Abstract: The genus Arsenophonus (γproteobacteria， Enterobacteriaceae) is an intracellular symbiotic bacteria， which are commonly found in insects and spiders as well as in plants (strawberry， sugarbeet， etc). Arsenophonus could be vertical or horizontal transmitted to the hosts. The distribution of most Arsenophonus is usually diffused in insect， and seldom could be found in bacteriocytes. The specific sequence of 16S rDNA and 23S rDNA or multilocus system based on three housekeeping genes fbaA， ftzK and yaeT， which were used for identifying Arsenophonus. To date， only five species of Arsenophonus were identified， named Arsenophonus nasoniae， Arsenophonus arthropodicus， Arsenophonus triatominarum， Riesia pediculicola and Phlomobacter frageriae respectively. Previous studies revealed Arsenophonus is male killing and maybe associated with the immunity， nutrition requirement and host adaptation of its insect hosts. Strawberry and sugar beet infected by Arsenophonus would have diseases. Until now， genome sequencing of A. nasoniae and R. pediculicola were conducted and the drafts had been reported. This paper reviewed recent research progress of Arsenophonus. Furthermore， future research directions were also discussed．

Key words: Arsenophonus, molecular identification, host distribution, biological function, genome