Bloodfeeding Patterns of Culex tarsali and Culex pipiens mosquitoes in the San Joaquin County

West Nile virus (WNV) is primarily an avian virus that can be transmitted to mammals, including humans, through the bite of a mosquito. In humans, the effects of the virus range from no symptoms to flu-like symptoms to death. The virus was once found only in isolated areas of Africa, but in the early 2000s, WNV spread and became established across much of North America, including California. In San Joaquin County, WNV is transmitted by two primary mosquito vectors: Culex tarsalis and Culex pipiens. The purpose of this research project was to determine the feeding patterns of these two mosquito species. Between August 2009 and November 2012, mosquitoes were collected from twelve different habitat types in San Joaquin County using carbon dioxide-baited traps. The bloodmeal was extracted from each sample to be analyzed. The DNA was then isolated, and a 658-base pair region of the mitochondrial cytochrome c oxidase I (COI) was amplified using polymerase chain reaction (PCR). Successful amplifications were then sequenced, and the resulting sequences were entered into BoldSystems for species identification. Of the 614 total specimens collected, 284 (55.4%) were Cx. pipiens and 224 (43.7%) were Cx. tarsalis. Riparian and the wetland habitats were the most abundant sources of mosquito samples (17.8% and 13.7% respectively). Over 500 individual mosquitoes were successfully matched with a vertebrate host species. The most commonly fed upon species were cattle (11.70%), house finches (8.97%), and the American Robin (6.25%). The data collected provides information regarding host selection in various habitats. This information can be used to elucidate general feeding patterns of Cx. tarsalis and Cx. pipiens and may be useful in establishing preventative measures against the spread of WNV