Effects of extreme temperature events on the parasitism performance ofDiadegma semiclausum, an endoparasitoid ofPlutella xylostella

Abstract

AbstractWith climate change, the occurrence of extreme weather events such as heatwaves is expected to increase. Extreme temperature events are short periods of high temperature (i.e., >95th percentile of temperature distribution), and their occurrences are difficult to predict. These extreme temperature events pose great challenges to living organisms, especially ectotherms such as insects whose body temperature is greatly influenced by environmental temperature. Temperature is known to play an essential role in driving insect performance as well as inducing behavioral changes. Exposure to extreme temperatures causes physiological damage leading to potential long‐lasting effects on insect performance. We aimed at assessing the impact of direct (i.e., current) and indirect (previously experienced) exposure to extreme temperature on the oviposition success ofDiadegma semiclausumHellén (Hymenoptera: Ichneumonidae).Diadegma semiclausumis a larval endoparasitoid ofPlutella xylostellaL. (Lepidoptera: Plutellidae), a worldwide pest of brassicaceous crops. Oviposition success, measured as the percentage of parasitizedP. xylostella, was significantly lower at 33 °C than at 25 °C. However, previous exposure to 33 °C did not significantly impact the egg‐laying performance ofD. semiclausum, indicating that, after a heatwave, the egg‐laying performance can recover. Neither the direct nor indirect exposure to extreme temperature alteredD. semiclausumhost‐instar preference. These results indicate that temperature directly impactsD. semiclausumparasitism performance, although more detailed research is needed to disentangle direct physiological mechanisms from behavioral responses. Overall, these study results confirm others, suggesting that control ofP. xylostellabyD. semiclausumis likely to be impaired by more frequent heatwaves predicted under climate change scenarios.