Host-Feeding Habits ofCulexand Other Mosquitoes (Diptera: Culicidae) in the Borough of Queens in New York City, with Characters and Techniques for Identification ofCulexMosquitoes

Abstract

The host-feeding patterns of mosquitoes (n = 247) collected in the Borough of Queens in New York City in July and August 2000 were investigated using an indirect ELISA and a polymerase chain reaction (PCR)-heteroduplex assay. Culex pipiens L. and Cx. restuans Theobald fed primarily on birds, and their feeding habits support their implication as enzootic vectors of West Nile virus. Culex salinarius Coquillett and Coquillettidia perturbans (Walker) fed mainly on mammals, with fewer blood meals taken from birds, and these two species are potential bridge vectors of West Nile virus. Culex mosquitoes took blood meals (n = 54) from 11 different avian species. Only the northern cardinal (Cardinalis cardinalis), American robin (Turdus migratorius), and Brown-headed cow bird (MolIothrus ater) were fed upon by all three Culex species. Multiple blood feedings on avian hosts were detected in Cx. pipiens and Cx. restuans. Species identifications of Culex mosquitoes made using morphological characteristics were confirmed with a PCR assay that employed species-specific primers. All Cx. pipiens (n = 20) and Cx. salinarius (n = 10) specimens were correctly identified, but three (20%) of 15 Cx. restuans were misidentified as Cx. pipiens.

Host Feeding Patterns ofCulexMosquitoes and West Nile Virus Transmission, Northeastern United States

“…restuans ; all analyzed blood meals were from avian species. These findings were consistent with prior host preference studies ( 8 , 9 , 16 , 20 ) and strongly support the view that this predominant "early season" species is most likely involved in initiation and amplification of WNV transmission among wild birds and rarely, if ever, feeds on humans in this region. This finding differs from a recent blood-meal analysis by Gingrich and Williams ( 19 ), who found that a limited number (n = 9) of Cx.…”

“…restuans are largely ornithophilic, whereas Cx. salinarius feeds more frequently on mammals ( 8 ), which supports the idea of a "bridge vector" role for this species. Nevertheless, collections from New Jersey indicate that mosquitoes of the Cx.…”

“…pipiens in surveillance activities conducted over the last 6 years ( 6 , 10 , 14 , 15 ) clearly incriminates this species as the predominant mosquito vector in this region. However, while enzootic transmission to birds is strongly supported by a number of host-preference studies on regional populations ( 8 , 9 , 16 – 18 ), no consensus has been reached on the role of Cx. pipiens in epidemic transmission of WNV to humans in the northeastern United States.…”

“…We cannot say whether all or most of these double-source blood meals represent multiple feeding episodes during the same gonotrophic cycle or the detection of residual DNA from a prior egg-laying cycle. However, mixed-source blood meals have been reported for a number of Culex species by using different methods for blood-meal identification ( 8 , 16 ). Regardless, our findings indicate that a relatively large fraction of the Cx.…”

“…Isolated DNA from the mosquito blood meals served as DNA templates in subsequent PCRs as previously described ( 8 , 9 ). PCR primers were based either on a multiple alignment of cytochrome b sequences of avian and mammalian species obtained from GenBank or previously published primer sequences cited in Table 2.…”