Pre‐release risk assessment of the egg‐parasitoid <i><scp>G</scp>ryon pennsylvanicum</i> for classical biological control of <i><scp>L</scp>eptoglossus occidentalis</i>

Abstract

Abstract Leptoglossus occidentalis H eidemann ( H eteroptera: C oreidae) is a N orth A merican conifer seed pest that was accidentally introduced to E urope. In the M editerranean area, it threatens the production of P inus pinea L innaeus seeds. The egg‐parasitoid G ryon pennsylvanicum ( A shmead) ( H ymenoptera: P latygastridae), the main natural enemy in the native range of L . occidentalis , was imported from B ritish C olumbia to I taly. Pre‐release risk assessments were made under quarantine conditions by no‐choice tests conducted with naïve and experienced G . pennsylvanicum offering single eggs of target and non‐target species for varying exposure times (1, 4, 48 h). G . pennsylvanicum successfully parasitized from 75% to 100% of the target host eggs. Only one female specimen of the egg‐parasitoid emerged from a non‐target egg ( G onocerus juniperi H errich‐ S chaeffer, H eteroptera: C oreidae). Two dead female specimens were found, one inside an egg of C oreus marginatus ( L innaeus) ( H eteroptera: C oreidae) and one in an egg of C amptopus lateralis ( G ermar) ( H eteroptera: A lydidae). All three cases occurred at the longest oviposition exposure time. Results obtained with this conservative approach suggest that the risk to non‐target species of releasing G . pennsylvanicum in Italy is low.