Social attraction mediates collective foraging decisions in invasive yellow-legged hornets

Group-living animals commonly use social information to locate and exploit resources. In many insects, fish, birds and mammals, this leads to collective foraging decisions by which animals aggregate on a single food source despite several alternatives of different or equal qualities. Here, we report collective foraging decisions in a widespread invasive hornet (Vespa velutina nigrithorax) that predates on bees and consume plant nectar. When given a choice between 2 identical sugar solutions (in feeders or in traps), wild hornets distributed asymmetrically between the 2 options, and this was more frequent as the number of hornets increased. Priming one of the food sources with dead hornets predictably biased the aggregation toward this particular food source, irrespective of whether the baits were conspecifics or hornets from a different species. Inter-attraction in yellow-legged hornets is thus passive and non-specific, possibly mediated by visual and/or chemical cues displayed by dead hornets. Social foraging may provide important benefits to hornets invading new territories and bring new perspectives for population control.