Gastral drumming in Vespula germanica: does a mechanical signal induce nestmates to forage?

Recruitment in social insects is communication that brings nestmates where work is required. Bees, ants, and termites utilize recruitment communication in the context of foraging, but most research in wasps has suggested that this group lacks a signal to recruit nestmates to food sources. Instead, foraging in wasps seems to be largely regulated by cues. Here, we ask whether a mechanical signal produced by Vespula germanica workers, gastral drumming, regulates foraging activity by alerting nestmates that foraging opportunities are available. Previous studies have suggested that this behavior functions as a hunger signal. However, we show that drumming decreases significantly when a colony is deprived of food, a result not predicted by the hunger signal hypothesis. In contrast, gastral drumming production increases significantly when a colony is supplemented with food, and playback of drumming to a colony results in an increased number of workers departing from the nest. Taken together, the results suggest that this mechanical signal informs nestmates that profitable foraging opportunities are available.