Abstract

Motohiko Ogawa*, Mamoru Takahashi, Minenosuke Matsutani, Nobuhiro Takada and Shinichi Noda

Mites of the Leptotrombidium genus (Acari: Trombiculidae) are important from a public health perspective because certain species can transmit Orientia tsutsugamushi, which is the causative agent of scrub typhus. In this study, we evaluated the endosymbiotic bacterial diversity of predominant Leptotrombidium mites in certain regions of Japan via next-generation sequencing of 16S rRNA gene amplicons. Members of the genus Wolbachia were the most common bacteria found in all surveyed areas of this study and were even found in different species of mites, Leptotrombidium scutellare and Leptotrombidium deliense. Full-length 16S rRNA sequences were used to cluster two genetically similar groups of Wolbachia-like endosymbionts. Phylogenetic analysis using the 16S rRNA sequences showed that the two Wolbachia-like endosymbiont groups were classified into a monophyletic cluster, which was phylogenetically distant from a cluster of all previously reported strains. Based on the results, the Wolbachia-like endosymbionts were suggested to have diverged from the cluster of previously identified Wolbachia a long time ago, even before L. scutellare and L. deliense were separated. The abundance of Wolbachia spp. in the host mites elicits academic interest in their role in the host mites. We speculated that the endosymbionts may enhance the reproduction of host mites. Keywords: Leptotrombidium mites, Microbiome, 16S rRNA, Wolbachia, Endos