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

Abstract

<i>Drosophila suzukii</i> 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 <i>D. suzukii</i> adult mortality and oviposition in cladding-protected sweet cherry crops. Tests included assessing adult <i>D. suzukii</i> 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 <i>D. suzukii</i> 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 <i>D. suzukii</i> in contact with untreated leaves. In eight commercial orchards, fortnightly spray applications including spinosad, cyantraniliprole, and lambda-cyhalothrin gave effective control of <i>D. suzukii</i> 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 <i>D. suzukii</i>.