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ARS Home » Northeast Area » Newark, Delaware » Beneficial Insects Introduction Research Unit » Research » Publications at this Location » Publication #244786
Title: Interactions between Spathius agrili (Hymenoptera: braconidae) and Tetrastichus planipennisi (Hymenoptera: Eulophidae), larval parasitoids of Agrilus planipennis (Coleoptera: Buprestidae)

Author
item ULYSHEN, MICHAEL - Michigan State University
item Duan, Jian
item BAUER, LEAH - Us Forest Service (FS)

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2009
Publication Date: 11/4/2009
Citation: Ulyshen, M.D., Duan, J.J., Bauer, L.S. 2010. Interactions between Spathius agrili (Hymenoptera: braconidae) and Tetrastichus planipennisi (Hymenoptera: Eulophidae), larval parasitoids of Agrilus planipennis (Coleoptera: Buprestidae). Biological Control.

Interpretive Summary: Three species of parasitic wasps introduced from China are currently being released in Michigan and surrounding states in an effort to control the emerald ash borer (EAB), an Asian beetle species responsible for widespread mortality of ash trees in North America. Two of the species (Spathius agrili and Tetrastichus planipennisi) require large EAB larvae, raising concerns about competition between the two wasp species at release sites. In a series of experiments, we found that both parasitic wasp species exhibited similar attack rates when presented alone with EAB larvae in both laboratory and field tests. However, one species (S. agrili) was much more efficient at locating and parasitizing hosts within the first 27 hrs, possibly explaining why this species excluded the other (T. planipennisi) in both laboratory and field trials when the two species were presented together with EAB larvae. We found that S. agrili) will parasitize larvae already parasitized by T. planipennisi, but not the reverse. However, S. agrili offspring failed to complete development on EAB larvae that were already parasitized by T. planipennisi. We recommend releasing the two species of parasitic wasps separately at different locations, or at least different times to avoid the antagonistic interactions documented in this study.

Technical Abstract: Three hymenopteran parasitoids introduced from China are currently being released in Michigan and surrounding states in an effort to control the emerald ash borer (EAB), Agrilus planipennis Fairmare, an Asian beetle species responsible for widespread mortality of Ash trees (Fraxinus spp.) in North America. Two of these, Spathius agrili Yang (Braconidae) and Tetrastichus planipennisi Yang (Eulophidae), require late-instar EAB larvae, raising concerns about interspecific competition at release sites. In a series of experiments, we found that S. agrili and T. planipennisi exhibited similar parasitism rates when presented alone with EAB larvae for 12-14 days in both laboratory and field assays. However, S. agrili was much more efficient at locating and parasitizing hosts within the first 27 hrs, possibly explaining why S. agrili excluded T. planipennisi in laboratory trials and nearly excluded T. planipennisi in field trials when the two species were presented together with EAB larvae. We found that S. agrili will parasitize larvae already parasitized by T. planipennisi but not the reverse. However, S. agrili offspring failed to complete development on hosts that were already parasitized by T. planipennisi. We recommend releasing the two species separately at different locations, or at least different times to avoid the antagonistic interactions documented in this study.