Incrimination of Aedes provocans as a vector of Jamestown Canyon virus in an enzootic focus of northeastern New York.

A 2-year field study was conducted in southern Saratoga County, New York, to determine which species of the Aedes communis group mosquitoes were potential vectors of Jamestown Canyon (JC) virus. A total of 23,890 mosquitoes (890 pools) were processed for virus isolation in 1988-89, yielding 17 JC virus isolates from Ae. provocans and one isolate each from Ae. communis, Ae. intrudens and Ae. punctor. Minimum field infection rates (MFIR) and daily MFIRs as high as 1:219 and 1:38, respectively, were found in adult female Ae. provocans. Virus isolation attempts from an additional 394 individual Ae. provocans produced a seasonal field infection rate (FIR) of 1:131 and daily FIRs of 1:71 and 1:22. Evidence of transovarial transmission of JC virus was demonstrated by the isolation of virus from 2 pools each of 50 male Ae. provocans reared in the insectary from pupae collected at the study site in 1989. We conclude that Ae. provocans is a potentially important vector of JC virus in northeastern New York.