Oviposition deterrent as a component of a push–pull management approach for <i>Drosophila suzukii</i>

Drosophila suzukii, spotted-wing drosophila, is a major pest of berries and cherries worldwide that attacks fruits at the ripening stage shortly before harvest. Recently, a mixture of octanoic acid and decanoic acid was developed as a 2-component oviposition deterrent (2c) as an alternative to spatial repellents for the behavioral control of spotted-wing drosophila infestation. In this study, we evaluated the efficacy of the oviposition deterrent as a "push" component in a spotted-wing drosophila push-pull, in combination with a previously identified 4-component spotted-wing drosophila attractant (4c) as the "pull", and compared the effect of push (2c), pull (4c), push-pull (2c + 4c), and control on spotted-wing drosophila oviposition in the laboratory and field. In both laboratory choice and no-choice bioassays using raspberry agar as an oviposition substrate, the pull treatment alone (4c) did not result in oviposition reduction. In contrast, both 2c and 2c + 4c resulted in a similar level of reduction in spotted-wing drosophila oviposition compared to control, indicating limited efficacy of the 4c as a pull as tested in this study. Similar results were also observed in the field, where fewer spotted-wing drosophila pupae emerged from raspberries from the 2c or 2c + 4c treated raspberries compared to untreated control, for both ripening field raspberries and store-bought sentinel raspberries. No significant difference in spotted-wing drosophila infestation was observed between control and 4c treatment. Our results suggest that an oviposition deterrent has a potential use as a push component in spotted-wing drosophila push-pull.