Giant hornet (Vespa soror) attacks trigger frenetic antipredator signalling in honeybee (Apis cerana) colonies

Abstract

Asian honeybees use an impressive array of strategies to protect nests from hornet attacks, although little is understood about how antipredator signals coordinate defences. We compared vibroacoustic signalling and defensive responses of Apis cerana colonies that were attacked by either the group-hunting giant hornet Vespa soror or the smaller, solitary-hunting hornet Vespa velutina . Apis cerana colonies produced hisses, brief stop signals and longer pipes under hornet-free conditions. However, hornet-attack stimuli—and V. soror workers in particular—triggered dramatic increases in signalling rates within colonies. Soundscapes were cacophonous when V. soror predators were directly outside of nests, in part because of frenetic production of antipredator pipes, a previously undescribed signal. Antipredator pipes share acoustic traits with alarm shrieks, fear screams and panic calls of primates, birds and meerkats. Workers making antipredator pipes exposed their Nasonov gland, suggesting the potential for multimodal alarm signalling that warns nestmates about the presence of dangerous hornets and assembles workers for defence. Concurrent observations of nest entrances showed an increase in worker activities that support effective defences against giant hornets. Apis cerana workers flexibly employ a diverse alarm repertoire in response to attack attributes, mirroring features of sophisticated alarm calling in socially complex vertebrates.

Defensive shimmering responses inApis dorsataare triggered by dark stimuli moving against a bright background

“…Hornets are major predators of A. dorsata hives (Kastberger et al, 2013; Seeley et al, 1982), and Vespa tropica (the greater banded hornet) is a common predator in our study location (Balamurali et al, 2021). Moreover, hornets can act as strong evolutionary drivers in the evolution of specialised anti-predatory responses in honeybees (Cappa et al, 2021; Ken et al, 2005; Mattila et al, 2020; Mattila et al, 2021; Papachristoforou et al, 2007; Tan et al, 2013). Shimmering resembles the anti-hornet ‘I-see-you’ display found in the sympatric cavity-nesting A. cerana in which guard bees at the entrance shake their abdomens in a to-and-fro motion in the presence of hornets, which supposedly warns the predator that the bees have detected its presence (Tan et al, 2013).…”

The biological roots of music and dance: Extending the credible signaling hypothesis to predator deterrence

“…Alarm calls, which function to warn fellow group members of a predator threat and inform the predator that it has been detected, can also serve to recruit defenders. In Asian honeybees, for example, hornet predators, especially group-hunting hornet species, trigger frenetic within-colony antipredator signaling that recruits more defenders (Mattila et al, 2021). Recruitment calls are also seen in birds and mammals (Furrer & Manser, 2009;Woods, Kings, McIvor, & Thornton, 2018).…”