The yellow-legged hornet, Vespa velutina, was accidentally introduced from Southeast Asia and then invaded France and Korea over the last 10 years. Since its introduction, its predation on honeybee colonies has rapidly become an economic problem in invaded countries. Using mitochondrial cytochrome C oxidase and 22 nuclear microsatellite loci, we showed that native hornet populations were well differentiated and highly diverse. In contrast, introduced populations from France and Korea suffered a genetic bottleneck, which did not prevent their rapid geographic expansion. Analysis of the genetic data indicates that French and Korean populations likely arose from two independent introduction events. The most probable source population is from an area between the Chinese provinces of Zhejiang and Jiangsu. This invasion route is in agreement with knowledge on trade and historical records. By studying colonies of V. velutina, we demonstrated its polyandry, which is very rare among Vespidae. This mating behavior could have favored the success of this Asian hornet in Europe and Korea. Combined, the population and colony results suggest that very few or possibly only one single multi-mated female gave rise to the invasion. Keywords Yellow-legged hornet Á Vespa velutina Á Invasive species Á Approximate Bayesian computation Data accessibility DNA sequences: Genbank accessions JQ780449 JQ780462.

The level of genetic diversity within populations of introduced species has received increasing attention as an important factor influencing their survival and adaptive potential. We examined this issue with the Guatemalan potato tuber moth Tecia solanivora, an agricultural pest which has successfully invaded South America and the Canary Islands within the last 20 years. To analyse changes in T. solanivora genetic diversity, the mitochondrial marker cytochrome b was sequenced from individuals collected across its known distribution area. High haplotypic diversity was observed in Guatemala, whereas only three haplotypes have been found in Venezuela and a single one in the remaining invaded South American countries and the Canary Islands. Invasive haplotypes were not observed in our samples from Guatemala but are closely related to Guatemalan haplotypes. These results are consistent with the hypotheses that (i) either a few individuals were introduced into Venezuela leading to a strong initial genetic bottleneck, or selection pressure may have lead to the disparition of all but a reduced number of introduced haplotypes, (ii) a second bottleneck occured between Venezuela and Colombia, and (iii) the invasion of the Canary Islands originated from South America. We further reviewed the recent literature to compare this change in genetic diversity with those reported for other invasive species. We quantified the changes in genetic diversity between native and introduced ranges for 57 biological invasions. We found that the genetic homogenization in T. solanivora was among the strongest reported and discuss factors that can explain the success of invasive populations with low genetic diversity.

No abstract

Tecia solanivora (Lepidoptera: Gelechiidae) is an invasive species that attacks the tubers of the potato Solanum tuberosum. It is considered a serious pest of potato crops and stocks in all countries where it occurs. In the present study, we sequenced 541 individuals sampled across the T. solanivora distribution range, using the mitochondrial DNA marker Cytochrome b (Cytb) to delimit the area of species origin. We also analyzed the genetic structure of T. solanivora in its putative area of origin and described differences in haplotype diversity between samples from different geographic origins affected by the invasion. We observed a gap in the level of genetic diversity between Guatemalan samples (h between 0.77 and 0.97) and those from Costa-Rica, Venezuela, Colombia, Ecuador and the Canary Islands (h between 0 and 0.56). The number of haplotypes has decreased over the colonization process, ending with the observation of a single haplotype in Colombia, Ecuador and the Canary Islands. Consequently, the invasion of South American countries by T. solanivora is likely to have had a front-like step-wise progression, where the most recently invaded country becomes the source of subsequent invasion.