Résumé
The incompatible insect technique (IIT) is a promising alternative strategy to broad-spectrum insecticides. It uses the bacteria Wolbachia to suppress pest populations in a more targeted and eco-friendly way. IIT is based on the phenomenon of cytoplasmic incompatibility (CI) manifested as embryonic lethality in crosses between Wolbachia-infected males and uninfected females. Understanding the factors that determine CI strength is important to develop IIT. Drosophila suzukii, an invasive agricultural pest, causes major economic losses and is both a strong candidate for IIT-based control and a useful model for studying CI mechanisms. We investigated the respective roles ofWolbachia and the host factors in driving CI using D. suzukii strains previously shown to vary in CI strength (0-70% of CI). We found no effects of Wolbachia genotype on CI strength based on comparison of bacterial genomes associated with high and low CI. Furthermore, CI strength does not correlate with Wolbachia titers in testes. However, we found a great effect of the male host genotype on the strength of the phenotype and no effects of the female host genotype. We emphasize that selecting a suitable host genotype is just as important as choosing the right Wolbachia strain. Potentially, the efficiency of incompatible insect techniques can be improved by using artificial selection of host genotypes to increase their susceptibility to Wolbachia-induced CI.