A rare, recently discovered nematode, Oscheius onirici (Rhabditida:Rhabditidae), kills Drosophila suzukii (Diptera: Drosophilidae)within fruit

Authors: FOYE, SHANE - University Of Wisconsin; Steffan, Shawn

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2019
Publication Date: 1/14/2020
Citation: Foye, S., Steffan, S.A. 2020. A rare, recently discovered nematode, Oscheius onirici (Rhabditida:Rhabditidae), kills Drosophila suzukii (Diptera: Drosophilidae)within fruit. Journal of Economic Entomology. 113(2):1047-1051. https://doi.org/10.1093/jee/toz365.
DOI: https://doi.org/10.1093/jee/toz365

Interpretive Summary: MAJOR FINDINGS: A nematode species native to Wisconsin can find, attack, and kill larvae of spotted-wing drosophila within fruit. IMPORTANCE OF RESULTS: The spotted-wing drosophila represents a major invasive pest of North American fruit crops. WHO WILL BENEFIT: US fruit crop growers SPECIFIC BENEFITS OF FINDINGS: Having a bio-control agent that can search within fruit means that growers can reduce fly populations that would otherwise be difficult/impossible to target with insecticides.

Technical Abstract: The spotted-wing drosophila, Drosophila suzukii, is an exotic species in North America and represents a major threat to fruit production. Ongoing efforts to manage D. suzukii have focused primarily on insecticides, but such controls may, at times, be unreliable, given that D. suzukii larvae are often ensconced within fruit. The fruit interior, however, may represent suitable foraging substrates for carnivorous/entomopathogenic nematodes. In preliminary trials, a rare nematode species, Oscheius onirici, was shown to be highly virulent against D. suzukii when the nematodes were applied directly to fly larvae. To address the question of whether this nematode would be as virulent when applied to fruit, we set up assays in which blueberries were infested with D. suzukii larvae, then sprayed with O. onirici infective juveniles (IJs). Across two highly replicated trials, O. onirici IJs suppressed D. suzukii puparia by 81.9% and adults by 76.9%. It appears O. onirici IJs were able to search on/in fruit substrates, find the fly larvae therein, and kill the flies before they could pupariate. O. onirici, therefore, may represent a viable new bio-control agent for D. suzukii management.