Arboviruses associated with mosquitoes from nine Florida counties during 1993

Mosquitoes were collected for virus isolation tests from 36 sites in Bradford, Lake, Leon, Manatee, Orange, Osceola, Pasco, Putnam, and Sarasota counties, FL, from April 6 through October 11, 1993. A total of 158,129 adult specimens were collected in 726 trap nights using CDC light traps, usually baited with dry ice. At least 35 species were represented, although 60% of the collections was made up of 3 species (Aedes infirmatus, 6.5%; Anopheles crucians, 14.4%; and Culex nigripalpus, 39.4%). Four of the 36 collecting sites were located at waste-tire sites, where 254 trap nights yielded 27,455 specimens (17.4% of 9-county total). Forty-three virus strains were isolated from 2,812 mosquito pools consisting of 158,129 specimens. The viruses isolated include eastern equine encephalitis (EEE), 5 strains; Everglades (EVE), 2 strains; Keystone (KEY), 6 strains; Tensaw (TEN), 21 strains; trivittatus (TVT), one strain; Shark River (SR), one strain; and Flanders (FLA), one strain. In addition, 2 strains that are either KEY or Jamestown Canyon (JC) virus, and 4 ungrouped viruses remain to be identified. Twenty-one (48.8%) of the 43 virus strains were isolated from mosquitoes collected at waste-tire sites as follows: EEE (1), KEY (5), KEY/JC (1), TEN (13), and one ungrouped virus. The vector relations of the viruses are discussed and the potential importance of waste-tire sites as breeding habitats and harborages for vector and nuisance species is emphasized.