Visual contagion in prey defense (anti-hornet) signals can enhance honest honey bee defense

In the co-evolutionary arms race between predators and their prey, complex signaling has arisen, especially in groups that benefit from the rapid transmission of alarm signals. For example, pursuit deterrence signals can allow individuals and groups to indicate, at relatively low cost to themselves, that a predator’s further approach or attack is fruitless. Such deterrence signals are often more effective if they are amplified, for example, by rapidly spreading among prey without requiring individual prey to confirm predator presence. However, such contagious signaling can also lead to runaway false signals. We provide the first evidence of a social insect contagious pursuit deterrence signal. The Asian honey bee, Apis cerana, makes an I See You (ISY) signal that can deter hornet from attacking. These signals enhance defensive signaling by attracting guard bees. Interestingly, the visual movements of appropriate stimuli alone (ISY signaling bees or hornets, but not harmless butterflies) provide sufficient stimuli. Olfaction and other potential cues are not necessary. Selection for honesty within the highly cooperative bee colony has likely buffered the ISY signal from runaway false signals because it has specific visual triggers. Our results expand the understanding of contagious signals and how they can be honestly maintained in highly cooperative groups.