Temperature-driven shifts in foraging behaviour during larval development in a dragonfly.

Predatory performance of dragonfly larvae is influenced by a multifaceted interplay of external factors such as temperature, prey density and interspecific competition, and life history traits like age and size. We investigated the relative impact of these factors and traits on the prey-capture behaviour of Sympetrum striolatum larvae i.e., the number of strikes, captures and capture success. The larvae were observed three times over a five-week period under a combination of three temperature levels, two prey densities, and with or without a conspecific competitor. To access the ontogenetic effects on foraging behaviour the larvae were reared from hatching and their size measured before each trial. Higher temperature, particularly for young and small larvae, and prey density significantly increased prey-capture behaviour. The life history traits strongly affected strikes, captures, and capture success and these effects were stronger than the external factor prey density or competition. These results underscore the crucial role of ontogeny on foraging performance. Future studies and predictive models of foraging behaviour should incorporate life history to better understand foraging dynamics. Our study highlights the importance of integrating developmental biology into understanding behaviour under environmental change, rather than focusing solely on external variables.