 ml/liter compared to the mortality at 19.5-ml/liter and 9.7-ml/liter application rates after 24-h exposure to the treated vegetation. Mortality of Culex quinquefasciatus exposed to treated vegetation was significantly (P < 0.05, df = 10, F = 114) different by week and by application rate.

Molecular identification of two Culex (Culex species of the neotropical region (Diptera: Culicidae.

Directory of Open Access Journals (Sweden)

Magdalena Laurito

Full Text Available Culex bidens and C. interfor, implicated in arbovirus transmission in Argentina, are sister species, only distinguishable by feature of the male genitalia; however, intermediate specimens of the species in sympatry have been found. Fourth-instar larvae and females of both species share apomorphic features, and this lack of clear distinction creates problems for specific identification. Geometric morphometric traits of these life stages also do not distinguish the species. The aim of the present study was to assess the taxonomic status of C. bidens and C. interfor using two mitochondrial genes and to determine the degree of their reproductive isolation using microsatellite loci. Sequences of the ND4 and COI genes were concatenated in a matrix of 993 nucleotides and used for phylogenetic and distance analyses. Bayesian and maximum parsimony inferences showed a well resolved and supported topology, enclosing sequences of individuals of C. bidens (0.83 BPP, 73 BSV and C. interfor (0.98 BPP, 97 BSV in a strong sister relationship. The mean K2P distance within C. bidens and C. interfor was 0.3% and 0.2%, respectively, and the interspecific variation was 2.3%. Bayesian clustering also showed two distinct mitochondrial lineages. All sequenced mosquitoes were successfully identified in accordance with the best close match algorithm. The low genetic distance values obtained indicate that the species diverged quite recently. Most morphologically intermediate specimens of C. bidens from Córdoba were heterozygous for the microsatellite locus GT51; the significant heterozygote excess observed suggests incomplete reproductive isolation. However, C. bidens and C. interfor should be considered good species: the ventral arm of the phallosome of the male genitalia and the ND4 and COI sequences are diagnostic characters.

Effects of heavy metals on population growth and metallothionein gene expression in the mosquito Culex quinquefasciatus, from Calcutta, India

International Nuclear Information System (INIS)

Sarkar, Sagartirtha; Duttagupta, Asish K.; Mal, Tarun K.

2004-01-01

Major water bodies in and around the city of Calcutta (India) receive heavy metal contaminated effluents from industries, households, and vehicular traffic through sewage or drainage. We quantified concentrations of Cu, Zn, and Cd from three water bodies at Kalighat, Tangra, and VIP Road, respectively. The concentrations of these heavy metals were significantly greater in the summer than in monsoon when heavy downpours resulted in reduced metal concentrations. Concentrations of metals in the mosquito Culex quinquefasciatus also reflected such seasonal fluctuations. Hatchability and survivorship of C. quinquefasciatus significantly differed among the sites and were reduced significantly from the control. Exposure to heavy metals also induced MT-gene expression in C. quinquefasciatus, likely helping them to survive in the water bodies stressed with heavy metals. MT-gene activity demonstrated significant variation among sites and seasons with the highest activity in the summer in the VIP Road population. This study suggests that C. quinquefasciatus could be used as an ecological indicator of heavy metal pollution by monitoring its MT-gene expression. - The mosquito, Culex quinquefasciatus, might be useful as an indicator of trace metals

Effects of heavy metals on population growth and metallothionein gene expression in the mosquito Culex quinquefasciatus, from Calcutta, India

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Sagartirtha; Duttagupta, Asish K.; Mal, Tarun K

2004-01-01

Major water bodies in and around the city of Calcutta (India) receive heavy metal contaminated effluents from industries, households, and vehicular traffic through sewage or drainage. We quantified concentrations of Cu, Zn, and Cd from three water bodies at Kalighat, Tangra, and VIP Road, respectively. The concentrations of these heavy metals were significantly greater in the summer than in monsoon when heavy downpours resulted in reduced metal concentrations. Concentrations of metals in the mosquito Culex quinquefasciatus also reflected such seasonal fluctuations. Hatchability and survivorship of C. quinquefasciatus significantly differed among the sites and were reduced significantly from the control. Exposure to heavy metals also induced MT-gene expression in C. quinquefasciatus, likely helping them to survive in the water bodies stressed with heavy metals. MT-gene activity demonstrated significant variation among sites and seasons with the highest activity in the summer in the VIP Road population. This study suggests that C. quinquefasciatus could be used as an ecological indicator of heavy metal pollution by monitoring its MT-gene expression. - The mosquito, Culex quinquefasciatus, might be useful as an indicator of trace metals.

Lethal Effects of Aspergillus niger against Mosquitoes Vector of Filaria, Malaria, and Dengue: A Liquid Mycoadulticide

Directory of Open Access Journals (Sweden)

Gavendra Singh

2012-01-01

Full Text Available Aspergillus niger is a fungus of the genus Aspergillus. It has caused a disease called black mold on certain fruits and vegetables. The culture filtrates released from the A. niger ATCC 66566 were grown in Czapek dox broth (CDB then filtered with flash chromatograph and were used for the bioassay after a growth of thirty days. The result demonstrated these mortalities with LC50, LC90, and LC99 values of Culex quinquefasciatus 0.76, 3.06, and 4.75, Anopheles stephensi 1.43, 3.2, and 3.86, and Aedes aegypti 1.43, 2.2, and 4.1 μl/cm2, after exposure of seven hours. We have calculated significant LT90 values of Cx. quinquefasciatus 4.5, An. stephensi 3.54, and Ae. aegypti 6.0 hrs, respectively. This liquid spray of fungal culture isolate of A. niger can reduce malaria, dengue, and filarial transmission. These results significantly support broadening the current vector control paradigm beyond chemical adulticides.

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

Mosquitos vetores potenciais de dirofilariose canina na Região Nordeste do Brasil Mosquitoes potential vectors of canine heartworm in the Northeast Region from Brazil

Directory of Open Access Journals (Sweden)

Silvia MM Ahid

1999-12-01

Full Text Available INTRODUÇÃO: Em alguns bairros costeiros de São Luís, Maranhão, a prevalência da dirofilariose chega a mais de 40% entre os cães domiciliados. Porém, desconhecem-se os vetores naturais, tanto lá quanto no resto do Nordeste do país. O objetivo do estudo foi identificar os prováveis vetores dessa parasitose. MÉTODOS: Realizaram-se coletas mensais de mosquitos em um bairro costeiro de São Luís, MA, de março de 1996 a maio de 1997, no peridomicílio, tendo cão e homem como iscas. Os mosquitos foram dissecados para a pesquisa de larvas da Dirofilaria immitis. RESULTADOS: Coletaram-se 1.738 mosquitos de 11 espécies. Culex quinquefasciatus, capturada todos os meses, porém menos freqüente na estação chuvosa, correspondeu a 54,5% do total, seguido de Aedes albopictus (20,3%, Aedes taeniorhynchus e Aedes scapularis (ambos 11%. Larvas de D.immitis foram encontradas em 0,1% dos Cx. quinquefasciatus e 0,5% dos Ae. taeniorhynchus. CONCLUSÕES: Ae. taeniorhynchus e Cx. quinquefasciatus foram considerados vetores potenciais da dirofilariose em São Luís. A importância local de Cx. quinquefasciatus como transmissor primário da D. immitis necessita ser melhor avaliada.INTRODUCTION: In some coastal districts of São Luís, capital of the state of Maranhão, Brazil, the prevalence of Dirofilaria immitis is more than 40% in house dogs. Natural potential vectors, as found in other areas of Northeastern Brazil, are unknown. The aim of this study was to identify probable vectors of the disease. METHODS: Mosquito catches were performed at a coastal, district Olho d'Água, in S. Luís, to look for local potential vectors. Captures were carried out monthly, from March 1996 to May 1997, outdoors, having a man and a dog as baits. Mosquitoes were dissected for D. immitis larvae. RESULTS: A total of 1,738 mosquitoes belonging to 11 species were collected. Culex quinquefasciatus, the only species collected every month, was more frequently in the dry

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.

Evaluation of released malathion and spinosad from chitosan/alginate/gelatin capsules against Culex pipiens larvae

Directory of Open Access Journals (Sweden)

Badawy MEI

2016-09-01

Full Text Available Mohamed EI Badawy,1 Nehad EM Taktak,2 Osama M Awad,2 Souraya A Elfiki,2 Nadia E Abou El-Ela2 1Department of Pesticide Chemistry and Technology, Faculty of Agriculture, 2Department of Tropical Health, High Institute of Public Health, Alexandria University, Alexandria, Egypt Abstract: Efficacy of spinosad and malathion loaded in eco-friendly biodegradable formulations was evaluated for controlling Culex pipiens larvae. Malathion (organophosphorus larvicide and spinosad (naturally derived insecticide were loaded on chitosan/alginate/gelatin capsules. Capsules were characterized by size measurement, scanning electron microscopy, Fourier transform infrared spectroscopy, and water uptake. In vitro release kinetics of the larvicides was studied in the running and stagnant water. Biochemical studies on the larvae treated with technical and formulated insecticides were also demonstrated. The results indicated that the released spinosad was active for a long time up to 48 and 211 days in the running and stagnant water, respectively. However, the capsules loaded with malathion showed larvicidal activity for 20 and 27 days in the running and stagnant water, respectively. Technical and formulated malathion and spinosad had an inhibition effect on acetylcholinesterase, carboxylesterase, and glutathione S-transferase. The results proved that the prepared capsules consisting of biodegradable polymers containing larvicides could be effective as controlled-release formulation against C. pipiens larvae for a long period. Keywords: chitosan capsules, larvicide, controlled-release formulation, swelling, mosquitocidal activity, Culex pipiens, biochemical study

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

Larval Habitat Substrates Could Affect the Biology and Vectorial Capacity of Culex quinquefasciatus (Diptera: Culicidae).

Science.gov (United States)

Shah, Rizwan Mustafa; Ali, Qasim; Alam, Mehboob; Shad, Sarfraz Ali; Majeed, Shahid; Riaz, Muhammad; Binyameen, Muhammad

2017-05-01

Culex quinquefasciatus Say is an important disease vector throughout much of the world. Experiments were conducted to determine the effects of different larval habitat substrates on the fitness and biting efficiency of Cx. quinquefasciatus adults. Our findings indicate that the development time (egg to adult) of larvae reared in irrigation water was 8.63 d while that of larvae reared in distilled water was 17.10 d (Effect size = 0.95). However, the rate of adult emergence was similar for all the tested treatments. Furthermore, the mean weight of an egg raft varied between larval habitats: distilled water (1.83 mg), rainfall water (1.25 mg), irrigation water (1.52 mg), and sewerage water (2.52 mg) (Effect size = 0.91). But, the fecundity (eggs per female) and hatchability (%) were statistically similar in all the rearing mediums (Effect size = 0.79). Longevity of females in all the tested populations did not differ significantly (Effect size = 0.91). The mean relative growth rates of larvae reared in tap water (0.80) and distilled water (0.86) habitats were lower than growth rates in all other rearing habitats (Effect size = 0.96). The intrinsic rate of natural increase in tap water (0.27) and irrigation water (0.35) was significantly higher than that in distilled water (0.09) and sewerage water (0.16) (Effect size = 0.84). Adults reared in rain water had the highest biting efficiency among all the tested populations. These results provide useful information for the management of Cx. quinquefasciatus. © 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.

Infection dynamics of western equine encephalomyelitis virus (Togaviridae: Alphavirus) in four strains of Culex tarsalis (Diptera: Culicidae): an immunocytochemical study.

Science.gov (United States)

Oviedo, Marco V Neira; Romoser, William S; James, Calvin Bl; Mahmood, Farida; Reisen, William K

2011-04-18

BACKGROUND: Vector competence describes the efficiency with which vector arthropods become infected with and transmit pathogens and depends on interactions between pathogen and arthropod genetics as well as environmental factors. For arbovirus transmission, the female mosquito ingests viremic blood, the virus infects and replicates in midgut cells, escapes from the midgut, and disseminates to other tissues, including the salivary glands. Virus-laden saliva is then injected into a new host. For transmission to occur, the virus must overcome several "barriers", including barriers to midgut infection and/or escape and salivary infection and/or escape. By examining the spatial/temporal infection dynamics of Culex tarsalis strains infected with western equine encephalomyelitis virus (WEEV), we identified tissue tropisms and potential tissue barriers, and evaluated the effects of viral dose and time postingestion. METHODS: Using immunostained paraffin sections, WEEV antigens were tracked in four Cx. tarsalis strains: two recently colonized California field strains - Coachella Valley, Riverside County (COAV) and Kern National Wildlife Refuge (KNWR); and two laboratory strains selected for WEEV susceptibility (high viremia producer, HVP), and WEEV resistance (WR). RESULTS AND CONCLUSIONS: Tissues susceptible to WEEV infection included midgut epithelium, neural ganglia, trachea, chorionated eggs, and salivary glands. Neuroendocrine cells in the retrocerebral complex were occasionally infected, indicating the potential for behavioral effects. The HVP and COAV strains vigorously supported viral growth, whereas the WR and KNWR strains were less competent. Consistent with earlier studies, WEEV resistance appeared to be related to a dose-dependent midgut infection barrier, and a midgut escape barrier. The midgut escape barrier was not dependent upon the ingested viral dose. Consistent with midgut infection modulation, disseminated infections were less common in the WR and KNWR

Determination of Mosquitoes Fauna (Culicidae: Diptera in Poldokhtar County of Lorestan Province, 2015

Directory of Open Access Journals (Sweden)

Zahirnia A H

2017-09-01

. mimeticus, Cx. perexiguus, Cx. hortensis, Cx. pipiens, Cx. sitiens, Cx. tritaeniorhynchus, Culiseta langiareolata, Anopheles superpictus An. stephensi, An. turkhudi and An. dthali.Culex pipiens (19.9.5% and Culex theileri (19.5% were the most abundant species, respectively. Conclusion: The results of this study indicate the presence of various species of mosquitoes throughout the city of Poldokhtar. Also, the results can lay the groundwork for doing more comprehensive and special studies particularly regarding the possible role of different species of mosquitoes in human and animal health in the future.

Genetic Characterization of Spondweni and Zika Viruses and Susceptibility of Geographically Distinct Strains of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus (Diptera: Culicidae to Spondweni Virus.

Directory of Open Access Journals (Sweden)

Andrew D Haddow

2016-10-01

Full Text Available Zika virus (ZIKV has extended its known geographic distribution to the New World and is now responsible for severe clinical complications in a subset of patients. While substantial genetic and vector susceptibility data exist for ZIKV, less is known for the closest related flavivirus, Spondweni virus (SPONV. Both ZIKV and SPONV have been known to circulate in Africa since the mid-1900s, but neither has been genetically characterized by gene and compared in parallel. Furthermore, the susceptibility of peridomestic mosquito species incriminated or suspected in the transmission of ZIKV to SPONV was unknown.In this study, two geographically distinct strains of SPONV were genetically characterized and compared to nine genetically and geographically distinct ZIKV strains. Additionally, the susceptibility of both SPONV strains was determined in three mosquito species. The open reading frame (ORF of the SPONV 1952 Nigerian Chuku strain, exhibited a nucleotide and amino acid identity of 97.8% and 99.2%, respectively, when compared to the SPONV 1954 prototype South African SA Ar 94 strain. The ORF of the SPONV Chuku strain exhibited a nucleotide and amino acid identity that ranged from 68.3% to 69.0% and 74.6% to 75.0%, respectively, when compared to nine geographically and genetically distinct strains of ZIKV. The ORF of the nine African and Asian lineage ZIKV strains exhibited limited nucleotide divergence. Aedes aegypti, Ae. albopictus and Culex quinquefasciatus susceptibility and dissemination was low or non-existent following artificial infectious blood feeding of moderate doses of both SPONV strains.SPONV and ZIKV nucleotide and amino acid divergence coupled with differences in geographic distribution, ecology and vector species support previous reports that these viruses are separate species. Furthermore, the low degree of SPONV infection or dissemination in Ae. albopictus, Ae. aegypti and Cx. quinquefasciatus following exposure to two

Larvicidal potential of some plants from West Africa against Culex quinquefasciatus (Say) and Anopheles gambiae Giles (Diptera: Culicidae).

Science.gov (United States)

Azokou, Alain; Koné, Mamidou W; Koudou, Benjamin G; Tra Bi, Honora F

2013-01-01

Mosquitoes increased resistance to insecticides, and environmental concerns about the use of insecticides, pose a major challenge in the search for new molecules to deplete and incapacitate mosquito populations. Plants are the valuable source as practices consisting in exploiting plant materials as repellents, and are still in wide use throughout developing countries. The aim of the present study was to screen plants from Cτte d'Ivoire for larvicidal activity against mosquitoes. Resistant and sensitive larvae (III and IV instar) of Anopheles gambiae and Culex quinquefasciatus were exposed to crude ethanol extracts (90%) of 45 plants and viability observed after 30 min, 6, 12 and 24 h postincubation. After partition of active extracts, each fraction (hexane and chloroform washed with NaCl 1%, tannins and aqueous) was tested using the same protocol at various concentrations (1000- 31.2 ppm). Of 49 extracts tested, 7 exhibited high potential (LC50 = 80 to 370 ppm) against resistant and sensitive III and IV instar larvae of An. gambiae and Cx. quinquefasciatus. These extracts were from Cissus populnea, Cochlospermum planchonii, Heliotropium indicum, Phyllanthus amarus, Vitex grandifolia and Alchornea cordifolia. However, three most active plant species (LC50 = 80- 180 ppm) were Cs. populnea, Cm. planchonii and P. amarus Their hexane and chloroform fractions showed high larvicidal activity. This study demonstrated that plants from Cτte d'Ivoire have a real potential for malaria, yellow fever, filarial and dengue vector control. Those could be used as sources or provide lead compounds for the development of safe plant-based biocides.

The effects of climate change and globalization on mosquito vectors: evidence from Jeju Island, South Korea on the potential for Asian tiger mosquito (Aedes albopictus influxes and survival from Vietnam rather than Japan.

Directory of Open Access Journals (Sweden)

Su Hyun Lee

Full Text Available BACKGROUND: Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change. METHODS AND RESULTS: In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan. CONCLUSION: Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter

A survey of mosquitoes breeding in used tires in Spain for the detection of imported potential vector species.

Science.gov (United States)

Roiz, D; Eritja, R; Escosa, R; Lucientes, J; Marquès, E; Melero-Alcíbar, R; Ruiz, S; Molina, R

2007-06-01

The used tire trade has facilitated the introduction, spread, and establishment of the Asian tiger mosquito, Aedes albopictus, and other mosquito species in several countries of America, Africa, Oceania, and Europe. A strategy for detecting these imported mosquito vectors was developed in Spain during 2003-2004 by EVITAR (multidisciplinary network for the study of viruses transmitted by arthropods and rodents). A survey in 45 locations found no invasive species. Eight autochthonous species of mosquitoes were detected in used tires, including Culex pipiens, Cx. hortensis, Cx. modestus, Anopheles atroparvus, An. claviger, Culiseta longiareolata, Cs. annulata, and Aedes caspius. Dominant species were Cx. pipiens and Cs. longiareolata. Aedes caspius was found in only once, near its natural breeding habitat. Considering the recent discovery of an established population of Ae. albopictus in Catalonia, the increasing commerce of used tires in Spain for recycling, storage, and recapping might greatly contribute to the rapid spread of this species across the Iberian Peninsula.

Essential Oils of Satureja Species: Insecticidal Effect on Culex pipiens Larvae (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Nikos G. Chorianopoulos

2007-12-01

Full Text Available The chemical composition of the essential oils of the wild growing plants of Greek S. spinosa L., S. parnassica subsp. parnassica Heldr.& Sart ex Boiss., S. thymbra and S. montana were determined by GC and GC/MS analysis. The larvicidal activities of the essential oils were assayed against Culex pipiens biotype molestus. The analytical data indicated that various monoterpene hydrocarbons and phenolic monoterpenes constitute the major constituents of the oils, but their concentration varied greatly among the oils examined. The bioassay results indicated that the oils possess significant larvicidal activities and represent an inexpensive source of natural substances mixture that exhibit potentials for use to control the mosquito larvae.

Statistical modeling of the abundance of vectors of West African Rift Valley fever in Barkédji, Senegal.

Directory of Open Access Journals (Sweden)

Cheikh Talla

Full Text Available Rift Valley fever is an emerging mosquito-borne disease that represents a threat to human and animal health. The exophilic and exophagic behavior of the two main vector in West Africa (Aedes vexans and Culex poicilipes, adverse events post-vaccination, and lack of treatment, render ineffective the disease control. Therefore it is essential to develop an information system that facilitates decision-making and the implementation of adaptation strategies. In East Africa, RVF outbreaks are linked with abnormally high rainfall, and can be predicted up to 5 months in advance by modeling approaches using climatic and environmental parameters. However, the application of these models in West Africa remains unsatisfactory due to a lack of data for animal and human cases and differences in the dynamics of the disease emergence and the vector species involved in transmission. Models have been proposed for West Africa but they were restricted to rainfall impact analysis without a spatial dimension. In this study, we developed a mixed Bayesian statistical model to evaluate the effects of climatic and ecological determinants on the spatiotemporal dynamics of the two main vectors. Adult mosquito abundance data were generated from July to December every fortnight in 2005-2006 at 79 sites, including temporary ponds, bare soils, shrubby savannah, wooded savannah, steppes, and villages in the Barkédji area. The results demonstrate the importance of environmental factors and weather conditions for predicting mosquito abundance. The rainfall and minimum temperature were positively correlated with the abundance of Cx. poicilipes, whereas the maximum temperature had negative effects. The rainfall was negatively correlated with the abundance of Ae. vexans. After combining land cover classes, weather conditions, and vector abundance, our model was used to predict the areas and periods with the highest risks of vector pressure. This information could support decision

Trial of spatial repellency of metofluthrin impregnated paper strip against Anopheles and Culex in shelters without walls in Lombok, Indonesia

OpenAIRE

Kawada, Hitoshi; Maekawa, Yoshihide; Tsuda, Yoshio; Takagi, Masahiro

2004-01-01

TriaIs of metofluthrin-impregnated multilayer paper strips against mosquitoes in shelters with no walls were carried out at 3 sites in Lombok, Indonesia. Major reductions in human biting by Culex quinquefasciatus,Anopheles balabacensis, and An. sundaicus were achieved. The device is a very praitical measure of preventing outdoor mosquito biting, with no need for electricity or heating to evaporate its active ingredient.

Trial of spatial repellency of metofluthrin-impregnated paper strip against Anopheles and Culex in shelters without walls in Lombok, Indonesia.

Science.gov (United States)

Kawada, Hitoshi; Maekawa, Yoshihide; Tsuda, Yoshio; Takagi, Masahiro

2004-12-01

Trials of metofluthrin-impregnated multilayer paper strips against mosquitoes in shelters with no walls were carried out at 3 sites in Lombok, Indonesia. Major reductions in human biting by Culex quinquefasciatus, Anopheles balabacensis, and An. sundaicus were achieved. The device is a very practical measure of preventing outdoor mosquito biting, with no need for electricity or heating to evaporate its active ingredient.

Composition and Genetic Diversity of Mosquitoes (Diptera: Culicidae) on Islands and Mainland Shores of Kenya’s Lakes Victoria and Baringo

Science.gov (United States)

Ajamma, Yvonne Ukamaka; Villinger, Jandouwe; Omondi, David; Salifu, Daisy; Onchuru, Thomas Ogao; Njoroge, Laban; Muigai, Anne W. T.; Masiga, Daniel K.

2016-01-01

The Lake Baringo and Lake Victoria regions of Kenya are associated with high seroprevalence of mosquito-transmitted arboviruses. However, molecular identification of potential mosquito vector species, including morphologically identified ones, remains scarce. To estimate the diversity, abundance, and distribution of mosquito vectors on the mainland shores and adjacent inhabited islands in these regions, we collected and morphologically identified adult and immature mosquitoes and obtained the corresponding sequence variation at cytochrome c oxidase 1 (COI) and internal transcribed spacer region 2 (ITS2) gene regions. A total of 63 species (including five subspecies) were collected from both study areas, 47 of which have previously been implicated as disease vectors. Fourteen species were found only on island sites, which are rarely included in mosquito diversity surveys. We collected more mosquitoes, yet with lower species composition, at Lake Baringo (40,229 mosquitoes, 32 species) than at Lake Victoria (22,393 mosquitoes, 54 species). Phylogenetic analysis of COI gene sequences revealed Culex perexiguus and Cx. tenagius that could not be distinguished morphologically. Most Culex species clustered into a heterogeneous clade with closely related sequences, while Culex pipiens clustered into two distinct COI and ITS2 clades. These data suggest limitations in current morphological identification keys. This is the first DNA barcode report of Kenyan mosquitoes. To improve mosquito species identification, morphological identifications should be supported by their molecular data, while diversity surveys should target both adults and immatures. The diversity of native mosquito disease vectors identified in this study impacts disease transmission risks to humans and livestock. PMID:27402888

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

Identification of the temperature- induced larvicidal efficacy of Agave angustifolia against Aedes, Culex and Anopheles larvae

Directory of Open Access Journals (Sweden)

Mithilesh eKajla

2016-01-01

Full Text Available Synthetic insecticides are generally employed to control the mosquito population. However, their injudicious over usage and non-biodegradability are associated with many adverse effects on the environment and mosquitoes. The application of environment-friendly mosquitocidals might be an alternate to overcome these issues. In this study, we found that organic or aqueous extracts of Agave angustifolia leaves exhibited a strong larvicidal activity (LD50 28.27 µg/ml against Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi larvae within a short exposure of 12h. The larvicidal activity of Agave angustifolia is inherited and independent of the plants vegetative growth. Interestingly, the plant larvicidal activity was observed exclusively during the summer season (April-August, when outside temperature is between 30oC to 50oC and it was significantly reduced during winter season (December-February, when the outside temperature falls to ~4oC or lower. Thus, we hypothesized that the larvicidal components of Agave angustifolia might be induced by the manipulation of environmental temperature and should be resistant to the hot conditions. We found that the larvicidal activity of Agave angustifolia was induced when plants were maintained at 37oC in a semi-natural environment against the controls that were growing outside in cold weather. Pre-incubation of Agave angustifolia extract at 100oC for 1h killed 60% larvae in 12h, which gradually increased to 100% mortality after 24h. In addition, the dry powder formulation of Agave angustifolia, also displayed a strong larvicidal activity after a long shelf life. Together, these findings revealed that Agave angustifolia is an excellent source of temperature induced bioactive metabolites that may assist the preparedness for vector control programs competently.

Bromeliad-inhabiting mosquitoes in an urban botanical garden of dengue endemic Rio de Janeiro. Are bromeliads productive habitats for the invasive vectors Aedes aegypti and Aedes albopictus?

Science.gov (United States)

Mocellin, Márcio Goulart; Simões, Taynãna César; do Nascimento, Teresa Fernandes Silva; Teixeira, Maria Lucia França; Lounibos, Leon Philip; de Oliveira, Ricardo Lourenço

2012-01-01

Immatures of both Aedes aegypti and Aedes albopictus have been found in water-holding bromeliad axils in Brazil. Removal of these plants or their treatment with insecticides in public and private gardens have been undertaken during dengue outbreaks in Brazil despite uncertainty as to their importance as productive habitats for dengue vectors. From March 2005-February 2006, we sampled 120 randomly selected bromeliads belonging to 10 species in a public garden less than 200 m from houses in a dengue-endemic neighborhood in Rio de Janeiro. A total of 2,816 mosquito larvae and pupae was collected, with an average of 5.87 immatures per plant per collection. Culex (Microculex) pleuristriatus and Culex spp of the Ocellatus Group were the most abundant culicid species, found in all species of bromeliads; next in relative abundance were species of the genus Wyeomyia. Only two individuals of Ae. aegypti (0.07%) and five of Ae. albopictus (0.18%) were collected from bromeliads. By contrast, immatures of Ae. aegypti were found in manmade containers in nearly 5% of nearby houses. These results demonstrate that bromeliads are not important producers of Ae. aegypti and Ae. albopictus and, hence, should not be a focus for dengue control. However, the results of this study of only one year in a single area may not represent outcomes in other urban localities where bromeliads, Ae. aegypti and dengue coincide in more disturbed habitats. PMID:20140379

Bromeliad-inhabiting mosquitoes in an urban botanical garden of dengue endemic Rio de Janeiro--are bromeliads productive habitats for the invasive vectors Aedes aegypti and Aedes albopictus?

Science.gov (United States)

Mocellin, Márcio Goulart; Simões, Taynãna César; Nascimento, Teresa Fernandes Silva do; Teixeira, Maria Lucia França; Lounibos, Leon Philip; Oliveira, Ricardo Lourenço de

2009-12-01

Immatures of both Aedes aegypti and Aedes albopictus have been found in water-holding bromeliad axils in Brazil. Removal of these plants or their treatment with insecticides in public and private gardens have been undertaken during dengue outbreaks in Brazil despite uncertainty as to their importance as productive habitats for dengue vectors. From March 2005-February 2006, we sampled 120 randomly selected bromeliads belonging to 10 species in a public garden less than 200 m from houses in a dengue-endemic neighborhood in Rio de Janeiro. A total of 2,816 mosquito larvae and pupae was collected, with an average of 5.87 immatures per plant per collection. Culex (Microculex) pleuristriatus and Culex spp of the Ocellatus Group were the most abundant culicid species, found in all species of bromeliads; next in relative abundance were species of the genus Wyeomyia. Only two individuals of Ae. aegypti (0.07%) and five of Ae. albopictus(0.18%) were collected from bromeliads. By contrast, immatures of Ae. aegypti were found in manmade containers in nearly 5% of nearby houses. These results demonstrate that bromeliads are not important producers of Ae. aegypti and Ae. albopictus and, hence, should not be a focus for dengue control. However, the results of this study of only one year in a single area may not represent outcomes in other urban localities where bromeliads, Ae. aegypti and dengue coincide in more disturbed habitats.

Bromeliad-inhabiting mosquitoes in an urban botanical garden of dengue endemic Rio de Janeiro - Are bromeliads productive habitats for the invasive vectors Aedes aegypti and Aedes albopictus?

Directory of Open Access Journals (Sweden)

Márcio Goulart Mocellin

2009-12-01

Full Text Available Immatures of both Aedes aegypti and Aedes albopictus have been found in water-holding bromeliad axils in Brazil. Removal of these plants or their treatment with insecticides in public and private gardens have been undertaken during dengue outbreaks in Brazil despite uncertainty as to their importance as productive habitats for dengue vectors. From March 2005-February 2006, we sampled 120 randomly selected bromeliads belonging to 10 species in a public garden less than 200 m from houses in a dengue-endemic neighborhood in Rio de Janeiro. A total of 2,816 mosquito larvae and pupae was collected, with an average of 5.87 immatures per plant per collection. Culex (Microculex pleuristriatus and Culex spp of the Ocellatus Group were the most abundant culicid species, found in all species of bromeliads; next in relative abundance were species of the genus Wyeomyia. Only two individuals of Ae. aegypti (0.07% and five of Ae. albopictus(0.18% were collected from bromeliads. By contrast, immatures of Ae. aegypti were found in manmade containers in nearly 5% of nearby houses. These results demonstrate that bromeliads are not important producers of Ae. aegypti and Ae. albopictus and, hence, should not be a focus for dengue control. However, the results of this study of only one year in a single area may not represent outcomes in other urban localities where bromeliads, Ae. aegypti and dengue coincide in more disturbed habitats.

Urban mosquito species (Diptera: Culicidae of dengue endemic communities in the Greater Puntarenas area, Costa Rica

Directory of Open Access Journals (Sweden)

Olger Calderón-Arguedas

2009-12-01

Full Text Available Field studies were conducted to determine the mosquito species richness in the urban area of Greater Puntarenas in Costa Rica. Two cross-sectional entomological surveys were performed in seven localities of Puntarenas: one survey was performed during the wet season and the other during the dry season. The sections evaluated were determined by applying a stratified cluster sampling method using satellite imagery, and a sample of 26 cells (100x100m was selected for the study. The number of cells per locality was proportional to the area of each locality. The presence of mosquito larvae and pupae in water-filled artificial and natural containers was determined in each cell. Infestation was expressed as a diversity index per type of container (Ii. Eight types of larvae were identified (Aedes aegypti, Culex quinquefasciatus, Culex interrogator, Culex nigripalpus, Culex corniger, Culex tarsalis, Limatus durhamii and Toxorhynchites theobaldi and in two cases it was only possible to identify the genus (Culex sp. and Uranotaenia sp.. A. aegypti was the most common species followed by C. quinquefascitus. Diversity of wet environments can explain the co-occurrence of various culicid species in some localities. Although A. aegypti is the only documented disease vector in the area, C quinquefasciatus, C. nigripalpus, and the other species of Culex could be considered potential vectors of other pathogens. The presence and ecology of all mosquito species should be studied to optimize surveillance and prevention of dengue and to prevent the emergence of other mosquito-transmitted diseases. Rev. Biol. Trop. 57 (4: 1223-1234. Epub 2009 December 01.La riqueza de especies de mosquitos urbanos de la Gran Puntarenas (Puntarenas, Costa Rica fue evaluada por medio de análisis larvales. Dos encuestas entomológicas fueron realizadas en siete localidades de la Gran Puntarenas durante un año. Una de las encuestas fue realizada en la estación seca y la otra se llevó a

Mammal decline, linked to invasive Burmese python, shifts host use of vector mosquito towards reservoir hosts of a zoonotic disease.

Science.gov (United States)

Hoyer, Isaiah J; Blosser, Erik M; Acevedo, Carolina; Thompson, Anna Carels; Reeves, Lawrence E; Burkett-Cadena, Nathan D

2017-10-01

Invasive apex predators have profound impacts on natural communities, yet the consequences of these impacts on the transmission of zoonotic pathogens are unexplored. Collapse of large- and medium-sized mammal populations in the Florida Everglades has been linked to the invasive Burmese python, Python bivittatus Kuhl. We used historic and current data to investigate potential impacts of these community effects on contact between the reservoir hosts (certain rodents) and vectors of Everglades virus, a zoonotic mosquito-borne pathogen that circulates in southern Florida. The percentage of blood meals taken from the primary reservoir host, the hispid cotton rat, Sigmodon hispidus Say and Ord, increased dramatically (422.2%) from 1979 (14.7%) to 2016 (76.8%), while blood meals from deer, raccoons and opossums decreased by 98.2%, reflecting precipitous declines in relative abundance of these larger mammals, attributed to python predation. Overall species diversity of hosts detected in Culex cedecei blood meals from the Everglades declined by 40.2% over the same period ( H (1979) = 1.68, H (2016) = 1.01). Predictions based upon the dilution effect theory suggest that increased relative feedings upon reservoir hosts translate into increased abundance of infectious vectors, and a corresponding upsurge of Everglades virus occurrence and risk of human exposure, although this was not tested in the current study. This work constitutes the first indication that an invasive predator can increase contact between vectors and reservoirs of a human pathogen and highlights unrecognized indirect impacts of invasive predators. © 2017 The Author(s).

Prevalence and distribution of pox-like lesions, avian malaria, and mosquito vectors in Kipahulu valley, Haleakala National Park, Hawai'i, USA

Science.gov (United States)

Aruch, Samuel; Atkinson, Carter T.; Savage, Amy F.; LaPointe, Dennis

2007-01-01

We determined prevalence and altitudinal distribution of introduced avian malarial infections (Plasmodium relictum) and pox-like lesions (Avipoxvirus) in forest birds from Kīpahulu Valley, Haleakalā National Park, on the island of Maui, and we identified primary larval habitat for the mosquito vector of this disease. This intensively managed wilderness area and scientific reserve is one of the most pristine areas of native forest remaining in the state of Hawai‘i, and it will become increasingly important as a site for restoration and recovery of endangered forest birds. Overall prevalence of malarial infections in the valley was 8% (11/133) in native species and 4% (4/101) in nonnative passerines; prevalence was lower than reported for comparable elevations and habitats elsewhere in the state. Infections occurred primarily in ‘Apapane (Himatione sanguinea) and Hawai‘i ‘Amakihi (Hemignathus virens) at elevations below 1,400 m. Pox-like lesions were detected in only two Hawai‘i ‘Amakihi (2%; 2/94) at elevations below 950 m. We did not detect malaria or pox in birds caught at 1,400 m in upper reaches of the valley. Adult mosquitoes (Culex quinquefasciatus) were captured at four sites at elevations of 640, 760, 915, and 975 m, respectively. Culex quinquefasciatus larvae were found only in rock holes along intermittent tributaries of the two largest streams in the valley, but not in standing surface water, pig wallows, ground pools, tree cavities, and tree fern cavities. Mosquito populations in the valley are low, and they are probably influenced by periods of high rainfall that flush stream systems.

Insecticides resistance in the Culex quinquefasciatus populations from northern Thailand and possible resistance mechanisms.

Science.gov (United States)

Yanola, Jintana; Chamnanya, Saowanee; Lumjuan, Nongkran; Somboon, Pradya

2015-09-01

The mosquito vector Culex quinquefasciatus is known to be resistant to insecticides worldwide, including Thailand. This study was the first investigation of the insecticide resistance mechanisms, involving metabolic detoxification and target site insensitivity in C. quinquefasciatus from Thailand. Adult females reared from field-caught larvae from six provinces of northern Thailand were determined for resistant status by exposing to 0.05% deltamethrin, 0.75% permethrin and 5% malathion papers using the standard WHO susceptibility test. The overall mortality rates were 45.8%, 11.4% and 80.2%, respectively. A fragment of voltage-gated sodium channel gene was amplified and sequenced to identify the knock down resistance (kdr) mutation. The ace-1 gene mutation was determined by using PCR-RFLP. The L1014F kdr mutation was observed in all populations, but the homozygous mutant F/F1014 genotype was found only in two of the six provinces where the kdr mutation was significantly correlated with deltamethrin resistance. However, none of mosquitoes had the G119S mutation in the ace-1 gene. A laboratory deltamethrin resistant strain, Cq_CM_R, has been established showing a highly resistant level after selection for a few generations. The mutant F1014 allele frequency was significantly increased after one generation of selection. A synergist assay was performed to assess the metabolic detoxifying enzymes. Addition of bis(4-nitrophenyl)-phosphate (BNPP) and diethyl maleate (DEM), inhibitors of esterases and glutathione S-transferases (GST), respectively, into the larval bioassay of the Cq_CM strain with deltamethrin showed no significant reduction. By contrast, addition of piperonyl butoxide (PBO), an inhibitor of cytochrome P450 monooxygenases, showed a 9-fold reduction of resistance. Resistance to pyrethroids in C. quinquefasciatus is widely distributed in northern Thailand. This study reports for the first time for the detection of the L1014F kdr mutation in wild populations

Risk Factors for the Presence of Chikungunya and Dengue Vectors (Aedes aegypti and Aedes albopictus), Their Altitudinal Distribution and Climatic Determinants of Their Abundance in Central Nepal

Science.gov (United States)

Dhimal, Meghnath; Gautam, Ishan; Joshi, Hari Datt; O’Hara, Robert B.; Ahrens, Bodo; Kuch, Ulrich

2015-01-01

Background The presence of the recently introduced primary dengue virus vector mosquito Aedes aegypti in Nepal, in association with the likely indigenous secondary vector Aedes albopictus, raises public health concerns. Chikungunya fever cases have also been reported in Nepal, and the virus causing this disease is also transmitted by these mosquito species. Here we report the results of a study on the risk factors for the presence of chikungunya and dengue virus vectors, their elevational ceiling of distribution, and climatic determinants of their abundance in central Nepal. Methodology/Principal Findings We collected immature stages of mosquitoes during six monthly cross-sectional surveys covering six administrative districts along an altitudinal transect in central Nepal that extended from Birgunj (80 m above sea level [asl]) to Dhunche (highest altitude sampled: 2,100 m asl). The dengue vectors Ae. aegypti and Ae. albopictus were commonly found up to 1,350 m asl in Kathmandu valley and were present but rarely found from 1,750 to 2,100 m asl in Dhunche. The lymphatic filariasis vector Culex quinquefasciatus was commonly found throughout the study transect. Physiographic region, month of collection, collection station and container type were significant predictors of the occurrence and co-occurrence of Ae. aegypti and Ae. albopictus. The climatic variables rainfall, temperature, and relative humidity were significant predictors of chikungunya and dengue virus vectors abundance. Conclusions/Significance We conclude that chikungunya and dengue virus vectors have already established their populations up to the High Mountain region of Nepal and that this may be attributed to the environmental and climate change that has been observed over the decades in Nepal. The rapid expansion of the distribution of these important disease vectors in the High Mountain region, previously considered to be non-endemic for dengue and chikungunya fever, calls for urgent actions to

Repellency of essential oils extracted from Thai native plants against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say).

Science.gov (United States)

Phukerd, Ubol; Soonwera, Mayura

2014-09-01

Repellent activity of essential oils derived from 10 Thai native plants, belonging to three families were evaluated against female Aedes aegypti and Culex quinquefasciatus and to compare them with a commercial chemical repellents (DEET; N,N-diethyl-3-methylbenzamide 20% w/w; Sketolene Shield). Each test repellent was applied at 1, 5, and 10% concentrations for testing by arm in cage method. The results showed significant differences in repellency among the repellents by mosquito species. The protection time of the essential oils against Ae. aegypti ranged from 3 to 30 min. According to the Culex mosquito, it showed the protection time ranged from 3 to 260 min. 10 % Boesenbergia rotunda essential oil provided the best efficiency, in which protection time was 4.3 h as equal as DEET. The essential oils which exhibited protection time more than 2 h were those of 10% Zingiber zerumbet, Litsea petiolata, Curcuma zedoaria, and Zingiber cassumunar essential oils (3.1, 2.8, 2.6, and 2.3 h, respectively). The biting percentage ranged from 0.9 to 18.0% and 0.8 to 3.6% against Ae. aegypti and Cx. quinquefasciatus, respectively. The results revealed that the potential of essential oil extracted from B. rotunda, Z. zerumbet, L. petiolata, C. zedoaria, and Z. cassumunar had attributes of good repellent and deterred biting. We recommend the five essential oils for further study to develop as commercial repellents.

Larvicidal potential of Asteraceae family endophytic actinomycetes against Culex quinquefasciatus mosquito larvae.

Science.gov (United States)

Tanvir, Rabia; Sajid, Imran; Hasnain, Shahida

2014-01-01

Pakistan is blessed with plants of Asteraceae family with known medicinal background used for centuries by Hakims (traditional physicians). Keeping in mind the background of their anti-larval potential, a total of 21 endophytic actinomycetes were isolated from four Asteraceae plants and screened against the first and fourth instar stages of Culex quinquefasciatus Say mosquito larvae. Of the 21 isolates, 6 of them gave strong larvicidal activity (80-100% mortality) in the screening results and 4 isolates gave a potent larvicidal activity (100% mortality) at the fourth instar stage. These isolates belonged to different species within the actinomycetes group, namely Streptomyces albovinaceus and Streptomyces badius. This communication reports the larvicidal potential of endophytic actinomycetes residing within the native Asteraceae plants in Pakistan. The study suggests further exploration through large-scale productions leading to the identification of the larvicidal compounds.

Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae)

International Nuclear Information System (INIS)

Sorensen, Mary A.; Jensen, Peter D.; Walton, William E.; Trumble, John T.

2006-01-01

Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC 5 s values for perchlorate and chromium were 74 ± 8.0 mg/L and 0.41 ± 0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC 5 values for perchlorate and Cr (VI) were 17,000 ± 3200 and 38 ± 1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes. - While pollution with hexavalent chromium may adversely affect Culex quinquefasciatus larvae, levels of perchlorate currently in the environment will not impact these insects

Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae)

Energy Technology Data Exchange (ETDEWEB)

Sorensen, Mary A. [Department of Entomology, University of California, Riverside, CA 92521 (United States)]. E-mail: mary.sorensen@email.ucr.edu; Jensen, Peter D. [Department of Entomology, University of California, Riverside, CA 92521 (United States); Walton, William E. [Department of Entomology, University of California, Riverside, CA 92521 (United States); Trumble, John T. [Department of Entomology, University of California, Riverside, CA 92521 (United States)

2006-12-15

Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC{sub 5}s values for perchlorate and chromium were 74 {+-} 8.0 mg/L and 0.41 {+-} 0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC{sub 5} values for perchlorate and Cr (VI) were 17,000 {+-} 3200 and 38 {+-} 1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes. - While pollution with hexavalent chromium may adversely affect Culex quinquefasciatus larvae, levels of perchlorate currently in the environment will not impact these insects.

EFEKTIVITAS Bacillus thuringiensis H-14 STRAIN LOKAL DALAM BUAH KELAPA TERHADAP LARVA Anopheles sp dan Culex sp di KAMPUNG LAUT KABUPATEN CILACAP

Directory of Open Access Journals (Sweden)

Blondine Ch. P

2013-07-01

Full Text Available Abstrak Bacillus thuringiensis serotipe H-14 strain lokal adalah bakteri patogen bersifat target spesifiknya larva nyamuk, aman bagi mamalia dan lingkungan. Penelitian bertujuan menentukan efektivitas B. thuringiensis H-14 strain lokal yang dikembangbiakkan dalam buah kelapa untuk pengendalian larva Anopheles sp dan Culex sp. Rancangan eksperimental semu, terdiri dari kelompok perlakuan dan kontrol. Bacillus thuringiensis H-14 strain lokal dikembangbiakan dalam10 buah kelapa umur 6–8 bulan, dengan berat kira-kira 1 kg, telah berisi air kelapa sekitar 400-500 ml/buah kelapa yang diperoleh dari Desa Klaces, Kampung Laut, Kabupaten Cilacap. Diinkubasi selama 14 hari pada temperatur kamar dan ditebarkan di 6 kolam yang menjadi habitat perkembangbiakan larva nyamuk dengan luas berkisar 3–100 m2.Hasil yang diperoleh menunjukkan efektivitas B. thuringiensis H-14 strain lokal terhadap larva Anopheles sp dan Culex sp selama 1 hari sesudah penebaran kematian larva berturut-turut sebesar 80–100% dan 79,31–100%. Sedangkan pada hari ke-14 sebesar 69,30–76,71% dan 67,69–86,04%. Buah kelapa dapat digunakan sebagai media lokal alternatif untuk pengembangbiakan B. thuringiensis H-14 strain lokal Kata kunci: B. thuringiensis H-14,  strain  lokal, buah kelapa, pengendalian larva Abstract Bacillus thuringiensis serotype H-14 local strain is pathogenic bacteria which specific  target to mosquito larvae. It is safe for mammals and enviroment. The aims of this study was to determine the effectivity of B. thuringiensis H-14 local strain which culturing in thecoconut wates against Anopheles sp and Culex sp mosquito larvae. This research is quasi experiment which consist of treated  and control groups. Bacillus thuringiensis H-14 local strain was cultured in 10 coconuts with 6–8 months age with weight around 1 kg that contained were approximately 400-500 ml/coconut were taken from Klaces village, Kampung Laut. After that the coconuts incubated for 14

Studies on some species of Culex (Melanoconion, with the description of a new one from Southern Brazil (Diptera: Culicidae Estudos sobre algumas espécies de Culex (Melanoconion, com a descrição de uma nova, da região meridional do Brasil

Directory of Open Access Journals (Sweden)

Oswaldo Paulo Forattini

1987-04-01

Full Text Available Redescription of Culex (Melanoconion oedipus Root and of Cx. (Mel. plectoporpe Root, as well as the description of a new one, named Cx. (Mel. rabelloi, are made. The material was collected in S.Paulo State, Southern Brazil. The descriptions include adults, pupal and larval stages, illustrating the morphological aspects and with pictures of breeding places. Some data about known distribution and bionomics are presented, remarking that all the three species seem to be closely associated with artificial manmade enviroments.Redescreve-se a espécie Culex (Melanoconion oedipus Root e Cx. (Mel. plectoporpe Root, bem como descreve-se outra nova, denominada Cx. (Mel. rabelloi. O material de estudo foi coletado no Estado de São Paulo, Brasil. As descrições incluem as formas adultas, pupais e larvais, e são acompanhadas de ilustrações representativas desses estágios, além de aspectos de criadouros naturais. Apresentam-se também alguns dados sobre a distribuição geográfica, conhecida até agora, e de comportamento dessas espécies. Assinala-se que as evidências indicam apreciável adaptabilidade desses três culicídeos ao ambiente artificial humano.

Host-feeding patterns of native Culex pipiens and invasive Aedes albopictus mosquitoes (Diptera: Culicidae) in urban zones from Barcelona, Spain.

Science.gov (United States)

Muñnoz, Joaquin; Eritja, Roger; Alcaide, Miguel; Montalvo, Tomás; Soriguer, Ramón C; Figuerola, Jordi

2011-07-01

The feeding patterns of haematophagous arthropods are of major importance in the amplification and transmission of infectious disease agents to vertebrate hosts, including humans. The establishment of new vector populations in nonnative range might alter transmission networks. The Asian tiger mosquito Aedes albopictus (Skuse) represents an example of how an invasive species can alter the risk of viral transmission to humans. Blood meal molecular identification from two sympatric mosquito species (the invasive Ae. albopictus and the native Culex pipiens) was carried out by polymerase chain reaction-based methods. Samples were collected in Barcelona metropolitan area, Spain, from June to October 2009 as part of a monitoring-control program. Blood meals were identified to the species level in 30 Ae. albopictus and 43 Cx. pipiens. Ae. albopictus acquired blood exclusively from human hosts (100%), whereas Cx. pipiens fed on a diversity of avian and mammalian hosts, including 35.7% of blood meals from humans. Based on mosquito diet, our results suggest that the Ae. albopictus invasion in Spain might increase the risk of virus transmission to humans and could support local outbreaks of imported tropical viruses such as dengue and chikungunya. However, in the studied area, the presence of this invasive species would have a negligible effect on the transmission of zoonotic agents such as West Nile virus. However, Cx. pipiens could amplify and transmit West Nile virus, but avian contribution to its diet was lower than that reported in North America. Feeding patterns of these mosquito species may help to understand the flavivirus outbreaks recently reported in southwestern Europe.

Surveillance of Mosquitoes and Selected Arthropod-Borne Viruses in the Context of Milan EXPO 2015

Directory of Open Access Journals (Sweden)

Mario Chiari

2016-07-01

Full Text Available From 1 May 2015 to 31 October 2015 over 20 million visitors from all over the world visited the Universal Exhibition (EXPO hosted by Milan (Lombardy region, Italy, raising concerns about the possible introduction of mosquito-borne diseases from endemic countries. The entomological surveillance protocol performed in Lombardy over the last three years was implemented in the EXPO area and in the two major regional airports using both Center for Disease Control CO2 and Biogents Sentinel traps. This surveillance aimed to estimate the presence and densities of putative vectors, and also to support investigations, including the vector species involved and area of diffusion, on the local spread of Chikungunya, Dengue and West Nile viruses (WNV by competent vectors. From 3544 mosquitoes belonging to five different species, 28 pools of Culex spp. and 45 pools of Aedes spp. were screened for the presence of WNV, and for both Chikungunya and flaviviruses, respectively. The entomological surveillance highlighted a low density of potential vectors in the surveyed areas and did not reveal the presence of Chikungunya or Dengue viruses in the local competent vectors inside the EXPO area or in the two airports. In addition, the surveillance reported a low density of Culex spp. mosquitoes, which all tested negative for WNV.

Modeling Culex tarsalis abundance on the northern Colorado front range using a landscape-level approach.

Science.gov (United States)

Schurich, Jessica A; Kumar, Sunil; Eisen, Lars; Moore, Chester G

2014-03-01

Remote sensing and Geographic Information System (GIS) data can be used to identify larval mosquito habitats and predict species distribution and abundance across a landscape. An understanding of the landscape features that impact abundance and dispersal can then be applied operationally in mosquito control efforts to reduce the transmission of mosquito-borne pathogens. In an effort to better understand the effects of landscape heterogeneity on the abundance of the West Nile virus (WNV) vector Culex tarsalis, we determined associations between GIS-based environmental data at multiple spatial extents and monthly abundance of adult Cx. tarsalis in Larimer County and Weld County, CO. Mosquito data were collected from Centers for Disease Control and Prevention miniature light traps operated as part of local WNV surveillance efforts. Multiple regression models were developed for prediction of monthly Cx. tarsalis abundance for June, July, and August using 4 years of data collected over 2007-10. The models explained monthly adult mosquito abundance with accuracies ranging from 51-61% in Fort Collins and 57-88% in Loveland-Johnstown. Models derived using landscape-level predictors indicated that adult Cx. tarsalis abundance is negatively correlated with elevation. In this case, low-elevation areas likely more abundantly include habitats for Cx. tarsalis. Model output indicated that the perimeter of larval sites is a significant predictor of Cx. tarsalis abundance at a spatial extent of 500 m in Loveland-Johnstown in all months examined. The contribution of irrigated crops at a spatial extent of 500 m improved model fit in August in both Fort Collins and Loveland-Johnstown. These results emphasize the significance of irrigation and the manual control of water across the landscape to provide viable larval habitats for Cx. tarsalis in the study area. Results from multiple regression models can be applied operationally to identify areas of larval Cx. tarsalis production

Medical Entomology Project.

Science.gov (United States)

1983-01-01

placed on examples from the Africanus Subgroup as they are important vectors of Yellow Fever, Rift Valley Fever, Chickungunya and Zika viruses . Currently...Mosquitoes Neo tropical Malaria Anophe lea Culicidae Asia Arbovirus diseases Culex Vectors Africa Biosystematics Aedes 2 ABSTRACT AmA ME iMW0 6 N 0meormp...Research continues on the arbovirus vector groups of the subgenus Stegomqj, genus Aedes , of the African Region. 4.. N7 "’Vic ° ’. ,tlt Cobes ;D i SECURITY

[Feeding pattern of Rift Valley Fever virus vectors in Senegal. Implications in the disease epidemiology].

Science.gov (United States)

Ba, Y; Diallo, D; Dia, I; Diallo, M

2006-10-01

During the rainy season 2003, an entomological survey was undertaken in the Sahelian bioclimatic zone of the Ferlo area in northern Senegal, in order to evaluate the degree of interaction between Rift valley fever (RVF) virus vectors and domestic animals and to determine the role of natural vertebrate hosts in the transmission and maintenance cycle. The study of vector-host contact was carried out under bed net traps using man, cow, sheep, chicken as bait whereas the RVFV vectors-vertebrate host interactions were studied through the analysis by an ELISA technique of the origin of the blood meals from naturally engorged females collected by aspiration. Blood meals sources were determined using a set of eight antibodies. Overall, the different known RVFV vectors (Culex poicilipes, Aedes vexans and Aedes ochraceus) were opportunistic although the bovine-baited net was, as far the more effective trap with 53.6% of collected mosquitoes. It was followed by the sheep-baited net (16.7%), man-baited net (12.6%) and chicken-baited net (11.6%). The more effectiveness of the bovine-baited net confirms the degree of implication of this host in RVF epidemiology. The study of vector-hosts interactions in nature showed that among the 1,112 mosquito blood meals tested, 701 were identified of which 693 were from Aedes vexans. The percentage of non-reacting blood meal was 36.7% whereas 16.9 % of the blood meals were taken at least on two vertebrate hosts. Overall, 53.2% of the blood meals from Ae. vexans were taken on equine, 18.6% on bovines, 7.1% on sheep and 0.6% on human. No blood meal was taken on rodent. The greatest diversity was observed in August. These host feedings patterns show that although equine is known to play a minor role in RVF epidemiology a thorough attention should be made to this host with regard to the percentage of blood meals taken in this host. The low percentage of blood meals taken on human could probably explain the low human infection rate observed up

Influence of warming tendency on Culex pipiens population abundance and on the probability of West Nile fever outbreaks (Israeli Case Study: 2001-2005).

Science.gov (United States)

Paz, Shlomit; Albersheim, Iris

2008-03-01

Climate change and West Nile fever (WNV) are both subjects of global importance. Many mosquitoes and the diseases they carry, including West Nile virus (WNV), are sensitive to temperature increase. The current study analyzes the lag correlations between weather conditions (especially air temperature) and 1) Culex pipiens mosquito population abundance, and 2) WNF frequency in humans, between 2001 and 2005 in Israel. These 5 years follow a long period with a documented tendency for temperature increase in the hot season in the country. Monthly anomalies of minimum and maximum temperatures, relative seasonal rainfall contribution, mosquito samplings (hazard level), and WNF cases (hospital admission dates and patients' addresses) were analyzed. Logistic regression was calculated between the climatic data and the mosquito samples, as Spearman correlations and Pearson cross-correlations were calculated between daily temperature values (or daily precipitation amounts) and the hospital admission dates. It was found that the disease appearance reflects the population distribution, while the risk tends to escalate around the metropolis characterized by an urban heat island. Positive anomalies of the temperature during the study period appear to have facilitated the mosquito abundance and, consequently, the disease emergence in humans. An important finding is the potential influence of extreme heat in the early spring on the vector population increase and on the disease's appearance weeks later. Awareness of such situations at the beginning of the spring may help authorities to reduce the disease risk before it becomes a real danger.

Associative learning of odor with food- or blood-meal by Culex quinquefasciatus Say (Diptera: Culicidae)

Science.gov (United States)

Tomberlin, Jeffery K.; Rains, Glen C.; Allan, Sandy A.; Sanford, Michelle R.; Lewis, W. Joe

2006-11-01

The ability of many insects to learn has been documented. However, a limited number of studies examining associative learning in medically important arthropods has been published. Investigations into the associative learning capabilities of Culex quinquefasciatus Say were conducted by adapting methods commonly used in experiments involving Hymenoptera. Male and female mosquitoes were able to learn a conditioned stimulus that consisted of an odor not normally encountered in nature (synthetic strawberry or vanilla extracts) in association with an unconditioned stimulus consisting of either a sugar (males and females) or blood (females) meal. Such information could lead to a better understanding of the ability of mosquitoes to locate and select host and food resources in nature.

Biological studies on the tolerance of different developmental stages of the mosquito, Culex Pipiens to gamma radiation through the first five generations

Energy Technology Data Exchange (ETDEWEB)

Soliman, I Abul Yazid I

1993-12-31

The biological effects of irradiating of the immature stages of Culex Pipiens with chronic doses of gamma radiation in the successive generations were studied. The results obtained a re summarized as follow: A- Egg Irradiation. B- Larval Irradiation. C-Pupal Irradiation. D-Combined effect of irradiation and dimilin on (a) Egg stage. (b) Larval Stage. (c) Pupal Stage. 23 tabs.,19 figs.,86 refs. Thesis (Ms.c)

Comparative susceptibility of introduced forest-dwelling mosquitoes in Hawai'i to avian malaria, Plasmodium relictum

Science.gov (United States)

Lapointe, D.A.; Goff, M.L.; Atkinson, C.T.

2005-01-01

To identify potential vectors of avian malaria in Hawaiian native forests, the innate susceptibility of Aedes albopictus, Wyeomyia mitchellii, and Culex quinquefasciatus from 3 geographical sites along an altitudinal gradient was evaluated using local isolates of Plasmodium relictum. Mosquitoes were dissected 5-8 and 9-13 days postinfective blood meal and microscopically examined for oocysts and salivary-gland sporozoites. Sporogony was completed in all 3 species, but prevalence between species varied significantly. Oocysts were detected in 1-2% and sporozoites in 1-7% of Aedes albopictus that fed on infected ducklings. Wyeomyia mitchellii was slightly more susceptible, with 7-19% and 7% infected with oocysts and sporozoites, respectively. In both species, the median oocyst number was 5 or below. This is only the second Wyeomyia species reported to support development of a malarial parasite. Conversely, Culex quinquefasciatus from all 3 sites proved very susceptible. Prevalence of oocysts and sporozoites consistently exceeded 70%, regardless of gametocytemia or origin of the P. relictum isolate. In trials for which a maximum 200 oocysts were recorded, the median number of oocysts ranged from 144 to 200. It was concluded that Culex quinquefasciatus is the primary vector of avian malaria in Hawai'i. ?? American Society of Parasitologists 2005.

Effects of a larval mosquito biopesticide and Culex larvae on a freshwater nanophytoplankton (Selenastrum capricornatum) under axenic conditions.

Science.gov (United States)

Duguma, Dagne; Ortiz, Sara L; Lin, Youjian; Wilson, P Chris; Walton, William E

2017-06-01

The effects of microbial biopesticides used for mosquito control on autotrophic microorganisms such as nanophytoplankton are equivocal. We examined impacts of mosquito biopesticides and mosquito larvae on primary producers in two independent experiments. In the first experiment, we examined the effects of a commonly used microbial biopesticide formulation (VectoMax ® CG) on a unicellular microalga, Selenastrum capricornatum Printz, under axenic laboratory conditions. The biopesticide treatments included two concentrations (0.008 and 0.016 g liter -1 ) of VectoMax ® CG and two controls (one untreated and another with autoclaved 0.016 g VectoMax ® CG liter -1 ) in replicated axenic experimental microcosms. Spectrophotometric analysis of chlorophyll a (proxy for algal biomass) and direct enumeration of algal cells following the treatments revealed no significant effects of the microbial biopesticide on algal population growth during the four-week study. In the second experiment, we tested the effects of different densities of Culex larvae on the population of S. capricornatum. Effects of mosquito larvae feeding on S. capricornatum were significant with a curvilinear relationship between larval density and algal abundance in the water column. Together, these studies demonstrated a lack of direct cytological/toxicological effects of Bacillus-based microbial pesticides on freshwater primary production and support the hypothesis that the reduction in algal primary production previously reported when Bti products were applied to aquatic environments was likely independent of the Bacillus-based larvicidal toxins. Instead, it was likely mediated by microbial interactions in the water column and the trophic cascade effects that resulted from the removal of larval mosquitoes. These studies suggest that mosquito larvae independent of pesticide application can influence primary production. Our method of evaluating biopesticides against small photoautotrophs can be very useful

Emerging Vector-Borne Diseases - Incidence through Vectors.

Science.gov (United States)

Savić, Sara; Vidić, Branka; Grgić, Zivoslav; Potkonjak, Aleksandar; Spasojevic, Ljubica

2014-01-01

Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests - ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples

Oviposition Attractancy of Bacterial Culture Filtrates: response of Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

S Poonam

2002-04-01

Full Text Available Oviposition attractants could be used for monitoring as well as controlling mosquitoes by attracting them to lay eggs at chosen sites. In the present study, culture filtrates of seven bacterial species were tested for their attractancy against gravid females of Culex quinquefasciatus. When their oviposition active indices (OAI were studied, the culture filtrates of Bacillus cereus and Pseudomonas fluorescens exhibited oviposition attractancy (OAI = >0.3 at 100 ppm and the OAI were respectively 0.70 and 0.47. Culture filtrates of B. thuringiensis var. israelensis (wild type, B. t. var. israelensis (mutant and B. sphaericus showed attractancy at 2000 ppm with OAI of respectively 0.71, 0.59 and 0.68. However, the OAI of B. megaterium as well as Azospirillum brasilense was 0.13 (at 2000 ppm, which was less than 0.3 required to be considered them as attractants. When the oviposition attractancy of the bacterial culture filtrates were compared with that of a known oviposition attractant, p-cresol (at 10 ppm, the culture filtrates of B. t. var. israelensis (wild type and B. cereus were found to be more active than p-cresol, respectively with 64.2 and 54.3% oviposition.

Comparative efficacy and pathogenicity of keratinophilic soil fungi against Culex quinquefasciatus larvae.

Science.gov (United States)

Mohanty, Suman Sundar; Prakash, Soam

2010-09-01

Out of seven fungal species belonging to four genera isolated from pond and wallow soils using feathers of Pavo cristatus as bait, four species viz., Aspergillus flavus, Aspergillus niger, Chrysosporium pseudomerdarium and Trichophyton ajelloi were most frequent. Chrysosporium and Trichophyton spp. were more pathogenic on Culex quinquefasciatus larvae than Aspergillus and Penicillium. The bioefficacy tests conducted as per the protocol of World Health Organization and the LC(50) values calculated by the Probit analysis showed that 3(rd)-instar C. quinquefasciatus were more susceptible to the conidia of above fungi. Highest mortality was observed in the larvae of C. quinquefasciatus when exposed to T. ajelloi. The density of fungal conidia was greatest on the ventral brush, palmate hair and anal region of the mosquito larvae after exposing for 72 hours. The potentiality of these fungi for use in the control of C. quinquefasciatus is discussed which can be exploited as a suitable biocontrol agent in the tropics.

Mosquito larvicidal activity of Rauvolfia serpentina L. seeds against Culex quinquefasciatus Say.

Science.gov (United States)

Das, Dipanwita; Chandra, Goutam

2012-01-01

To establish the larvicidal activities, if any of solvent extracts of Rauvolfia serpentina (R. serpentina) L. seeds against Culex quinquefasciatus (Cx. quinquefasciatus) Say, 1823 as target species. Seeds of R. serpentina were extracted with five solvents graded according to the polarity [viz. petroleum ether, benzene, ethyl acetate, acetone and absolute alcohol] continuing one after another with the same seeds. Mortality rate with petroleum ether extract was significantly higher than other extracts. The mortality rates of late 3rd instar larvae were 50.33±5.51, 10.00±1.00, 0.00±0.00, 21.33±1.53 and 0.00±0.00 in 100 ppm concentration of petroleum ether, benzene, ethyl acetate, acetone and absolute alcohol respectively, after 24 h of exposure period. Results of this study show that petroleum ether extract of R. serpentina seed may be considered as a potent source of mosquito larvicidal agent. Copyright © 2012 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

The metabolism of C14-labeled phenylalanine and tyrosine in malaria-infected Culex-females

International Nuclear Information System (INIS)

Maier, W.A.; Nassif-Makki, H.

1975-01-01

Culex females are fed on C14-phenylalanine or C14-tyrosine in sugar solution. Autoradiographic studies on homogenated females 1 or 4 days after feeding, show that the labeled amino acids are metabolized on the first day and are not detectable on the fourth day. After increase of the amino acid concentration by saturation of the sugar solution with the unlabeled amino acid, the labeled acid and its metabolites are visible over a longer period of time. Phenylalanine is metabolized to tyrosine and at least four other substances. Radioactivity on the starting point of the chromatogram can be interpreted as incorporation of tyrosine into proteins. After infection with Plasmodium cathemerium, and feeding of C14-phenylalanine C14-tyrosine is demonstrable over a longer period. (orig.) [de

Vector analysis

CERN Document Server

Newell, Homer E

2006-01-01

When employed with skill and understanding, vector analysis can be a practical and powerful tool. This text develops the algebra and calculus of vectors in a manner useful to physicists and engineers. Numerous exercises (with answers) not only provide practice in manipulation but also help establish students' physical and geometric intuition in regard to vectors and vector concepts.Part I, the basic portion of the text, consists of a thorough treatment of vector algebra and the vector calculus. Part II presents the illustrative matter, demonstrating applications to kinematics, mechanics, and e

Vector-Tensor and Vector-Vector Decay Amplitude Analysis of B0→φK*0

International Nuclear Information System (INIS)

Aubert, B.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Tisserand, V.; Zghiche, A.; Grauges, E.; Palano, A.; Chen, J. C.; Qi, N. D.; Rong, G.; Wang, P.; Zhu, Y. S.; Eigen, G.; Ofte, I.; Stugu, B.; Abrams, G. S.

2007-01-01

We perform an amplitude analysis of the decays B 0 →φK 2 * (1430) 0 , φK * (892) 0 , and φ(Kπ) S-wave 0 with a sample of about 384x10 6 BB pairs recorded with the BABAR detector. The fractions of longitudinal polarization f L of the vector-tensor and vector-vector decay modes are measured to be 0.853 -0.069 +0.061 ±0.036 and 0.506±0.040±0.015, respectively. Overall, twelve parameters are measured for the vector-vector decay and seven parameters for the vector-tensor decay, including the branching fractions and parameters sensitive to CP violation

The effect of three environmental conditions on the fitness of cytochrome P450 monooxygenase-mediated permethrin resistance in Culex pipiens quinquefasciatus

OpenAIRE

Lazzaro Brian P; Hardstone Melissa C; Scott Jeffrey G

2009-01-01

Abstract Background The evolution of insecticide resistance and persistence of resistance phenotypes are influenced by the fitness of resistance alleles in the absence of insecticide pressure. Experimental determination of fitness is difficult, but fitness can be inferred by measuring changes in allele frequencies in appropriate environments. We conducted allele competition experiments by crossing two highly related strains of Culex pipiens quinquefasciatus mosquitoes. One strain (ISOP450) wa...

About vectors

CERN Document Server

Hoffmann, Banesh

1975-01-01

From his unusual beginning in ""Defining a vector"" to his final comments on ""What then is a vector?"" author Banesh Hoffmann has written a book that is provocative and unconventional. In his emphasis on the unresolved issue of defining a vector, Hoffmann mixes pure and applied mathematics without using calculus. The result is a treatment that can serve as a supplement and corrective to textbooks, as well as collateral reading in all courses that deal with vectors. Major topics include vectors and the parallelogram law; algebraic notation and basic ideas; vector algebra; scalars and scalar p

Adulticidal potentials of dichloromethane extracts of some selected ...

African Journals Online (AJOL)

Culex mosquitoes are vectors of Lymphatic filariasis and Japanese encephalitis diseases and the control of these diseases using synthetic chemical insecticides such as Pyrethroids results in development of resistance by the mosquitoes and polluting the ecosystem. This research was aim at evaluating the adulticidal ...

Vectors

DEFF Research Database (Denmark)

Boeriis, Morten; van Leeuwen, Theo

2017-01-01

should be taken into account in discussing ‘reactions’, which Kress and van Leeuwen link only to eyeline vectors. Finally, the question can be raised as to whether actions are always realized by vectors. Drawing on a re-reading of Rudolf Arnheim’s account of vectors, these issues are outlined......This article revisits the concept of vectors, which, in Kress and van Leeuwen’s Reading Images (2006), plays a crucial role in distinguishing between ‘narrative’, action-oriented processes and ‘conceptual’, state-oriented processes. The use of this concept in image analysis has usually focused...

Larvicidal efficacy of Scabiosa arenaria Forssk. (Dipsacaceae organs extracts against Culex pipiens L.

Directory of Open Access Journals (Sweden)

Malek Besbes Hlila

2017-11-01

Full Text Available Objective: To determine the larvicidal activity of sixteen extracts of Scabiosa arenaria Forssk. (S. arenaria against the third instar larvae of Culex pipiens L. (C. pipiens. Methods: Larvicidal activity of S. arenaria extracts was determined according to World Health Organization. Twenty third instars of the C. pipiens were exposed to different concentrations (15 µg/mL to 60 µg/mL of extracts. Mortality was recorded after 24 h of exposure. Results: The roots ethyl acetate fraction of S. arenaria had a significant toxic effect on larvae of C. pipiens, with high mortality percentage (100.0% ± 2.2% at 60 µg/mL, and 50% lethal concentration value of LC50 = (15.00 ± 0.09 µg/mL. Conclusions: Results show that roots ethyl acetate could be used for the production of natural bio-pesticides which could decrease our dependence on chemical pesticides.

Vector regression introduced

Directory of Open Access Journals (Sweden)

Mok Tik

2014-06-01

Full Text Available This study formulates regression of vector data that will enable statistical analysis of various geodetic phenomena such as, polar motion, ocean currents, typhoon/hurricane tracking, crustal deformations, and precursory earthquake signals. The observed vector variable of an event (dependent vector variable is expressed as a function of a number of hypothesized phenomena realized also as vector variables (independent vector variables and/or scalar variables that are likely to impact the dependent vector variable. The proposed representation has the unique property of solving the coefficients of independent vector variables (explanatory variables also as vectors, hence it supersedes multivariate multiple regression models, in which the unknown coefficients are scalar quantities. For the solution, complex numbers are used to rep- resent vector information, and the method of least squares is deployed to estimate the vector model parameters after transforming the complex vector regression model into a real vector regression model through isomorphism. Various operational statistics for testing the predictive significance of the estimated vector parameter coefficients are also derived. A simple numerical example demonstrates the use of the proposed vector regression analysis in modeling typhoon paths.

Attractiveness of botanical infusions to ovipositing Culex quinquefasciatus, Cx. nigripalpus, and Cx. erraticus in San Antonio, Texas.

Science.gov (United States)

McPhatter, Lee P; Debboun, Mustapha

2009-12-01

Field experiments were conducted on the Fort Sam Houston Military Reservation, San Antonio, TX, in fall 2008 to observe the attractiveness of selected botanical infusions to ovipositing female mosquitoes. The following infusions were tested in Centers for Disease Control and Prevention gravid traps: Bermuda grass (Cynodon dactylon), oak leaf (Quercus virginiana), acacia leaf (Acacia schaffneri), rabbit chow (alfalfa pellets), and algae (Spirogyra sp.). Four (Bermuda, acacia, oak, and algae) of the 5 infusions were effective in collecting Culex quinquefasciatus, Cx. nigripalpus, and Cx. erraticus. Of the 4 infusions, Bermuda collected the greatest number of the mosquitoes sampled. Female Aedes albopictus mosquitoes were collected in moderate numbers during this study.

Distribution and abundance of key vectors of Rift Valley fever and other arboviruses in two ecologically distinct counties in Kenya.

Directory of Open Access Journals (Sweden)

Rosemary Sang

2017-02-01

Full Text Available Rift Valley fever (RVF is a mosquito-borne viral zoonosis of ruminants and humans that causes outbreaks in Africa and the Arabian Peninsula with significant public health and economic consequences. Humans become infected through mosquito bites and contact with infected livestock. The virus is maintained between outbreaks through vertically infected eggs of the primary vectors of Aedes species which emerge following rains with extensive flooding. Infected female mosquitoes initiate transmission among nearby animals, which amplifies virus, thereby infecting more mosquitoes and moving the virus beyond the initial point of emergence. With each successive outbreak, RVF has been found to expand its geographic distribution to new areas, possibly driven by available vectors. The aim of the present study was to determine if RVF virus (RVFV transmission risk in two different ecological zones in Kenya could be assessed by looking at the species composition, abundance and distribution of key primary and secondary vector species and the level of virus activity.Mosquitoes were trapped during short and long rainy seasons in 2014 and 2015 using CO2 baited CDC light traps in two counties which differ in RVF epidemic risk levels(high risk Tana-River and low risk Isiolo,cryo-preserved in liquid nitrogen, transported to the laboratory, and identified to species. Mosquito pools were analyzed for virus infection using cell culture screening and molecular analysis.Over 69,000 mosquitoes were sampled and identified as 40 different species belonging to 6 genera (Aedes, Anopheles, Mansonia, Culex, Aedeomyia, Coquillettidia. The presence and abundance of Aedes mcintoshi and Aedes ochraceus, the primary mosquito vectors associated with RVFV transmission in outbreaks, varied significantly between Tana-River and Isiolo. Ae. mcintoshi was abundant in Tana-River and Isiolo but notably, Aedes ochraceus found in relatively high numbers in Tana-River (n = 1,290, was totally

S argassum muticum-synthesized silver nanoparticles: an effective control tool against mosquito vectors and bacterial pathogens.

Science.gov (United States)

Madhiyazhagan, Pari; Murugan, Kadarkarai; Kumar, Arjunan Naresh; Nataraj, Thiyagarajan; Dinesh, Devakumar; Panneerselvam, Chellasamy; Subramaniam, Jayapal; Mahesh Kumar, Palanisamy; Suresh, Udaiyan; Roni, Mathath; Nicoletti, Marcello; Alarfaj, Abdullah A; Higuchi, Akon; Munusamy, Murugan A; Benelli, Giovanni

2015-11-01

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Furthermore, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. In this research, silver nanoparticles (AgNP) were synthesized using the aqueous extract of the seaweed Sargassum muticum. The production of AgNP was confirmed by surface plasmon resonance band illustrated in UV-vis spectrophotometry. AgNP were characterized by FTIR, SEM, EDX, and XRD analyses. AgNP were mostly spherical in shape, crystalline in nature, with face-centered cubic geometry, and mean size was 43-79 nm. Toxicity of AgNP was assessed against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. In laboratory, AgNP were highly toxic against larvae and pupae of the three mosquito species. Maximum efficacy was observed against A. stephensi larvae, with LC50 ranging from 16.156 ppm (larva I) to 28.881 ppm (pupa). In the field, a single treatment with AgNP (10 × LC50) in water storage reservoirs was effective against the three mosquito vectors, allowing complete elimination of larval populations after 72 h. In ovicidal experiments, egg hatchability was reduced by 100% after treatment with 30 ppm of AgNP. Ovideterrence assays highlighted that 10 ppm of AgNP reduced oviposition rates of more than 70% in A. aegypti, A. stephensi, and C. quinquefasciatus (OAI = -0.61, -0.63, and -0.58, respectively). Antibacterial properties of AgNP were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. AgNP tested at 50 ppm evoked growth inhibition zones larger than 5 mm in all tested bacteria. Overall, the chance to use S. muticum-synthesized AgNP for control of mosquito vectors seems promising since they are effective at low doses and may constitute an advantageous alternative to build newer and safer mosquito control tools. This is the first

Kochen-Specker vectors

International Nuclear Information System (INIS)

Pavicic, Mladen; Merlet, Jean-Pierre; McKay, Brendan; Megill, Norman D

2005-01-01

We give a constructive and exhaustive definition of Kochen-Specker (KS) vectors in a Hilbert space of any dimension as well as of all the remaining vectors of the space. KS vectors are elements of any set of orthonormal states, i.e., vectors in an n-dimensional Hilbert space, H n , n≥3, to which it is impossible to assign 1s and 0s in such a way that no two mutually orthogonal vectors from the set are both assigned 1 and that not all mutually orthogonal vectors are assigned 0. Our constructive definition of such KS vectors is based on algorithms that generate MMP diagrams corresponding to blocks of orthogonal vectors in R n , on algorithms that single out those diagrams on which algebraic (0)-(1) states cannot be defined, and on algorithms that solve nonlinear equations describing the orthogonalities of the vectors by means of statistically polynomially complex interval analysis and self-teaching programs. The algorithms are limited neither by the number of dimensions nor by the number of vectors. To demonstrate the power of the algorithms, all four-dimensional KS vector systems containing up to 24 vectors were generated and described, all three-dimensional vector systems containing up to 30 vectors were scanned, and several general properties of KS vectors were found

Efficacy of fipronil-(S)-methoprene, metaflumizone combined with amitraz, and pyriprole commercial spot-on products in preventing Culex pipiens pipiens from feeding on dogs.

Science.gov (United States)

Bouhsira, E; Fysikopoulos, A; Franc, M

2009-08-01

A controlled clinical trial was carried out to assess the effectiveness of pyriprole, metaflumizone combined with amitraz, and fipronil-(S)-methoprene commercial spot-on products in preventing adult female Culex pipiens pipiens from feeding on dogs. Twenty-four beagle dogs were tested for their attractiveness to the mosquitoes and ranked accordingly to produce four groups of equivalent sensitivity to mosquitoes; six were treated with the pyriprole spot-on, six with the metaflumizone combined with amitraz spot-on, six with the fipronil-(S)-methoprene spot-on, and six were left untreated. All the dogs were challenged with 50 unfed adult female Culex in cages for one hour seven days before the treatment, and one and seven days after it. The mosquitoes were checked for blood feeding after one hour and for mortality 24 hours after they had been released into the cages. There was a significant reduction in the number of engorged mosquitoes only with the fipronil-(S)-methoprene product and there were significantly more dead mosquitoes with this product and the pyriprole product, but their effects were too small for them to be recommended for use in a dirofilariosis prevention programme.

Elementary vectors

CERN Document Server

Wolstenholme, E Œ

1978-01-01

Elementary Vectors, Third Edition serves as an introductory course in vector analysis and is intended to present the theoretical and application aspects of vectors. The book covers topics that rigorously explain and provide definitions, principles, equations, and methods in vector analysis. Applications of vector methods to simple kinematical and dynamical problems; central forces and orbits; and solutions to geometrical problems are discussed as well. This edition of the text also provides an appendix, intended for students, which the author hopes to bridge the gap between theory and appl

Tanzania Journal of Health Research - Vol 15, No 3 (2013)

African Journals Online (AJOL)

Comparison of sampling techniques for Rift Valley Fever virus potential vectors, Aedes aegypti and Culex pipiens complex, in Ngorongoro District in northern Tanzania · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Clement N. Mweya, Sharadhuli I. Kimera, Esron D.

[Record of epidemiologically important Culicidae in the rural area of Manaus, Amazonas].

Science.gov (United States)

Barbosa, Maria das Graças Vale; Fé, Nelson Ferreira; Marcião, Alexandre Herculano Ribera; Silva, Ana Paula Thomé da; Monteiro, Wuelton Marcelo; Guerra, Marcus Vinitius de Farias; Guerra, Jorge Augusto de Oliveira

2008-01-01

The biodiversity of the Amazon region includes many species of arthropod vectors in different ecotopes, thus enabling occurrences of diseases like malaria, filariasis and arbovirosis. From August 2001 to July 2002, we gathered culicids from inside homes, from areas surrounding these homes and from forested areas of the São João Community, in the rural zone of Manaus, State of Amazonas. 1240 specimens were collected, belonging to the Culicinae (99%) and Anophelinae (1%) subfamilies, with 50 species. The Culicini tribe clearly predominated, with 904 specimens (72.9%), and the species Culex usquatus (22.6%) and Culex quinquefasciatus (17.7%) were prominent. Out of the total number of culicids, 1,077 (86.9%) were caught in the forests, 101 (8.1%) in the areas surrounding homes and 62 (5%) inside homes. Forests were the ecotope that presented the highest species diversity. The presence of Anopheles darlingi, Anopheles triannulatus, Aedes aegypti, Haemagogus janthinomys and other proven or potential vectors was recorded.

Vertebrate host specificity and experimental vectors of Plasmodium (Novyella) kempi sp. n. from the eastern wild turkey in Iowa.

Science.gov (United States)

Christensen, B M; Barnes, H J; Rowley, W A

1983-07-01

Vertebrate host specificity, experimental laboratory vectors, and a description of Plasmodium (Novyella) kempi sp. n. from eastern wild turkeys (Meleagris gallopavo silvestris Vieillot) in Iowa are presented. Plasmodium kempi is infective for domestic turkeys, bobwhites (Colinus virginianus), chukars (Alectoris graeca), guinea fowl (Numida meleagris), peacocks (Pavo cristatus), and canaries (Serinus canaria), produces a transient infection in mallards (Anas platyrhynchos) and domestic geese (Anser anser), but will not infect ring-necked pheasants (Phasianus colchicus), pigeons (Columba livia), Japanese quail (Coturnix coturnix), leghorn white chickens (Gallus gallus), or starlings (Sturnus vulgaris). Oocysts and (or) sporozoites were recovered from 68% (84/124) and 98% (60/61) of the Culex pipiens pipiens and C. tarsalis examined, respectively. Oocysts developed faster and sporozoites invaded the salivary glands sooner in C. tarsalis (6 days) than in C. p. pipiens (7 days). Culex tarsalis transmitted P. kempi more effectively than C. p. pipiens, although both species were capable of transmitting the parasite by natural feeding. Oocysts developed and sporozoites also were produced in C. restuans, but its ability to transmit the parasite was not determined. Aedes aegypti (Rockefeller strain) and A. triseriatus were refractive to P. kempi. Plasmodium kempi produces trophozoites with large refractile globules and fine cytoplasmic extensions, mature schizonts in the form of a condensed fan containing four to eight nuclei (usually 5), and elongate gametocytes with irregular borders. All stages are confined almost exclusively to mature erythrocytes, with no effect on host cell size or position of host cell nucleus. Plasmodium kempi is most similar morphologically to P. (Novyella) hexamerium and P. (Novyella) vaughani. It differs from P. hexamerium in having large refractile globules in trophozoites and immature schizonts, an inability to infect starlings, an absence of

Temperature effects on the immature development time of Culex eduardoi Casal and Garcia (Diptera: Culicidae)

Energy Technology Data Exchange (ETDEWEB)

Loetti, V.; Schweigmann, N.J.; Burroni, N.E., E-mail: nburroni@ege.fcen.uba.a [Universidad de Buenos Aires (Argentina). Facultad de Ciencias Exactas y Naturales. Grupo de Estudio de Mosquitos

2011-01-15

The effect of constant temperatures on the development time from first instar to adult emergence was studied in Culex eduardoi Casal and Garcia reared at 7, 10, 15, 20, 25, 30 or 33 deg C. Data were adjusted to the linear degree-day model and the nonlinear Briere model. According to the linear model, the development time was inversely related to the rearing temperatures between 7 deg C and 25 deg C. Maximum mortality (100%) was recorded at temperatures > 30 deg C. According to the linear model, the development threshold temperature and thermal constant were 5.7 deg C and 188.8 degree days, respectively. The lower and upper threshold temperatures and the optimum temperature for the nonlinear model were -2.3, 30.0 and 28.1 deg C, respectively. (author)

Bancroftian filariasis in Belém, Pará State: possibilities for eradication by introducing modern methods of control for Culex quinquefasciatus A filariose bancroftiana em Belém, Pará: possibilidades atuais de erradicação mediante a integração à campanha de novos métodos de controle da população de Culex quinquefasciatus

Directory of Open Access Journals (Sweden)

Habib Fraiha Neto

1993-12-01

Full Text Available For the past four decades, Belém has been considered to be the largest focus of Bancroftian filariasis in the Amazon region and one of the most important ones in Brazil. In 1952, practically one-fifth of the population was infected and it was estimated that there were 2,500 cases of Bancroftian elephantiasis. The major factor considered to be responsible for this situation was the high density of the main vector species: it was calculated that in April 1943 there was a mean of 67 infected mosquitoes per house. A control campaign was initiated in 1952, involving treatment of patients with diethylcarbamazine, as well as control of the vector. In 1956, vector control was discontinued because of a lack of efficient insecticides and financial limitations. Even so, the campaign was very successful and the incidence was reduced from 19.9% to 0.03%. Total eradication could be achieved if new methods of vector control were introduced, such as the use of Reiter's expanded polystyrene balls in cesspits and pit latrines, biological control using pathogenic bacteria, and improvement of basic sanitation.Há mais de quatro décadas Belém é considerada o maior foco de bancroftose da região amazônica e um dos mais importantes do Brasil. Em 1952, praticamente um quinto de sua população apresentava microfilárias no sangue, estimando-se em 2.500 os casos de elefantíase. O fator considerado o maior condicionante de tão extraordinária freqüência era a alta densidade local do principal vetor, Culex quinquefasciatus. Em abril de 1943 calculava-se uma média de 67 fêmeas da espécie infectadas por domicílio. Uma campanha de controle foi deflagrada em 1952, incluindo busca ativa e tratamento dos casos com dietilcarbamazina, além medidas de combate ao vetor. Estas foram abandonadas em 1956, por força da ineficácia ou do alto custo dos inseticidas. Ainda assim, a campanha foi muito bem sucedida, reduzindo a incidência de 19,9 para 0,03%. Hoje, a erradica

Feeding patterns of Culex quinquefasciatus (Diptera: Culicidae) from eastern Santa Catarina state, Brazil.

Science.gov (United States)

Alencar, Jeronimo; Silva, Júlia dos Santos; de Oliveira, Luis Claudio Motta; Marcondes, Carlos Brisola; Morone, Fernanda; Lorosa, Elias Seixas

2012-07-01

Blood-feeding sources of Culex quinquefasciatus Say (Diptera: Culicidae) collected in the eastern region of the Brazilian state of Santa Catarina were analyzed by precipitin technique. One hundred fifty-four female mosquitoes collected by CDC traps in the Navegantes municipality 13-15 February 2005 reacted to one or more of eight antisera, including chicken, dog, goat, sheep, horse, opossum, human and rodent antisera. One hundred thirty-seven specimens (89%) reacted to only one source, and 17 (11%) specimens reacted to two sources. Among the 137 specimens reacting to only one source, reactions to rodent (50.4%), sheep (5.8%), chicken (5.1%), goat (5.1%), dog (2.2%), horse (3.6%), and human (3.6%) antisera were observed. The analyzed species demonstrated a high degree of opportunistic feeding behavior in relation to host preference. Results are compared with results from similar studies, and the low proportion of reactions to human antisera is discussed.

Eficiencia del extracto de Ricinus communis para el control del mosquito Culex

Directory of Open Access Journals (Sweden)

Diego Tomás Corradine Mora

2014-05-01

Full Text Available Este artículo evaluó el efecto insecticida del extracto de Ricinus communis sobre larvas de mosquitos Culex. A las 24 h la mortalidad es de 8.33 % con dosis de 1 mL del extracto en una concentración de 500 ppm; 35 % en dosis de 1 mL de una concentración de 1000 ppm; 65 % en dosis de 5 mL de una concentración de 1000 ppm; 98.33 % con 10 mL en concentración de 1000 ppm; testigos 3.3 %. Cuando se evaluó el efecto insecticida del extracto aplicado por aspersión en concentraciones de 500, 750 y 1000 ppm, se consiguieron mortalidades de 18.33, 36.66 y 48.32 %, respectivamente. Ninguna de las concentraciones evaluadas alcanzó el cien por ciento de letalidad. En la prueba de semicampo, solo se logró una mortalidad de 9 %. Se evidenció que el extracto tiene un mejor efecto insecticida para el control de ejemplares inmaduros en estado larvario que sobre los adultos.

Modelling West Nile virus transmission risk in Europe

NARCIS (Netherlands)

Vogels, Chantal B.F.; Hartemink, Nienke; Koenraadt, Constantianus J.M.

2017-01-01

West Nile virus (WNV) is a mosquito-borne flavivirus which has caused repeated outbreaks in humans in southern and central Europe, but thus far not in northern Europe. The main mosquito vector for WNV, Culex pipiens, consists of two behaviourally distinct biotypes, pipiens and molestus, which can

Functional characterization of the dual allatostatin-A receptors in mosquitoes

DEFF Research Database (Denmark)

Christ, Peter; Hill, Sharon R.; Schachtner, Joachim

2018-01-01

, there are two copies of AstAR, contrasting with the single copy found in other insects. In this study, we identified and cloned the dual AstAR system of two important disease vectors Aedes aegypti and Culex quinquefasciatus, and compared them with those previously described, including those in Anopheles...

Host selection patterns of Culex tarsalis (Diptera: Culicidae) at wetlands near the Salton Sea, Coachella Valley, California, 1998-2002.

Science.gov (United States)

Reisen, William K; Lothrop, Hugh D; Thiemann, Tara

2013-09-01

The bloodmeal hosts used by Culex tarsalis Coquillett collected along the Salton Sea in Coachella Valley, CA, during 1998-2002 were identified using sequences of the cytochrome c oxidase I gene identified from Barcode of Life database. Overall, 265 (83.3%) of 318 bloodmeals were identified, of which 76.6% fed on birds, 18.1% on mammals, and 5.3% on reptiles. Forty-seven different hosts were identified, none of which comprised > 12.5% of the total. Although Cx. tarsalis exhibits specific host-seeking flight patterns, bloodmeals seemed to be acquired opportunistically, thereby limiting potential arbovirus transmission efficiency in species-rich environments.

Genetic manipulation of endosymbionts to control vector and vector borne diseases

Directory of Open Access Journals (Sweden)

Jay Prakash Gupta

Full Text Available Vector borne diseases (VBD are on the rise because of failure of the existing methods of control of vector and vector borne diseases and the climate change. A steep rise of VBDs are due to several factors like selection of insecticide resistant vector population, drug resistant parasite population and lack of effective vaccines against the VBDs. Environmental pollution, public health hazard and insecticide resistant vector population indicate that the insecticides are no longer a sustainable control method of vector and vector-borne diseases. Amongst the various alternative control strategies, symbiont based approach utilizing endosymbionts of arthropod vectors could be explored to control the vector and vector borne diseases. The endosymbiont population of arthropod vectors could be exploited in different ways viz., as a chemotherapeutic target, vaccine target for the control of vectors. Expression of molecules with antiparasitic activity by genetically transformed symbiotic bacteria of disease-transmitting arthropods may serve as a powerful approach to control certain arthropod-borne diseases. Genetic transformation of symbiotic bacteria of the arthropod vector to alter the vector’s ability to transmit pathogen is an alternative means of blocking the transmission of VBDs. In Indian scenario, where dengue, chikungunya, malaria and filariosis are prevalent, paratransgenic based approach can be used effectively. [Vet World 2012; 5(9.000: 571-576

Molecular cloning and preliminary function study of iron responsive element binding protein 1 gene from cypermethrin-resistant Culex pipiens pallens

Directory of Open Access Journals (Sweden)

Tan Wenbin

2011-11-01

Full Text Available Abstract Background Insecticide resistance jeopardizes the control of mosquito populations and mosquito-borne disease control, which creates a major public health concern. Two-dimensional electrophoresis identified one protein segment with high sequence homology to part of Aedes aegypti iron-responsive element binding protein (IRE-BP. Method RT-PCR and RACE (rapid amplification of cDNA end were used to clone a cDNA encoding full length IRE-BP 1. Real-time quantitative RT-PCR was used to evaluate the transcriptional level changes in the Cr-IRE strain Aedes aegypti compared to the susceptible strain of Cx. pipiens pallens. The expression profile of the gene was established in the mosquito life cycle. Methyl tritiated thymidine (3H-TdR was used to observe the cypermethrin resistance changes in C6/36 cells containing the stably transfected IRE-BP 1 gene of Cx. pipiens pallens. Results The complete sequence of iron responsive element binding protein 1 (IRE-BP 1 has been cloned from the cypermethrin-resistant strain of Culex pipiens pallens (Cr-IRE strain. Quantitative RT-PCR analysis indicated that the IRE-BP 1 transcription level was 6.7 times higher in the Cr-IRE strain than in the susceptible strain of 4th instar larvae. The IRE-BP 1 expression was also found to be consistently higher throughout the life cycle of the Cr-IRE strain. A protein of predicted size 109.4 kDa has been detected by Western blotting in IRE-BP 1-transfected mosquito C6/36 cells. These IRE-BP 1-transfected cells also showed enhanced cypermethrin resistance compared to null-transfected or plasmid vector-transfected cells as determined by 3H-TdR incorporation. Conclusion IRE-BP 1 is expressed at higher levels in the Cr-IRE strain, and may confer some insecticide resistance in Cx. pipiens pallens.

Emerging vector borne diseases – incidence through vectors

Directory of Open Access Journals (Sweden)

Sara eSavic

2014-12-01

Full Text Available Vector borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowdays, in intercontinetal countries, there is a struggle with emerging diseases which have found their way to appear through vectors. Vector borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector borne infectious diseases and disease outbreaks. It could affect the range and popultion of pathogens, host and vectors, transmission season, etc. Reliable surveilance for diseases that are most likely to emerge is required. Canine vector borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, erlichiosis, leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fudamental role at primeraly prevention and then treatment of vector borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases.During a four year period, from 2009-2013, a total number of 551 dog samples were analysed for vector borne diseases (borreliosis, babesiosis, erlichiosis, anaplasmosis, dirofilariosis and leishmaniasis in routine laboratory work. The analysis were done by serological tests – ELISA for borreliosis, dirofilariosis and leishmaniasis, modified Knott test for dirofilariosis and blood smear for babesiosis, erlichiosis and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on avarege more then half of the samples

Vector-vector production in photon-photon interactions

International Nuclear Information System (INIS)

Ronan, M.T.

1988-01-01

Measurements of exclusive untagged /rho/ 0 /rho/ 0 , /rho//phi/, K/sup *//bar K//sup */, and /rho/ω production and tagged /rho/ 0 /rho/ 0 production in photon-photon interactions by the TPC/Two-Gamma experiment are reviewed. Comparisons to the results of other experiments and to models of vector-vector production are made. Fits to the data following a four quark model prescription for vector meson pair production are also presented. 10 refs., 9 figs

Rare Hadronic B Decays to Vector, Axial-Vector and Tensors

International Nuclear Information System (INIS)

Gao, Y.Y.

2011-01-01

The authors review BABAR measurements of several rare B decays, including vector-axial-vector decays B ± → φK 1 ± (1270), B ± → φ K 1 ± (1400) and B ± → b 1 # -+ρ# ± , vector-vector decays B ± → φK* ± (1410), B 0 → K* 0 (bar K)* 0 , B 0 → K*0K*0 and B 0 → K*+K*-, vector-tensor decays B ± → φK* 2 (1430) ± and φK 2 (1770)/ ± (1820), and vector-scalar decays B ± → φK* 0 (1430) ± . Understanding the observed polarization pattern requires amplitude contributions from an uncertain source.

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.

Vector analysis

CERN Document Server

Brand, Louis

2006-01-01

The use of vectors not only simplifies treatments of differential geometry, mechanics, hydrodynamics, and electrodynamics, but also makes mathematical and physical concepts more tangible and easy to grasp. This text for undergraduates was designed as a short introductory course to give students the tools of vector algebra and calculus, as well as a brief glimpse into these subjects' manifold applications. The applications are developed to the extent that the uses of the potential function, both scalar and vector, are fully illustrated. Moreover, the basic postulates of vector analysis are brou

The Mosquitoes of the Subgenus Culex in Southwestern Asia and Egypt (Diptera: Culicidae) (Contributions of the American Entomological Institute. Volume 24, Number 1, 1988)

Science.gov (United States)

1988-01-01

Pathol. Exot. 53: 531-542. 1968. Contribution a I’etude des moustiques du Maroc (Diptera, Culicidae) six especes nouvelles pour le pays. Cah. ORSTOM...quelques moustiques du Maroc. Arch. inst. Pasteur Maroc 2: 361-365. 1957. Sur Culex torrentium Martini. Ann. Parasitol. Hum. Comp. 32: 438-442...De Grandpre, A.D. and D. D’E. De Charmoy 1900(1901). Les moustiques : anatomie et biologie. Contribution a I’etude des Culicides et principalement

Vectors and Rotations in 3-Dimensions: Vector Algebra for the C++ Programmer

Science.gov (United States)

2016-12-01

release; distribution is unlimited. 1. Introduction This report describes 2 C++ classes: a Vector class for performing vector algebra in 3-dimensional...ARL-TR-7894•DEC 2016 US Army Research Laboratory Vectors and Rotations in 3-Dimensions:Vector Algebra for the C++ Programmer by Richard Saucier...Army Research Laboratory Vectors and Rotations in 3-Dimensions:Vector Algebra for the C++ Programmer by Richard Saucier Survivability/Lethality

Identification of Blood Meal Sources in Aedes vexans and Culex quinquefasciatus in Bernalillo County, New Mexico

Science.gov (United States)

Greenberg, Jacob A.; Lujan, Daniel A.; DiMenna, Mark A.; Wearing, Helen J.; Hofkin, Bruce V.

2013-01-01

Culex quinquefasciatus Say (Diptera: Culicidae) and Aedes vexans Meigen are two of the most abundant mosquitoes in Bernalillo County, New Mexico, USA. In this study, a polymerase chain reaction based methodology was used to identify the sources of blood meals taken by these two species. Ae. vexans was found to take a large proportion of its meals from mammals. Although less specific in terms of its blood meal preferences, Cx. quinquefasciatus was found to feed more commonly on birds. The results for Ae. vexans are similar to those reported for this species in other parts of their geographic range. Cx. quinquefasciatus appears to be more variable in terms of its host feeding under different environmental or seasonal circumstances. The implications of these results for arbovirus transmission are discussed. PMID:24224615

Medical Entomology Studies - III. A Revision of the Subgenus Culex in the Oriental Region (Diptera: Culicidae) (Contributions of the American Entomological Institute. Volume 12, Number 2)

Science.gov (United States)

1976-01-01

Subgroup with quinquefasciatus which is widespread throughout tropical parts of the world, (2) TrifiZatus Subgroup with vegans and hutchinsoni, both...region; torrentium Martini 1925 from the western Palearctic; vegans Wiedemann 1828 from the eastern Pale- arctic; pervigiluns Bergroth 1889, pacificus...discovered when the fauna is thoroughly examined. 2. C ULEX (C ULEX) VAGANS WIEDEMANN (Figs. 4, 5, 14) Culex vegans Wiedemann 1828: 545 (d, 0

Measurement of Charmless B to Vector-Vector decays at BaBar

International Nuclear Information System (INIS)

Olaiya, Emmanuel

2011-01-01

The authors present results of B → vector-vector (VV) and B → vector-axial vector (VA) decays B 0 → φX(X = φ,ρ + or ρ 0 ), B + → φK (*)+ , B 0 → K*K*, B 0 → ρ + b 1 - and B + → K* 0 α 1 + . The largest dataset used for these results is based on 465 x 10 6 Υ(4S) → B(bar B) decays, collected with the BABAR detector at the PEP-II B meson factory located at the Stanford Linear Accelerator Center (SLAC). Using larger datasets, the BABAR experiment has provided more precise B → VV measurements, further supporting the smaller than expected longitudinal polarization fraction of B → φK*. Additional B meson to vector-vector and vector-axial vector decays have also been studied with a view to shedding light on the polarization anomaly. Taking into account the available errors, we find no disagreement between theory and experiment for these additional decays.

A list of mosquito species of the Brazilian State of Pernambuco, including the first report of Haemagogus janthinomys (Diptera: Culicidae, yellow fever vector and 14 other species (Diptera: Culicidae Lista de espécies de mosquitos do Estado de Pernambuco e primeiro relato de Haemagogus janthinomys (Diptera: Culicidae vetor de febre amarela silvestre e outras 14 espécies (Diptera: Culicidae

Directory of Open Access Journals (Sweden)

Nádia Consuelo Aragão

2010-08-01

Full Text Available INTRODUCTION: Besides mosquito species adapted to urban environments (Culex quinquefasciatus, Aedes aegypti and Aedes albopictus, only 15 species of Anopheles had been recorded in the State of Pernambuco. METHODS: Human-landing mosquitoes were collected in Dois Irmãos Park, in Recife. RESULTS: The first report for the state of Haemagogus janthinomys, an important vector of yellow fever virus, and 14 other species, including Trichoprosopon lampropus, a first reported for Brazil. CONCLUSIONS: The mosquito fauna in the area is diversified and has potential medical and veterinary importance.INTRODUÇÃO: Além de mosquitos adaptados ao ambiente urbano (Culex quinquefasciatus, Aedes aegypti e Ae. albopictus, apenas 15 espécies de Anopheles haviam sido relatadas no Estado de Pernambuco. MÉTODOS: Mosquitos que pousavam em humanos no Parque Dois Irmãos, em Recife foram coletados. RESULTADOS: Haemagogus janthinomys, importante vetor de vírus de febre amarela, e outras 14 espécies são relatadas pela primeira vez no estado, incluindo Trichoprosopon lampropus, relatado pela primeira vez no Brasil. CONCLUSÕES: A fauna de mosquitos na área é muito diversificada e tem potencial importância médica e veterinária.

The haemagglutination activity in the different developmental stages and changes of this activity caused by analogues of insect hormones in two members of the Culex pipiens complex of mosquitoes

Czech Academy of Sciences Publication Activity Database

Gelbič, Ivan; Olejníček, Jiří

2004-01-01

Roč. 29, č. 4 (2004), s. 320-326 ISSN 0307-6962 R&D Projects: GA ČR GA522/02/1458; GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z5007907 Keywords : anautogenous mosquitoes * autogenous mosquitoes * Culex pipiens molestus Subject RIV: ED - Physiology Impact factor: 1.352, year: 2004

Effect of environmental temperature on the vector competence of mosquitoes for Rift Valley fever virus

Science.gov (United States)

Environmental temperature has been shown to affect the ability of mosquitoes to transmit numerous arboviruses and for Rift Valley fever virus (RVFV) in particular. We evaluated the effect of incubation temperatures ranging from 14-26ºC on infection, dissemination, and transmission rates for Culex ta...

Vectorization of KENO IV code and an estimate of vector-parallel processing

International Nuclear Information System (INIS)

Asai, Kiyoshi; Higuchi, Kenji; Katakura, Jun-ichi; Kurita, Yutaka.

1986-10-01

The multi-group criticality safety code KENO IV has been vectorized and tested on FACOM VP-100 vector processor. At first the vectorized KENO IV on a scalar processor became slower than the original one by a factor of 1.4 because of the overhead introduced by the vectorization. Making modifications of algorithms and techniques for vectorization, the vectorized version has become faster than the original one by a factor of 1.4 and 3.0 on the vector processor for sample problems of complex and simple geometries, respectively. For further speedup of the code, some improvements on compiler and hardware, especially on addition of Monte Carlo pipelines to the vector processor, are discussed. Finally a pipelined parallel processor system is proposed and its performance is estimated. (author)

Host-Feeding Preference of the Mosquito, Culex quinquefasciatus, in Yucatan State, Mexico

Science.gov (United States)

Garcia-Rejon, Julian E.; Blitvich, Bradley J.; Farfan-Ale, Jose A.; Loroño-Pino, Maria A.; Chi Chim, Wilberth A.; Flores-Flores, Luis F.; Rosado-Paredes, Elsy; Baak-Baak, Carlos; Perez-Mutul, Jose; Suarez-Solis, Victor; Fernandez-Salas, Ildefonso; Beaty, Barry J.

2010-01-01

Studies were conducted to determine the host-feeding preference of Culex quinquefasciatus Say (Diptera: Culicidae) in relation to the availability of human and domestic animals in the city of Merida, Yucatan State, Mexico. Mosquitoes were collected in the backyards of houses using resting wooden boxes. Collections were made five times per week from January to December 2005. DNA was extracted from engorged females and tested by PCR using universal avian- and mammalian-specific primers. DNA extracted from avian-derived blood was further analyzed by PCR using primers that differentiate among the birds of three avian orders: Passeriformes, Columbiformes and Galliformes. PCR products obtained from mammalian-derived blood were subjected to restriction enzyme digestion to differentiate between human-, dog-, cat-, pig-, and horse-derived blood meals. Overall, 82% of engorged mosquitoes had fed on birds, and 18% had fed on mammals. The most frequent vertebrate hosts were Galliformes (47.1%), Passeriformes (23.8%), Columbiformes (11.2%) birds, and dogs (8.8%). The overall human blood index was 6.7%. The overall forage ratio for humans was 0.1, indicating that humans were not a preferred host for Cx. quinquefasciatus in Merida. PMID:20578953

Versatile generation of optical vector fields and vector beams using a non-interferometric approach.

Science.gov (United States)

Tripathi, Santosh; Toussaint, Kimani C

2012-05-07

We present a versatile, non-interferometric method for generating vector fields and vector beams which can produce all the states of polarization represented on a higher-order Poincaré sphere. The versatility and non-interferometric nature of this method is expected to enable exploration of various exotic properties of vector fields and vector beams. To illustrate this, we study the propagation properties of some vector fields and find that, in general, propagation alters both their intensity and polarization distribution, and more interestingly, converts some vector fields into vector beams. In the article, we also suggest a modified Jones vector formalism to represent vector fields and vector beams.

Hydrological modeling of geophysical parameters of arboviral and protozoan disease vectors in Internally Displaced People camps in Gulu, Uganda.

Science.gov (United States)

Jacob, Benjamin G; Muturi, Ephantus J; Caamano, Erick X; Gunter, James T; Mpanga, Enoch; Ayine, Robert; Okelloonen, Joseph; Nyeko, Jack Pen-Mogi; Shililu, Josephat I; Githure, John I; Regens, James L; Novak, Robert J; Kakoma, Ibulaimu

2008-03-14

The aim of this study was to determine if remotely sensed data and Digital Elevation Model (DEM) can test relationships between Culex quinquefasciatus and Anopheles gambiae s.l. larval habitats and environmental parameters within Internally Displaced People (IDP) campgrounds in Gulu, Uganda. A total of 65 georeferenced aquatic habitats in various IDP camps were studied to compare the larval abundance of Cx. quinquefasciatus and An. gambiae s.l. The aquatic habitat dataset were overlaid onto Land Use Land Cover (LULC) maps retrieved from Landsat imagery with 150 m x 150 m grid cells stratified by levels of drainage. The LULC change was estimated over a period of 14 years. Poisson regression analyses and Moran's I statistics were used to model relationships between larval abundance and environmental predictors. Individual larval habitat data were further evaluated in terms of their covariations with spatial autocorrelation by regressing them on candidate spatial filter eigenvectors. Multispectral QuickBird imagery classification and DEM-based GIS methods were generated to evaluate stream flow direction and accumulation for identification of immature Cx. quinquefasciatus and An. gambiae s.l. and abundance. The main LULC change in urban Gulu IDP camps was non-urban to urban, which included about 71.5 % of the land cover. The regression models indicate that counts of An. gambiae s.l. larvae were associated with shade while Cx. quinquefasciatus were associated with floating vegetation. Moran's I and the General G statistics for mosquito density by species and instars, identified significant clusters of high densities of Anopheles; larvae, however, Culex are not consistently clustered. A stepwise negative binomial regression decomposed the immature An. gambiae s.l. data into empirical orthogonal bases. The data suggest the presence of roughly 11% to 28 % redundant information in the larval count samples. The DEM suggest a positive correlation for Culex (0.24) while for

Hematophagous insects as vectors for frog trypanosomes.

Science.gov (United States)

Ramos, B; Urdaneta-Morales, S

1977-12-01

Experimental infections of three hematophagous arthropods (Rhodnius prolixus, Aedes aegypti, and Culex pipiens) with a trypanosome of the Trypanosoma rotatorium complex found in the frogs Hyla crepitans and Leptodactylus insularum revealed that A. aegypti is a good host for the flagellate; the course of development in the intestinal tract of the mosquito is described from 15 minutes to 168 hours. C. pipiens showed only low intestinal infections and R. prolixus did not permit development of the parasite. It is postulated that, in addition to the transmission of T. rotatorium by leeches, batrachophilic mosquitoes may transmit the parasite to frogs of more terrestrial habits by being ingested by these anurans.

Vectorized Monte Carlo

International Nuclear Information System (INIS)

Brown, F.B.

1981-01-01

Examination of the global algorithms and local kernels of conventional general-purpose Monte Carlo codes shows that multigroup Monte Carlo methods have sufficient structure to permit efficient vectorization. A structured multigroup Monte Carlo algorithm for vector computers is developed in which many particle events are treated at once on a cell-by-cell basis. Vectorization of kernels for tracking and variance reduction is described, and a new method for discrete sampling is developed to facilitate the vectorization of collision analysis. To demonstrate the potential of the new method, a vectorized Monte Carlo code for multigroup radiation transport analysis was developed. This code incorporates many features of conventional general-purpose production codes, including general geometry, splitting and Russian roulette, survival biasing, variance estimation via batching, a number of cutoffs, and generalized tallies of collision, tracklength, and surface crossing estimators with response functions. Predictions of vectorized performance characteristics for the CYBER-205 were made using emulated coding and a dynamic model of vector instruction timing. Computation rates were examined for a variety of test problems to determine sensitivities to batch size and vector lengths. Significant speedups are predicted for even a few hundred particles per batch, and asymptotic speedups by about 40 over equivalent Amdahl 470V/8 scalar codes arepredicted for a few thousand particles per batch. The principal conclusion is that vectorization of a general-purpose multigroup Monte Carlo code is well worth the significant effort required for stylized coding and major algorithmic changes

Vector Network Coding

OpenAIRE

Ebrahimi, Javad; Fragouli, Christina

2010-01-01

We develop new algebraic algorithms for scalar and vector network coding. In vector network coding, the source multicasts information by transmitting vectors of length L, while intermediate nodes process and combine their incoming packets by multiplying them with L X L coding matrices that play a similar role as coding coefficients in scalar coding. Our algorithms for scalar network jointly optimize the employed field size while selecting the coding coefficients. Similarly, for vector co...

Vector independent transmission of the vector-borne bluetongue virus.

Science.gov (United States)

van der Sluijs, Mirjam Tineke Willemijn; de Smit, Abraham J; Moormann, Rob J M

2016-01-01

Bluetongue is an economically important disease of ruminants. The causative agent, Bluetongue virus (BTV), is mainly transmitted by insect vectors. This review focuses on vector-free BTV transmission, and its epizootic and economic consequences. Vector-free transmission can either be vertical, from dam to fetus, or horizontal via direct contract. For several BTV-serotypes, vertical (transplacental) transmission has been described, resulting in severe congenital malformations. Transplacental transmission had been mainly associated with live vaccine strains. Yet, the European BTV-8 strain demonstrated a high incidence of transplacental transmission in natural circumstances. The relevance of transplacental transmission for the epizootiology is considered limited, especially in enzootic areas. However, transplacental transmission can have a substantial economic impact due to the loss of progeny. Inactivated vaccines have demonstrated to prevent transplacental transmission. Vector-free horizontal transmission has also been demonstrated. Since direct horizontal transmission requires close contact of animals, it is considered only relevant for within-farm spreading of BTV. The genetic determinants which enable vector-free transmission are present in virus strains circulating in the field. More research into the genetic changes which enable vector-free transmission is essential to better evaluate the risks associated with outbreaks of new BTV serotypes and to design more appropriate control measures.

VectorBase

Data.gov (United States)

U.S. Department of Health & Human Services — VectorBase is a Bioinformatics Resource Center for invertebrate vectors. It is one of four Bioinformatics Resource Centers funded by NIAID to provide web-based...

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.

Custodial vector model

DEFF Research Database (Denmark)

Becciolini, Diego; Franzosi, Diogo Buarque; Foadi, Roshan

2015-01-01

We analyze the Large Hadron Collider (LHC) phenomenology of heavy vector resonances with a $SU(2)_L\\times SU(2)_R$ spectral global symmetry. This symmetry partially protects the electroweak S-parameter from large contributions of the vector resonances. The resulting custodial vector model spectrum...

Experimental demonstration of vector E x vector B plasma divertor

International Nuclear Information System (INIS)

Strait, E.J.; Kerst, D.W.; Sprott, J.C.

1977-01-01

The vector E x vector B drift due to an applied radial electric field in a tokamak with poloidal divertor can speed the flow of plasma out of the scrape-off region, and provide a means of externally controlling the flow rate and thus the width of the density fall-off. An experiment in the Wisconsin levitated toroidal octupole, using vector E x vector B drifts alone, demonstrates divertor-like behavior, including 70% reduction of plasma density near the wall and 40% reduction of plasma flux to the wall, with no adverse effects on confinement of the main plasma

Efficacy of diflubenzuron, a chitin synthesis inhibitor, against Culex pipiens larvae in septic tank water.

Science.gov (United States)

Cetin, H; Yanikoglu, A; Cilek, J E

2006-06-01

The mosquito Culex pipiens L. is an important pest in urban and suburban areas in many parts of the world. Septic tanks are the most important habitats supporting the production of this species in the city of Antalya, southwestern Turkey. Diflubenzuron, in a 25% wettable powder (Du-dim 25 WP), and a 4% granular formulation (Du-dim 4 G) was evaluated against late 2nd to early 3rd instars of Cx. pipiens in single-family septic tanks. Both formulations were tested at 0.01, 0.02, and 0.03 mg (AI)/liter. The results indicated that both formulations applied at the rate of 0.02 and 0.03 mg (AI)/liter achieved 100% adult inhibition, at intervals of 7, 14, 21, and 28 days after treatment. Septic tanks treated with 0.01 mg (AI)/liter WP formulation resulted in complete (100%) adult inhibition through 14 days, whereas the G formulation gave the same effect through 21 days posttreatment at this rate.

Culex pipiens crossing type diversity is governed by an amplified and polymorphic operon of Wolbachia.

Science.gov (United States)

Bonneau, Manon; Atyame, Celestine; Beji, Marwa; Justy, Fabienne; Cohen-Gonsaud, Martin; Sicard, Mathieu; Weill, Mylène

2018-01-22

Culex pipiens mosquitoes are infected with Wolbachia (wPip) that cause an important diversity of cytoplasmic incompatibilities (CIs). Functional transgenic studies have implicated the cidA-cidB operon from wPip and its homolog in wMel in CI between infected Drosophila males and uninfected females. However, the genetic basis of the CI diversity induced by different Wolbachia strains was unknown. We show here that the remarkable diversity of CI in the C. pipiens complex is due to the presence, in all tested wPip genomes, of several copies of the cidA-cidB operon, which undergoes diversification through recombination events. In 183 isofemale lines of C. pipiens collected worldwide, specific variations of the cidA-cidB gene repertoires are found to match crossing types. The diversification of cidA-cidB is consistent with the hypothesis of a toxin-antitoxin system in which the gene cidB co-diversifies with the gene cidA, particularly in putative domains of reciprocal interactions.

Biological and biomatrial effects of gamma radiation on the mosquito Culex Pipiens L. Vol. 4.

Energy Technology Data Exchange (ETDEWEB)

Wakid, A M; Shoman, A A [Applied Biology Dept., NRC, Atomic Energy Authority. Cairo (Egypt); Amin, A H; Kansouh, A H [Plant Protection Dept., FaC. of Agriculture, Ain Shams Univ. Cairo (Egypt)

1996-03-01

The mosquito, Culex Pipiens L. Was irradiated in the pupal stage with three gamma doses (40, 60 and 80 Gy). The effect of irradiation on the biology and ovarian development of the adult stage were assayed in comparison with a non-irradiated control group. The results showed that the gamma doses used decreased significantly adult emergence and increased malformations, while the sex ratio was not affected. fecundity of irradiated females was severely affected at 40 and 60 Gy, and 80 Gy produced in fecund females. Egg hatch ability was severely affected when males were irradiated at all doses. The gamma doses used decreased the number of ovarioles that reached the 5 th stage of christopher cycle. these ovarioles failed to produce mature eggs normally. The size of the irradiated female ovary was decreased either in length or in width at all doses used particularly at 80 Gy where the ovarian development was completely stopped on the first day of feeding. 6 figs.

Rotations with Rodrigues' vector

International Nuclear Information System (INIS)

Pina, E

2011-01-01

The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears to be a fundamental matrix that is used to express the components of the angular velocity, the rotation matrix and the angular momentum vector. The Hamiltonian formalism of rotational dynamics in terms of this vector uses the same matrix. The quantization of the rotational dynamics is performed with simple rules if one uses Rodrigues' vector and similar formal expressions for the quantum operators that mimic the Hamiltonian classical dynamics.

Native Argentinean cyclopoids (Crustacea: Copepoda as predators of Aedes aegypti and Culex pipiens (Diptera: Culicidae mosquitoes

Directory of Open Access Journals (Sweden)

María C Tranchida

2009-12-01

Full Text Available Copepods from La Plata, Argentina were investigated to characterize the local community of larvivorous copepods inhabiting mosquito breeding sites and to identify new predator species of the mosquitoes which occur in artificial containers, Aedes aegypti and Culex pipiens. Diversity of larvivorous cyclopoids was highest in permanent pools. Predation by sex and age, selectivity on mosquito species, and daily predation rate during five days were studied for Acanthocyclops robustus, Diacyclops uruguayensis, Macrocyclops albidus and Mesocyclops longisetus. Female copepods presented the highest predatory capacity. No predatory preference for mosquito species was found. According to overall predation potential, copepods were ranked as follows: D. uruguayensis Se hizo una prospección de copépodos en La Plata, Argentina, con los objetivos de caracterizar la comunidad local de copépodos larvívoros en sitios de cría de mosquitos, e identificar nuevas especies depredadoras de los mosquitos de contenedores artificiales Aedes aegypti y Culex pipiens. La diversidad de ciclopoides larvívoros fue máxima en charcos permanentes. Se examinó la depredación por sexos y edad, la selectividad por especies de mosquito, y la tasa de depredación diaria durante cinco días en Acanthocyclops robustus, Diacyclops uruguayensis, Macrocyclops albidus y Mesocyclops longisetus. Los copépodos hembra presentaron la capacidad depredadora más alta. No se encontró preferencia por alguna especie de mosquito. De acuerdo al potencial de depredación en general, los copépodos se ordenan así: D. uruguayensis < A. robustus < M. albidus < M. longisetus. También se evaluó la tolerancia a la desecación del hábitat y la capacidad de resistir en agua de contenedores artificiales. D. uruguayensis y A. robustus sobrevivieron en condiciones de sequía, pero D. uruguayensis presentó menor supervivencia en agua de floreros de cementerio. M. albidus no sobrevivió condiciones de

Violation of vector dominance in the vector manifestation

International Nuclear Information System (INIS)

Sasaki, Chihiro

2003-01-01

The vector manifestation (VM) is a new pattern for realizing the chiral symmetry in QCD. In the VM, the massless vector meson becomes the chiral partner of pion at the critical point, in contrast with the restoration based on the linear sigma model. Including the intrinsic temperature dependences of the parameters of the hidden local symmetry (HLS) Lagrangian determined from the underlying QCD through the Wilsonian matching together with the hadronic thermal corrections, we present a new prediction of the VM on the direct photon-π-π coupling which measures the validity of the vector dominance (VD) of the electromagnetic form factor of the pion. We find that the VD is largely violated at the critical temperature, which indicates that the assumption of the VD made in several analysis on the dilepton spectra in hot matter may need to be weakened for consistently including the effect of the dropping mass of the vector meson. (author)

Larvicidal activity of lignans and alkaloid identified in Zanthoxylum piperitum bark toward insecticide-susceptible and wild Culex pipiens pallens and Aedes aegypti.

Science.gov (United States)

Kim, Soon-Il; Ahn, Young-Joon

2017-05-04

The yellow fever mosquito, Aedes aegypti, and the common house mosquito, Culex pipiens pallens, transmit dengue fever and West Nile virus diseases, respectively. This study was conducted to determine the toxicity of the three lignans (-)-asarinin, sesamin and (+)-xanthoxylol-γ,γ-dimethylallylether (XDA), and the alkaloid pellitorine from Zanthoxylum piperitum (Rutaceae) bark to third-instar larvae from insecticide-susceptible C. pipiens pallens and Ae. aegypti as well as wild C. pipiens pallens resistant to deltamethrin, cyfluthrin, fenthion, and temephos. The toxicities of all isolates were compared with those of mosquito larvicide temephos. LC 50 values for each species and their treatments were significantly different from one another when their 95% confidence intervals did not overlap. XDA was isolated from Z. piperitum as a new larvicidal principle. XDA (LC 50 , 0.27 and 0.24 mg/l) was 4, 53, and 144 times and 4, 100, and 117 times more toxic than pellitorine, sesamin, and asarinin toward larvae from susceptible C. pipiens pallens and Ae. aegypti, respectively. Overall, all the isolates were less toxic than temephos (LC 50 , 0.006 and 0.009 mg/l). These constituents did not differ in toxicity to larvae from the two Culex strains. The present finding indicates that the lignans and alkaloid and the insecticides do not share a common mode of larvicidal action or elicit cross-resistance. Naturally occurring Z. piperitum bark-derived compounds, particularly XDA, merit further study as potential mosquito larval control agents or as lead compounds for the control of insecticide-resistant mosquito populations.

Relative performance of indoor vector control interventions in the Ifakara and the West African experimental huts.

Science.gov (United States)

Oumbouke, Welbeck A; Fongnikin, Augustin; Soukou, Koffi B; Moore, Sarah J; N'Guessan, Raphael

2017-09-19

West African and Ifakara experimental huts are used to evaluate indoor mosquito control interventions, including spatial repellents and insecticides. The two hut types differ in size and design, so a side-by-side comparison was performed to investigate the performance of indoor interventions in the two hut designs using standard entomological outcomes: relative indoor mosquito density (deterrence), exophily (induced exit), blood-feeding and mortality of mosquitoes. Metofluthrin mosquito coils (0.00625% and 0.0097%) and Olyset® Net vs control nets (untreated, deliberately holed net) were evaluated against pyrethroid-resistant Culex quinquefasciatus in Benin. Four experimental huts were used: two West African hut designs and two Ifakara hut designs. Treatments were rotated among the huts every four nights until each treatment was tested in each hut 52 times. Volunteers rotated between huts nightly. The Ifakara huts caught a median of 37 Culex quinquefasciatus/ night, while the West African huts captured a median of 8/ night (rate ratio 3.37, 95% CI: 2.30-4.94, P  4-fold higher mosquito exit relative to the West African huts (odds ratio 4.18, 95% CI: 3.18-5.51, P < 0.0001), regardless of treatment. While blood-feeding rates were significantly higher in the West African huts, mortality appeared significantly lower for all treatments. The Ifakara hut captured more Cx. quinquefasciatus that could more easily exit into windows and eave traps after failing to blood-feed, compared to the West African hut. The higher mortality rates recorded in the Ifakara huts could be attributable to the greater proportions of Culex mosquitoes exiting and probably dying from starvation, relative to the situation in the West African huts.

Evaluation of larvicidal activity of medicinal plant extracts against three mosquito vectors.

Science.gov (United States)

Bagavan, A; Rahuman, A Abdul

2011-01-01

To evaluate the mosquito larvicidal activity of plant extracts. The hexane, chloroform, ethyl acetate, acetone, and methanol leaf, flower and seed extracts of Abrus precatorius (A. precatorius), Croton bonplandianum (C. bonplandianum), Cynodon dactylon (C. dactylon), Musa paradisiaca (M. paradisiaca) and Syzygium aromaticum (S. aromaticum) were tested against fourth instar larvae of Anopheles vagus (An. vagus), Armigeres subalbatus (Ar. subalbatus) and Culex vishnui (Cx. vishnui). The highest larval mortality was found in seed ethyl acetate extracts of A. precatorius and leaf extracts of C. bonplandianum, flower chloroform and methanol extracts of M. paradisiaca, and flower bud hexane extract of S. aromaticum against An. vagus with LC(50) values of 19.31, 39.96, 35.18, 79.90 and 85.90 μg/mL; leaf ethyl acetate and methanol extracts of C. dactylon, flower methanol extract of M. paradisiaca, flower bud methanol extract of S. aromaticum against Ar. subalbatus with LC(50) values of 21.67, 32.62, 48.90 and 78.28 μg/mL, and seed methanol of A. precatorius, flower methanol extract of M. paradisiaca, flower bud hexane extract of S. aromaticum against Cx. vishnui with LC(50) values of 136.84, 103.36 and 149.56 μg/mL, respectively. These results suggest that the effective plant crude extracts have the potential to be used as an ideal ecofriendly approach for the control of disease vectors. This study provides the first report on the larvicidal activity of crude solvent extracts of different mosquitoes. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Species composition and fauna distribution of mosquitoes (Diptera: Culicidae and its importance for vector-borne diseases in a rural area of Central Western - Mato Grosso, Brazil

Directory of Open Access Journals (Sweden)

Fábio Alexandre Leal-Santos

2017-08-01

Full Text Available Abstract. This study describes ecological data obtained in a rural area in the State of Mato Grosso, including the insects belonging to the family Culicidae, especially those framed as potential vectors of tropical diseases. In 2015, we collected adult mosquitoes in fragments of forest in a rural area located in Mato Grosso Central West of Brazil. We captured 18,256 mosquitoes of the sub-families Culicinae and Anophelinae and have identified 34 species belonging to 12 genera: Aedes (1 species, Anopheles (8 species, Coquillettidia (1 species, Haemagogus (1 species, Culex (5 species, Psorophora  (5 species, Ochlerotatus (4 species, Deinocerites (1 species,  Mansonia (4 species, Sabethes (2 species, Limatus (1 species, Wyeomyia (1 species. The family Culicidae presented high richness and abundance, established by diversity indexes (Margalef α =3.26; Shannon H' = 2.09; Simpson D = 0.19 with dominance of the species Anopheles (Nyssorhyncus darlingi Root (89.8%. This species has considerable epidemiological value, considered the main vector of malaria in Mato Grosso. Many species of mosquitoes are vectors of pathogens that cause disease in humans and domestic animals, transmitting pathogens including viruses (arboviruses, filaria worms (helminths and protozoa. Composição de espécies e distribuição da fauna de mosquitos (Diptera: Culicidae e sua importância para doenças transmitidas por vetores em uma área rural do centro-ocidental - Mato Grosso, Brasil Resumo. Este estudo descreve dados ecológicos de uma área rural do Estado de Mato Grosso e dos insetos da família Culicidae especialmente aqueles enquadrados como vetores potenciais de doenças tropicais. Em 2015, coletamos mosquitos adultos em fragmentos de floresta em localidades de áreas rurais no Mato Grosso região Centro Oeste do Brasil. Foram capturados 18.256 exemplares alados de mosquitos das subfamílias Culicinae e Anophelinae e identificadas 34 espécies pertencentes a 12 g

Measurement of K/sub NN/, K/sub LL/ in p vector d → n vector X and p vector 9Be → n vector X at 800 MeV

International Nuclear Information System (INIS)

Riley, P.J.; Hollas, C.L.; Newsom, C.R.

1980-01-01

The spin transfer parameters, K/sub NN/ and K/sub LL/, have been measured in p vector d → n vector X and p vector 9 Be → n vector X at 0 0 and 800 MeV. The rather large values of K/sub LL/ demonstrate that this transfer mechanism will provide a useful source of polarized neutrons at LAMPF energies

Raster images vectorization system

OpenAIRE

Genytė, Jurgita

2006-01-01

The problem of raster images vectorization was analyzed and researched in this work. Existing vectorization systems are quite expensive, the results are inaccurate, and the manual vectorization of a large number of drafts is impossible. That‘s why our goal was to design and develop a new raster images vectorization system using our suggested automatic vectorization algorithm and the way to record results in a new universal vectorial file format. The work consists of these main parts: analysis...

Vectorization of phase space Monte Carlo code in FACOM vector processor VP-200

International Nuclear Information System (INIS)

Miura, Kenichi

1986-01-01

This paper describes the vectorization techniques for Monte Carlo codes in Fujitsu's Vector Processor System. The phase space Monte Carlo code FOWL is selected as a benchmark, and scalar and vector performances are compared. The vectorized kernel Monte Carlo routine which contains heavily nested IF tests runs up to 7.9 times faster in vector mode than in scalar mode. The overall performance improvement of the vectorized FOWL code over the original scalar code reaches 3.3. The results of this study strongly indicate that supercomputer can be a powerful tool for Monte Carlo simulations in high energy physics. (Auth.)

Regulation of P450-mediated permethrin resistance in Culex quinquefasciatus by the GPCR/Gαs/AC/cAMP/PKA signaling cascade.

Science.gov (United States)

Li, Ting; Liu, Nannan

2017-12-01

This study explores the role of G-protein-coupled receptor-intracellular signaling in the development of P450-mediated insecticide resistance in mosquitoes, Culex quinquefasciatus , focusing on the essential function of the GPCRs and their downstream effectors of Gs alpha subunit protein (Gαs) and adenylyl cyclase (ACs) in P450-mediated insecticide resistance of Culex mosquitoes. Our RNAi-mediated functional study showed that knockdown of Gαs caused the decreased expression of the downstream effectors of ACs and PKAs in the GPCR signaling pathway and resistance P450 genes, whereas knockdown of ACs decreased the expression of PKAs and resistance P450 genes. Knockdown of either Gαs or ACs resulted in an increased susceptibility of mosquitoes to permethrin. These results add significantly to our understanding of the molecular basis of resistance P450 gene regulation through GPCR/Gαs/AC/cAMP-PKA signaling pathways in the insecticide resistance of mosquitoes. The temporal and spatial dynamic analyses of GPCRs, Gαs, ACs, PKAs, and P450s in two insecticide resistant mosquito strains revealed that all the GPCR signaling pathway components tested, namely GPCRs, Gαs, ACs and PKAs, were most highly expressed in the brain for both resistant strains, suggesting the role played by these genes in signaling transduction and regulation. The resistance P450 genes were mainly expressed in the brain, midgut and malpighian tubules (MTs), suggesting their critical function in the central nervous system and importance for detoxification. The temporal dynamics analysis for the gene expression showed a diverse expression profile during mosquito development, indicating their initially functional importance in response to exposure to insecticides during their life stages.

Forty years of erratic insecticide resistance evolution in the mosquito Culex pipiens.

Directory of Open Access Journals (Sweden)

Pierrick Labbé

2007-11-01

Full Text Available One view of adaptation is that it proceeds by the slow and steady accumulation of beneficial mutations with small effects. It is difficult to test this model, since in most cases the genetic basis of adaptation can only be studied a posteriori with traits that have evolved for a long period of time through an unknown sequence of steps. In this paper, we show how ace-1, a gene involved in resistance to organophosphorous insecticide in the mosquito Culex pipiens, has evolved during 40 years of an insecticide control program. Initially, a major resistance allele with strong deleterious side effects spread through the population. Later, a duplication combining a susceptible and a resistance ace-1 allele began to spread but did not replace the original resistance allele, as it is sublethal when homozygous. Last, a second duplication, (also sublethal when homozygous began to spread because heterozygotes for the two duplications do not exhibit deleterious pleiotropic effects. Double overdominance now maintains these four alleles across treated and nontreated areas. Thus, ace-1 evolution does not proceed via the steady accumulation of beneficial mutations. Instead, resistance evolution has been an erratic combination of mutation, positive selection, and the rearrangement of existing variation leading to complex genetic architecture.

Biochemical effects of gamma radiation on the mosquito; Culex Pipiens L. Vol. 4

International Nuclear Information System (INIS)

Amin, A.H.; Kansouh, A.H.; Wakid, A.M.; Shoman, A.A.; Aly, M.A.S.

1996-01-01

Three doses of gamma radiation (40, 60, and 80 Gy) were applied to pupae of Culex Pipiens L. An unirradiated control group was treated similarly. Newly emerged non-fed adults were assayed for carbohydrate, lipid, and protein contents in the whole body after three periods of 24,48, and 72 hours post emergence. The carbohydrate content of both sexes decreased significantly at lower doses of radiation. However, at 80 Gy, the males showed significant increase, while females showed significant decrease. Carbohydrates in both sexes were decreased with increasing the time after emergence. However, in females, carbohydrates were increased after 72 hours, at all doses tested, compared to control. The lipid content was reduced significantly with increasing gamma dose in both sexes. This content was also decreased significantly with time at all doses tested and in the controls. Irradiation decreased insignificantly protein content in the male whole body after 48 hours especially at higher doses. The reduction in female protein content at 80 Gy was very highly significant compared to control after 48 hours post emergence. Gamma irradiation with high doses reduced protein content in testes and ovaries. 9 figs

Biochemical effects of gamma radiation on the mosquito; Culex Pipiens L. Vol. 4.

Energy Technology Data Exchange (ETDEWEB)

Amin, A H; Kansouh, A H [Plant Protection Dept., Fac. of Agriculture, Ain Shams Univ. Cairo (Egypt); Wakid, A M; Shoman, A A [Applied Biology Dept., NRC, Atomic Energy Authority Cairo, (Egypt); Aly, M A.S. [Radio Isotope Dept., NRC, Atomic Energy Authority Cairo (Egypt)

1996-03-01

Three doses of gamma radiation (40, 60, and 80 Gy) were applied to pupae of Culex Pipiens L. An unirradiated control group was treated similarly. Newly emerged non-fed adults were assayed for carbohydrate, lipid, and protein contents in the whole body after three periods of 24,48, and 72 hours post emergence. The carbohydrate content of both sexes decreased significantly at lower doses of radiation. However, at 80 Gy, the males showed significant increase, while females showed significant decrease. Carbohydrates in both sexes were decreased with increasing the time after emergence. However, in females, carbohydrates were increased after 72 hours, at all doses tested, compared to control. The lipid content was reduced significantly with increasing gamma dose in both sexes. This content was also decreased significantly with time at all doses tested and in the controls. Irradiation decreased insignificantly protein content in the male whole body after 48 hours especially at higher doses. The reduction in female protein content at 80 Gy was very highly significant compared to control after 48 hours post emergence. Gamma irradiation with high doses reduced protein content in testes and ovaries. 9 figs.

Vector grammars and PN machines

Institute of Scientific and Technical Information of China (English)

蒋昌俊

1996-01-01

The concept of vector grammars under the string semantic is introduced.The dass of vector grammars is given,which is similar to the dass of Chomsky grammars.The regular vector grammar is divided further.The strong and weak relation between the vector grammar and scalar grammar is discussed,so the spectrum system graph of scalar and vector grammars is made.The equivalent relation between the regular vector grammar and Petri nets (also called PN machine) is pointed.The hybrid PN machine is introduced,and its language is proved equivalent to the language of the context-free vector grammar.So the perfect relation structure between vector grammars and PN machines is formed.

Vector velocimeter

DEFF Research Database (Denmark)

2012-01-01

The present invention relates to a compact, reliable and low-cost vector velocimeter for example for determining velocities of particles suspended in a gas or fluid flow, or for determining velocity, displacement, rotation, or vibration of a solid surface, the vector velocimeter comprising a laser...

Cloning vector

Science.gov (United States)

Guilfoyle, Richard A.; Smith, Lloyd M.

1994-01-01

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

Cloning vector

Science.gov (United States)

Guilfoyle, R.A.; Smith, L.M.

1994-12-27

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

Identification of Avian and Hemoparasite DNA in Blood-Engorged Abdomens of Culex pipiens (Diptera; Culicidae) from a West Nile Virus Epidemic region in Suburban Chicago, Illinois.

Science.gov (United States)

Boothe, Emily; Medeiros, Matthew C I; Kitron, Uriel D; Brawn, Jeffrey D; Ruiz, Marilyn O; Goldberg, Tony L; Walker, Edward D; Hamer, Gabriel L

2015-05-01

Multiple mosquito-borne parasites cocirculate in nature and potentially interact. To understand the community of parasites cocirculating with West Nile virus (WNV), we screened the bloodmeal content of Culex pipiens L. mosquitoes for three common types of hemoparasites. Blood-fed Cx. pipiens were collected from a WNV-epidemic area in suburban Chicago, IL, from May to September 2005 through 2010. DNA was extracted from dissected abdomens and subject to PCR and direct sequencing to identify the vertebrate host. RNA was extracted from the head or thorax and screened for WNV using quantitative reverse transcriptase PCR. Seventy-nine engorged females with avian host origin were screened using PCR and amplicon sequencing for filarioid nematodes, Haemosporida, and trypanosomatids. Filarioid nematodes were identified in 3.8% of the blooded abdomens, Plasmodium sp. in 8.9%, Haemoproteus in 31.6%, and Trypanosoma sp. in 6.3%. The sequences from these hemoparasite lineages were highly similar to sequences from birds in prior studies in suburban Chicago. Overall, 50.6% of blood-fed Culex pipiens contained hemoparasite DNA in their abdomen, presumably from current or prior bloodmeals. Additionally, we detected hemoparasite DNA in the blooded abdomen of three of 10 Cx. pipiens infected with WNV. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Urbanization impact on mosquito community and the transmission potential of filarial infection in central Europe

Czech Academy of Sciences Publication Activity Database

Čabanová, V.; Miterpáková, M.; Valentová, D.; Blažejová, Hana; Rudolf, Ivo; Stloukal, E.; Hurníková, Z.; Dzidová, M.

2018-01-01

Roč. 11, č. 1 (2018), č. článku 261. ISSN 1756-3305 Institutional support: RVO:68081766 Keywords : Culex pipiens complex * West Nile virus * Diptera Culicidae * Anopheles hyrcanus * Dirofilaria immitis * Aedes albopictus * endemic area * 1st record * Slovakia * vector * Dirofilaria * mosquito-borne diseases * Anopheles maculipennis complex * xenomonitoring Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 3.080, year: 2016

Vector 33: A reduce program for vector algebra and calculus in orthogonal curvilinear coordinates

Science.gov (United States)

Harper, David

1989-06-01

This paper describes a package with enables REDUCE 3.3 to perform algebra and calculus operations upon vectors. Basic algebraic operations between vectors and between scalars and vectors are provided, including scalar (dot) product and vector (cross) product. The vector differential operators curl, divergence, gradient and Laplacian are also defined, and are valid in any orthogonal curvilinear coordinate system. The package is written in RLISP to allow algebra and calculus to be performed using notation identical to that for operations. Scalars and vectors can be mixed quite freely in the same expression. The package will be of interest to mathematicians, engineers and scientists who need to perform vector calculations in orthogonal curvilinear coordinates.

Probing deformed orbitals with vector A( vector e, e' N)B reactions

International Nuclear Information System (INIS)

Garrido, E.; Caballero, J.A.; Moya de Guerra, E.; Sarriguren, P.; Udias, J.M.

1995-01-01

We present results for response functions and asymmetries in the nuclear reactions 37 vector Ar( vector e, e' n) 36 Ar and 37 vector K( vector e,e' p) 36 Ar at quasifree kinematics. We compare PWIA results obtained using deformed HF wave functions with PWIA and DWIA results obtained assuming a spherical mean field. We show that the complex structure of the deformed orbitals can be probed by coincidence measurements with polarized beam and targets. ((orig.))

British Container Breeding Mosquitoes: The Impact of Urbanisation and Climate Change on Community Composition and Phenology

Science.gov (United States)

Townroe, Susannah; Callaghan, Amanda

2014-01-01

The proliferation of artificial container habitats in urban areas has benefitted urban adaptable mosquito species globally. In areas where mosquitoes transmit viruses and parasites, it can promote vector population productivity and fuel mosquito-borne disease outbreaks. In Britain, storage of water in garden water butts is increasing, potentially expanding mosquito larval habitats and influencing population dynamics and mosquito-human contact. Here we show that the community composition, abundance and phenology of mosquitoes breeding in experimental water butt containers were influenced by urbanisation. Mosquitoes in urban containers were less species-rich but present in significantly higher densities (100.4±21.3) per container than those in rural containers (77.7±15.1). Urban containers were dominated by Culex pipiens (a potential vector of West Nile Virus [WNV]) and appear to be increasingly exploited by Anopheles plumbeus (a human-biting potential WNV and malaria vector). Culex phenology was influenced by urban land use type, with peaks in larval abundances occurring earlier in urban than rural containers. Among other factors, this was associated with an urban heat island effect which raised urban air and water temperatures by 0.9°C and 1.2°C respectively. Further increases in domestic water storage, particularly in urban areas, in combination with climate changes will likely alter mosquito population dynamics in the UK. PMID:24759617

Multi-perspective views of students’ difficulties with one-dimensional vector and two-dimensional vector

Science.gov (United States)

Fauzi, Ahmad; Ratna Kawuri, Kunthi; Pratiwi, Retno

2017-01-01

Researchers of students’ conceptual change usually collects data from written tests and interviews. Moreover, reports of conceptual change often simply refer to changes in concepts, such as on a test, without any identification of the learning processes that have taken place. Research has shown that students have difficulties with vectors in university introductory physics courses and high school physics courses. In this study, we intended to explore students’ understanding of one-dimensional and two-dimensional vector in multi perspective views. In this research, we explore students’ understanding through test perspective and interviews perspective. Our research study adopted the mixed-methodology design. The participants of this research were sixty students of third semester of physics education department. The data of this research were collected by testand interviews. In this study, we divided the students’ understanding of one-dimensional vector and two-dimensional vector in two categories, namely vector skills of the addition of one-dimensionaland two-dimensional vector and the relation between vector skills and conceptual understanding. From the investigation, only 44% of students provided correct answer for vector skills of the addition of one-dimensional and two-dimensional vector and only 27% students provided correct answer for the relation between vector skills and conceptual understanding.

miRNA genes of an invasive vector mosquito, Aedes albopictus.

Directory of Open Access Journals (Sweden)

Jinbao Gu

Full Text Available Aedes albopictus, a vector of Dengue and Chikungunya viruses, is a robust invasive species in both tropical and temperate environments. MicroRNAs (miRNAs regulate gene expression and biological processes including embryonic development, innate immunity and infection. While a number of miRNAs have been discovered in some mosquitoes, no comprehensive effort has been made to characterize them from different developmental stages from a single species. Systematic analysis of miRNAs in Ae. albopictus will improve our understanding of its basic biology and inform novel strategies to prevent virus transmission. Between 10-14 million Illumina sequencing reads per sample were obtained from embryos, larvae, pupae, adult males, sugar-fed and blood-fed adult females. A total of 119 miRNA genes represented by 215 miRNA or miRNA star (miRNA* sequences were identified, 15 of which are novel. Eleven, two, and two of the newly-discovered miRNA genes appear specific to Aedes, Culicinae, and Culicidae, respectively. A number of miRNAs accumulate predominantly in one or two developmental stages and the large number that showed differences in abundance following a blood meal likely are important in blood-induced mosquito biology. Gene Ontology (GO analysis of the targets of all Ae. albopictus miRNAs provides a useful starting point for the study of their functions in mosquitoes. This study is the first systematic analysis of miRNAs based on deep-sequencing of small RNA samples of all developmental stages of a mosquito species. A number of miRNAs are related to specific physiological states, most notably, pre- and post-blood feeding. The distribution of lineage-specific miRNAs is consistent with mosquito phylogeny and the presence of a number of Aedes-specific miRNAs likely reflects the divergence between the Aedes and Culex genera.

Custodial vector model

Science.gov (United States)

Becciolini, Diego; Franzosi, Diogo Buarque; Foadi, Roshan; Frandsen, Mads T.; Hapola, Tuomas; Sannino, Francesco

2015-07-01

We analyze the Large Hadron Collider (LHC) phenomenology of heavy vector resonances with a S U (2 )L×S U (2 )R spectral global symmetry. This symmetry partially protects the electroweak S parameter from large contributions of the vector resonances. The resulting custodial vector model spectrum and interactions with the standard model fields lead to distinct signatures at the LHC in the diboson, dilepton, and associated Higgs channels.

Vector Differential Calculus

OpenAIRE

HITZER, Eckhard MS

2002-01-01

This paper treats the fundamentals of the vector differential calculus part of universal geometric calculus. Geometric calculus simplifies and unifies the structure and notation of mathematics for all of science and engineering, and for technological applications. In order to make the treatment self-contained, I first compile all important geometric algebra relationships,which are necesssary for vector differential calculus. Then differentiation by vectors is introduced and a host of major ve...

Vectorization, parallelization and porting of nuclear codes. Vectorization and parallelization. Progress report fiscal 1999

Energy Technology Data Exchange (ETDEWEB)

Adachi, Masaaki; Ogasawara, Shinobu; Kume, Etsuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishizuki, Shigeru; Nemoto, Toshiyuki; Kawasaki, Nobuo; Kawai, Wataru [Fujitsu Ltd., Tokyo (Japan); Yatake, Yo-ichi [Hitachi Ltd., Tokyo (Japan)

2001-02-01

Several computer codes in the nuclear field have been vectorized, parallelized and trans-ported on the FUJITSU VPP500 system, the AP3000 system, the SX-4 system and the Paragon system at Center for Promotion of Computational Science and Engineering in Japan Atomic Energy Research Institute. We dealt with 18 codes in fiscal 1999. These results are reported in 3 parts, i.e., the vectorization and the parallelization part on vector processors, the parallelization part on scalar processors and the porting part. In this report, we describe the vectorization and parallelization on vector processors. In this vectorization and parallelization on vector processors part, the vectorization of Relativistic Molecular Orbital Calculation code RSCAT, a microscopic transport code for high energy nuclear collisions code JAM, three-dimensional non-steady thermal-fluid analysis code STREAM, Relativistic Density Functional Theory code RDFT and High Speed Three-Dimensional Nodal Diffusion code MOSRA-Light on the VPP500 system and the SX-4 system are described. (author)

Elliptic-symmetry vector optical fields.

Science.gov (United States)

Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

2014-08-11

We present in principle and demonstrate experimentally a new kind of vector fields: elliptic-symmetry vector optical fields. This is a significant development in vector fields, as this breaks the cylindrical symmetry and enriches the family of vector fields. Due to the presence of an additional degrees of freedom, which is the interval between the foci in the elliptic coordinate system, the elliptic-symmetry vector fields are more flexible than the cylindrical vector fields for controlling the spatial structure of polarization and for engineering the focusing fields. The elliptic-symmetry vector fields can find many specific applications from optical trapping to optical machining and so on.

Fauna of mosquito larvae (Diptera: Culicida) in Asir Provence, Kingdom of Saudi Arabia.

Science.gov (United States)

Al Ashry, Hamdy A; Kenawy, Mohamed A; Shobrak, Mohammed

2014-04-01

An entomological survey was undertaken for one year to update the mosquito fauna of Asir Region, Kingdom of Saudi Arabia. A total of 31 species of 8 genera were reported of which genus Culex (55%) was the most common. Most of collected larvae (59%) belonged to genus Culex (+ Lutzia) followed by Culiseta (26%), Anopheles (13%) and Aedine spp. (2%). Cx. pipiens (39%) and Cs. longiareolata (26.%) were generally the most abundant of all collected larvae. Of the Anopheles spp., An. dthali was common (40%), of Culex spp., Cx. pipiens was predominating (66%) and of Aedine spp., St. aegypti was predominating (71%). Four species: An. fluviatilis, Cx. mattinglyi, Cx. arbieeni and Cx. mimeticus were new reports in Asir Region and Cx. wigglesworthi recorded for the first time from the kingdom. Larvae were more common in low- and highlands than in the moderately altitude areas. In general all species prefer stagnant water but with the exception of Aedine larvae (altogether), the other species prefer presence of algae, vegetation and shade and absence of turbidity (except Culex spp.). A total of 98 different forms of association were reported of which 9 forms were common. All genera breed year round with peaks of abundance during spring for Anopheles spp. and Culex spp. and during winter for Aedine spp. and Cs. longiareolata. A complete list of mosquito fauna of Asir Region comprising 45 spp. was presented based on the present and previous surveys. The study concluded that the occurrence and prevalence of mosquito species mainly the disease vectors in Asir carry the thread of maintaining and transmission of several mosquito-borne diseases.

Interactions between the invasive Burmese python, Python bivittatus Kuhl, and the local mosquito community in Florida, USA.

Science.gov (United States)

Reeves, Lawrence E; Krysko, Kenneth L; Avery, Michael L; Gillett-Kaufman, Jennifer L; Kawahara, Akito Y; Connelly, C Roxanne; Kaufman, Phillip E

2018-01-01

The Burmese python, Python bivittatus Kuhl, is a well-established invasive species in the greater Everglades ecosystem of southern Florida, USA. Most research on its ecological impacts focuses on its role as a predator and its trophic interactions with native vertebrate species, particularly mammals. Beyond predation, there is little known about the ecological interactions between P. bivittatus and native faunal communities. It is likely that established populations of P. bivittatus in southern Florida serve as hosts for native mosquito communities. To test this concept, we used mitochondrial cytochrome c oxidase subunit I DNA barcoding to determine the hosts of blood fed mosquitoes collected at a research facility in northern Florida where captive P. bivittatus and Argentine black and white tegu, Salvator merianae (Duméril and Bibron), are maintained in outdoor enclosures, accessible to local mosquitoes. We recovered python DNA from the blood meals of three species of Culex mosquitoes: Culex erraticus (Dyar and Knab), Culex quinquefasciatus Say, and Culex pilosus (Dyar and Knab). Culex erraticus conclusively (P = 0.001; Fisher's Exact Test) took more blood meals from P. bivittatus than from any other available host. While the majority of mosquito blood meals in our sample were derived from P. bivittatus, only one was derived from S. merianae. These results demonstrate that local mosquitoes will feed on invasive P. bivittatus, a recently introduced host. If these interactions also occur in southern Florida, P. bivittatus may be involved in the transmission networks of mosquito-vectored pathogens. Our results also illustrate the potential of detecting the presence of P. bivittatus in the field through screening mosquito blood meals for their DNA.

Interactions between the invasive Burmese python, Python bivittatus Kuhl, and the local mosquito community in Florida, USA.

Directory of Open Access Journals (Sweden)

Lawrence E Reeves

Full Text Available The Burmese python, Python bivittatus Kuhl, is a well-established invasive species in the greater Everglades ecosystem of southern Florida, USA. Most research on its ecological impacts focuses on its role as a predator and its trophic interactions with native vertebrate species, particularly mammals. Beyond predation, there is little known about the ecological interactions between P. bivittatus and native faunal communities. It is likely that established populations of P. bivittatus in southern Florida serve as hosts for native mosquito communities. To test this concept, we used mitochondrial cytochrome c oxidase subunit I DNA barcoding to determine the hosts of blood fed mosquitoes collected at a research facility in northern Florida where captive P. bivittatus and Argentine black and white tegu, Salvator merianae (Duméril and Bibron, are maintained in outdoor enclosures, accessible to local mosquitoes. We recovered python DNA from the blood meals of three species of Culex mosquitoes: Culex erraticus (Dyar and Knab, Culex quinquefasciatus Say, and Culex pilosus (Dyar and Knab. Culex erraticus conclusively (P = 0.001; Fisher's Exact Test took more blood meals from P. bivittatus than from any other available host. While the majority of mosquito blood meals in our sample were derived from P. bivittatus, only one was derived from S. merianae. These results demonstrate that local mosquitoes will feed on invasive P. bivittatus, a recently introduced host. If these interactions also occur in southern Florida, P. bivittatus may be involved in the transmission networks of mosquito-vectored pathogens. Our results also illustrate the potential of detecting the presence of P. bivittatus in the field through screening mosquito blood meals for their DNA.

Chikungunya Virus–Vector Interactions

Directory of Open Access Journals (Sweden)

Lark L. Coffey

2014-11-01

Full Text Available Chikungunya virus (CHIKV is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed.

Extended vector-tensor theories

Energy Technology Data Exchange (ETDEWEB)

Kimura, Rampei; Naruko, Atsushi; Yoshida, Daisuke, E-mail: rampei@th.phys.titech.ac.jp, E-mail: naruko@th.phys.titech.ac.jp, E-mail: yoshida@th.phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)

2017-01-01

Recently, several extensions of massive vector theory in curved space-time have been proposed in many literatures. In this paper, we consider the most general vector-tensor theories that contain up to two derivatives with respect to metric and vector field. By imposing a degeneracy condition of the Lagrangian in the context of ADM decomposition of space-time to eliminate an unwanted mode, we construct a new class of massive vector theories where five degrees of freedom can propagate, corresponding to three for massive vector modes and two for massless tensor modes. We find that the generalized Proca and the beyond generalized Proca theories up to the quartic Lagrangian, which should be included in this formulation, are degenerate theories even in curved space-time. Finally, introducing new metric and vector field transformations, we investigate the properties of thus obtained theories under such transformations.

Hyperbolic-symmetry vector fields.

Science.gov (United States)

Gao, Xu-Zhen; Pan, Yue; Cai, Meng-Qiang; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

2015-12-14

We present and construct a new kind of orthogonal coordinate system, hyperbolic coordinate system. We present and design a new kind of local linearly polarized vector fields, which is defined as the hyperbolic-symmetry vector fields because the points with the same polarization form a series of hyperbolae. We experimentally demonstrate the generation of such a kind of hyperbolic-symmetry vector optical fields. In particular, we also study the modified hyperbolic-symmetry vector optical fields with the twofold and fourfold symmetric states of polarization when introducing the mirror symmetry. The tight focusing behaviors of these vector fields are also investigated. In addition, we also fabricate micro-structures on the K9 glass surfaces by several tightly focused (modified) hyperbolic-symmetry vector fields patterns, which demonstrate that the simulated tightly focused fields are in good agreement with the fabricated micro-structures.

Supergravity inspired vector curvaton

International Nuclear Information System (INIS)

Dimopoulos, Konstantinos

2007-01-01

It is investigated whether a massive Abelian vector field, whose gauge kinetic function is growing during inflation, can be responsible for the generation of the curvature perturbation in the Universe. Particle production is studied and it is shown that the vector field can obtain a scale-invariant superhorizon spectrum of perturbations with a reasonable choice of kinetic function. After inflation the vector field begins coherent oscillations, during which it corresponds to pressureless isotropic matter. When the vector field dominates the Universe, its perturbations give rise to the observed curvature perturbation following the curvaton scenario. It is found that this is possible if, after the end of inflation, the mass of the vector field increases at a phase transition at temperature of order 1 TeV or lower. Inhomogeneous reheating, whereby the vector field modulates the decay rate of the inflaton, is also studied

Constraining vectors and axial-vectors in walking technicolour by a holographic principle

DEFF Research Database (Denmark)

D. Dietrich, Dennis; Kouvaris, Christoforos

2008-01-01

We use a holographic principle to study the low-energy spectrum of walking technicolour models. In particular, we predict the masses of the axial vectors as well as the decay constants of vectors and axial vectors as functions of the mass of the techni-rho. Given that there are very few...

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

Directory of Open Access Journals (Sweden)

Irish SR

2008-06-01

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

Recommendation on vectors and vector-transmitted diseases

OpenAIRE

Netherlands Food and Consumer Product Safety Authority

2009-01-01

In view of their increasing risk of introduction and their possible implications in causing major disease outbreaks, vectors, as well as vector-transmitted diseases like dengue, West Nile disease, Lyme disease and bluetongue need to be recognised as a threat to public and animal health and to the economy, also in the Netherlands. There has been an increase in the incidence of these diseases in the past two to three decades. Climate changes and changes in the use of land, water managemen...

Gauge anomaly with vector and axial-vector fields in 6D curved space

Science.gov (United States)

Yajima, Satoshi; Eguchi, Kohei; Fukuda, Makoto; Oka, Tomonori

2018-03-01

Imposing the conservation equation of the vector current for a fermion of spin 1/2 at the quantum level, a gauge anomaly for the fermion coupling with non-Abelian vector and axial-vector fields in 6D curved space is expressed in tensorial form. The anomaly consists of terms that resemble the chiral U(1) anomaly and the commutator terms that disappear if the axial-vector field is Abelian.

Vector manifestation and violation of vector dominance in hot matter

International Nuclear Information System (INIS)

Harada, Masayasu; Sasaki, Chihiro

2004-01-01

We show the details of the calculation of the hadronic thermal corrections to the two-point functions in the effective field theory of QCD for pions and vector mesons based on the hidden local symmetry (HLS) in hot matter using the background field gauge. We study the temperature dependence of the pion velocity in the low-temperature region determined from the hadronic thermal corrections, and show that, due to the presence of the dynamical vector meson, the pion velocity is smaller than the speed of the light already at one-loop level, in contrast to the result obtained in the ordinary chiral perturbation theory including only the pion at one-loop. Including the intrinsic temperature dependences of the parameters of the HLS Lagrangian determined from the underlying QCD through the Wilsonian matching, we show how the vector manifestation (VM), in which the massless vector meson becomes the chiral partner of pion, is realized at the critical temperature. We present a new prediction of the VM on the direct photon-π-π coupling which measures the validity of the vector dominance (VD) of the electromagnetic form factor of the pion: we find that the VD is largely violated at the critical temperature, which indicates that the assumption of the VD made in several analyses on the dilepton spectra in hot matter may need to be weakened for consistently including the effect of the dropping mass of the vector meson

Heavy Scalar, Vector, and Axial-Vector Mesons in Hot and Dense Nuclear Medium

Directory of Open Access Journals (Sweden)

Arvind Kumar

2014-01-01

Full Text Available In this work we shall investigate the mass modifications of scalar mesons (D0; B0, vector mesons (D*; B*, and axial-vector mesons (D1; B1 at finite density and temperature of the nuclear medium. The above mesons are modified in the nuclear medium through the modification of quark and gluon condensates. We will find the medium modification of quark and gluon condensates within chiral SU(3 model through the medium modification of scalar-isoscalar fields σ and ζ at finite density and temperature. These medium modified quark and gluon condensates will further be used through QCD sum rules for the evaluation of in-medium properties of the above mentioned scalar, vector, and axial vector mesons. We will also discuss the effects of density and temperature of the nuclear medium on the scattering lengths of the above scalar, vector, and axial-vector mesons. The study of the medium modifications of the above mesons may be helpful for understanding their production rates in heavy-ion collision experiments. The results of present investigations of medium modifications of scalar, vector, and axial-vector mesons at finite density and temperature can be verified in the compressed baryonic matter (CBM experiment of FAIR facility at GSI, Germany.

Vector Fields on Product Manifolds

OpenAIRE

Kurz, Stefan

2011-01-01

This short report establishes some basic properties of smooth vector fields on product manifolds. The main results are: (i) On a product manifold there always exists a direct sum decomposition into horizontal and vertical vector fields. (ii) Horizontal and vertical vector fields are naturally isomorphic to smooth families of vector fields defined on the factors. Vector fields are regarded as derivations of the algebra of smooth functions.

Light scattering of rectangular slot antennas: parallel magnetic vector vs perpendicular electric vector

Science.gov (United States)

Lee, Dukhyung; Kim, Dai-Sik

2016-01-01

We study light scattering off rectangular slot nano antennas on a metal film varying incident polarization and incident angle, to examine which field vector of light is more important: electric vector perpendicular to, versus magnetic vector parallel to the long axis of the rectangle. While vector Babinet’s principle would prefer magnetic field along the long axis for optimizing slot antenna function, convention and intuition most often refer to the electric field perpendicular to it. Here, we demonstrate experimentally that in accordance with vector Babinet’s principle, the incident magnetic vector parallel to the long axis is the dominant component, with the perpendicular incident electric field making a small contribution of the factor of 1/|ε|, the reciprocal of the absolute value of the dielectric constant of the metal, owing to the non-perfectness of metals at optical frequencies.

Generalization of concurrence vectors

International Nuclear Information System (INIS)

Yu Changshui; Song Heshan

2004-01-01

In this Letter, based on the generalization of concurrence vectors for bipartite pure state with respect to employing tensor product of generators of the corresponding rotation groups, we generalize concurrence vectors to the case of mixed states; a new criterion of separability of multipartite pure states is given out, for which we define a concurrence vector; we generalize the vector to the case of multipartite mixed state and give out a good measure of free entanglement

Vector Network Coding Algorithms

OpenAIRE

Ebrahimi, Javad; Fragouli, Christina

2010-01-01

We develop new algebraic algorithms for scalar and vector network coding. In vector network coding, the source multicasts information by transmitting vectors of length L, while intermediate nodes process and combine their incoming packets by multiplying them with L x L coding matrices that play a similar role as coding c in scalar coding. Our algorithms for scalar network jointly optimize the employed field size while selecting the coding coefficients. Similarly, for vector coding, our algori...

Complex Polynomial Vector Fields

DEFF Research Database (Denmark)

Dias, Kealey

vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...... of parameter spaces into structurally stable domains, and a description of the bifurcations. For this reason, the talk will focus on these questions for complex polynomial vector fields.......The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...

Chemical composition and larvicidal activity of essential oil of Origanum majorana (Lamiaceae) cultivated in Morocco against Culex pipiens (Diptera:Culicidae)

Institute of Scientific and Technical Information of China (English)

Fouad El-Akhal; Abdelhakim El Ouali Lalami; Yassine Ez Zoubi; Hassane Greche; Raja Guemmouh

2014-01-01

Objective:To evaluate the larvicidal activity of essential oil of Origanum majorana (Lamiaceae) cultivated in Morocco against Culex pipiens (Diptera:Culicidae). Methods: The analysis and the identification of the various constituents of essential oil were carried out by gas chromatography coupled with mass spectrometry. Biological test was performed according to a standard methodology inspired by the World Health Organization protocol with slight modification. Results:This oil mainly consisted of monoterpene and sesquiterpenes. The majority compounds are 4-terpinene (28.96%), γ-terpinene (18.57%), α-terpinene (12.72%) and sabinene (8.02%). The lethal concentrations (LC50 and LC90) measured for the essential oil Origanum majorana, were respectively of the order of 258.71 mg/L and 580.49 mg/L.

Validation of SplitVectors Encoding for Quantitative Visualization of Large-Magnitude-Range Vector Fields.

Science.gov (United States)

Henan Zhao; Bryant, Garnett W; Griffin, Wesley; Terrill, Judith E; Jian Chen

2017-06-01

We designed and evaluated SplitVectors, a new vector field display approach to help scientists perform new discrimination tasks on large-magnitude-range scientific data shown in three-dimensional (3D) visualization environments. SplitVectors uses scientific notation to display vector magnitude, thus improving legibility. We present an empirical study comparing the SplitVectors approach with three other approaches - direct linear representation, logarithmic, and text display commonly used in scientific visualizations. Twenty participants performed three domain analysis tasks: reading numerical values (a discrimination task), finding the ratio between values (a discrimination task), and finding the larger of two vectors (a pattern detection task). Participants used both mono and stereo conditions. Our results suggest the following: (1) SplitVectors improve accuracy by about 10 times compared to linear mapping and by four times to logarithmic in discrimination tasks; (2) SplitVectors have no significant differences from the textual display approach, but reduce cluttering in the scene; (3) SplitVectors and textual display are less sensitive to data scale than linear and logarithmic approaches; (4) using logarithmic can be problematic as participants' confidence was as high as directly reading from the textual display, but their accuracy was poor; and (5) Stereoscopy improved performance, especially in more challenging discrimination tasks.

Vectorization, parallelization and porting of nuclear codes (vectorization and parallelization). Progress report fiscal 1998

International Nuclear Information System (INIS)

Ishizuki, Shigeru; Kawai, Wataru; Nemoto, Toshiyuki; Ogasawara, Shinobu; Kume, Etsuo; Adachi, Masaaki; Kawasaki, Nobuo; Yatake, Yo-ichi

2000-03-01

Several computer codes in the nuclear field have been vectorized, parallelized and transported on the FUJITSU VPP500 system, the AP3000 system and the Paragon system at Center for Promotion of Computational Science and Engineering in Japan Atomic Energy Research Institute. We dealt with 12 codes in fiscal 1998. These results are reported in 3 parts, i.e., the vectorization and parallelization on vector processors part, the parallelization on scalar processors part and the porting part. In this report, we describe the vectorization and parallelization on vector processors. In this vectorization and parallelization on vector processors part, the vectorization of General Tokamak Circuit Simulation Program code GTCSP, the vectorization and parallelization of Molecular Dynamics NTV (n-particle, Temperature and Velocity) Simulation code MSP2, Eddy Current Analysis code EDDYCAL, Thermal Analysis Code for Test of Passive Cooling System by HENDEL T2 code THANPACST2 and MHD Equilibrium code SELENEJ on the VPP500 are described. In the parallelization on scalar processors part, the parallelization of Monte Carlo N-Particle Transport code MCNP4B2, Plasma Hydrodynamics code using Cubic Interpolated Propagation Method PHCIP and Vectorized Monte Carlo code (continuous energy model / multi-group model) MVP/GMVP on the Paragon are described. In the porting part, the porting of Monte Carlo N-Particle Transport code MCNP4B2 and Reactor Safety Analysis code RELAP5 on the AP3000 are described. (author)

Equivalent Vectors

Science.gov (United States)

Levine, Robert

2004-01-01

The cross-product is a mathematical operation that is performed between two 3-dimensional vectors. The result is a vector that is orthogonal or perpendicular to both of them. Learning about this for the first time while taking Calculus-III, the class was taught that if AxB = AxC, it does not necessarily follow that B = C. This seemed baffling. The…

Speculative dynamic vectorization to assist static vectorization in a HW/SW co-designed environment

OpenAIRE

Kumar, R.; Martinez, A.; Gonzalez, A.

2013-01-01

Compiler based static vectorization is used widely to extract data level parallelism from computation intensive applications. Static vectorization is very effective in vectorizing traditional array based applications. However, compilers inability to reorder ambiguous memory references severely limits vectorization opportunities, especially in pointer rich applications. HW/SW co-designed processors provide an excellent opportunity to optimize the applications at runtime. The availability of dy...

Evaluation of Aedes Aegypti Presence and Abundance in Septic Tanks and Their Impacts on Dengue Transmission

Science.gov (United States)

2009-03-10

aforementioned applications, GIS has been used for cost analysis decisions in vector control planning . GIS software was used to remotely identify... plan for dengue outbreaks, a contingency plan to hospitalize large numbers of dengue hemorrhagic patients if necessary, education of the medical...de nicho en tres culicidae urbanos (Culex fatigans Weid, C. coringer Theo, y Aedes aegypti L.) en el cemeterio de Caracas. Acta Cientifica

Effect of the Essential Oil Composition and Biological Activity of Ziziphora clinopodiodes Lam. on the Against Anopheles Stephensi and Culex pipiens Parva from Iran

International Nuclear Information System (INIS)

Rivi, Mohammadreza Verdian

2008-01-01

The chemical composition of the essential oil obtained by hydrodistillation from the aerial parts of Ziziphora clinopodioides Lam. growing in Iran was analysed by GC and GC/MS. Twenty-six components accounting to 97.62% of the total oil were identified. The major components were pulegone (36.45%), piperitenone (19.12%), Menth-2-en-1-ol (5.31%), carvacrol (5.10%) neomenthol (4.78) and menthone (4.46%). The essential oil was tested against Anopheles stephensi and Culex pipiens larvae. The results obtained show that the essential oil could be considered as natural larvicidal agents. (author)

Vectorization at the KENO-IV code

International Nuclear Information System (INIS)

Asai, K.; Higuchi, K.; Katakura, J.

1986-01-01

The multigroup criticality safety code KENO-IV has been vectorized and tested on the FACOM VP-100 vector processor. At first, the vectorized KENO-IV on a scalar processor was slower than the original one by a factor of 1.4 because of the overhead introduced by vectorization. Making modifications of algorithms and techniques for vectorization, the vectorized version has become faster than the original one by a factor of 1.4 on the vector processor. For further speedup of the code, some improvements on compiler and hardware, especially on addition of Monte Carlo pipelines to the vector processor, are discussed

Reciprocity relationships in vector acoustics and their application to vector field calculations.

Science.gov (United States)

Deal, Thomas J; Smith, Kevin B

2017-08-01

The reciprocity equation commonly stated in underwater acoustics relates pressure fields and monopole sources. It is often used to predict the pressure measured by a hydrophone for multiple source locations by placing a source at the hydrophone location and calculating the field everywhere for that source. A similar equation that governs the orthogonal components of the particle velocity field is needed to enable this computational method to be used for acoustic vector sensors. This paper derives a general reciprocity equation that accounts for both monopole and dipole sources. This vector-scalar reciprocity equation can be used to calculate individual components of the received vector field by altering the source type used in the propagation calculation. This enables a propagation model to calculate the received vector field components for an arbitrary number of source locations with a single model run for each vector field component instead of requiring one model run for each source location. Application of the vector-scalar reciprocity principle is demonstrated with analytic solutions for a range-independent environment and with numerical solutions for a range-dependent environment using a parabolic equation model.

Vectors and their applications

CERN Document Server

Pettofrezzo, Anthony J

2005-01-01

Geared toward undergraduate students, this text illustrates the use of vectors as a mathematical tool in plane synthetic geometry, plane and spherical trigonometry, and analytic geometry of two- and three-dimensional space. Its rigorous development includes a complete treatment of the algebra of vectors in the first two chapters.Among the text's outstanding features are numbered definitions and theorems in the development of vector algebra, which appear in italics for easy reference. Most of the theorems include proofs, and coordinate position vectors receive an in-depth treatment. Key concept

Convexity and Marginal Vectors

NARCIS (Netherlands)

van Velzen, S.; Hamers, H.J.M.; Norde, H.W.

2002-01-01

In this paper we construct sets of marginal vectors of a TU game with the property that if the marginal vectors from these sets are core elements, then the game is convex.This approach leads to new upperbounds on the number of marginal vectors needed to characterize convexity.An other result is that

Diversity of mosquitoes and larval breeding preference based on physico-chemical parameters in Western Ghats, Tamilnadu, India

Directory of Open Access Journals (Sweden)

Periyasamy Senthamarai Selvan

2015-06-01

Full Text Available Objective: To study the diversity and distribution of mosquitoes in Western Ghats of Coimbatore and Nilgiris District, Tamilnadu, India. Methods: Random collections were carried out during August-2013 to July-2014 in cesspits, animal footprints, rock holes, tree holes, drainages at study areas of Marudhamalai, Valparai, Mettupalayam in Coimbatore District and Dhottapeta, Coonoor, Gudalur in Nilgiris District of Tamilnadu, India by using suction tube and kerosene pump. Mosquitoes were identified by standard entomological procedures. Results: A total of 1 018 mosquitoes (larvae and pupae were collected from all over the study areas comprising 6 genera and 23 species. They are, Culex mimulus, Culex pseudovishnui, Culex quinquefasciatus, Culex vishnui, Culex khazani, Culex uniformis, Heizmannia chandi, Heizmannia grenii, Heizmannia indica, Oclerotatus anureostriatus, Oclerotatus albotaeniatis, Oclerotatus deccanus, Oclerotatus gubernatoris, Aedes aegypti, Aedes albopictus, Aedes edwardsi, Aedes krombeini, Toxorhynchites minimus, Toxorhynchites splendens, Anopheles aitkenii, Anopheles barbirostris, Anopheles culiciformis and Anopheles maculatus. ShannonWeaver diversity index, Margalef’s index of richness and Simpsons dominance index was also studied. From 6 sites, the highest mosquitoes were collected from Marudhamalai (309 and the least mosquitoes were collected in Mettupalayam (68. The study determined whether physicochemical characteristics differ between habitats with high and low presence of mosquito larvae. Based on Margalef’s index of richness (Dmg, the highest values were present in Mettupalayam (5.214 study area and the lowest in Marudhamalai (3.837. It can be concluded from Shanon-Weaver index of diversity that, the highest values were present in Mettupalayam (2.947 and the least value were in Gudalur (2.410 during the study period. Conclusions: In areas with reservoirs of disease, mosquito abundance information can help to identify the

Integrating Transgenic Vector Manipulation with Clinical Interventions to Manage Vector-Borne Diseases.

Directory of Open Access Journals (Sweden)

Kenichi W Okamoto

2016-03-01

Full Text Available Many vector-borne diseases lack effective vaccines and medications, and the limitations of traditional vector control have inspired novel approaches based on using genetic engineering to manipulate vector populations and thereby reduce transmission. Yet both the short- and long-term epidemiological effects of these transgenic strategies are highly uncertain. If neither vaccines, medications, nor transgenic strategies can by themselves suffice for managing vector-borne diseases, integrating these approaches becomes key. Here we develop a framework to evaluate how clinical interventions (i.e., vaccination and medication can be integrated with transgenic vector manipulation strategies to prevent disease invasion and reduce disease incidence. We show that the ability of clinical interventions to accelerate disease suppression can depend on the nature of the transgenic manipulation deployed (e.g., whether vector population reduction or replacement is attempted. We find that making a specific, individual strategy highly effective may not be necessary for attaining public-health objectives, provided suitable combinations can be adopted. However, we show how combining only partially effective antimicrobial drugs or vaccination with transgenic vector manipulations that merely temporarily lower vector competence can amplify disease resurgence following transient suppression. Thus, transgenic vector manipulation that cannot be sustained can have adverse consequences-consequences which ineffective clinical interventions can at best only mitigate, and at worst temporarily exacerbate. This result, which arises from differences between the time scale on which the interventions affect disease dynamics and the time scale of host population dynamics, highlights the importance of accounting for the potential delay in the effects of deploying public health strategies on long-term disease incidence. We find that for systems at the disease-endemic equilibrium, even

Complex Polynomial Vector Fields

DEFF Research Database (Denmark)

The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...... or meromorphic (allowing poles as singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic...... vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...

Vector financial rogue waves

International Nuclear Information System (INIS)

Yan, Zhenya

2011-01-01

The coupled nonlinear volatility and option pricing model presented recently by Ivancevic is investigated, which generates a leverage effect, i.e., stock volatility is (negatively) correlated to stock returns, and can be regarded as a coupled nonlinear wave alternative of the Black–Scholes option pricing model. In this Letter, we analytically propose vector financial rogue waves of the coupled nonlinear volatility and option pricing model without an embedded w-learning. Moreover, we exhibit their dynamical behaviors for chosen different parameters. The vector financial rogue wave (rogon) solutions may be used to describe the possible physical mechanisms for the rogue wave phenomena and to further excite the possibility of relative researches and potential applications of vector rogue waves in the financial markets and other related fields. -- Highlights: ► We investigate the coupled nonlinear volatility and option pricing model. ► We analytically present vector financial rogue waves. ► The vector financial rogue waves may be used to describe the extreme events in financial markets. ► This results may excite the relative researches and potential applications of vector rogue waves.

Video Vectorization via Tetrahedral Remeshing.

Science.gov (United States)

Wang, Chuan; Zhu, Jie; Guo, Yanwen; Wang, Wenping

2017-02-09

We present a video vectorization method that generates a video in vector representation from an input video in raster representation. A vector-based video representation offers the benefits of vector graphics, such as compactness and scalability. The vector video we generate is represented by a simplified tetrahedral control mesh over the spatial-temporal video volume, with color attributes defined at the mesh vertices. We present novel techniques for simplification and subdivision of a tetrahedral mesh to achieve high simplification ratio while preserving features and ensuring color fidelity. From an input raster video, our method is capable of generating a compact video in vector representation that allows a faithful reconstruction with low reconstruction errors.

Selection vector filter framework

Science.gov (United States)

Lukac, Rastislav; Plataniotis, Konstantinos N.; Smolka, Bogdan; Venetsanopoulos, Anastasios N.

2003-10-01

We provide a unified framework of nonlinear vector techniques outputting the lowest ranked vector. The proposed framework constitutes a generalized filter class for multichannel signal processing. A new class of nonlinear selection filters are based on the robust order-statistic theory and the minimization of the weighted distance function to other input samples. The proposed method can be designed to perform a variety of filtering operations including previously developed filtering techniques such as vector median, basic vector directional filter, directional distance filter, weighted vector median filters and weighted directional filters. A wide range of filtering operations is guaranteed by the filter structure with two independent weight vectors for angular and distance domains of the vector space. In order to adapt the filter parameters to varying signal and noise statistics, we provide also the generalized optimization algorithms taking the advantage of the weighted median filters and the relationship between standard median filter and vector median filter. Thus, we can deal with both statistical and deterministic aspects of the filter design process. It will be shown that the proposed method holds the required properties such as the capability of modelling the underlying system in the application at hand, the robustness with respect to errors in the model of underlying system, the availability of the training procedure and finally, the simplicity of filter representation, analysis, design and implementation. Simulation studies also indicate that the new filters are computationally attractive and have excellent performance in environments corrupted by bit errors and impulsive noise.

Symbolic computer vector analysis

Science.gov (United States)

Stoutemyer, D. R.

1977-01-01

A MACSYMA program is described which performs symbolic vector algebra and vector calculus. The program can combine and simplify symbolic expressions including dot products and cross products, together with the gradient, divergence, curl, and Laplacian operators. The distribution of these operators over sums or products is under user control, as are various other expansions, including expansion into components in any specific orthogonal coordinate system. There is also a capability for deriving the scalar or vector potential of a vector field. Examples include derivation of the partial differential equations describing fluid flow and magnetohydrodynamics, for 12 different classic orthogonal curvilinear coordinate systems.

Vector continued fractions using a generalized inverse

International Nuclear Information System (INIS)

Haydock, Roger; Nex, C M M; Wexler, Geoffrey

2004-01-01

A real vector space combined with an inverse (involution) for vectors is sufficient to define a vector continued fraction whose parameters consist of vector shifts and changes of scale. The choice of sign for different components of the vector inverse permits construction of vector analogues of the Jacobi continued fraction. These vector Jacobi fractions are related to vector and scalar-valued polynomial functions of the vectors, which satisfy recurrence relations similar to those of orthogonal polynomials. The vector Jacobi fraction has strong convergence properties which are demonstrated analytically, and illustrated numerically

The Cross Product of Two Vectors Is Not Just Another Vector--A Major Misconception Being Perpetuated in Calculus and Vector Analysis Textbooks.

Science.gov (United States)

Elk, Seymour B.

1997-01-01

Suggests that the cross product of two vectors can be more easily and accurately explained by starting from the perspective of dyadics because then the concept of vector multiplication has a simple geometrical picture that encompasses both the dot and cross products in any number of dimensions in terms of orthogonal unit vector components. (AIM)

Major vectors and vector-borne diseases in small ruminants in Ethiopia: A systematic review.

Science.gov (United States)

Asmare, Kassahun; Abayneh, Takele; Sibhat, Berhanu; Shiferaw, Dessie; Szonyi, Barbara; Krontveit, Randi I; Skjerve, Eystein; Wieland, Barbara

2017-06-01

Vector-borne diseases are among major health constraints of small ruminant in Ethiopia. While various studies on single vector-borne diseases or presence of vectors have been conducted, no summarized evidence is available on the occurrence of these diseases and the related vectors. This systematic literature review provides a comprehensive summary on major vectors and vector-borne diseases in small ruminants in Ethiopia. Search for published and unpublished literature was conducted between 8th of January and 25th of June 2015. The search was both manual and electronic. The databases used in electronic search were PubMed, Web of Science, CAB Direct and AJOL. For most of the vector-borne diseases, the summary was limited to narrative synthesis due to lack of sufficient data. Meta-analysis was computed for trypanosomosis and dermatophilosis while meta-regression and sensitivity analysis was done only for trypanososmosis due to lack of sufficient reports on dermatophilosis. Owing emphasis to their vector role, ticks and flies were summarized narratively at genera/species level. In line with inclusion criteria, out of 106 initially identified research reports 43 peer-reviewed articles passed the quality assessment. Data on 7 vector-borne diseases were extracted at species and region level from each source. Accordingly, the pooled prevalence estimate of trypanosomosis was 3.7% with 95% confidence interval (CI) 2.8, 4.9), while that of dermatophilosis was 3.1% (95% CI: 1.6, 6.0). The in-between study variance noted for trypanosomosis was statistically significant (pparasitic presence in blood was documented for babesiosis (3.7% in goats); and anaplasmosis (3.9% in sheep). Serological evidence was retrieved for bluetongue ranging from 34.1% to 46.67% in sheep, and coxiellosis was 10.4% in goats. There was also molecular evidence on the presence of theileriosis in sheep (93%, n=160) and goats (1.9%, n=265). Regarding vectors of veterinary importance, 14 species of ticks in

GPU Accelerated Vector Median Filter

Science.gov (United States)

Aras, Rifat; Shen, Yuzhong

2011-01-01

Noise reduction is an important step for most image processing tasks. For three channel color images, a widely used technique is vector median filter in which color values of pixels are treated as 3-component vectors. Vector median filters are computationally expensive; for a window size of n x n, each of the n(sup 2) vectors has to be compared with other n(sup 2) - 1 vectors in distances. General purpose computation on graphics processing units (GPUs) is the paradigm of utilizing high-performance many-core GPU architectures for computation tasks that are normally handled by CPUs. In this work. NVIDIA's Compute Unified Device Architecture (CUDA) paradigm is used to accelerate vector median filtering. which has to the best of our knowledge never been done before. The performance of GPU accelerated vector median filter is compared to that of the CPU and MPI-based versions for different image and window sizes, Initial findings of the study showed 100x improvement of performance of vector median filter implementation on GPUs over CPU implementations and further speed-up is expected after more extensive optimizations of the GPU algorithm .

Isolation and characterization of halotolerant bacteria associated with the midgut of Culex quinquefasciatus Say (Diptera: Culicidae).

Science.gov (United States)

Reegan, Appadurai Daniel; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu

2013-11-01

We show for the first time that the midgut of Culex quinquefasciatus (Say) mosquito larvae harbors halotolerant bacteria. The midgut from field collected Cx. quinquefasciatus larvae were dissected under aseptic conditions, homogenized and plated on LB agar medium with 2% (w/v) NaCl. Two different colonies were successfully isolated and bacterial isolates were identified by 16S rRNA sequences. The halotolerant bacterial isolates were: Halobacillus litoralis (CxH1) and Staphylococcus cohnii (CxH2). The gene sequence of these isolates has been deposited in GenBank (JN016804 and JN183986). These halotolerant bacteria grew in the absence of salt (0%) as well as in the presence of relatively high salt concentrations in culture medium (20%), and grew best in the presence of 8-10% (w/v) NaCl. H. litoralis and S. cohnii showed growth up to 18 and 20% (w/v) NaCl, respectively. Optimum growth temperatures for both the bacteria were between 30-37 degrees C. H. litoralis was resistant to the antibiotics oxacillin, penicillin, polymixin and S. cohnii was resistant to the antibiotic oxacillin.

Effects of Climate and Climate Change on Vectors and Vector-Borne Diseases: Ticks Are Different.

Science.gov (United States)

Ogden, Nick H; Lindsay, L Robbin

2016-08-01

There has been considerable debate as to whether global risk from vector-borne diseases will be impacted by climate change. This has focussed on important mosquito-borne diseases that are transmitted by the vectors from infected to uninfected humans. However, this debate has mostly ignored the biological diversity of vectors and vector-borne diseases. Here, we review how climate and climate change may impact those most divergent of arthropod disease vector groups: multivoltine insects and hard-bodied (ixodid) ticks. We contrast features of the life cycles and behaviour of these arthropods, and how weather, climate, and climate change may have very different impacts on the spatiotemporal occurrence and abundance of vectors, and the pathogens they transmit. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Hierarchal scalar and vector tetrahedra

International Nuclear Information System (INIS)

Webb, J.P.; Forghani, B.

1993-01-01

A new set of scalar and vector tetrahedral finite elements are presented. The elements are hierarchal, allowing mixing of polynomial orders; scalar orders up to 3 and vector orders up to 2 are defined. The vector elements impose tangential continuity on the field but not normal continuity, making them suitable for representing the vector electric or magnetic field. Further, the scalar and vector elements are such that they can easily be used in the same mesh, a requirement of many quasi-static formulations. Results are presented for two 50 Hz problems: the Bath Cube, and TEAM Problem 7

Generation of arbitrary vector fields based on a pair of orthogonal elliptically polarized base vectors.

Science.gov (United States)

Xu, Danfeng; Gu, Bing; Rui, Guanghao; Zhan, Qiwen; Cui, Yiping

2016-02-22

We present an arbitrary vector field with hybrid polarization based on the combination of a pair of orthogonal elliptically polarized base vectors on the Poincaré sphere. It is shown that the created vector field is only dependent on the latitude angle 2χ but is independent on the longitude angle 2ψ on the Poincaré sphere. By adjusting the latitude angle 2χ, which is related to two identical waveplates in a common path interferometric arrangement, one could obtain arbitrary type of vector fields. Experimentally, we demonstrate the generation of such kind of vector fields and confirm the distribution of state of polarization by the measurement of Stokes parameters. Besides, we investigate the tight focusing properties of these vector fields. It is found that the additional degree of freedom 2χ provided by arbitrary vector field with hybrid polarization allows one to control the spatial structure of polarization and to engineer the focusing field.

Enhanced vector borne disease surveillance of California Culex mosquito populations reveals spatial and species-specific barriers of infection.

Energy Technology Data Exchange (ETDEWEB)

VanderNoot, Victoria A.; Curtis, Deanna Joy; Koh, Chung-Yan; Brodsky, Benjamin H; Lane, Todd

2014-08-01

terium and c am p y l o bacter bac t er i al spec i e s . W e utilized the s e mic r obial transcri p tomes pre s e nt in g e ogra p hical l y defined Cul e x po p ul a tions to defi n e spatial and m osqui t o specie s -spec i fic ba r r iers of i n fecti o n. T he v i r ome and microbi o me c o mpos i tion id e ntified in e ach mosqui t o p o ol pr o v i ded suf f icient resolut i on to dete r m i ne both the mosq u ito species and the g e o graphic regi o n in Californ i a w h e re t h e mosqui t o po o l orig i n ated. T his d a ta pr o v i des ins i ght in t o the compl e x i t y of microb i al spec i es cir c ulati n g in med i cal l y i mport a nt Culex mosqui t oes a nd t h eir potent i al im p act o n t he tran s missi o n of v ector-b o rne human / veter i na r y p a t hogens in C a liforn i a.

Calculus with vectors

CERN Document Server

Treiman, Jay S

2014-01-01

Calculus with Vectors grew out of a strong need for a beginning calculus textbook for undergraduates who intend to pursue careers in STEM. fields. The approach introduces vector-valued functions from the start, emphasizing the connections between one-variable and multi-variable calculus. The text includes early vectors and early transcendentals and includes a rigorous but informal approach to vectors. Examples and focused applications are well presented along with an abundance of motivating exercises. All three-dimensional graphs have rotatable versions included as extra source materials and may be freely downloaded and manipulated with Maple Player; a free Maple Player App is available for the iPad on iTunes. The approaches taken to topics such as the derivation of the derivatives of sine and cosine, the approach to limits, and the use of "tables" of integration have been modified from the standards seen in other textbooks in order to maximize the ease with which students may comprehend the material. Additio...

Test of understanding of vectors: A reliable multiple-choice vector concept test

Science.gov (United States)

Barniol, Pablo; Zavala, Genaro

2014-06-01

In this article we discuss the findings of our research on students' understanding of vector concepts in problems without physical context. First, we develop a complete taxonomy of the most frequent errors made by university students when learning vector concepts. This study is based on the results of several test administrations of open-ended problems in which a total of 2067 students participated. Using this taxonomy, we then designed a 20-item multiple-choice test [Test of understanding of vectors (TUV)] and administered it in English to 423 students who were completing the required sequence of introductory physics courses at a large private Mexican university. We evaluated the test's content validity, reliability, and discriminatory power. The results indicate that the TUV is a reliable assessment tool. We also conducted a detailed analysis of the students' understanding of the vector concepts evaluated in the test. The TUV is included in the Supplemental Material as a resource for other researchers studying vector learning, as well as instructors teaching the material.

Patterns of phenoloxidase activity in insecticide resistant and susceptible mosquitoes differ between laboratory-selected and wild-caught individuals

OpenAIRE

Cornet, St?phane; Gandon, Sylvain; Rivero, Ana

2013-01-01

Background Insecticide resistance has the potential to alter vector immune competence and consequently affect the transmission of diseases. Methods Using both laboratory isogenic strains and field-caught Culex pipiens mosquitoes, we investigated the effects of insecticide resistance on an important component of the mosquito immune system: the phenoloxidase (PO) activity. As infection risk varies dramatically with the age and sex of mosquitoes, allocation to PO immunity was quantified across d...

Leishmaniasis vector behaviour in Kenya

International Nuclear Information System (INIS)

Mutinga, M.J.

1980-01-01

Leishmaniasis in Kenya exists in two forms: cutaneous and visceral. The vectors of visceral leishmaniasis have been the subject of investigation by various researchers since World War II, when the outbreak of the disease was first noticed. The vectors of cutaneous leishmaniasis were first worked on only a decade ago after the discovery of the disease focus in Mt. Elgon. The vector behaviour of these diseases, namely Phlebotomus pedifer, the vector of cutaneous leishmaniasis, and Phlebotomus martini, the vector of visceral leishmaniasis, are discussed in detail. P. pedifer has been found to breed and bite inside caves, whereas P. martini mainly bites inside houses. (author)