Stage-specific impacts of a simulated natural heatwave on Aedes albopictus

The increase in the frequency and intensity of heatwaves (HWs) under global warming is expected to have more dramatic biological impacts on insects than mean temperature increases. However, evidence of the impact of HWs on insects in their ecological context is limited. Here, we measured across multiple biological scales (e.g., fitness, physiology, transcriptomic and microbiota) the stage-specific responses of the arboviral vector Aedes albopictus when experiencing an ecologically relevant HW. In arboviral vectors, only females require a blood-meal thus contributing to the transmission cycle, but other stages can also be the target of vector control strategies. As such understanding the responses to a HW during development has both biological and epidemiological relevance.

We observed HW stage-specific responses across the mosquito life cycle. We saw the rate of larvae hatching from eggs exposed to a HW to hatch decreasing and their emergence time increasing. Larvae showed to be resilient to HW by repurposing their energy resulting in trivial mortality. Adults showed sex-specific responses, with extensive male mortality, and a small (16) number of genes elicited following HW exposure, indicating that males are less heat tolerant than females. In females, we observed a reduced reproductive output, only when HW occurred after a blood meal. Finally, we saw extensive HW-dependent changes in the microbial composition of larvae, but female microbiota remained dominated by Wolbachia regardless of the thermal challenge.

Ae. albopictus exhibit stage-specific thermal sensitivities to a HW, which have relevant implications for both the understanding of mosquito biology and the implementation of vector control strategies as the climate crisis progresses.