全球变化知识资源中心

Aphidius ervi Haliday (Hymenoptera: Braconidae) is a major natural enemy of several agricultural pests in North America. Yet little is known about its overwintering strategy, especially concerning the plastic response to photoperiod and temperature that induce diapause. Information on parasitoid overwintering patterns is of great importance if we aim to predict their phenology and better inform pest outbreak control. Moreover, there is increasing evidence of plastic and genetic changes in overwintering strategies in insect from temperate areas following climate change. We set up a laboratory approach to better understand the factors acting on diapause induction in A. ervi. We studied the diapause incidence in a population from Quebec, Canada, using the combination of two temperatures (14 degrees C and 20 degrees C) and three photoperiod treatments (10:14, 12:12, 14:10 [light:dark] hours). We found an effect of both factors on diapause incidence; A. ervi expressed close to 95% of diapause at the most fall-like conditions (14 degrees C, 10:14 [light:dark] hours) and almost no diapause (3.5%) at the most summer-like conditions tested (20 degrees C, 14:10 [light:dark] hours). This parasitoid species does have the potential to enter diapause in Quebec before lethal frosts, despite a recent introduction from France (1960s), where mild winter occurs compared with Quebec.