As West Nile virus (WNV) expands its range westward across the United States, it is crucial to identify California mosquito species competent for WNV so that arbovirus surveillance and mosquito control programs may target suspect species. We evaluated the vector competence of ten California mosquito species that are major pests or known vectors of other arboviruses: Culex tarsalis
, Cx. pipiens pipiens
, Cx. p. quinquefasciatus
, Cx. erythrothorax
, Cx. stigmatasoma
, Ochlerotatus dorsalis
, Oc. melanimon
, Oc. sierrensis
, Aedes vexans
, and Culiseta inornata
. Ochlerotatus
, Culiseta
, and Aedes
were moderately efficient vectors. Because they feed primarily on mammals, we expect that they may play a secondary role or serve as bridge vectors. Oc. sierrensis
, a major pest species, and Cx. p. quinquefasciatus
(Coachella Valley) were the least efficient laboratory vectors. In general, Culex
species were the most efficient laboratory vectors. Considering their behavior, ecology, and laboratory vector competence, Culex
species are likely to play a primary role in the enzootic maintenance and transmission of WNV in California. Variation in the vector competence of Cx. pipiens
complex mosquitoes indicates that their role in WNV transmission may vary geographically. All species tested in this study were able to transmit WNV at some level, results consistent with the notion that WNV can become established in California.
Species 1: Diptera Culicidae Culex tarsalis
Species 2: Diptera Culicidae Culex pipiens
Species 3: Diptera Culicidae Culex quinquefasciatus
Keywords: West Nile virus, vector competence
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