Resident parasitoids associated with Drosophilidae in Michigan tart cherry orchards and woodland edges

Abstract

Knowledge of the distribution and abundance of resident parasitoid species of Drosophila flies constitutes an important base for developing and implementing a biological control program for Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), an invasive pest that attacks ripening thin-skinned wild and cultivated berries and stone fruits. For this purpose, a field survey was conducted to identify the parasitoid community associated with D. suzukii infested sites in tart cherry orchards and woodlots in west, northwest, and central Michigan. Sentinel traps baited with D. suzukii larvae and pupae in banana slices were deployed in the center of tart cherry orchards, in woodlots adjacent to tart cherry orchards, and in woodlots isolated from any known commercial host of D. suzukii. Traps were placed from the beginning of July to the end of October 2021. Three parasitoid species that are known to use drosophilids as hosts were recovered from these traps. Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Leptopilina boulardi Barbotin, Carton & Keiner-Pillault (Hymenoptera: Figitidae) emerged from the infested bananas. Leptopilina heterotoma (Thomson) was collected as an adult in a sentinel trap. Among these wasps, only P. vindemiae successfully parasitized D. suzukii pupae in the laboratory. This pupal parasitoid was abundant and widely distributed in both cherry orchards and woodlots. The highest number of P. vindemiae was collected from orchards, followed by woodlots adjacent to orchards, with woodlots without nearby cultivated fruit having the lowest detections. These findings suggest that future release of augmentative or classical biological control agents for D. suzukii could be successful in orchards post-harvest to control late-season populations of this pest.