Vector competence of Aedes dorsalis (Diptera: Culicidae) from Morro Bay, California, for western equine encephalomyelitis virus

In laboratory vector competence studies, Aedes dorsalis (Meigen) collected from Morro Bay, CA, did not vertically transmit sympatric strains of western equine encephalomyelitis virus (WEE). This population of Ae. dorsalis was highly susceptible to oral infection and was a competent horizontal vector of WEE. The E2 region of the viral genome of the 3 virus strains isolated from Ae. dorsalis in Morro Bay were closely related genetically to a strain of WEE isolated in 1953 from a geographically separate location that is used regularly in the laboratory. These laboratory findings support recent field research and indicate that Ae. dorsalis probably does not play a significant role in WEE persistence in coastal California.