Soil emergence of Drosophila suzukii adults: a susceptible period for entomopathogenic nematodes infection

Drosophila suzukii is a global invasive pest of soft-skinned and small stone fruits. Fly larvae fall from fruit to the soil to pupate, after which time adults emerge. Biological control of D. suzukii larvae with entomopathogenic nematodes has been reported in previous studies with positive results, but susceptibility of adults has still not been evaluated. In this study, the susceptibility of mature adults to Heterorhabditis bacteriophora, Steinernema feltiae and S. carpocapsae was tested. We also evaluated the infection and dispersion of adults after emerging from soil treated with S. carpocapsae. The results showed that 65% of mature adults were infected with S. carpocapsae while the other nematode treatments barely reached 4% infection. This nematode was also able to reproduce inside the D. suzukii fly. When adults emerged from treated soil, S. carpocapsae infection reached 89%. The results of the dispersion assay showed that 21.4% of nematode-infected adults could fly. These results showed the potential of S. carpocapsae applications to soil in order to control adult emergence of D. suzukii.