Individual behaviour and temperature: simulation of an insect parasitoid population

The impact of temperature on the physiology of insects has been extensively studied. Conversely, we know much less about the impact on insect behaviour. In the context of climate change, we urgently need to better understand the effect of temperature on animal behaviour, and to include these effects in predictive population models. To evaluate the importance of such inclusions, we created two temperature-based population dynamics simulation models of parasitoid’s life cycle. The first one is based on development, mortality and oviposition rate data, while the second model includes those plus behavioural components: mating, host searching and host exploitation. Including behaviours in the population dynamics model resulted in slightly lower predicted populations, but the change was small, suggesting that including behaviours did not increase the prediction efficiency. This is expected in temperature conditions under which the species has evolved, because individuals can behave optimally. Behaviours and development traits all had different thermal performance curves, with optimal temperature and tolerance range varying. Therefore, while the inclusion of behaviours did not change much the dynamics of simulated populations at intermediate temperature conditions, this would no longer hold true when temperatures become more extreme. In the context of climate change, extreme temperatures are expected to occur more frequently, thus strongly affecting insect behavioural performance, and likely resulting in changes in population dynamics. Consequently, behavioural components should be considered when studying more extreme conditions, because physiological components alone overlook certain effects of temperature on the life cycle of an individual.