S14 - Session P4 - Is the sterile insect technique (SIT) an efficient pest control method against the spotted wing drosophila (Drosophila suzukii)?

Authors: Benjamin Gard *, Aurore Panel, Alexandra Labbetoul, Natacha Bosshard, Anne Xuereb, Bérénice Cariou, Allan Debelle, Clélia Oliva, Simon Fellous

The spotted wing drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae) is a highly problematic pest in soft fruit crops. Since its introduction in Europe in 2008, no satisfying control method has emerged against this species. The sterile insect technique (SIT) has proven to be very efficient to control fruit flies worldwide, but it is not yet fully developed on SWD . In recent years, successive research projects have allowed for key elements of SIT against SWD to become available: the optimal irradiation dose for sterilizing males, the semi-mass rearing protocols, the selection of an improved SWD strain producing more attractive males and the first male competitivity assessments in small microcosms and at very low density. The next step is thus to test the efficacy of SWD sterile males in more natural conditions and at a higher density, to mimic typical sterile male releases in crops. For that purpose, we designed an experiment in an insect-proof greenhouse to evaluate the success of SIT to protect strawberry crops against wild SWD. We set up a semi-mass rearing of the selected SWD strain described above to produce sterile insects. Two ratios of wild SWD adults vs sterile insects were tested (1:1:1:1 and 1:1:5:5 of wild male:wild female, sterile male:sterile female, respectively), and compared to a control treatment containing only wild individuals. Each replicate consisted of a large cage containing 15 strawberry plants, in which flies were released and allowed to mate and lay eggs in ripe strawberries for 4 days. Then, ripe fruits were harvested, and the efficacy of sterile males was estimated by measuring the number of infested fruits and the number of larvae per fruit. The experiment is ongoing, and the results will be available by the end of November 2021 and presented at the conference.