Assessment of Asobara japonica as a potential biological control agent for the spotted wing drosophila, Drosophila suzukii

To assess the potential of Asobara japonica Belokobylskij (Hymenoptera: Braconidae) as a biological control agent for the invasive Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), key biological traits were evaluated: preference and suitability of different host ages, relative performance on two host species (D. suzukii and Drosophila melanogaster Meigen), female life-time fecundity and egg maturation on the two host species, and parasitism levels on D. suzukii larvae infesting different host fruits (blackberry, cherry and strawberry). Asobara japonica preferred young over old hosts, and although host age did not affect offspring survival, parasitoid offspring developed faster in older than younger hosts but had a reduced body size. There was higher A. japonica offspring survival, longer developmental time, and larger body when reared from D. suzukii than D. melanogaster. Female wasps emerged with around one third of their lifetime egg load and matured eggs rapidly with mature egg load reaching a peak 2–3 d post-emergence. Large females (typically reared from D. suzukii) contained more mature eggs than small females (typically from D. melanogaster). During their lifetime, A. japonica females produced 117.4 and 92.5 progeny on D. suzukii and D. melanogaster, respectively, with a corresponding intrinsic rate of increase of 0.217 and 0.210, respectively. Progeny were strongly female-biased (> 90% females), regardless of host age or species. This larval parasitoid was able to develop from D. suzukii infesting cherry, blackberry or strawberry. This information may help improve protocols for the rearing and future evaluations of this parasitoid for a potential biological control program against D. suzukii.