Mapping the abundance of Culex tarsalis to environmental variables in Montana

Abstract

In Montana, West Nile Virus (WNV) was first recorded in 2002, and by 2003 there were 222 reported cases statewide. Currently, WNV still causes high fever, vomiting, muscle weakness, convulsions and paralysis in over 1,000 Americans each year. The primary vector of WNV differs spatially across the United States, with Culex pipiens as the primary vector in the east and Culex tarsalis contributing to the majority of human cases west of the Mississippi River. Different primary vectors suggest that geographical barriers of Cx. pipiens and Cx. tarsalis may be related to ecological factors. In the present study, mosquitoes were collected from three different locations in Montana using CDC light traps. Elevation, trap distance to water and canopy closure were measured at each location. Total mosquito abundance and Cx. tarsalis abundance were compared with each environmental characteristic independently. Although no correlations were linked to total mosquito abundance, Cx. tarsalis displayed preferential habitat patterns. Elevation and location were shown to impact Cx. tarsalis presence. Knowledge of environmental conditions conducive to the primary western vector can be used to target primary prevention efforts, decrease incidence of human WNV cases and advance subsequent undergraduate research of WNV ecology at Carroll College.