Reconstructing the invasion and the demographic history of the yellow-legged hornet, Vespa velutina, in Europe

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.