Abstract
Wolbachiaare maternally inherited intracellu-lar bacteria present in a wide range of differ-ent arthropod species. Key factor in the suc-cessful establishment within a host population is its ability to manipulate the reproduction of its host, promoting vertical transmission. A common mechanism Wolbachiauses to influ-ence host reproduction is the induction of cytoplasmic incompatibility (CI). If host popu-lations are infected by different strains of Wolbachia CI can lead to postzygotic repro-ductive isolation and can therefore promote speciationRhagoletisfruit flies (Diptera: Tephritidae) are important pests species in North America. The best-studied member in the genus is the apple maggot, Rhagoletis pomonellaWalsh. Natu-rally infesting hawthorns, a population shifted to domesticated apples as a new host that resulted in the formation of an ecologically and genetically distinct host race. In contrast to R. pomonella, cherry infesting Rhagoletis cingulataand Rhagoletis indifferensradiated by classic allopatric speciation. Here, we characterize the Wolbachiainfection of different R. cingulatapopulations from the eastern and southwestern United States and Mexico and R. indifferensfrom the Pacific Northwest and compare the infection status with the genomic background of the flies. We describe two hot spots of ongoing Wolbachiainvasion and discuss potential impacts of the endosymbiont on the evolution of their hosts.