|STOKES, AKER - University Of Maryland|
|RAFAEL, DE ANDRADE - University Of Maryland|
|GRUNDER, DANIEL - University Of Maryland|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2021
Publication Date: 12/23/2021
Citation: Stokes, A.A., Rafael, D.B., Duan, J.J., Grunder, D.S. 2021. Rapid spread of an introduced parasitoid for biological control of Emerald Ash Borer (Coleoptera: Buprestidae) in Maryland. Journal of Economic Entomology. https://doi.org/10.1093/jee/toab248.
Interpretive Summary: The emerald ash borer (EAB), a serious invasive forest pest, has killed millions of ash trees in the U.S. Several natural enemies (parasitic wasps) attacking EAB larvae in Asia were introduced to the U.S. for biocontrol of the pest between 2007 and 2015. We determined the establishment and spatial spread of two introduced parasitic wasps (Spathius galinae and Spathius agrili) in the state of Maryland. Our findings show that one species (S. galinae) is both established and spreading rapidly following field releases whereas the other species (S. agrili) is not. Although it is still too early to evaluate the level of pest control and ash protection afforded by the established wasp (S. galinae), these findings indicate the need for continued investment in this natural enemy for EAB biocontrol.
Technical Abstract: Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive phloem-feeding beetle native to Asia, has devastated North American ash forests since its discovery in Michigan USA in 2002. As the EAB has continued to spread, the potential for successful management hinges upon the release, establishment, and spread of introduced larval and egg parasitoids for biological control. Here, we focus on the establishment and evidence for spatial spread of introduced larval parasitoid, Spathius agrili Yang and S. galinae Belokobylskij & Strazanac (Hymenoptera: Braconidae) in the state of Maryland. To assess each species, we analyzed historical release and recovery data and resampled previous release sites and non-release sites for establishment. We found little evidence of establishment or spread for S. agrili, despite a comparatively large number of release locations, events, and individuals. By contrast, despite much lower propagule pressure and shorter history of releases, we detected multiple established populations of S. galinae at release sites and at sites up to 45 kilometers from the nearest release point approximately 3 years after its last field releases. Our findings show that S. galinae is both established and spreading rapidly following field releases whereas its congener, S. agrili is not. Although it may still be too early to evaluate the level of population control and ash protection afforded by S. galinae, these findings indicate the need for continued investment in S. galinae for EAB classical biological control efforts.