Potential interactions of larval and pupal drosophila parasitoids and their implications for biological control of Drosophila suzukii

Authors: LISI, FABRIZIO - University Of Catania; ROGERS, VALLE - University Of California Berkeley; HENRY, EMILY - University Of California Berkeley; Hogg, Brian; Wang, Xingeng; BIONDI, ANTONIO - University Of Catania; DAANE, KENT - University Of California Berkeley

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2025
Publication Date: 3/28/2025
Citation: Lisi, F., Rogers, V.D., Henry, E.E., Hogg, B.N., Wang, X., Biondi, A., Daane, K.M. 2025. Potential interactions of larval and pupal drosophila parasitoids and their implications for biological control of Drosophila suzukii. Biological Control. 204/1-9. https://doi.org/10.1016/j.biocontrol.2025.105756.
DOI: https://doi.org/10.1016/j.biocontrol.2025.105756

Interpretive Summary: A parasitic wasp from Asia is being released in the US and Europe to help control the invasive fly spotted wing drosophila (SWD), a hugely damaging invasive pest of berries and cherries from Asia. The wasp parasitizes SWD larvae, which continue to develop into pupae after being parasitized. The pupae could then be attacked by two other widespread parasitoid species that are present in the US and Europe and that attack SWD pupae. This study assessed whether these two wasps are likely to attack SWD pupae that were previously parasitized by the Asian wasp. Both wasps could parasitize pupae that had been parasitized by the Asian wasp, but only one of them was able to successfully develop and emerge from previously parasitized pupae. Female wasps that emerged from previously parasitized pupae produced fewer female offspring than ones that emerged from unparasitized pupae. When given a choice, both wasps preferred unparasitized pupae. These findings provide new insights into ecological interactions that could affect control of SWD by parasitic wasps.

Technical Abstract: Drosophila parasitoid guilds consist primarily of larval and pupal parasitoids. Most larval parasitoids are koinobiont and do not kill their hosts until they form pupae within puparia. Thus, a host parasitized by a larval parasitoid could be attacked subsequently by a pupal parasitoid via multi-parasitism or hyperparasitism. Ganaspis kimorum is a key larval parasitoid that has recently been introduced into Europe and the US as a classical biological control agent against Drosophila suzukii. Pachycrepoideus vindemiae and Trichopria drosophilae are two cosmopolitan pupal drosophila parasitoids that may affect the performance of G. kimorum. This study investigated potential interactions of P. vindemiae and T. drosophilae with G. kimorum in D. suzukii puparia and with Leptopilina heterotoma (a common larval parasitoid of Drosophila melanogaster) in D. melanogaster puparia. Both no-choice and choice tests were conducted to determine the pupal parasitoids’ preference to attack unparasitized or parasitized puparia containing a third instar larva of the larval parasitoid (which becomes ectoparasitic and can be easily recognized in the puparium). No-choice tests demonstrated that both pupal parasitoids could parasitize puparia previously parasitized by either larval parasitoid, but only P. vindemiae successfully developed from multiparasitized puparia, with a significant reduction in female offspring. In choice tests, both pupal parasitoids preferred unparasitized over parasitized puparia, although no differences in the progeny sex-ratio were observed. Stereomicroscopic observations of multiparasitized D. suzukii puparia suggest that physiological host suppression by P. vindemiae has limited impact on ectoparasitic G. kimorum. These findings provide new insights on the potential interactions between larval and pupal drosophila parasitoids and their implications for biological control of D. suzukii.