Thermal consequences of sodium channel point mutations, conferred by pyrethroid selection, in the yellow fever mosquito, Aedes aegypti

The yellow fever mosquito, Aedes aegypti, is a vector of several significant public health pathogens. Overuse of pyrethroids has resulted in the evolution of resistance resulting in a decline in product efficacy and even product failures.  A key mechanism driving resistance to pyrethroids in Ae. aegypti is a target-site resistance mutation called knockdown resistance (kdr). Knockdown resistance is generally known to incur a reproductive fitness cost in adults, but it has also shown an effect on an organism’s response to different thermal regimes. To date, little is known about the impact kdr mutations have on thermal responses in Ae. aegypti. This study examines how kdr mutations affect thermal tolerance in Ae. aegypti adults and larvae. We used two congenic laboratory and three congenic wild-type strains of Ae. aegypti, which differed in the presence of F1534C and V1016I kdr mutations. Critical thermal limits (CTmin and CTmax) were tested using a ramping water bath. Thermal preference was tested along a gradient with two ranges (50 ˚C to 25 ˚C and 30 ˚C to 0 ˚C). Results indicate kdr mutations affect thermal tolerance in Ae. aegypti adults and larvae, with susceptible strains enduring more extreme temperatures compared to resistant ones. These findings shed light on the complex interplay between insecticide resistance mutations and thermal physiology in Ae. aegypti mosquitoes. Understanding how target-site resistance mutations influence thermal response has implications for vector control strategies, as it may inform the development of more effective and sustainable approaches.