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ARS Home » Northeast Area » Newark, Delaware » Beneficial Insects Introduction Research Unit » Research » Publications at this Location » Publication #425576
Research Project: Biology, Ecology, Genetics, and Genomics of Introduced Species for Biological Control of Invasive and Other Insect Pests

Location: Beneficial Insects Introduction Research Unit

Title: Establishment of key Asian larval parasitoids of Drosophila suzukii (Diptera: Drosophilidae) in the US Mid-Atlantic states

Author
item Wang, Xingeng
item HAMBY, KELLY - University Of Maryland
item DEMCHAK, KATHLEEN - Pennsylvania State University
item STOUT, AMANDA - Former ARS Employee
item BIDDINGER, DAVID - Pennsylvania State University
item REGAN, KARLY - Pennsylvania State University
item LUE, CHIA-HUA - University Of Maryland
item HOELMER, KIM - Former ARS Employee

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2025
Publication Date: 8/26/2025
Citation: Wang, X., Hamby, K., Demchak, K., Stout, A., Biddinger, D., Regan, K., Lue, C., Hoelmer, K. 2025. Establishment of key Asian larval parasitoids of Drosophila suzukii (Diptera: Drosophilidae) in the US Mid-Atlantic states. Journal of Economic Entomology. https://doi.org/10.1093/jee/toaf188.
DOI: https://doi.org/10.1093/jee/toaf188

Interpretive Summary: USDA-ARS scientists in Newark, DE, are working to manage the invasive spotted-wing drosophila (SWD) by introducing a parasitic wasp, its natural enemy, into Delaware, Maryland, and Pennsylvania. After releasing 26,950 wasps in 2022 and 2023, monitoring confirmed their successful overwintering, and fruit sampling showed promising establishment across nine host plants. While their impact on SWD populations remains limited due to ecological factors, researchers are refining strategies to enhance effectiveness. This research is essential for developing sustainable pest control methods, reducing reliance on pesticides, and supporting fruit growers, agricultural researchers, pest management experts, and policymakers in protecting crops and ensuring long-term agricultural sustainability.

Technical Abstract: The widespread establishment of Drosophila suzukii (Diptera: Drosophilidae) has instigated a classical biological program in the US and Europe for this invasive pest of soft-skinned fruits. This study reports the first release of an introduced key Asian larval parasitoid, Ganaspis kimorum (Hymenoptera: Figitidae) in three Mid-Atlantic states (Delaware, Maryland, Pennsylvania). A total of 26,950 wasps were released in six different counties in this region during the 2022 and 2023 fruit seasons. Pre-release monitoring in 2023 and 2024 recovered G. kimorum individuals, indicating successful overwintering of released parasitoids in 2022 and 2023. A total of 617 pre- and post-release fruit collections were conducted in a temporal sequence of ripening fruits of 30 different fruit species throughout the 2022 and 2023 fruit seasons in the vicinities of all released locations. Ganaspis kimorum were recovered in 40 post-release samples from 9 different host plants in all released locations. However, the overall levels of mean parasitism by G. kimorum were still low (< 2%) at this early stage of release. At the same time, adventive populations of an unreleased but another key Asian larval parasitoid, Leptopilina japonica (Hymenoptera: Figitidae) were found from 16 sampled host plants throughout the fruit seasons in this region. The mean percentage parasitism of D. suzukii (primarily by L. japonica) ranged from 0 to 20.0 %, which varied by season and host plants but peaked with the fruiting seasons of most infested wild hosts by D. suzukii. We discussed potential ecological mechanisms that could affect the establishment and impacts of these two key parasitoids on D. suzukii in Mid-Atlantic region and future release strategies for G. kimorum.