General Information: Endosymbiont. Obligate intracellular bacterium infects around 20% of all insect species. Naturally infects Drosophila simulans and induces almost complete cytoplasmic incompatibility in its host. Wolbachia sp. subsp. Drosophila simulans (strain wRi) is an intracellular proteobacterium that infect insects as well as isopods, spiders, scorpions, mites, and filarial nematodes. It is maternally inherited and induces reproductive alterations of insect populations by male killing, feminization, parthenogenesis, or cytoplasmic incompatibility. In insect populations, Wolbachia sp. induce reproductive manipulations to enhance their own spreading. The most frequently observed reproductive abnormality is cytoplasmic incompatibility, where uninfected females are unable to produce offspring with infected males, whereas infected females can produce offspring with both infected and uninfected males, thus creating a reproductive advantage for infected females. Other spectacular effects of Wolbachia sp. infections are male embryo killing, feminization, and parthenogenesis induction.