Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/25/2009
Publication Date: 12/1/2009
Publication URL: www.bioone.org/doi/pdf/10.1653/024.092.0409
Citation: Duan, J.J., Fuester, R.W., Wildonger, J.A., Taylor, P.B., Barth, S.E., Sven-Eric, S. 2009. Parasitoids attacking the emerald ash borer (Coleoptera: Buprestidae) in western Pennsylvania. Florida Entomologist. 92(4):588-592. Interpretive Summary: Field survey of the emerald ash borer (EAB), a serious invasive pest of American ash trees, and its natural enemies (parasitic wasps) was conducted at Cranberry, PA, from March 11th to October 23rd, 2008. Several species of parasitic wasps were recovered and collected from green ash trees infested with EAB, including the most abundant parasitic wasp, Balcha indica, accounting for 82 percent of all the parasitoids recovered. These natural enemies together resulted in approximately 3.5 percent parasitism of EAB in the field. Laboratory assays further indicated that B. indica and another parasitic wasp (Eupelmus sp) are solitary parasitic wasps attacking immature stages of EAB. In addition, both parasitic wasps reproduce without males – i.e., virgin females reproducing daughters, and thus may be potentially complementary to the current classical biological control programs against EAB in North America, that have been focusing solely on the introduction and release of exotic natural enemies.
Technical Abstract: Current biological control programs against the emerald ash borer (EAB), Agrilus planipennis, have primarily focused on the introduction and releases of exotic parasitoids from China, home of the pest origin (USDA APHIS 2007; Liu et al. 2008). However, recent field surveys in Michigan indicate that some North American native or extant parasitoids might have already become associated with EAB and play an important role in suppressing the local populations of EAB (Bauer et al. 2004; Cappaert & McCullough 2008). The objective of the present study is two-fold: (1) to investigate if any extant parasitoid guilds have become associated with emerald ash borers in western Pennsylvania, where the pest was first discovered in 2007; and (2) to study the most abundant parasitoid for future development of augmentative biological control programs against EAB. A total of 44 green (Fraxinus pennsylvanica) ash trees (average DBH = 21.5 cm ranging from 10 – 45 cm) with obvious symptoms of EAB infestation (i.e., holes drilled by woodpeckers and/or thin canopy covers) were randomly located in Cranberry Township, PA from March 11th to October 23th, 2008. Several species of parasitic Hymenoptera were recovered and collected from these green ash trees infested with late instar EAB larvae, prepupae, and/or pupae, including the most abundant species, Balcha indica (Mani & Kaul), accounting for 82% of all the parasitoids recovered. These parasitoids together resulted in approximately 3.5% parasitism of EAB in the field. Laboratory assays further indicated that B. indica and another eupelmid wasp (Eupelmus pini) are solitary ectoparasitoids of EAB larvae, prepupae and/or pupae. In addition, both B. indica and Eupelmus sp. reproduce thelytokously – i.e., virgin females reproducing daughters, and thus may be potentially complementary to the current classical biological control programs against EAB in North America.