Large-arena field cage releases of a candidate classical biological control agent for spotted wing drosophila suggest low risk to non-target species

Abstract Classical biological control, i.e., the introduction of natural enemies from an invasive pest’s area origin, has been proposed repeatedly to control spotted wing drosophila Drosophila suzukii in Americas and Europe. Results surveys Asia laboratory experiments suggest parasitoid G1 Ganaspis cf. brasiliensis as a suitable agent. To study host specificity under semi-field conditions, we conducted large-arena field cage releases. Parasitoids were released into cages at three dates August 2021 two regions Switzerland. Released parasitoids had choice parasitize either D. larvae fresh fruits (blueberries or elderberries) non-target native species melanogaster decomposing fruits. The results unequivocal that apparent parasitism feeding was on average 15%, whereas only one emerged (0.02% parasitism). Thus, support findings previous G. is highly specific closely related very rare. Because its invaded range, can attack develop undamaged fruits, conclude open releases should not pose significant risks non-targets.