Developing of artificial fruits to assess ovipositional responses of Drosophila suzukii under laboratory conditions

The spotted wing drosophila, Drosophila suzukii, is an invasive pest of soft-skinned fruits. The efficacy of pesticides and repellents against this pest has often been evaluated in laboratory bioassays through the use of fresh fruits as a test subject. However, the use of fresh fruits may have several limitations, including variability in their attractiveness, high perishability, and the potential presence of agrochemical residuals. To address these challenges, this study aimed to assess the efficacy of artificial fruits produced from inexpensive, edible, and readily accessible ingredients as oviposition substrates for D. suzukii. Blueberry-grape juice, blueberry-apple juice, raspberry jam, strawberry jam, and D. suzukii solid artificial diet were used as food sources. Artificial fruits prepared with uncolored artificial diet were then colored using three different red edible colorings. Drosophila suzukii females were exposed to all artificial fruits, and the ovipositional responses of the pest were evaluated by counting the total number of eggs laid in food-based substrates. Artificial fruits prepared with artificial diet and colored with red edible colorings were found to be the most attractive substrates to D. suzukii females, exhibiting an average number of eggs up to nine times higher than that of other tested ones. Our findings indicate that artificial fruits represent a viable alternative to fresh fruits for testing the ovipositional responses of D. suzukii under laboratory conditions, thereby facilitating the standardization of fruit-making procedures.