Insecticide Control of Drosophila suzukii in Commercial Sweet Cherry Crops under Cladding

Drosophila suzukii Matsumura is a damaging invasive pest of sweet cherry. Using a series of laboratory leaf contact assays, semi-field, and orchard spray programs we aimed to determine the impact of insecticide programs on D. suzukii adult mortality and oviposition in cladding-protected sweet cherry crops. Tests included assessing adult D. suzukii mortality after contact with leaves sprayed either one or two weeks previously and emergence of adults from fruits. Spinosad, lambda-cyhalothrin, acetamiprid, lime, pyrethrin, deltamethrin, and cyantraniliprole all reduced fruit damage up to day 7 after application. Of these active ingredients, only spinosad, lambda-cyhalothrin, and cyantraniliprole gave satisfactory control up to 14 days. There was no significant difference in D. suzukii mortality when exposed to leaves treated either one or two weeks previously with an application of either spinosad, cyantraniliprole, or lambda-cyhalothrin; however, mortality was significantly higher than D. suzukii in contact with untreated leaves. In eight commercial orchards, fortnightly spray applications including spinosad, cyantraniliprole, and lambda-cyhalothrin gave effective control of D. suzukii until harvest with very few damaged fruits. These experiments demonstrate that currently approved plant protection products, applied to sweet cherry under protection, give at least two weeks protection from D. suzukii.