Pine wilt disease in Yunnan,China: Evidence of non-local pine sawyer Monochamus alternatus (Coleoptera: Cerambycidae) populations revealed by mitochondrial DNA

Abstract Monochamus alternatus (Hope) specimens were collected from nine geographical populations in China, where the pinewood nematode Bursaphelenchus xylophilus (Steiner et Buhrer) was present. There were seven populations in southwestern China in Yunnan Province (Ruili, Wanding, Lianghe, Pu’er, Huaning, Stone Forest and Yongsheng), one in central China in Hubei Province (Wuhan), and one in eastern China in Zhejiang Province (Hangzhou). Twenty-two polymorphic sites were recognized and 18 haplotypes were established by analyzing a 565 bp gene fragment of mitochondrial cytochrome oxidase subunit II (CO II). Kimura two-parameter distances demonstrated that M. alternatus populations in Ruili, Wanding and Lianghe (in southwestern Yunnan) differed from the other four Yunnan populations but were similar to the Zhejiang population. No close relationship was found between the M. alternatus populations in Yunnan and Hubei. Phylogenetic reconstruction established a neighbor-joining (NJ) tree, which divided haplotypes of southwestern Yunnan and the rest of Yunnan into different clades with considerable bootstrapping values. Analysis of molecular variance and spatial analysis of molecular variance also suggested significant genetic differentiation between M. alternatus populations in southwestern Yunnan and the rest of Yunnan. Our research suggests that non-local populations of M. alternates, possibly from eastern China, have become established in southwestern Yunnan.