Selective Pressures and Resistance Evolution in Mosquito Populations: Challenges and Opportunities

Insecticide resistance in mosquitoes poses a significant threat to global vector control efforts. To better understand the evolutionary dynamics of resistance, we examined selective pressures acting on Aedes aegypti mosquitoes carrying kdr mutations (L410V, V1016I, F1534C) under varying insecticide dosages. Using genetic crosses of resistant and wildtype strains, we quantified selective pressures at high and waning insecticide doses, demonstrating that the fitness advantage of resistance is dose-dependent and shaped by the dominance of resistance alleles. Through a simple simulation model, we identified a dynamic window of selection where resistance evolution is most pronounced. Furthermore, we assessed fitness costs associated with resistance in the absence of insecticides across 10 generations, as well as showing the influence of temperature and humidity on selection pressures. Finally, we tested four resistance management strategies empirically, finding that low-dose exposure and high-dose refuge approaches offered the best resistance management, though at a cost of reduced population control. Field data from Maricopa County, Arizona, reveal the rapid rise of kdr mutations, underscoring the need for evidence-based resistance management strategies. These studies combined provide novel insights into resistance evolution and offer a framework for optimizing vector control strategies through a combination of empirical research and mathematical modeling.

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