Assessing phenological synchrony between the Chinese sawfly, Cephus fumipennis (Hymenoptera: Cephidae), its egg-larval parasitoid, Collyria catoptron (Hymenoptera: Ichneumonidae), and the North American sawfly, Cephus cinctus: implications for biological control

Abstract

AbstractMany pest and beneficial insects overwinter as larvae in a state of diapause, with development resuming in the spring. In these cases, rates of post-diapause development of parasitoids must be synchronised with the vulnerable life stages of their hosts. Phenological asynchrony between introduced parasitoids and their targeted hosts has limited the success of some biological control efforts. Here, we assess the potential synchrony between Collyria catoptron Wahl (Hymenoptera: Ichneumonidae), a parasitoid of the Chinese wheat stem sawfly, Cephus fumipennis Eversmann (Hymenoptera: Cephidae), which is being considered as a biological control against a novel host species, Cephus cinctus Norton, in North America. We compared development timing and emergence patterns of both native and exotic species of sawflies with that of the parasitoid. We found that the mean number of days between termination of larval diapause and adult eclosion varied by less than one day across species, and patterns of emergence were also similar. The rate of development of this egg-larval parasitoid was within the range necessary to attack C. cinctus eggs. Furthermore, the development of C. cinctus from western Montana, United States of America most closely matched that of the parasitoid, suggesting western Montana as a possible release area.