Host-feeding patterns of suspected West Nile virus mosquito vectors in Delaware, 2001-2002

Paucity of data on host-feeding patterns and behavior of 43 mosquito species that are reported as suspected West Nile virus (WN) vectors has limited full evaluation of their vectorial capacity. Recent studies addressing this issue need additional confirmation and should also be expanded to include collections of species or subpopulations attracted to humans. We used 4 types of collection methods to collect mosquitoes, including omnidirectional Fay-Prince traps, Centers for Disease Control-type light traps, gravid traps, and human-landing collections. Mosquitoes were collected during 2 full WN transmission seasons in 2001 and 2002, at 9 different sites across Delaware. We collected from various habitats, including salt marshes, brackish water areas, woodlands, a tire dump, a racetrack, and a mushroom farm. Blood-meal analyses were performed on parous mosquitoes by using a sandwich-type enzyme-linked immunosorbent assay. We tested primarily for 5 common host species, including rabbits, dogs, deer, horses, and chickens. We obtained substantial host-feeding data from 8 mosquito species. The most mammalophilic species were Anopheles quadrimaculatus, Coquillettidia perturbans, and Aedes albopictus, whereas the most ornithophilic species was Culex pipiens. Aedes albopictus was the most anthropophilic species, whereas Ae. vexans and Cq. perturbans exhibited relatively low attraction to humans. Culex salinarius was the species with the most diverse host-feeding activity. Based on feeding behavior, Cx. pipiens and Cx. salinarius appear to be the most likely bridge vectors. Other species may have opportunities to be bridge vectors under special circumstances, as discussed in the paper.