Drivers of mosquito free-flight and resting behavior indoors

Mosquito flight and resting behaviors mediate pathogen transmission and vector control success, yet their environmental and genetic determinants remain poorly understood. We combined novel high-resolution 3D tracking with factorial semi-field experiments in Merida, Mexico, to quantify how endogenous traits (strain, sex, physiological state) and exogenous conditions (microclimate, visual cues) influence the flight and resting behavior of Aedes aegypti, the primary vector of Dengue, Zika, and Chikungunya. Mosquitoes with a Wild-type genetic background flew and rested at lower heights than mosquitoes from with a laboratory strain background. Such difference was not explained by microclimate, with progeny from reciprocal cross experiments demonstrating wild-type-like behavior, which suggest a potentially heritable behavioral divergence. Microclimatic (temperature and relative humidity) gradients differed across time and height, with estimated Vapor Pressure Deficits (VPDs) indicating that mosquitoes adjusted flight height to minimize desiccation risk. However, this microclimatic influence was overridden by presence of black surfaces, which strongly attracted mosquitoes to rest, even if such resting heights had unfavorable conditions. These findings reveal a trade-off between visual, genetic, and microclimatic drivers of behavior which have important influence in the design and impact of vector control interventions. Significance StatementThis study integrates high-resolution, three-dimensional mosquito tracking with analogue sticky traps and mathematical modeling to understand innate free-flight and resting behavior of indoor-dwelling mosquitoes. Factorial semi-field experiments conducted in Merida, Mexico, demonstrate that wild and laboratory mosquito strains differ markedly in flight and resting preferences. By quantifying microclimatic gradients and vapor-pressure deficits, we show mosquitoes may dynamically adjust their vertical position to minimize desiccation risk, however, presence of strong visual cues can override these microclimatic constraints. Together, we demonstrate a mechanistic framework that links genetics, physiology, and environment to explain Ae. aegypti behavior indoors.