Resistance in Aedes aegypti and Aedes albopictus to commercial pyrethroid insecticides Aqualuer 20-20 and DUET

Abstract

Insecticide resistance is a global issue in effective mosquito control. Since only a limited number of insecticide classes are available to mosquito control programs, reliance on a few active ingredients has developed resistance in many mosquito species. Several studies have been published documenting the development of resistance to pyrethroid active ingredients in Florida populations of Aedes aegypti (Linnaeus). However, there are only a few published studies on resistance levels of Aedes species to formulated products used in mosquito control programs. This study was conducted to determine baseline laboratory resistance levels of different populations of Ae. aegypti and Aedes albopictus (Skuse) in St. Johns County (SJC), Florida to Aqualuer 20-20® and Duet®. Ae. aegypti and Ae. albopictus were collected separately from five mosquito control zones where they received different treatment pressures of insecticides. Topical application bioassays were conducted on those populations to determine the doses required to achieve 100% population mortalities and resistance ratios compared to a susceptible population of each species. Based on the availability of mosquitoes, the Centers for Disease Control and Prevention (CDC) bottle bioassays were conducted on the same populations. All three Ae. aegypti populations tested were detected as having high resistance to at least one formulation, irrespective of the insecticide treatment pressure. The only Ae. albopictus population to display resistance came from the highest insecticide-pressured mosquito control zone and this is the first quantification of high pyrethroid resistance (RR>10) in Ae. albopictus in Florida. The study established the baseline laboratory resistance levels of Ae. aegypti and Ae. albopictus in SJC to the two pyrethroid formulations. Results indicated the limited efficacy of the synergist piperonyl butoxide (PBO) in reversing high insecticide resistance and highlighted the need for routine monitoring in different populations in the target area.

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