West Nile Virus Presence and Blood-Feeding Behavior of Culex tarsalis in Wildlife Refuges and Management Areas in Montana

Abstract

West Nile virus (WNV) has been documented across the state of Montana since 2002. Humans, other mammals, and birds have been affected by this virus in a heterogeneous manner throughout the state. Correlating the feeding patterns of Culex tarsalis, the principal WNV vector in the Western United States, with the presence of virus at Nine Pipe, Freezeout, Benton, and Bowdoin wildlife refuges and management areas allowed for analysis of the link between competent avian hosts and the presence of WNV. Further, identification of avian species present in Cx. tarsalis blood-meals allowed for the analysis of the correlation between relative abundance of avian species and their incidence in blood-meals. Presence of WNV RNA in mosquito pools was measured using RT-PCR and TaqMan assay. Mitochondrial cytochrome b and cytochrome c oxidase I gene sequence analysis of DNA extracted from individual bloodfed Cx. tarsalis mosquitoes was used for blood-meal identification by the comparison of sequences of both the cytochrome b and cytochrome oxidase I gene fragments with the GenBank DNA database. The combination of WNV detection and blood-meal analysis can be used to better understand the temporal relationship of viral presence or absence and seasonal feeding patterns of the WNV vector mosquito Cx. tarsalis.