Complex invasion history of the Asian long-horned beetle: fifteen years after first detection in Europe

Abstract

The Asian long-horned beetle (ALB), a Cerambycidae, is an urban tree pest native to East Asia accidentally introduced to other continents via solid wood packing material. It was first detected in Europe in 2001, and since then infestations have been found in ten European countries. Using a 485-bp-long fragment of the mitochondrial barcode gene (COI), we studied the genetic diversity and structure of ALB populations in both native and invaded ranges, with a specific focus on Europe. Three main haplotypes were found across the native and invaded distribution of ALB. The native area in Asia was the most diverse with 23 haplotypes, but a low genetic structure was observed. Our results revealed up to nine distinct haplotypes that was diverged by no more than six mutational steps in European populations collected from 2001 to 2016. Nevertheless, the genetic structure was characterized by one widespread dominant haplotype in Europe. The overall complex genetic structure observed in Europe suggested a convoluted invasion scenario. Indeed, invasion history may include several introduction events as well as secondary dispersal

Deciphering the worldwide invasion of the Asian long‐horned beetle: A recurrent invasion process from the native area together with a bridgehead effect

“…Interestingly, this bridgehead scenario could not be inferred from previous studies (Javal, Roques et al, ). Indeed, based on a single mtDNA marker, the French population of Gien (population 19) appeared genetically homogeneous and distinct from any other population, including the North American population.…”

“…Clustering analyses indicated differentiation along a north–south gradient between the northeastern populations (27–29, 39–41) and all other populations. This geographic structuring was highlighted in several other studies on ALB in its native range (An et al, ; Carter et al, ; Javal, Roques et al, ), and it might have resulted from the low natural dispersal capability of ALB adults (Smith, Bancroft, Li, Gao, & Teale, ; Smith, Tobin, Bancroft, Li, & Gao, ). However, demographic events and human‐mediated translocations seem to have attenuated the putative global ancestral structure.…”

“…Our study is the first to shed light on the worldwide invasion scenario of ALB by analysing populations from both native and invaded ranges. We used recently developed ABC‐RF procedures to retrace the main invasion routes, by analysing data in the light of field observations and previous phylogeographic studies (Carter et al, ; Javal, Roques et al, ). Although we could not infer the specific history of each population with sufficient statistical support, we were able to provide an overall outline of the global invasion scenario.…”

“…Europe was the second continent to be invaded by ALB, and, following the first detection of an established population in Austria in 2001, infestations and interceptions at entry points have been reported regularly (EPPO Global Database). The high frequency of these reports, as well as the distribution of mitochondrial haplotypes (Javal, Roques et al, ), has suggested that the European infestation was most likely due to multiple independent introductions. The high F ST values in our study support this hypothesis.…”

“…Previous studies involved investigations of the genetic structure of invasive ALB populations in both the native (Carter, Smith, & Harrison, ) and invaded range (Carter, Smith, & Harrison, ; Javal, Roques et al, ). Their findings highlighted a complex genetic structure in the native zone that is dominated by a few major genetic clusters.…”