Submitted to: USDA Interagency Research Forum on Invasive Species
Publication Type: Proceedings
Publication Acceptance Date: 12/20/2009
Publication Date: 6/17/2009
Citation: Duan, J.J., Fuester, R.W., Wildonger, J.A., Taylor, P.B., Barth, S.E., Spichger, S. 2009. Parasitoids attacking emerald ash borers in western Pennsylvania and their potential use in biological control. USDA Interagency Research Forum on Invasive Species.
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 (woodpecker pecks and thin canopy covers) were randomly located in the Cranberry Township from March 11th to October 23rd, 2008, and sampled monthly for presence of various immature stages of emerald ash borers and associated parasitoids. 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 sp) are solitary ectoparasitoids of EAB larvae, prepupae and 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. Studies are currently in progress in our laboratory on the reproductive and development biology and host finding and selection behavior of these two local parasitoids, and eventual development of mass rearing methods for their use in augmentative biological control programs against emerald ash borers in PA and elsewhere.