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.

Dispersal of the Japanese Pine Sawyer, Monochamus alternatus (Coleoptera: Cerambycidae), in Mainland China as Inferred from Molecular Data and Associations to Indices of Human Activity

“…Similar genetic proximity was reported by Kawai et al and Shoda-Kagaya [24], [58] on the population genetic structure of M. alternatus in Japan, as well as in other agricultural pests which are commonly relocated through human activity [52], [59]. The close genetic connections between the above-mentioned distantly-isolated M. alternatus populations in the present study also imply human-mediated relocation as reported earlier by Fu et al [15]. Overall, our results suggest that the genetic structure of M. alternatus has been admixed by recent, human-mediated population dispersal of this insect within mainland China.…”

“…It is logical that some non-local M. alternatus populations can originate from PWN-free areas, or that not all M. alternatus from PWN-infested areas carry PWN. Such a scenario was reported in southwestern Yunnan by Fu et al [15] in which non-local M. alternatus were detected in a PWN-free site (Lianghe) while two other nearby sites (Wanding and Ruili) were both infested with PWN. Overall, the present research confirms that the inadvertent introduction of non-local M. alternatus can lead to the spread of PWN, but that the invasion and spread of PWN would not necessarily affect the genetic structure of M. alternatus .…”

“…The first index was the ratio of shared haplotypes (denoted as R shr ) because it can indicate a recent introduction/establishment of a non-local population of a native organism [15], [51], [52]. Two indices like Nei’s average number of pairwise differences within populations (denoted as K ) and the haplotype diversity (denoted as D hap ) which reflect the genetic diversity within populations were also used in correlation analysis to estimate the influence of human activity on population genetic diversity.…”

“…For example, Fu et al [15] stated that the outbreak of the PWN in Yunnan, in southwestern China, was likely caused by inadvertent introduction of M. alternatus and PWN from eastern China. Similarly, molecular techniques have been used to explore the origins of other invasive forest pests such as Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) and Tomicus piniperda (L.) (Coleoptera: Curculionidae: Scolytinae) in North America [16]–[18].…”

Genetic analysis of emerald ash borer (Agrilus planipennis Fairmaire) populations in Asia and North America

“…Molecular markers are widely used to study invasive species, with applications ranging from assessing genetic variation (Roderick 1996;Sakai et al 2001), to reconstructing invasion history (Elderkin et al 2004), identifying population origin (population assignment tests) and the number of introductions (Grapputo et al 2005), and developing control strategies (Szalanski and Owens 2003;Conord et al 2006;Kim et al 2006;Fu et al 2010). Understanding the geographic origin, population biology and genetic variation of an invasive species can provide important information on suitable habitat, potential location(s) of effective biological control agents, or predict the effectiveness of a control agent (Allendorf and Lundquist 2003;Sakai et al 2001;Kambhampati and Rai 1991;Lee 2002;Scheffer and Grissell 2003).…”