Arizona State University Tempe, Arizona, United States
Abstract: Mosquito vector control relies heavily on insecticides to control or prevent the (re)emergence of vector-borne diseases, yet the efficacy of insecticides is greatly limited by widespread resistance to the active ingredient. Insecticide resistance is an evolutionary problem at the core. To design optimal insecticide resistance management (IRM), a deep understanding of the evolutionary ecology of mosquito populations is essential. For this, we need to measure both the fitness benefits in the presence of insecticides at different dosages (phenotypic resistance), and fitness costs in absence of insecticide of resistance mutations. To establish phenotypic resistance, we compared the variability in mortality between different bioassays that measure insecticide resistance: CDC bottle bioassay, WHO tube test, and topical application bioassay. This study showed that topical application bioassays performed best by introducing the least amount of variability in mortality assays. In contrast, the CDC bottle bioassays introduced a high level of variability. Next, we compared the frequency of kdr resistance mutations (V1016I and kdr F1534C) in the Ae. aegypti population in Maricopa County in recent years, showing an increase in kdr resistance over time. Finally, we measured the fitness benefits and fitness costs of various homozygous and heterozygous kdr genotypes using lab crosses at different insecticidal pressures and different ambient temperatures.
