Abstract:
Mosquito populations are likely to develop genetic resistance to insecticides with prolonged and/or improper application. Regular assessments of insecticide resistance should be performed on exposed populations to optimize local integrated mosquito management strategies. Current strategies within Valdosta, Georgia, especially chemical insecticide application, may prove to be outdated and inefficient due to the absence of a designated resistance testing center. The current study aims to provide a baseline resistance report for the nuisance biter and potential disease vector, Aedes albopictus (Skuse) to the type I pyrethroid, permethrin. Although Ae. albopictus is primarily a nuisance biter in southern Georgia, this species has the physiological potential to be a vector of numerous arboviruses and other pathogens. Ae. albopictus colonies were established from eggs collected at 15 independent sites within and near Valdosta, GA between July and November of 2019. The majority of the sites were located in residential neighborhoods. Post-rearing, survivability upon permethrin exposure was tested using the Centers for Disease Control and Prevention (CDC) Bottle Bioassay Kit. This bioassay accounts for resistance by comparing a ‘diagnostic time’ (the maximum time required to kill 100% of susceptible mosquitoes of a particular species and insecticide dosage) to the actual time taken for experimental mosquitoes to die. The occurrence of permethrin resistance in Valdosta populations of Ae. albopictus was observed in this study. According to World Health Organization (WHO) standards, <90% mortality at the diagnostic time indicates resistance, and mosquitoes from all 15 collection sites exhibited mortality <82%. This level of resistance suggests that mosquito abatement methods currently used in Valdosta, Georgia should be modified to mitigate insecticide resistance. Population reduction of this potential vector species should then reduce the risk of rapid disease transmission should the respective pathogens be introduced into the area.
Keywords: Permethrin, Pyrethroid, Insecticide Resistance, Asian Tiger Mosquito, Aedes albopictus, CDC Bottle Bioassay