Vector competence of North American mosquitoes (Diptera : Culicidae) for West Nile virus

We evaluated the potential for several North American mosquito species to t ransmit the newly introduced West Nile (WN) virus. Mosquitoes collected in the New York City metropolitan area during the recent WN virus outbreak, at the Assateague Island Wildlife Refuge, VA, or from established colonies we re allowed to feed on chickens infected with WN virus isolated from a crow that died during the 1999 outbreak. These mosquitoes were tested approximat e to2 wk later to determine infection, dissemination, and transmission rate s. Aedes albopictus (Skuse),Aedes atropalpus (Coquillett), and Aedes japoni cus (Theobald) were highly susceptible to infection, and nearly all individ uals with a disseminated infection transmitted virus by bite. Culex pipiens L, and Aedes sollicitans (Walker) were moderately susceptible. In contrast , Aedes vexans (Meigen),Aedes aegypti (L.), and Aedes taeniorhynchus (Wiede mann) were relatively refractory to infection, but individual mosquitoes in oculated with WN virus did transmit virus by bite. Infected female CN, pipi ens transmitted WN virus to one of 1,618 F-1 progeny, indicating the potent ial for vertical transmission of this virus. In addition to laboratory vect or competence, host-feeding preferences, relative abundance, and season of activity also determine the role that these species could play in transmitt ing WN virus.