Abstract: 【Aim】 Wolbachia are endosymbionts which were frequently found in arthropods and filarial nematodes. They can manipulate reproduction of their hosts by several mechanisms. Cytoplasmic incompatibility (CI) is the most common phenotype Wolbachia causes, resulting in no or few viable progenies when Wolbachia-infected males cross with uninfected females or females carrying different Wolbachia strains, while the progenies can be produced normally when males and females carrying the same Wolbachia strain cross. We previously found that Drosophila melanogaster flies collected from Wuhan of Hubei (WH), Liuku of Yunnan (LK) and Tianjin (TJ) were infected by Wolbachia. This study aims to investigate the relationships between Wolbachia in these D. melanogaster populations and their effects on host reproduction. 【Methods】 Alignments of nucleic acid homology of Wolbachia wsp genes were performed by Clustal X, and phylogenetic tree was constructed with MEGA. Sequence types (ST) of Wolbachia were analyzed using multilocus sequence typing (MLST). Crossing experiments within and between the three populations of D. melanogaster were conducted to assay CI intensity and the effect of Wolbachia on reproduction of Drosophila hosts. 【Results】 All Wolbachia in the three populations of D. melanogaster belonged to Mel group in supergroup A. MLST analysis showed different sequence types (ST) of Wolbachia in the flies from the three regions. The Wolbachia in the flies from WH and TJ could induce strong CI. Comparatively, the Wolbachia in the flies from LK expressed weaker CI. The Wolbachia in the flies from WH could not entirely rescue the CI phenotype induced by the Wolbachia in TJ flies, and vise versa. 【Conclusion】 The Wolbachia in the flies from WH might be less related with those from TJ. The long-time symbiosis of Wolbachia might affect the evolution of their Drosophila hosts. Wolbachia in WH and LK populations of D. melanogaster belong to different STs, and a definite reproductive isolation between their hosts exists.

Key words: Drosophila melanogaster, Wolbachia, wsp gene, multilocus sequence typing (MLST), cytoplasmic incompatibility (CI), phylogenesis