Mosquito fertility is (mostly) resilient to sublethal heat shocks

Insects can experience a loss of fertility under acute heat stress, but impacts vary among species and depend on life stage and sex. We examined the effects of sublethal heat shocks on the fertility of three mosquito species (Aedes aegypti, Aedes notoscriptus and Culex quinquefasciatus) when males or females were exposed at the pupal and adult stages. Reproductive performance was assessed through egg-laying success, fecundity, egg hatchability and viable offspring production. Female heat shock had limited effects on fertility in all three species, though exposure of adult females to 41 °C for 1 h reduced viable offspring production in Ae. notoscriptus. Male heat shock reduced egg hatchability in Cx. quinquefasciatus and viable offspring production in Ae. aegypti depending on the life stage exposed. We investigated several other aspects of heat shock exposure on Ae. aegypti fertility. In this species, male fertility partially recovered within 24-48 h following heat shock exposure, while effects of heat shocks on female fertility occurred regardless of whether heat exposure occurred pre- or post-mating. In addition, maternal heat shock exposure enhanced offspring fecundity and viable offspring production under subsequent sublethal heat stress. Overall, our findings demonstrate that mosquito fertility is largely robust to short-term heat shocks, but there are also complex trait, sex, stage, temporal and species-specific effects, with implications for predicting mosquito population persistence and species persistence under future climate extremes.