Abstract:  【Aim】 Monolepta hieroglyphica is a polyphagous pest feeding on a large number of cultivated plant species. The aim of this study is to investigate the genetic diversity, genetic structure, and levels of genetic differentiation and gene flow among geographical populations of M. hieroglyphica distributed in South China, and to clarify the diversity and prevalence of the bacterial endosymbiont Wolbachia in M. hieroglyphica geographical populations in South China. 【Methods】 The mitochondrial COII gene was used as genetic marker. The partial COII gene sequences in a total of 403 individuals from 14 geographical populations of M. hieroglyphica were amplified by PCR and sequenced. The haplotype diversity (Hd), genetic differentiation coefficient (F_st) and gene flow (Nm) between populations were analyzed, and the analysis of molecular variance (AMOVA) and Tajima’s D and Fu’s Fs neutrality tests were performed. Median-joining network and phylogenetic tree were constructed based on haplotype sequences. Wolbachia wsp gene was amplified by PCR to detect population infection rates, and the obtained wsp sequences were used for strain typing and phylogenetic analysis of Wolbachia. 【Results】 For all the 403 test individuals of M. hieroglyphica in this study, 23 COII haplotypes were observed and divided into two clusters in phylogenetic tree. The Hd of total population was 0.748, ranging from 0.394 to 0.782 within each population. The neutrality test results suggested that M. hieroglyphica populations followed the neutral evolution model and there was no evidence of population expansion in recent history. The values of F_st and Nm of total population were 0.2481 and 0.76, respectively. The AMOVA results showed that a high proportion (73.75%) of the total genetic variance attributed to variation within population. There was no significant correlation between genetic distance and geographical distance among populations (R=0.2898, P=0.0640). The Wolbachia infection rates in the 14 geographical populations of M. hieroglyphica ranged from 92.59% to 100%, with an average infection rate of 97.60%. Six Wolbachia strains (named as wMhie1-wMhie6) were identified based on wsp sequences, and these strains all belong to the supergroup A, which is clearly distinguished from other representative stains and forms a unique cluster in the phylogenetic tree. 【Conclusion】 The genetic diversity of M. hieroglyphica populations distributed in South China is comparatively high. There is significant genetic differentiation among most populations and the gene flow is low among populations. No significant correlation exists between genetic differentiation and geographical isolation. High infection rates and diversity of Wolbachia exist in M. hieroglyphica populations in South China.

Key words: Monolepta hieroglyphica, geographical population, COII, haplotype, genetic structure, Wolbachia