Taking Europe by storm: a first insight in the introduction and expansion of Dryocosmus kuriphilus in central Europe by mtDNA.
The chestnut gall wasp, Dryocosmus kuriphilus, poses one of the latest additions to the long list of exotic pests that invaded Europe. After its introduction in Italy, chestnut gall wasp expanded rapidly in Europe in a very short period of time. Analysis of a polymorphic mtDNA locus from nine European populations verified the Chinese origin of this invasion. Moreover, the results revealed traces of a severe bottleneck during the phase of introduction that reduced considerably the genetic diversity. It was also shown that the rapid and successful post-introductory expansion was accomplished by a single mtDNA haplotype that has spread in three European countries. The paradox of successful establishment despite the absence of genetic diversity could be attributed to the synergistic effect of several agents. Uniparental propagation and general-purpose genotypes, lack of natural enemies and human-mediated transport seem to have facilitated the invasion and subsequent expansion of D. kuriphilus in Europe.