Early exposure to predation risk carries over metamorphosis in two distantly related freshwater insects

Abstract

1. Predation and competition play a central role in ecological communities, and it is increasingly recognised that animals use early warning cues to reduce the impact of these antagonistic interactions.

2. Strategies to avoid risk can occur during embryo development through plasticity in egg hatching time. This strategy, and its associated costs and carryover effects on adults are little understood in insects. In this study, these are explored in two distantly related freshwater insects: the damselfly Ischnura elegans and the mosquito Aedes albopictus.

3. As predicted, damselfly eggs hatched earlier in response to larval predators cues, a treatment that also affected adult size. Risk cues did not affect mosquito egg hatching time, but they did affect larval development time in a sex-dependent manner.

4. The results suggest that responses aimed at avoiding risks can be triggered during the egg stage, and although they can vary dramatically among species, they are likely to be widespread in insects. Early warning responses can be particularly important to understand the ecology of aquatic insects, some of them global vectors of human diseases.