Invasion genetics of the yellow-legged hornet Vespa velutina in the Westernmost Mediterranean archipelago

The yellow-legged hornet ( Vespa velutina ) is a social Hymenoptera native from Asia and an invasive species in Europe, where it was first detected in France in 2004. Since then, the species has spread across the continent invading mainland Spain and Mallorca island (Balearic archipelago, Western Mediterranean) in 2010 and 2015, respectively. Yellow-legged hornets cause severe damage to ecosystem by predating over a wide variety of pollinators including honeybees. Such a threat situation requires the development of effective management and prevention plans, which can greatly benefit from knowing both the origin and the genetic structure of the invading populations. Here we conduct a genetic study to shed light on both the origin and the phylogenetic relationships of V. velutina populations from Mallorca and mainland Spain using nuclear (STRs) and mitochondrial (cytochrome oxidase c subunit 1) gene markers. Our results show that Mallorca populations originated from invasive European specimens. Moreover, FST values, DAPC and genetic structure analysis suggest two independent incursions in the island with bottleneck and founder effect signatures. Finally, we contribute additional genetic evidence of the polyandrous behavior of this invasive species based on the inference of a mean number of mattings per nest of 3.94 (range 2–6.5). This study supports the human-mediated pathways of this species and highlights the importance of implementing effective biosecurity measures to prevent the spread of invasive alien species in island habitats.