Invasion History of Sirex noctilio Based on COI Sequence: The First Six Years in China

Abstract

Sirex noctilio F. (Hymenoptera: Siricidae: Siricinae), a new invasive species in China, is a significant international forestry pest which, transported via logs and related wood packing materials, has led to environmental damage and substantial economic loss in many countries around the world. It was first detected in China in 2013, and since then infestations have been found in 18 additional sites. Using a 322 bp fragment of the mitochondrial barcode gene COI, we studied the genetic diversity and structure of S. noctilio populations in both native and invaded ranges, with a specific focus in China. Twelve haplotypes were found across the native and invaded distribution of the pest, of which three were dominant; among these there were only one or two mutational steps between each pair of haplotypes. No obvious genetic structure was found other than in Chinese populations. China has a unique and dominant haplotype not found elsewhere, and compared with the rest of the world, the genetic structure of Chinese populations suggested a multiple invasion scenario.

Mitochondrial COI Sequence Variations within and among Geographic Samples of the Hemp Pest Psylliodes attenuata from China

“…Instead, the observed haplotype sharing among fields located thousands of kilometers apart was likely due to incomplete lineage sorting and/or recent anthropogenic activities such as human travel and trade. Indeed, anthropogenic activities have been found to impact the distributions of a variety of plant pathogens and pests [ 15 , 19 , 20 , 34 , 35 , 36 ]. Even for the Yunnan population of P. attenuata , where no haplotype was found shared with those from other geographic areas, the Yunnan haplotypes were found closely related to those in other regions separated by one or a few mutations, consistent with their recent shared histories.…”

“…Despite its broad distribution and significant economic impact on the hemp industry, we know very little about the genetic diversity and phylogeography of hemp flea beetle. Molecular markers, such as those based on nuclear and organelle DNA sequences, have become increasingly popular for investigating the diversity and genetic relationships among populations of insects [ 15 ]. Specifically, the animal DNA barcode locus, a fragment of the mitochondrial cytochrome oxidase I gene (mt-COI), is often used as a molecular marker to determine the intraspecific and interspecific genetic relationship in insects [ 16 ].…”

“…For example, at the above-species level, DNA sequence variations at COI locus have been used to assess systematics and taxonomy of insects in Pseudococcidae [ 18 ] and Lepidoptera [ 19 ]. Furthermore, COI sequences have been used to investigate the invasion history of the sirex woodwasp Sirex noctilio populations in China [ 15 ] and to identify the genotypes of three-cornered alfalfa hopper Spissistilus festinus in the United States [ 20 ].…”