Native parasitoid response to emerald ash borer (Coleoptera: Buprestidae) and ash decline in recently invaded forests of the Central United States

Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a wood-boring pest of Asian origin that has caused widespread mortality of ash, Fraxinus spp., in North America since its accidental introduction in the 1990s. Studies conducted at the epicenter of the infestation in the Great Lakes region have discovered several species of native parasitoids capable of utilizing A. planipennis; however, little is known of how these natural enemy complexes vary across the shifting forest types and habitats encompassed by the expanding infestation. We characterized the assemblage of native natural enemies being recruited to A. planipennis at five sites in north-central Kentucky, where infestations have been documented since 2009. Through destructive sampling, dissection, and rearing of infested ash material, 12 native parasitoid morpho-species were found being recruited to A. planipennis, nine of which have not been reported previously. Catogenus rufus (F.) (Coleopter: Passandridae), Phasgonophora sulcata Westwood (Hymenoptera: Chalcididae), and Leluthia asgtigma (Ashmead) (Hymenoptera: Braconidae) have been discovered utilizing A. planipennis in more northerly infested regions of North America and were present in our study. Native hymenopteran parasitoid responses to A. planipennis presence and associated ash decline, measured using visual assessments of canopy decline, revealed a positive correlation between parasitoid guilds and ash decline.