West Nile virus transmission in wetlands of northern California
Wetlands are among the most biologically diverse and productive ecosystems in the world providing valuable ecosystem services and critical habitat for many wildlife species. However, wetlands can also provide habitat for larval mosquitoes important for the transmission of vector borne pathogens. In many areas there is a direct conflict between preserving the remaining ecologically-rich wetlands and minimizing disease risk. Often, large expanses of wetlands have been drained and destroyed without prior information of how wetlands actually contributed to disease risk. This project examines vector borne pathogen transmission in wetlands using West Nile virus (WNV) as a case study to examine how different ecological factors, surrounding land use, and human water use interact and contribute to differences in local pathogen transmission. At 80 different wetland sites, we quantified local mosquito abundance, WNV infection prevalence, and host community composition.
In total, >1.2 million mosquitoes were captured during the summers of 2012 and 2013, representing 18 species and 6 genera. The three most abundant species were: Aedes melanimon (55%), Anopheles freeborni (20%) and Culex tarsalis (16%). Five species were found from the genera Culex which are important vectors of WNV. WNV-positive mosquitoes were found at nearly all wetland sites. Large variations in mosquito abundance and WNV prevalence were found among sites. Preliminary results suggest a large influence of surrounding land use on local abundance of mosquitoes at these wetlands.