Molecular phylogenetic analysis of Wolbachia infection in the Ostrinia furnacalis species group

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DNA sequences for two Wolbachia genes (ftsZ and wsp) were determined for more than 20, in total, Wolbachia-infected individuals of four Ostrinia species (O. furnacalis, O. scapulalis, O. orientalis and O. zaguliaevi). These samples shared identical sequences for both genes, suggesting that Wolbachia strains infected in the four moth species are identical or very closely related to each other.DNA sequences for the mitochondrial COII gene were determined for a total of 35 Wolbachia-infected infections in the four host species share the same, single infection event in ancestry. Besides the COII gene was sequenced for a total of more than 200 individuals of seven species including the four Ostrinia species, O. zealis, O. nublialis and O. sp. Phylogenetic analysis of all the COII sequences showed that the Wolbachia-associated COII sequences do not belong to major mitochondrial phylogroups in the seven species. This suggests that the Wolbachia-associated COII lineage has a very old origin in the O. furnacalis species group.Based on the findings, I concluded that the Wolbachia infection has expanded its host range through hybridization of hosts in the O. furnacalis species group. The source species which has supplied the Wolbachia infection to other host species could not be specified from the present findings. The evolutionary origin of Wolbachia infection in the O. furnacalis group is most likely to date back older than speciation events of hosts.