How to recognize and combat spotted wing flies on fruit

Drosophila suzukii, known as the spotted wing drosophila, is a species of fly in the family Drosophilidae that is particularly problematic in soft, thin-skinned fruit crops. Unlike many other Drosophila species, which typically colonize overripe or damaged fruit, female D. suzukii possess a serrated ovipositor that allows them to pierce the epidermis of healthy fruit that is still ripening. Adults are small, generally only a few millimeters in size, and males are characterized by dark spots on their wings, while females lack these spots. After fertilization, females seek out fruit that has reached an appropriate stage of ripeness and lay their eggs directly under the epidermis using their ovipositor. Small larvae hatch from the eggs and remain inside the fruit, feeding on the pulp. The larvae go through several stages as they consume and degrade the tissues, causing damage that can later facilitate the entry of secondary microorganisms. Once larval development is complete, pupae can form inside the fruit, on its surface, or in the nearby soil, depending on the conditions and the fruit's stage of ripening. A new generation of adults then emerges and can move to other fruits, continuing the infestation. Under favorable conditions, D. suzukii can complete a generation in a relatively short period and produce numerous generations during a single growing season. Moderate temperatures particularly favor its development, while extremely high temperatures can limit survival and reproduction. The continuous availability of susceptible fruits allows populations to remain active for extended periods. Adults can move between plants, plots, and nearby crops, especially when fruits are at different stages of ripening. Furthermore, infested fruits can facilitate the accidental dispersal of eggs, larvae, and pupae through harvesting, transport, and marketing. The pest can survive between production periods in protected shelters, nearby vegetation, and other suitable locations, depending on climatic conditions. The combination of high reproductive capacity, adult mobility, a large number of susceptible fruits, and the difficulty in reaching the larvae once they are protected inside the fruit makes D. suzukii a particularly difficult pest to manage.