Pre-release risk assessment of the egg-parasitoid Gryon pennsylvanicum for classical biological control of Leptoglossus occidentalis.

Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae) is a North American conifer seed pest that was accidentally introduced to Europe. In the Mediterranean area, it threatens the production of Pinus pinea Linna- eus seeds. The egg-parasitoid Gryon pennsylvanicum (Ashmead) (Hymenop- tera: Platygastridae), the main natural enemy in the native range of L. occidentalis, was imported from British Columbia to Italy. Pre-release risk assessments were made under quarantine conditions by no-choice tests conducted with na€ıve and experienced G. pennsylvanicum offering single eggs of target and non-target species for varying exposure times (1, 4, 48 h). G. pennsylvanicum successfully parasitize…