The phenomenon of “shimmering” in giant honeybees, in which hundreds—or even thousands—of individual honeybees flip their abdomens upwards within a split-second to produce a Mexican Wave-like pattern across the bee nest, has received much interest but both its precise mode of action and its purpose have long remained a mystery.
In a new study published in the journal PLoS ONE this week, researchers at the University of Graz, Austria, and the Royal Botanic Gardens Kew, UK, report the finding that shimmering—a remarkable capacity of rapid communication in giant honeybees—acts as a defensive mechanism, which repels predatory hornets, forcing them to hunt free-flying bees, further afield, rather than foraging bees directly from the honeybee nest. …
In their paper, Kastberger and colleagues show that shimmering is invoked as a means of anti-predatory defense. They analysed around 500 episodes of interactions between bees and hornets, frame by frame, and found that shimmering is triggered by giant honeybee colonies in response to approaching hornets, the strength and rate of the phenomenon being linked to the hornets’ flight speed and proximity.
The researchers also found that hornets respond to shimmering, showing an avoidance response, which is strongly tied to the time course of shimmering. Predatory hornets are deterred by the visual cue of large-scale shimmering (in particular, when they are closer than 50 cm to the giant honeybee nest), whereas small-scale shimmering has the capacity to confuse hornets, which are extremely close to the honeybee nest. As a result, shimmering forces the hornets to alter their hunting strategy, travelling at least 50 cm away from the honeybee nest to forage for free-flying bees. – sd