Back and forth Wolbachia transfers reveal efficient strains to control spotted wing Drosophila populations.
Since its recent invasion of the European and American continents, the spotted wing Drosophila Drosophila suzukii has become a burden of the fruit industry. Armed with a highly sclerotized ovipositor, females can lay eggs in a wider variety of ripening and healthy fruits than other Drosophila species. Economic losses due to D. suzukii reach millions of dollars annually and methods to control natural populations in the field mainly rely on the use of chemical pesticides. We tested if Wolbachia bacteria represents a potential ally to control this pest. These symbionts are naturally present in many insects and often induce a form of conditional sterility called cytoplasmic incompatibility (CI): the offspring of infected males die, unless the eggs are rescued by the compatible infection, inherited from the mother that protects the embryo. A long-recognized strategy called the incompatible insect technique (IIT) makes use of the CI phenotype to control insect populations through the mass release of infected males. To implement this technique in D. suzukii, we used back and forth Wolbachia transfers between D. suzukii and Drosophila simulans to identify Wolbachia strains that can sterilize D. suzukii females despite the presence of wSuz, a natural Wolbachia infection in this species. We identified two Wolbachia strains as potential candidates for developing IIT in D. suzukii. Both induce a very high level of CI in this pest which is not attenuated by the presence of wSuz in females. Moreover, the newly transferred Wolbachia do not affect the fitness or the mating competitiveness of the sterilizing males. Synthesis and applications. However, several critical steps still need to be tested and developed outside the laboratory to achieve the control of Drosophila suzukii using Incompatible Insect Technique. By an experimental approach in large population cages, we showed that releases of transinfected males limit population size. Thus, we provide in this study the proof of concept that this technique can be a very promising approach to control Drosophila suzukii populations.