Abstract
Arthropods harbor various microorganisms in their internal organs. Spider mites and predatory mites possess Wolbachia, which is known to be a causative agent of cytoplasmic incompatibility, parthenogenesis and feminization. Some Wolbachia-infected mites show cytoplasmic incompatibility, which leads to high mortality in fertilized eggs and a low female ratio, but some others do not. Reproductive incompatibility of mites is reviewed with special reference to Wolbachia. Tick symbiotes were first observed many years ago but their phylogenetic affiliations have been unclear. They are closely related to pathogens transmitted by ticks, such as the causativeagents of tularemia, Q fever and spotted fever. Various aspects of the symbiotes are discussed and the importance of further extensive studies on the symbiotes in relation to tick-borne pathogens is stressed.
