University of the Pacific Stockton, California, United States
Abstract: Monitoring the status of mutations linked to insecticide resistance is essential as we move forward in combating vector-borne diseases. One such mutation, kdr, currently has an unknown status in California populations of Culex tarsalis, a vector of West Nile virus and St. Louis encephalitis. By assessing the status of this mutation in Cx. tarsalis, we can better understand the evolutionary implications of such mutations and how pesticide usage may lead to evolutionary pressure. To investigate these mutations, we utilize Quantitative Polymerase Chain Reaction, identifying the allele at the kdr mutation site for individual samples, where we expect a leucine to phenylalanine or serine switch. The samples included in our analysis range from Southern California (Coachella Valley) to Northern California (the Sutter-Yuba region) and begin in 1990 and continue to 2 different time points (2007-2009 and 2016-2018) through samples collected in 2022. Continued work in our lab on developing a qPCR melt curve assay has led us to efficiently and accurately identify each individual’s kdr genotype by designing primers specific to the kdr mutation site. The primary goal of this project is to evaluate the current status of the kdr mutation in Cx. tarsalis and the relation to past allele frequencies. Additionally, with access to the California Department of Pesticide Regulation’s data on pyrethroid application in California, we hope to identify whether there is a correlation between pyrethroid usage by different constituencies and changes in allele frequency over time.
