Naturally occurring parasitoids of Drosophila suzukii (Diptera: Drosophilidae) and other drosophilids in California

Authors: DAANE, KENT - University Of California Berkeley; Hogg, Brian; STAHL, JUDITH - University Of California Berkeley; HAVILAND, DAVID - University Of California - Cooperative Extension Service; Wang, Xingeng

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2025
Publication Date: 6/20/2025
Citation: Daane, K., Hogg, B.N., Stahl, J.M., Haviland, D.R., Wang, X. 2025. Naturally occurring parasitoids of Drosophila suzukii (Diptera: Drosophilidae) and other drosophilids in California. Journal of Economic Entomology. Article toaf132.. https://doi.org/10.1093/jee/toaf132.
DOI: https://doi.org/10.1093/jee/toaf132

Interpretive Summary: The invasive fruit fly spotted wing drosophila (SWD) is a devastating pest of small fruits in the Americas, Europe and North Africa. This study surveyed naturally occurring parasitic wasps of SWD in California’s coastal and interior fruit production regions. Two wasp species were found attacking SWD pupae; one species was more abundant in the interior of California while the other was more abundant along the coast. The parasitic wasps were most active during the spring and fall and parasitized up to 74% of SWD pupae in traps, and attacked SWD at a higher rate than other fruit flies. No wasps were found consistently attacking SWD larvae. Two wasp species were collected from larvae of other fruit flies, but not from SWD. Naturally occurring parasitic wasps appear to help in controlling SWD, but are unlikely to be wholly effective on their own, and wasps that attack SWD larvae are being imported from Asia to provide additional control.

Technical Abstract: Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) has become a damaging economic pest of small fruits in its invaded range in the Americas, Europe and North Africa. This study surveyed naturally occurring parasitoids of D. suzukii and other frugivorous Drosophilidae in California’s coastal and interior fruit production regions. Surveys were conducted from 2012 to 2018 through collections of infested fruits and the use of sentinel fruit or host traps. Two pupal parasitoids, Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae) were collected from D. suzukii and other drosophilids; the former species dominated in the interior while the latter species dominated in the coastal region. Two larval parasitoids, Leptopilina boulardi Barbotin et al. and L. heterotoma (Thomson) (Hymenoptera: Figitidae) were collected only from other drosophilids, and were the dominant species in the interior and coastal regions, respectively. These four common parasitoids were most active during the spring and fall. The levels of parasitism on D. suzukii was < 10% from field-collected fruits but was as high as 74% in sentinel traps. Pupal parasitoids attacked D. suzukii at a higher rate than D. melanogaster in sentinel traps baited with both fly species. These results are discussed in conjunction with ongoing efforts to introduce larval parasitoids from the native range to compensate for the absence of resident larval parasitoids of D. suzukii in invaded regions.