Land Cover Association of Culex tarsalis in Western Montana

Abstract

Cx. tarsalis is the major vector of West Nile Virus (WNV) in Montana, so a higher concentration of Cx. tarsalis would most likely correspond to an area of high WNV incidence. Previous studies performed in the U.S. found that wetland land cover had a positive influence on Cx. tarsalis, while the studies on Normalized Difference Vegetation Index (NDVI) presented conflicting results. In this experiment I attempted to answer the question: Does land cover type and NDVI affect Culex tarsalis distribution in Western Montana? It was hypothesized that both land cover type and a high NDVI value would have a positive effect on Cx. tarsalis distribution. In order to test this hypothesis, mosquitoes were trapped in Western Montana and the Cx. tarsalis were sorted from other species of mosquitoes. The land cover type and an NDVI value was observed for each trap site. The presence and amount of Cx. tarsalis was recorded, and statistical analysis was performed to determine which land cover type and NDVI value had the largest influence on Cx. tarsalis distribution. I found that wetland land cover had the largest positive effect on Cx. tarsalis, while forest land cover had the largest negative effect on Cx. tarsalis. On average, the sites where Cx. tarsalis was present had a larger NDVI value associated to it. These results agree with the findings that other studies have found on Cx. tarsalis and land cover, while adding to Cx. tarsalis and NDVI studies.