Insect species associated with human goods continue to be accidentally introduced into new locations. A small proportion of these introduced species become invasive, causing a range of impacts in the receiving community.

No abstract

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.

Since its introduction in France 10 years ago, the yellow-legged hornet, Vespa velutina, has rapidly spread to neighbouring countries (Spain, Portugal, Belgium, Italy and Germany). It showed efficient social traits facilitating its invasive success. Only scarce and incomplete natural history studies were known from its native distribution area. Studying the biology of this species in its invasive distribution range was thus a prerequisite to the implementation of efficient control methods in a near future. During a 3-year field survey, we collected 77 nests to investigate several of the species' key colony characteristics. Our results enabled us to accurately quantify each of the castes and to better understand their synchronicity throughout the season. Our study showed that mature nests are able to produce up to 13 000 individuals and that the size of mature nests is correlated to the number of individuals produced. This correlation enables the inference of one characteristic from the other. Furthermore, each mature nest can produce up to several hundreds of potential founder queens, a crucial datum in the light of today's unregulated spring queen trapping control campaigns. In addition, nest dissections enabled to record the incidence of nest relocation for the first time in this species. Results are discussed with regards to what is known in other Vespidae species, with a focus on Vespula species that are known to be invasive in many other countries worldwide.

Predictive studies are of paramount importance for biological invasions, one of the biggest threats for biodiversity. To help and better prioritize management strategies, species distribution models (SDMs) are often used to predict the potential invasive range of introduced species. Yet, SDMs have been regularly criticized, due to several strong limitations, such as violating the equilibrium assumption during the invasion process. Unfortunately, validation studies–with independent data–are too scarce to assess the predictive accuracy of SDMs in invasion biology. Yet, biological invasions allow to test SDMs usefulness, by retrospectively assessing whether they would have accurately predicted the latest ranges of invasion. Here, we assess the predictive accuracy of SDMs in predicting the expansion of invasive species. We used temporal occurrence data for the Asian hornet Vespa velutina nigrithorax, a species native to China that is invading Europe with a very fast rate. Specifically, we compared occurrence data from the last stage of invasion (independent validation points) to the climate suitability distribution predicted from models calibrated with data from the early stage of invasion. Despite the invasive species not being at equilibrium yet, the predicted climate suitability of validation points was high. SDMs can thus adequately predict the spread of V. v. nigrithorax, which appears to be—at least partially–climatically driven. In the case of V. v. nigrithorax, SDMs predictive accuracy was slightly but significantly better when models were calibrated with invasive data only, excluding native data. Although more validation studies for other invasion cases are needed to generalize our results, our findings are an important step towards validating the use of SDMs in invasion biology.

No abstract

No abstract

No abstract