|BIONDI, ANTONIO - University Of Catania|
|DAANE, KENT - University Of California|
Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2020
Publication Date: 8/20/2020
Publication URL: https://handle.nal.usda.gov/10113/7111149
Citation: Biondi, A., Wang, X., Daane, K.M. 2020. Host preference of three Asian larval parasitoids to closely related Drosophila species: implications for biological control of Drosophila suzukii. Journal of Pest Science. https://doi.org/10.1007/s10340-020-01272-0.
Interpretive Summary: Spotted-wing drosophila has become a key invasive pest of soft, thin-skinned fruit crops in the Americas and Europe, where locally occurring natural enemies of fruit flies are not effective for the suppression of this pest or are largely absent. Three species of parasitic wasps that attack spotted-wing drosophila larvae in its native range in Asia are under consideration for release in North America to help control this pest. As a part of systematic evaluations of these candidate agents, their host preferences were examined by comparing the spotted-wing drosophila with a closely related drosophila species. Larval survival for all three parasitic wasps was similar on both host species, and none of the parasitic wasps showed a host preference. The results provide insights for classical biological control of this invasive pest and for understanding potential interactions between the two hosts and their common parasitoids.
Technical Abstract: Insect parasitoids can attack phylogenetically related hosts that share similar physiological properties and defense mechanisms and, more importantly, overlapping ecological niches. Here, host preferences of three parasitoids, Asobara japonica (Hymenoptera: Braconidae), Ganaspis brasiliensis and Leptopilina japonica (Hymenoptera: Figitidae), were examined on two closely related hosts, Drosophila suzukii and D. melanogaster (Diptera: Drosophilidae). Each parasitoids’ rate of successful parasitism and offspring survival on these hosts were first compared in no choice tests. Results showed that A. japonica had higher parasitism levels than G. brasiliensis and L. japonica, and that larval survival for all parasitoids were similar on both host species. Host preferences in choice tests were then compared, with each parasitoid presented with the two host species at different proportions of host abundance. None of the parasitoids showed host preference or host switching, even though these parasitoids have different degrees of host specificity, from more generalized (A. japonica) to more specialized (G. brasiliensis). Further examination of parasitoid olfactory responses showed all three parasitoid species were attracted to volatiles from fruit infested by either host species and showed no preference to either D. suzukii or D. melanogaster. Results suggest that the hosts’ phylogenetical similarity and a lack of any obvious fitness costs for offspring survival may reduce host preference by these larval parasitoids.