Spotted wing drosophila, Drosophila suzukii, is native to East Asia but has rapidly become a devastating pest of soft-skinned fruits in its invaded range in the Americas, Europe and North Africa. Control of D. suzukii is complicated by its wide host range and its ability to overwinter on non-crop hosts, and by its seasonal movement into crops from other habitats. Augmenting numbers of resident parasitoids may help to reduce pest pressure by D. suzukii. The pupal parasitoid Pachycrepoideusvindemmiae is widely distributed in North America and consistently attacks D. suzukii, although its potential use in augmentation programs against D. suzukii remains largely unexplored. We tested whether augmentative releases of P. vindemmiae could help control D. suzukii in caneberry hoop houses in California, Oregon and Minnesota. Results were inconsistent. Most trials showed no detectable post-release effects on parasitism or D. suzukii levels, although parasitism levels in California were very high after releases on some dates, and one trial in Oregon showed elevated parasitism levels in release plots.
