The long-term objective of this project will continue to be to gain a knowledge of the ecology of arboviruses sufficient to allow development of effective strategies for control of arboviral diseases of public health and veterinary importance. This will be accomplished by pursuit of 7 immediate and interrelated specific aims. To continue laboratory studies on the elucidation of intrinsic factors and mechanisms that control the vector competence of selected mosquito species for selected arboviruses. To define further the effect of temperature on the seasonal and yearly patterns of western equine encephalomyelities (WEE) viral activity and on the extrinsic incubation period of arboviruses in their mosquito vectors. To conduct in-depth studies on the ecology of arboviruses, particularly WEE virus, in rural agricultural and semi-natural riparian/marshland habitats in Kern County, California, for the purpose of identifying foci of viral transmission and determining the relative importance of the Culex tarsalis-bird and Aedes melanimon-jack rabbit transmission cycles in the maintenance and amplification of WEE viral transmission. To develop statistical-epidemiological models that integrate the variables which control mosquito populations and the arboviral transmission cycles they perpetuate. To develop a more comprehensive knowledge of the genetics of Cx. tarsalis that allows a better understanding of how genetic variations in vector competence, autogeny, diapause, and host preferences alter the transmission cycles of arboviruses vectored by this species. To continue collaborative efforts with the California State Department of Health Services on the surveillance of mosquito populations and WEE, St. Louis encephalitis and California encephalitis viral activity during the summer in California. To compile a monograph on "The Epidemiology of the Arthropod-Borne Viral Encephalitides in California, l953-l983."