Rhagoletis cerasi (Diptera: Tephritidae) is a major pest of sweet and sour cherries in Europe and parts of Asia. Despite its economic significance, there is a lack of studies on the genetic structure of R. cerasi populations. Elucidating the genetic structure of insects of economic importance is crucial for developing phenological-predictive models and environmental friendly control methods. All natural populations of R. cerasi have been found to harbor the endosymbiont Wolbachia pipientis, which widely affects multiple biological traits contributing to the evolution of its hosts, and has been suggested as a tool for the biological control of insect pests and disease vectors. In the current study, the analysis of 18 R. cerasi populations collected in Greece, Germany, and Russia using 13 microsatellite markers revealed structuring of R. cerasi natural populations, even at close geographic range. We also analyzed the Wolbachia infection status of these populations using 16S rRNA-, MLST- and wsp-based approaches. All 244 individuals screened were positive for Wolbachia. Our results suggest the fixation of the wCer1 strain in Greece while wCer2, wCer4, wCer5, and probably other uncharacterized strains were also detected in multiply infected individuals. The role of Wolbachia and its potential extended phenotypes needs a thorough investigation in R. cerasi. Our data suggest an involvement of this symbiont in the observed restriction in the gene flow in addition to a number of different ecological factors.

The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is a major pest of cherries in Europe and parts of Asia. Despite its big economic significance, there is a lack of studies on the genetic structure of its natural populations. Knowledge about an insect pest on molecular, genetic and population levels facilitates the development of environmentally friendly control methods. In this study, we present the development of 13 microsatellite markers for R. cerasi, through cross-species amplification. These markers have been used for the genotyping of 130 individuals from five different sampling sites in Greece. Our results indicate that (i) cross-species amplification is a versatile and rapid tool for developing microsatellite markers in Rhagoletis spp., (ii) the microsatellite markers presented here constitute an important tool for population studies on this pest, and (iii) there is clear structuring of natural European cherry fly populations.