Too hot to handle: male dragonflies decrease time spent mating at higher temperatures

Traits and patterns of time allocation that improve mating success can impose costs with respect to other functions, including thermoregulation. In dragonflies, melanin on their wings can be used as a sexual signal. However, melanin also absorbs solar radiation and can cause animals to overheat in warm temperatures. We examined how dragonfly mating effort and thermoregulatory behaviour change in response to temperature and whether those responses vary based on levels of wing melanin ornamentation in the calico pennant dragonfly, Celithemis elisa. We conducted our study at the northern edge of C. elisa's range and measured the time spent on mating effort behaviours and thermoregulatory behaviours as a function of ambient and microhabitat temperature in male dragonflies. We found a trade-off between mating effort and thermoregulatory behaviour in response to temperature; time spent on mating effort significantly decreased with increasing temperatures, while time spent on thermoregulation was positively related to temperature. However, we found no effect of wing melanin on behavioural patterns. These findings suggest that, as temperatures rise in response to climate change, some species may be forced to reduce important life history activities (including mating effort) with potential population level consequences for animals living in temperate areas.(c) 2023 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study examines the trade-off between mating effort and thermoregulatory behavior in dragonflies in response to temperature changes, and investigates the effect of wing melanin on these behaviors. The results indicate that as temperature increases, dragonflies reduce their mating effort and increase their thermoregulatory behavior.