Laboratory and field evaluation of a combination of attractants and repellents to control Drosophila suzukii.
Drosophila suzukii is an invasive pest which lays eggs in ripe fruits. Its short generation time, high fertility and wide host-range allow this species to cause important yield loss: from 40 to 100% in strawberries. Current chemical methods are not effective, and producers call for the development of biological alternatives. In this work, we aim at contributing to the development of a semiochemical-based strategy that combines attractants and repellents. During laboratory assays, we evaluated and compared the attractiveness and repellency of several biological substances originating from plants and fruits, presented individually or as mixtures. We found the essential oil of peppermint to be the most repellent, while the most attractive mixture of semiochemicals was made out of ethanol and acetoin. These volatile blends were included in semiochemical releasers (i.e. rubber septa) and the release rate was shown to be effective for a minimum of 20 days. Finally, we performed a field assay in commercial strawberry greenhouses. We associated repellents located at the entrance of the greenhouses with attractant-containing traps located in the strawberry lines. Although this result is not statistically significant, the association of attractants and repellents reduced the number of D. suzukii trapped inside the greenhouse by 42%. Moreover, the proportion of marketable fruit was higher in the greenhouses where attractants were introduced. We discuss the potential of combining attractants and repellents to control D. suzukii, as well as the association of semiochemicals with microbial agents.