Not just honeybees: predatory habits of Vespa velutina (Hymenoptera: Vespidae) in France

Abstract

Summary Understanding the impact of a predatory invasive alien species requires data on its diet. Vespa velutina Lepeletier, 1836, is a notorious bee-hawking hornet accidentally introduced in France before 2004 which spread across the European continent. Despite numerous studies and the impact on beekeeping activities, there are very few data on the diet of this species in its invaded range in Europe. To fill this knowledge gap, we studied 16 nests in the south-west of France between 2008 and 2010. Using a combination of morphological and barcoding approaches, we identified 2151 prey pellets showing that V. velutina acts as a generalist predator, preying on honeybees (38.1%), flies (29.9%) and social wasps (19.7%), as well as a wide spectrum of animal organisms (no less than 159 species identified). The prey spectrum is influenced by the nest surroundings, urban colonies preying more on honeybees and forest colonies preying more on social wasps. The predation intensity reaches its peak in early October. By comparing the dry weight of prey pellets to that of V. velutina larvae and considering the colony dynamics, we estimated that a single hornet nest can consume on average 11.32 kg of insect biomass in one season. Overall, our results suggest that V. velutina is a generalist opportunistic predator targeting mostly locally abundant prey. While the species may have an impact on honeybees, its generalist, opportunistic behaviour on abundant insects suggests a minor impact on wild species. Instead, attempts to manage this species using non-selective traps have a much greater impact on wild and domesticated entomofauna than the hornet itself.