Washington, September 10 : Ever wondered why predatory wasps hunt free-flying bees, rather than foraging bees directly from the honeybee nest?
Well, researchers at the University of Graz, Austria, and the Royal Botanic Gardens Kew, UK, say that it is all because the shimmering-a remarkable capacity of rapid communication in giant honeybees-acts as a defensive mechanism and repels predatory hornets.
The researchers describe shimmering as a phenomenon wherein thousands of honeybees flip their abdomens upwards within a split-second to produce a Mexican Wave-like pattern across their nests.
During the study, research leader Gerald Kastberger and colleagues analysed around 500 episodes of interactions between bees and hornets, frame by frame.
Published in the journal PLoS ONE, the study revealed that shimmering is invoked as a means of anti-predatory defense.
The researchers found that shimmering was 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.
They also found that hornets responded to shimmering, showing an avoidance response, which is strongly tied to the time course of shimmering.
Predatory hornets were deterred by the visual cue of large-scale shimmering, whereas small-scale shimmering had the capacity to confuse those that were extremely close to the honeybee nest.
The researchers said that shimmering forced the hornets to alter their hunting strategy, travelling at least 50 cm away from the honeybee nest to forage for free-flying bees.
Based on their observations, the researchers came to the conclusion that shimmering is a pivotal trait that allows giant honeybees to maintain their open-nesting life style which they evolved millions of years ago.
The way giant honeybee colonies and bee-hawking hornets interact during the shimmering process supports the hypothesis that a co-evolutionary mutual adjustment between prey and predator is at play here, they say.