Sweet deception: exploring erythritol formulations for management of <i>Drosophila suzukii</i> (Diptera: Drosophilidae) in berry crops

Spotted wing drosophila, Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae), poses a significant threat to berry crops and requires sustainable management strategies. This study evaluated the efficacy of macroformulation mixtures of the sugar alcohol erythritol and two matrix materials, gum Arabic and maltodextrin, as a control agent for D. suzukii under semi-field settings. This study included 8 experiments to assess the efficacy and nontarget impacts of erythritol macroformulations. Experiments 1 and 3 compared the toxicity of erythritol macroformulations to the insecticide Delegate on blueberries and raspberries, respectively. Experiment 2 investigated dose-dependent toxicity on blueberries. Experiments 4, 5, and 6 focused on residual toxicity, with field and laboratory trials up to 4 wk postapplication. Experiment 7 examined the antifungal properties of the formulations on Botrytis cinerea, while experiment 8 assessed toxicity to bumblebees. Initial tests demonstrated that a 2 M concentration of erythritol was as effective as the insecticide Delegate, and subsequent trials demonstrated a concentration-dependent reduction in D. suzukii emergence, with 1 M erythritol showing optimal control, though less than the synthetic insecticide Delegate (spinetoram). Erythritol was effective in both blueberries and raspberries, particularly in semienclosed environments. Residual activity was limited, but macroformulations may enhance persistence. Erythritol exhibited moderate toxicity to bumblebees, primarily through topical contact. Gum Arabic and maltodextrin formulations showed antifungal activity. The addition of erythritol to Arabic and maltodextrin reduced antifungal activity, though maltodextrin-erythritol showed some antifungal synergy. These findings suggest erythritol, particularly when delivered in macroformulations, offers a promising, food-safe D. suzukii control option but requires careful application to minimize nontarget impacts.