Genetic diversity of Trichopria drosophilae, a natural enemy of spotted wing drosophila

Drosophila suzukii is an invasive species recently introduced in Europe and causing damages to fruit production. Trichopria drosophilae is considered one of the most suitable indigenous parasitoid to be used in biocontrol programs against D. suzukii. To characterize genetic variability and the spatial genetic structure of populations of T. drosophilae, we developed 21 species-specific molecular markers. Samples of T. drosophilae were collected in 16 localities and each of three different habitats and revealed three genetic groups. Though most of the sampled individuals showed mixed assignment probabilities to one of three genetic groups, we found a coincidence between the highest assignment probability to one of the three groups and the preferred habitat (limited gene flow among habitats within localities). Futher analyses suggested that T. drosophilae disperses well among different regions (high gene flow among localities). These findings indicate how genetic studies may be used to track the dispersal of a species that is released for biological control.