Community Associates of an Exotic Gallmaker, <I>Dryocosmus kuriphilus</I> (Hymenoptera: Cynipidae), in Eastern North America

Abstract

Abstract Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) is a potentially devastating exotic invasive gall wasp that is rapidly spreading throughout the eastern United States, and infests all species of chestnut, Castanea spp. We investigated the community associates of D. kuriphilus in three geographic locations: Meadowview, VA, Bowling Green, KY, and Broadview Heights, OH. Dissection of galls and observation of chamber contents revealed that gall wasp larval mortality is approaching 47%, and parasitism accounts for nearly 70% of the mortality. Six parasitoid wasp species emerged from chestnut galls, including one introduced species and five of unknown origin. The life histories of each parasitoid and their potential roles within the D. kuriphilus community complex are discussed. Investigation of parasitoid interactions revealed a negative correlation between certain parasitoids, suggesting competition for resources, hyperparasitism, or both. The small chestnut weevil, Curculio sayi (Gyllenhal) (Coleoptera: Curculionidae), caused external damage to galls. Galls also were readily attacked by an unknown fungal pathogen resulting in gall wasp larval mortality. This study is the first to investigate the community associates of D. kuriphilus in North America. Our results have beneficial implications for commercial chestnut production, blight resistance breeding programs, and restoration of American chestnut.