Field parasitism and host specificity of Oobius primorskyensis (Hymenoptera: Encyrtidae), an egg parasitoid of the emerald ash borer (Coleoptera: Buprestidae) in the Russian Far East

Authors: Duan, Jian; Schmude, Jonathan; LARSON, KRISTI - University Of Delaware; Fuester, Roger; GOULD, JULI - Animal And Plant Health Inspection Service (APHIS); ULYSHEN, MICHAEL - Us Forest Service (FS)

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2018
Publication Date: 12/20/2018
Citation: Duan, J.J., Schmude, J.M., Larson, K.M., Fuester, R.W., Gould, J.R., Ulyshen, M. 2018. Field parasitism and host specificity of Oobius primorskyensis (Hymenoptera: Encyrtidae), an egg parasitoid of the emerald ash borer (Coleoptera: Buprestidae) in the Russian Far East. Biological Control. 130: 44-50. https://doi.org/10.1016/j.biocontrol.2018.12.005.
DOI: https://doi.org/10.1016/j.biocontrol.2018.12.005

Interpretive Summary: Because classical biological control involves the introduction and establishment of non-native beneficial insects such as predators and parasitic wasps as biocontrol agents, potential risks of the would-be introduced biocontrol agents to non-target organisms need to be assessed prior to environmental release. Scientists from the USDA ARS and APHIS evaluated the potential non-target risk of introducing a beneficial wasp from the Russian Far East for biological control in the United States of the emerald ash borer, which has killed millions of ash trees. Results of the study showed that this beneficial wasp is specialized to attack emerald ash borer and only attacked some of EAB's close relatives out of the 30 tested-species or groups of North American non-target insects. These findings provided critical information needed to assess the non-target impact of this beneficial wasp prior to seeking approval for environmental releases in the U.S.

Technical Abstract: Oobius primorskyensis Yao and Duan (Hymenoptera: Encyrtidae) is a recently described egg parasitoid of the emerald ash borer (EAB), Agrilus plannipennis Fairmaire, from the Russian Far East. To support the potential introduction of this new parasitoid for biocontrol of EAB in North America, we surveyed EAB eggs on infested green ash (Fraxinus pennsylvanica Marsh) trees in the Russian Far East and documented the rate of EAB egg parasitism by O. primorskyensis. Results from the field survey show that O. primorskyensis is the only egg parasitoid attacking EAB eggs in the Russian Far East, with a parasitism rate ranging from 23 to 44%. After establishing quarantine colonies of O. primorskyensis in the United States, we tested the parasitoid against eggs of 30 species of nontarget insects, including native North American wood-boring beetles in the families Buprestidae and Cerambycidae plus one pentatomid and one moth. Quarantine testing showed that O. primorskyensis attacked seven out of nine Agrilus species, but none of the other non-target species tested. Percentage parasitism of A. anxius (40%) and A. fallax (30%) was comparable to parasitism of their corresponding EAB (positive) control (29 - 30%). However, percentage parasitism of the other five attacked species (A. bilineatus, A. egenus, A. fallax, A. macer, and A. oblongus) were significantly less (4 – 17%) than for the EAB control (60 – 90%). These results indicate that the host specificity of O. primorskyensi may be limited to species in the genus Agrilus, especially those phylogenetically closely related to EAB. Additional testing is needed to determine whether the eggs of other buprestid genera are utilized by the species as well.