Parasitoids attacking the emerald ash borer (Coleoptera: Buprestidae) in western Pennsylvania.
Field surveys of the emerald ash borer (EAB), Agrilus planipennis Fairmaire, and associated parasitoids were conducted in Cranberry Township, PA from 11 Mar to 23 Oct 2008. Several species of parasitic Hymenoptera were collected from EAB-infested green ash trees or reared from late-instar EAB larvae, prepupae, and/or pupae. These included Balcha indica (Mani & Kaul), Eupelmus pini Taylor (Eupelmidae), Dolichomitus vitticrus Townes (Ichneumonidae), and 2 additional unidentified ichneumonids, Orthizema sp. Townes and Cubocephalus sp. Townes. Together, these parasitoids caused about 3.6% parasitism of EAB in the field. The most abundant species was B. indica accounting for 82% of all parasitoids recovered during our survey. Subsequent laboratory assays confirmed that B. indica and E. pini are solitary ectoparasitoids of EAB larvae, prepupae, and/or pupae. In addition, both B. indica and E. pini reproduce through thelytokous parthenogenesis; i.e., virgin females produce daughters. These parasitoids may be complementary to current classical biological control programs against EAB in North America, which have been focusing primarily on the introduction of exotic larval and egg parasitoids from China.