Biological control of Drosophila suzukii: Testing the interactions between Steinernema feltiae and Ganaspis kimorum

Spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is an invasive pest that has caused millions in economic loss all over the world. Chemical insecticides are the primary control method, but alternative strategies such as biological control are being explored. Entomopathogenic nematodes (EPNs) are commercially available and widely used against soil-dwelling life stages of pests. This study evaluated several EPN species for their potential to control SWD in blueberries through laboratory and field trials. In preliminary lab experiments, Steinernema feltiae and S. carpocapsae caused significantly higher SWD mortality compared to Heterorhabditis bacteriophora and S. riobrave. A field trial was conducted in spring 2025 on an organic southern highbush blueberry farm using a completely randomized block design with four blocks and five treatments: lab-reared S. feltiae, lab-reared S. carpocapsae, commercial S. feltiae, commercial S. carpocapsae, and a water control. The EPNs were applied twice during the season at a rate of 25 infective juveniles (IJs)/cm³. Traps were used to monitor SWD activity in each treatment area. To assess treatment effectiveness, 50 berries were collected weekly for two weeks from each plot, and SWD emergence from the berries was recorded. Results showed that the lab-reared S. feltiae significantly reduced SWD populations compared to all other treatments. These findings highlight the potential of S. feltiae as a biological control agent for SWD and suggest that EPNs could be an effective tool in integrated pest management strategies for organic blueberry production.