Effect of temperature on Wolbachia infections in field collected Culex pipiens hybrids

A number of novel mosquito controls are being investigated and used for reduction of mosquito populations for the protection of public health. These novel methods include using Wolbachia-infected mosquitoes for IIT or population replacement. In California, the Culex pipiens complex is a highly managed mosquito, as it transmits West Nile Virus (WNV). The Culex pipiens complex is well known for its association with Wolbachia bacteria. Many mosquitoes infected with Wolbachia can be more resistant to infectious disease. Wolbachia is sensitive to high temperatures, and lab studies have shown that increasing temperatures can reduce Wolbachia levels in insects. The Central Valley of California is a hybrid zone of Cx. pipiens and Cx quinquefasciatus. Summer temperatures often exceed 40⁰C. This study uses field collected Cx. pipiens hybrids to investigate variation in Wolbachia levels under varied, natural field conditions. Adult Cx. pipiens hybrids are collected using EVS traps at field sites with historically high and low WNV detections. Adults will be collected through the surveillance season, starting with cooler field temperatures which increase throughout the season. Relative Wolbachia abundance in adults will be examined used qPCR. This will determine whether the high summer temperatures have an impact on Wolbachia levels in adults, and whether Wolbachia abundance are lower at field sites with higher historical WNV detections. Results will be discussed, along with potential considerations for other mosquito controls.