A newly discovered nematode, Oscheius onirici, attacks Drosophila suzukii within fruit

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

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2019
Publication Date: 1/14/2020
Citation: Foye, S., Steffan, S.A. 2020. A newly discovered nematode, Oscheius onirici, attacks Drosophila suzukii within fruit. Insects. 113(2), 2020, 1047–1051. https://doi.org/10.1093/jee/toz365.
DOI: https://doi.org/10.1093/jee/toz365

Interpretive Summary: The spotted-wing drosophila represents a major invasive pest of North American fruit crops. A nematode species native to Wisconsin can find, attack, and kill larvae of spotted-wing drosophila within fruit. US fruit crop growers will benefit by 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. Control tactics that broaden the timeframe in which D. suzukii can be targeted are needed. A recently described entomopathogenic nematode, Oscheius onirici, was discovered in the wild marshlands of Wisconsin and represents a promising bio-control agent for cranberry pests. Preliminary trials suggest O. onirici is highly virulent against D. suzukii when applied directly to larvae, but a major question remains: can these nematodes kill D. suzukii larvae within fruit? To address this question, we set up assays in which ripe blueberries were infested with D. suzukii larvae, and the blueberries were then sprayed with O. onirici infective juveniles (IJs). Across two highly replicated trials, O. onirici IJs suppressed D. suzukii puparia by 81.8% and adults by 77.0%. It appears that these nematodes can search within the soft mesocarp tissues of host fruit, find the fly larvae within, and kill them before the flies can pupariate. O. onirici, therefore, may represent an important new bio-control agent for fruit crop protection.