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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #405499
Research Project: Biological Control of Invasive Pests in Agroecosystems and Wetland, Forest and Rangeland Ecosystems in the Far Western U.S.

Location: Invasive Species and Pollinator Health

Title: Foraging abilities and competitive interactions between two egg parasitoids of bagrada bug in California

Author
item Hougardy, Evelyne
item Rogers, Dylan
item Hogg, Brian

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2024
Publication Date: 1/8/2025
Citation: Hougardy, E.H., Rogers, D., Hogg, B.N. 2025. Foraging abilities and competitive interactions between two egg parasitoids of bagrada bug in California. Bulletin of Entomological Research. 114(6):737-743. https://doi.org/10.1017/S0007485324000531.
DOI: https://doi.org/10.1017/S0007485324000531

Interpretive Summary: Bagrada bug is an invasive stinkbug pest of cole crops (cabbage, broccoli, cauliflower, kale, etc.) in the United States. Pesticides are often ineffective against bagrada bug because it persists in natural habitat surrounding crop fields where pesticides are not applied. Two parasitic wasps were found attacking bagrada bug eggs in California recently. One is particularly promising because it can dig in soil where most bagrada bug eggs are laid. In this study, we compared the abilities of these two wasps to forage for bagrada bug eggs in soil. We also tested whether competition between these wasps occurs, and whether it affects the wasps’ combined effect on bagrada bug. One wasp parasitized eggs that were either laid naturally in soil or buried by hand, whereas the other one did not and could only parasitize exposed eggs glued to cards. Competition between the two wasps did not appear to affect bagrada bug control. These results show that the wasp that can forage in soil is likely to help control bagrada bug in California, and is unlikely to be affected by the other wasp.

Technical Abstract: Bagrada bug, Bagrada hilaris Burmeister (Hemiptera: Pentatomidae), is an invasive pest of cole crops in the United States. Because it also feeds on widespread weeds and persists in natural habitat surrounding crop fields, conventional insecticides are often ineffective at providing long-term control of this pest. In its region of origin, one egg parasitoid, Gryon aetherium Talamas (Hymenoptera: Scelionidae) appears to be a promising biological control candidate for B. hilaris because of its ability to find and parasitize eggs in the soil. Recently, adventive G. aetherium were recovered from sentinel eggs in California along with another native egg parasitoid, Ooencyrtus californicus Girault (Hymenoptera: Encyrtidae). In this study, we compared the foraging abilities of these two parasitoid species for eggs deposited below and above ground. We also investigated the effect of interspecific competition on host suppression and the ability of O. californicus to parasitize eggs previously parasitized by G. aetherium. Gryon aetherium parasitized naturally and manually buried eggs, whereas O. californicus did not. In another experiment, O. californicus parasitized eggs glued to cards, but only eggs that were fully exposed and not eggs that were surrounded by sand. The presence of O. californicus in arenas did not appear to affect host suppression by G. aetherium. The impact the resident O. californicus could have on the biological control by the adventive G. aetherium in the invaded region is discussed.