Aedes Vexans Meigen Research Articles

Host-Feeding Patterns of Mosquito Species in Aras Valley, Turkey

Identifying hosts of blood-feeding mosquito species is important to elucidate the role of vector species in disease transmission cycles. Herein, the aim was to identify the vertebrate hosts of mosquito species using the polymerase chain reaction-based reverse line blotting method. The mosquito species were Anopheles maculipennis sensu lato Meigen, 1818; Aedes caspius Pallas, 1771; Aedes vexans Meigen, 1830; Culex theileri Theobald, 1903; Anopheles hyrcanus Pallas 1771; Culex pipiens sensu lato Linnaeus, 1758; and Culiseta annulata Schrank, 1776, which were collected from the Aras Valley between July-August 2012 and June-September 2013. The analysis of mosquito blood-meal samples revealed several mammalian and avian host species. And also varying degrees of opportunistic mosquito feeding behavior in both birds and mammals were noted. These mosquito species fed on eight mammal species, i.e., humans, cows, sheep, horses, dogs, cats, goats, and porcupines, as well as avian species. Studies on the host-feeding patterns of blood-feeding vector arthropods may provide information about the vector potential of these species. However, the host-feeding patterns of the vector species are only one part of the vector capacity. To detect the exact potential of vector species, further studies are needed on vector competence for different pathogens.

Mosquito Capture Rate Using CO2-Baited Traps in Relation to Distance From Water and Height: Implications for Avian Disease Transmission.

Accumulating evidence suggests that enzootic transmission of pathogens such as West Nile virus (WNV) by mosquitoes is governed by host-bird interactions, including mosquito preferences for specific species and developmental stages of host birds, host bird availability, and host defensive behavior. Here, we examined how the attack rate of five mosquito species in southern California was influenced by the position of CO2-baited traps in relation to distance from water and trap height. We identified 44,207 female mosquitoes representing five species: Aedes vexans Meigen, Anopheles franciscanus McCracken, Anopheles hermsi Barr & Guptavanij, and the two most abundant species which are also WNV vectors, Culex erythrothorax Dyar and Culex tarsalis Coquillett. Mosquito captures decreased markedly with trap height, and also decreased with distance from a riparian area but not with distance from an open water source lacking a vegetated border. The results of this study suggest that WNV-competent ornithophilic mosquitoes may amplify the virus especially in reservoir birds that roost or nest close to the ground and near riparian vegetation.

Identification of Blood Meal Sources inAedes vexansandCulex quinquefasciatusin Bernalillo County, New Mexico

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.

Altitudinal variation in the morphometric characteristics of Aedes vexans Meigen from northeastern Turkey

Body size is one of the most significant features of organisms and is correlated with a large number of ecological and physiological variables. Similar to size, biological shape is one of the most conspicuous aspects of an organism's phenotype and provides a link between the genotype and the environment. Body size may change with altitude and also habitat differences associated with altitude may affect the biological shape and some morphological characteristics. Four populations of Aedes vexans Meigen occurring in different ecological subregions at altitudes between 808-1,620 m in the Aras Valley from northeastern Turkey were compared using traditional and geometric morphometrics. When the wing shape differences of populations were analyzed by UPGM, the cluster analyses recognized two main groups of populations. Gödekli (808 m) comprised the first group while Zülfikar (848 m), Sürmeli (944 m), and Cilehane (1,620 m) populations comprised the second group. In the second group, Zülfikar and Cilehane populations showed a similar grouping pattern while Sürmeli appeared as a different group. Centroid sizes were used as measures of overall wing size differences among different regions. Aedes vexans from the Sürmeli region had relatively larger wings.

Weather and Land Cover Influences on Mosquito Populations in Sioux Falls, South Dakota

This study compared the spatial and temporal patterns of Culex tarsalis Coquillett and Aedes vexans Meigen populations and examined their relationships with land cover types and climatic variability in Sioux Falls, SD. Between 24 and 30 CDC CO2-baited light traps were set annually in Sioux Falls from May to September 2005-2008. Land cover data were acquired from the 2001 National Land Cover Dataset and the percentages of selected land cover types were calculated within a 600-m buffer zone around each trap. Meteorological information was summarized from local weather stations. Cx. tarsalis exhibited stronger spatial autocorrelation than Ae. vexans. Land cover analysis indicated that Cx. tarsalis was positively correlated with grass/hay, and Ae. vexans was positively correlated with wetlands. No associations were identified between irrigation and the host-seeking population of each species. Higher temperature in the current week and 2 wk prior and higher precipitation 3-4 wk before collection of host-seeking adult mosquitoes had positive influences on Cx. tarsalis abundance. Temperature in the current week and rainfall 2-3 wk before sampling had positive influences on Ae. vexans abundance. This study revealed the different influences of weather and land cover on important mosquito species in the Northern Great Plains region, which can be used to improve local vector control strategies and West Nile virus prevention efforts.

Ecological Niche Modeling of Potential West Nile Virus Vector Mosquito Species in Iowa

Ecological niche modeling (ENM) algorithms, Maximum Entropy Species Distribution Modeling (Maxent) and Genetic Algorithm for Rule-set Prediction (GARP), were used to develop models in Iowa for three species of mosquito — two significant, extant West Nile virus (WNV) vectors (Culex pipiens L and Culex tarsalis Coquillett (Diptera: Culicidae)), and the nuisance mosquito, Aedes vexans Meigen (Diptera: Culicidae), a potential WNV bridge vector. Occurrence data for the three mosquito species from a state-wide arbovirus surveillance program were used in combination with climatic and landscape layers. Maxent successfully created more appropriate niche models with greater accuracy than GARP. The three Maxent species' models were combined and the average values were statistically compared to human WNV incidence at the census block group level. The results showed that the Maxent-modeled species' niches averaged together were a useful indicator of WNV human incidence in the state of Iowa. This simple method for creating probability distribution maps proved useful for understanding WNV dynamics and could be applied to the study of other vector-borne diseases.

West Nile Virus Infection in Mosquitoes in the Mid-South USA, 2002–2005

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) was first detected in the Tennessee Valley and in Alabama in August 2001. In summer 2002, intensive viral activity was seen, but in subsequent years, viral activity settled into an enzootic pattern. Here, we report an analysis of viral activity in the mosquito fauna in the Mid-South from 2002 (the first year viral activity was detected in mosquitoes) through 2005. Eight mosquito species were infected with WNV during 2002. However, viral activity was only detected in four species--Culex salinarius Coquillett, Culex erraticus Dyar & Knab, Coquillettidia perturbans Walker, and Aedes vexans Meigen--in multiple years. The greatest number of positive pools was in Cx. erraticus and Cx. salinarius. Despite being specifically targeted for collection, Aedes albopictus Skuse was only found to be infected during the epiornitic year (2002), suggesting that under enzootic transmission conditions its role as a bridge vector in the region may not be significant. Virus-positive pools of Cx. erraticus were identified from winter-resting and early season dry ice-baited trap collections in 2005, implicating this species in WNV overwintering in Alabama. Molecular analysis of individuals initially identified as members of the Culex pipiens L. complex suggested that alleles characteristic of Cx. pipiens predominated in mosquitoes collected in Huntsville, AL, whereas alleles in the Auburn, AL, population were predominately characteristic of Culex quinquefaciatus Say. The southern boundary of the overlap zone of the two species seems to be located primarily between Huntsville and Auburn, a distance of 350 km.

Targeted Trapping of Mosquito Vectors in the Chesapeake Bay Area of Maryland

Abstract Most adult mosquito surveillance in Maryland is performed using dry ice-baited or unbaited Centers for Disease Control (CDC) miniature light traps suspended ≈1.5 m above the ground. However, standardized trapping methods may miss mosquito species involved in disease transmission cycles. During a 2-yr study, the effectiveness of the olfactory attractant 1-octen-3-ol alone and in combination with carbon dioxide was evaluated for collecting mosquito vector species. In addition, trap heights were examined to determine the optimal vertical placement to target various species. We evaluated the results during the second year by targeting selected species by using various habitat–height–bait combinations. Although Culex erraticus Dyar & Knab and Anopheles quadrimaculatus Say were not successfully targeted, Culex salinarius Coquillett, Aedes vexans Meigen, Anopheles bradleyi/crucians King, Coquillettidia perturbans Walker, Aedes sollicitans Walker, and Aedes taeniorhynchus Wiedemann were preferentially captured using targeted trapping schemes.

Targeted Trapping of Mosquito Vectors in the Chesapeake Bay Area of Maryland

Most adult mosquito surveillance in Maryland is performed using dry ice-baited or unbaited Centers for Disease Control (CDC) miniature light traps suspended approximately 1.5 m above the ground. However, standardized trapping methods may miss mosquito species involved in disease transmission cycles. During a 2-yr study, the effectiveness of the olfactory attractant 1-octen-3-ol alone and in combination with carbon dioxide was evaluated for collecting mosquito vector species. In addition, trap heights were examined to determine the optimal vertical placement to target various species. We evaluated the results during the second year by targeting selected species by using various habitat- height-bait combinations. Although Culex erraticus Dyar & Knab and Anopheles quadrimaculatus Say were not successfully targeted, Culex salinarius Coquillett, Aedes vexans Meigen, Anopheles bradleyi/crucians King, Coquillettidia perturbans Walker, Aedes sollicitans Walker, and Aedes taeniorhynchus Wiedemann were preferentially captured using targeted trapping schemes.

Aspects of Bioecology of Two Rift Valley Fever Virus Vectors in Senegal (West Africa): <I>Aedes vexans</I> and <I>Culex poicilipes</I> (Diptera: Culicidae)

The dispersal, population dynamics, and age structure of two Rift Valley Fever Virus (Phlebovirus: Bunyaviridae) (RVFV) vectors, Aedes vexans Meigen and Culex poicilipes Theobald, were investigated in northern Senegal. The main objective was to investigate possible factors that mediate RVFV emergence and propagation at a site where humans and livestock live in proximity to temporary surface pools. In mark-release-recapture studies, recapture rates of 0.18% (156/85,500) and 3.46% (201/5,800) were obtained for Ae. vexans and Cx. poicilipes, respectively. The number of mosquitoes recaptured decreased with increasing distance from the release point and over time. The estimated daily survival rate for released females ranged from 91 to 96% for Ae. vexans and 70-79% for Cx. poicilipes. The maximum time after release when marked mosquitoes were collected was 23 and 12 d for Ae. vexans and Cx. poicilipes, respectively. The maximum distances from the release point that marked females were recaptured was 620 and 550 m for Ae vexans and Cx. poicilipes, respectively. Rainfall periodicity was a key factor controlling Ae. vexans population abundance. In contrast, rainfall had no discernible effect on the fluctuation of Cx. poicilipes numbers. The involvement of these two species in the transmission of RVFV is discussed with respect to their longevity and daily survival rate.

Aspects of Bioecology of Two Rift Valley Fever Virus Vectors in Senegal (West Africa):Aedes vexansandCulex poicilipes(Diptera: Culicidae)

The dispersal, population dynamics, and age structure of two Rift Valley Fever Virus (Phlebovirus: Bunyaviridae) (RVFV) vectors, Aedes vexans Meigen and Culex poicilipes Theobald, were investigated in northern Senegal. The main objective was to investigate possible factors that mediate RVFV emergence and propagation at a site where humans and livestock live in proximity to temporary surface pools. In mark-release-recapture studies, recapture rates of 0.18% (156/85,500) and 3.46% (201/5,800) were obtained for Ae. vexans and Cx. poicilipes, respectively. The number of mosquitoes recaptured decreased with increasing distance from the release point and over time. The estimated daily survival rate for released females ranged from 91 to 96% for Ae. vexans and 70-79% for Cx. poicilipes. The maximum time after release when marked mosquitoes were collected was 23 and 12 d for Ae. vexans and Cx. poicilipes, respectively. The maximum distances from the release point that marked females were recaptured was 620 and 550 m for Ae vexans and Cx. poicilipes, respectively. Rainfall periodicity was a key factor controlling Ae. vexans population abundance. In contrast, rainfall had no discernible effect on the fluctuation of Cx. poicilipes numbers. The involvement of these two species in the transmission of RVFV is discussed with respect to their longevity and daily survival rate.

Detection of spirochetes in, and isolation from, culicine mosquitoes.

In mosquitoes, spirochetes were first detected in 1907, when Jaffe reported a spirochete in Culex sp. and named it Spirochaeta culicis (Arch. Protistenkd. 9: 100-107.). Spirochetes were also detected in Anopheles funestus and A. maculipennis (Sinton J.A., Shute P.G. 1939: J. Trop. Med. Hyg. 42: 125-126) and in the salivary glands of Anopheles gambiae (Masseguin A., Palinacci A. 1954: Bull. Soc. Pathol. Exot. 47: 3). The presence of the Lyme disease (LD) spirochete, Borrelia burgdorferi has also been reported in mosquitoes and other bloodsucking insects (Magnarelli F.A., Freier J.E., Anderson J.F. 1987: J. Infect. Dis. 156: 694-695). In South Moravia (Czech Republic), spirochetes have been previously observed in mosquitoes (Halouzka J. 1993: Biologia 48: 123-124), and one strain of Borrelia afzelii was isolated from Aedes vexans (Halouzka J., Postic D., Hubalek Z. 1998: Med. Vet. Entomol. 12: 103-105). In this study, we examined 2,583 female mosquitoes collected in South Moravia during the years 1993-1997. In the summer season (June to September), 571 mosquitoes were sampled from various localities and habitats: lowland floodplain forest, mixed oak forest with bushes, deciduous mixed forest and shores of a fishpond covered with reedbelts. Three species of the genus Aedes – Aedes vexans Meigen, 1830, Aedes sticticus (Meigen, 1838), Aedes cantans (Meigen, 1818) and, moreover, Culex pipiens Linnaeus, 1758 biotype pipiens were sampled. During the winter period, 2,012 overwintering Culex pipiens biotype molestus were obtained from cool and humid basement rooms of buildings. The mosquitoes were kept alive at the temperature of about 4°C until dissected. The abdomen content of each mosquito was triturated in a drop of saline and individually examined by darkfield microscopy at a magnification 400×. Specimens with a high number (>100) of motile spirochetes were occasionally inoculated into BSK-H liquid medium (Sigma) supplemented with 5% rabbit serum (Sigma), antibiotics (phosphomycin 100 μg/ml, rifampicin 50 μg/ml), and incubated at 33°C up to six weeks. The mean prevalence of spirochetes in mosquitoes caught in the summer season was 1.9%. In the winter collection, the mean prevalence of spirochetes in Culex pipiens molestus was 5.1% (Table 1). As much as 22 mosquitoes contained more than 100 spirochetes, and 11 of them were inoculated into BSK-H medium. Due to heavy bacterial contamination, only Table 1. Prevalence of spirochetes in mosquitoes.

Distribution and Age Composition of Mosquito Species (Diptera: Culicidae) Inhabiting Commercial Rice Fields in Southeast Arkansas

Five species of immature mosquitoes were identified from semiweekly and weekly sampling of four commercial rice fields in southeastern Arkansas. Psorophora columbiae (Dyar and Knab) and Anopheles quadrimaculatus Say were most abundant. Large numbers of P. columbiae were encountered immediately following flood applications, with larvae from the upper halves of each field being older than those from the lower halves due to the time required for irrigation water to inundate the entire field. Significantly more P. columbiae larvae were found in ditch than pan samples (69 and 31%, respectively). Anopheles quadrimaculatus were collected on every sample date. Moderate numbers peaked 10 July and thereafter were very low. Young larvae predominated in samples until 10 July, when slightly more than half of the immature A. quadrimaculatus collected were third and fourth-stage larvae. Larvae sampled were evenly distributed between ditch and pan areas (49 and 51%, respectively). Culex erraticus (Dyar and Knab) larvae were also collected on every sample date at very low levels. A significantly larger proportion were taken from levee ditches than pan areas (62 and 38%, respectively). Aedes vexans Meigen and Uranotaenia sapphirina (Osten-Sacken) were collected occasionally.

Bloodmeal sources of Aedes triseriatus and Aedes vexans in a southern Wisconsin forest endemic for La Crosse encephalitis virus.

The micro enzyme-linked immunosorbent assay (ELISA) was used to specifically identify bloodmeal sources of Aedes triseriatus Say and Aedes vexans Meigen collected at a site endemic for La Crosse (LAC) encephalitis virus. Deer were the source of 65% of Ae. triseriatus and 94% of Aedes vexans bloodmeals, respectively. Chipmunks and tree squirrels, which are considered to be the major vertebrate amplifying hosts of LAC virus, were the sources of 8% and 16%, respectively, of the bloodmeals of Ae. triseriatus, the vector of LAC virus. The relatively small proportion of vector bloodmeals taken from the amplifying hosts raises further doubts as to the significance of vertebrate amplification in perpetutation of La Crosse virus in nature, i.e. whether vertebrate amplification alone is sufficient to make up for the shortfall of virus infection that occurs during vertical transmission.

EFFECT OF CONSTANT TEMPERATURE ON THE LARVAL DEVELOPMENT OF AEDES VEXANS (DIPTERA: CULICIDAE)

AbstractThe most suitable temperature for larval development of Aedes vexans Meigen was found to be 25 °C. At this temperature 86% of the larvae survived and pupated in 7 days. At 10°, 15°, 20°, and 30 °C larval development time was 46, 22, 10, and 8 days and survival rates were 17, 56, 74, and 71%, respectively. At 5 °C mortality was 100% in the first-instar stage, the last larva dying 12 days after hatching. Adults emerged in 2 to 5 days after being transferred into water at 25 °C, males emerging 2 days before the females.

Associations of Wiscosin mosquitoes and woodland vertebrate hosts.

Host-feeding associations of mosquitoes were determined by exposing 20 species of woodland vertebrates to natural mosquito populations. Only Culex pipiens (L.) and C. restuans (Theobald) showed a definite host preference to the avian hosts. However, C. pipiens fed also on several of the mammal hosts. Aedes and Psorophora showed a preference for mammal hosts especially nonrodents. Aedes vexans Meigen, A. stimulans group, and Psorophora ferox (Humboldt) exhibited little response to rodents or cold-blooded vertebrates. Aedes trivittatus (Coquillett); A. sticticus (Meigen); and Mansonia perturbans (Walker) were general feeders. Aedes canadensis (Theobald) had a high attraction and engorgement rate on turtles as well as on some mammals, while A. cincreus Meigen showed a strong association with chipmunks and ground squirrels. Of the 7 rodent hosts the 13-lined ground squirrel, Citellus tridecemlincatus (Metchill), was the most acceptable. Most of the Aedes mosquitoes appeared to attack the most available host in an area.

Mermithid parasites of the mosquito Aedes vexans Meigen in British Columbia.

Newly emerged and apparently healthy female adults of Aedes vexans Meigen were collected in the Fraser Valley, British Columbia, After they had fed once on man at the time of collection and daily on guinea pigs thereafter in the laboratory, they were found to be infected with mermithid worms that developed rapidly at 25 °C. The parasites suppressed ovarian development and caused nearly 100% mortality within 10 days. They started to leave morbid hosts within 7 days. More detailed studies of the life cycle of the mermithid parasites are needed to assess their effectiveness and specificity in the biological control of A. vexans.

New Mosquito Hosts for Plasmodium gallinaceum

Mosquito species previously reported to be susceptible to Plasmodium gallinaceum include 13 species of Aedes, 5 species of Armigeres and 2 species of Culex (Brumpt 1936, Roubaud, Colas-Belcour and Mathis 1939, Vargas and Beltran 1941, Russell and Mohan 1942, Russell and Menon 1942). These records include only 3 species indigenous to North America, i.e., Aedes vexans Meigen, Aedes aegypti Linnaeus and Culex quinquefasciatus Say. This report includes the results of observations on 2 American species that have and 7 that have not been previously studied. The mosquitoes were either reared from larvae or captured in the field as adults. They were allowed to feed on an infected chicken and were kept at 28? C. From 3 to 9 days later most of them were dissected and examined for o6cysts. A few were examined for sporozoites and oocysts after 9 to 21 days. As may be seen in Table 1, oocysts were observed in Aedes camnpestris Dyar and