Julia Weicheld

Project title: Impact of Environmental Factors on Mosquito Populations and Distribution in King County, WA

Degree: MS | Program: Environmental Health (EH) | Project type: Thesis/Dissertation
Completed in: 2015 | Faculty advisor: Charles D. (Chuck) Treser


Climate, land cover, and other environmental factors have been shown to have a direct impact on the epidemiology of vector-borne diseases. Warming temperatures combined with other effects of climate change and changes in land use have the potential to amplify vector mosquito populations and transmission of arboviruses such as West Nile Virus (WNV) in Washington. The relationship of vector-borne disease transmission with the environment is complex and highly localized. To date, very little research has been conducted on this issue in Washington State. This research aims to provide insight into vector populations that may govern vector-borne disease transmission in King County, WA. Mosquitoes were trapped at selected areas in King County during the summer of 2014. Additional mosquito data collected by previous DEOHS students and the WA State Department of Health were gathered and assessed for quality and completeness. Four identical sites sampled in 2003 and 2014 were directly compared to assess any changes in mosquito abundance and diversity over an 11-year period. Temperature, precipitation, and land cover data were obtained and investigated for their influence on mosquito abundance during these seasons. Our results indicate that mosquito abundance was significantly higher in 2003 than in 2014. Culex pipiens was the dominant species both years, although in 2014 there appeared to be greater mosquito diversity. Medium-high developed land cover was significantly associated with Culex pipiens abundance. Total mosquito abundance was associated with maximum temperature, with higher temperature weeks having greater numbers of mosquitoes. The relationship of mosquito abundance with precipitation remains less clear. These results suggest that mosquito abundance is related to environmental factors in King County, however more research should be done to better understand these and other influences on mosquito populations.