Evaluating potential phytotoxicity of erythritol solution, a novel control method for Drosophila suzukii, in blueberry, cherry, and wild Himalayan blackberry

Abstract

Drosophila suzukii, commonly referred to as spotted-wing drosophila, is a recent pest of small and stone fruits across the United States. While its control is commonly achieved through broad-spectrum pesticides, these chemicals are often harmful to beneficial insects. A new candidate for control is erythritol, a non-nutritive sugar alcohol with insecticidal properties. Erythritol solutions with a sucrose (E:S) or sucralose (E:Sul) phagostimulant reduce larval infestation and deter oviposition when applied to fruits pre-harvest, but lead to spotting and other damage to sprayed plant leaves. Our objectives were to determine the extent and physiological impacts of the damage in several plant systems and assess the role of individual components in potential phytotoxicity. In the first year, bulk or lab-grade erythritol were combined with a sucrose or sucralose phagostimulant to evaluate the effects of the solutions and a water control on visible damage, stomatal conductance, chlorophyll fluorescence, relative water content, and osmolality in blueberry, cherry, and blackberry leaves. When bulk erythritol did not have discernible impacts, second year trials evaluated solutions of lab-grade erythritol with a phagostimulant and solutions of individual chemicals on leaf damage and physiological factors. Solutions of E:S and E:Sul caused the greatest visible damage, but damage was highly variable between years, treatments, and plant systems. There were no consistent plant physiological effects associated with any formulation. These results suggest that while visible leaf damage may be a dose-dependent effect of erythritol solutions, the lack of associated physiological impacts make it a viable candidate for further testing.