Abstract: Wolbachia is a common and widespread group of symbiotic bacteria found in reproductive tissues of arthropods. These bacteria are transmitted through the cytoplasm of eggs and have evolved various mechanisms for manipulating reproduction of their hosts, including induction of reproductive incompatibility, parthenogenesis, feminization, male killing, fecundity or fertility modifying. Wolbachia is thought to be major factors in the evolution of sex determination, eusociality, and speciation. It is a new clue for those research fields. Wolbachia is also of interest as vectors for the modification of their host populations, in the improvement of parasitoid wasps in biological pest control, and as a new method for interfering with diseases caused by filarial nematodes. In this paper, Wolbachia biology is reviewed, including morphological description and distribution, genome sequences, phylogeny and naming of Wolbachia species, horizontal transfer and phenotypic effects on their host. The science value of Wolbachia and potential directions for future research are also discussed.

Key words: Wolbachia, symbiotic bacteria, arthropods, manipulation of reproduction, cytoplasmic incompatibility