Investigating the Prevalence of an Insecticide Resistance Gene in Culex Mosquito Populations of Central Illinois

The globalization of society has led to the spread of the vectors, mosquitoes, and diseases. Each year millions of people are killed by diseases vectored by mosquitoes. For example, West Nile Virus alone killed over 2,000 people in North America in 2017; 8 of those deaths being in Illinois. Two prominent vectors of West Nile Virus are Culex pipiens and Culex restuans; which are difficult to differentiate based upon morphological features. In this study, mosquitoes collected from two Illinois counties, Coles County and Champaign County, were first identified based upon morphology and this identification was then compared to probe-based PCR analysis for species identification. Culex mosquitoes were also tested for a point mutation in the voltage-gated sodium channel that has been linked to insecticide resistance. Culex pipiens have tested positive for this point mutation. This study was the first of its kind to be performed on both Culex pipiens and Culex restuans in central Illinois, and showed that PCR identification is the most accurate way to identify the West Nile Virus vectors, Cx. pipiens and Cx. restuans, to the species level. It also showed that two known point mutations for the voltage-gated sodium channel were found in Culex pipiens populations in both Champaign and Coles Counties, with some individuals perhaps containing a novel point mutation. Future studies should continue to assess mosquito populations in these counties and others in the Midwest at the species level, and monitor the prevalence of insecticide resistance. Collectively, these data can be used to prevent and mitigate mosquito-borne illness, and help guide the use of pesticides to control mosquito populations