Isolation of arboviruses from Culicoides midges (Diptera: Ceratopogonidae) in Colorado during an epizootic of vesicular stomatitis New Jersey

An arbovirus survey was conducted in Colorado and Utah during an epizootic of vesicular stomatitis New Jersey (VSNJ) that occurred in the western United States in 1982-1983. From 120,422 insect specimens assayed, 106 viruses were isolated. Four were rhabdoviruses (VSNJ), three were orbiviruses (bluetongue serotype-11), 92 were Bunyamwera group (65 Main Drain and 27 Lokern), and seven were Simbu group (Buttonwillow) bunyaviruses. Culicoides spp. accounted for 105 viral isolates (C. (Selfia) spp., C. variipennis (Coquillett), C. stellifer (Coquillett), and C. cockerellii (Coquillett], and one was from Simulium bivittatum Malloch. C. (Selfia) spp. accounted for 59% of all pooled specimens and was the source of 89.6% (95) of the isolates. Insects from two sites accounted for 44% (52,802) of all pooled specimens and 67% (71) of the viral isolates. The isolations of VSNJ, Main Drain, Lokern, and Buttonwillow viruses from C. (Selfia) spp. are the first arbovirus isolations reported for this subgenus; this is the first time these viruses have been isolated from Culicoides species other than C. variipennis.