Mitochondrial sequence polymorphism in Chinese populations of <Emphasis Type="Italic">Hylobitelus xiaoi</Emphasis> (Coleoptera: Curculionidae)

The Chinese weevil, Hylobitelus xiaoi Zhang, is a major pest affecting the pine industry throughout southern China, but its dispersal is still poorly understood. We aimed to investigate its dispersal by assessing the genetic structure of seven geographical populations, using the distribution of two mitochondrial genes (cytochrome c oxidase subunit I and cytochrome b). A 1212-bp fragment of the two mitochondrial genes was sequenced for 70 individuals from seven geographical populations. The gene sequences included 861 conserved sites, 351 variable sites, 254 parsim-info sites, and 97 singleton sites. These polymorphic sites defined 24 haplotypes with a haplotype diversity of 0.825. Nucleotide diversity was low (0.04568). The differentiation parameter (0.619) was much greater than the coefficient of genetic differentiation (0.285). An analysis of molecular variance suggested that most of the variation was due to within-population differences (61.68%). This molecular data also demonstrated that there is significant divergence among the seven sampled populations of H. xiaoi. This is probably due to habitat fragmentation, preventing effective gene flow between sites. Our molecular evidence supports the view that the Chinese weevil is a native pest, and that outbreaks of H. xiaoi are caused by large plantations of the exotic slash pine.