infection in field-collected in Yunnan Province, southwestern China.

Background: is gram-negative and common intracellular bacteria, which is maternally inherited endosymbionts and could expand their propagation in host populations by means of various manipulations. Recent reports reveal the natural infection of in in Malaysia, India, Philippines, Thailand and the United States. At present, none of natural infection in has been reported in China.

Methods: A total of 480 adult mosquitoes were collected from October and November 2018 based on the results of previous investigations and the distribution of in Yunnan. Each individual sample was processed and screened for the presence of by PCR with primers. Phylogenetic trees for the gene was constructed using the neighbour-joining method with 1,000 bootstrap replicates, and the p-distance distribution model of molecular evolution was applied.

Results: 24 individual adult mosquito samples and 10 sample sites were positive for infection. The infection rate (IR) of each population ranged from 0 - 41.7%. The infection rate of group A alone was 0%-10%, the infection rate of group B alone was 0%-7.7%, and the infection rate of co-infection with A and B was 0-33.3%.

Conclusions: infection in wild in China is the first report based on PCR amplification of the gene. The infection is 5%, and the and strains were found to be prevalent in the natural population of in Yunnan Province.