Abstract
Wolbachia is an endosymbiotic bacterium that infects numerous insects and crustaceans. Its ability to alter the reproduction of hosts results in incompatibilities of differentially infected individuals. Therefore, Wolbachia has been applied to suppress agricultural and medical insect pests. The European cherry fruit fly, Rhagoletis cerasi, is mainly distributed throughout Europe and Western Asia, and is infected with at least five different Wolbachia strains. The strain wCer2 causes incompatibilities between infected males and uninfected females, making it a potential candidate to control R. cerasi. Thus, the prediction of its spread is of practical importance. Like mitochondria, Wolbachia is inherited from mother to offspring, causing associations between mitochondrial DNA and endosymbiont infection. Misassociations, however, can be the result of imperfect maternal transmission, the loss of Wolbachia, or its horizontal transmission from infected to uninfected individuals. These are important parameters influencing the spread of infection. Here, we studied Wolbachia-mitochondrial haplotype associations in R. cerasi in two transition zones in the Czech Republic and Hungary, where wCer2 is currently spreading. Our results suggest imperfect maternal transmission only in the early phases of wCer2 invasion and no evidence of horizontal transmission of wCer2 in R. cerasi.