Laboratory evaluation of natural compounds and insect growth regulators against the spotted wing drosophila Drosophila suzukii (Diptera: Drosophilidae) in cherries

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) can cause extensive damage to many cultivated stone and small fruits. Larvae feed and develop inside the fruits, which deteriorate and rot, leading to high economic losses. Concern about this pest has motivated research into many possible control methods. However, at present the main control strategies are based on the application of insecticides, some of which may pose risks to human health and the environment. Therefore, research is needed to find more secure strategies to control this pest. Here, 2 natural compounds (kaolin, azadirachtin) and 2 insect growth regulators (pyriproxyfen, cyromazine) with safer ecotoxicological properties than conventional pesticides were evaluated for the control of D. suzukii in cherries. In no choice assays, kaolin showed a strong effect reducing female activity, so the adult offspring production in treated cherries was almost completely inhibited (96% reduction), whereas azadirachtin showed a lesser nonsignificant effect (47% reduction). Pyriproxyfen completely prevented the immature development both in treated cherries exposed to D. suzukii females and in cherries previously exposed to the females and subsequently treated (100% reduction), and with cyromazine only a few adult flies were produced in both cases (99% and 93% reduction, respectively). In choice assays, the adult offspring reduction indices were 100% for kaolin, pyriproxyfen and cyromazine. Additionally, a residue analysis showed that pyriproxyfen and cyromazine were present in the pulp of the treated cherries and in the flies exposed to them. Kaolin, pyriproxyfen and cyromazine could be considered for the control of D. suzukii in cherry orchards.