When an enemy hornet attacks, bees rely on a lethal weapon: asphyxiation
Confronted by an Oriental hornet, hundreds of Cyprian honeybees swarm their archenemy -- and smother it to death.
Writing in the journal Current Biology this week, a research team led by Alexandros Papachristoforou of Aristotle University in Greece reported on the honeybees, the first insect known to employ such a defense.
The hornet, which feasts on honeybee larvae, is well equipped for battle. It is two to three times the size of the bees and is covered with armor plates the bees’ stingers cannot penetrate. The hornet has powerful mandibles, clawlike appendages near its mouth used to grab and crush prey.
A few hornets can wipe out a bee colony in a matter of hours.
Scientists had long assumed that mobs of Cyprian honeybees killed their enemies by raising the hornets’ body temperature to lethal levels.
But Papachristoforou and his colleagues from both Aristotle University and France’s national research institute, CNRS, discovered that the Oriental hornet, which thrives in a dry climate, can withstand heat.
Closely observing honeybee attacks, scientists found that the bees pressed against the hornet’s abdomen, blocking its ability to breathe. A hornet inhales and exhales by pumping its abdomen like a bellows to force air through small openings called spiracles.
In an experiment, researchers attached tiny plastic blocks to hornets’ abdomens so honeybees could not completely restrict the pumping action. After that, it took 200 honeybees two hours to suffocate one hornet, twice as long as normal.
The bees, researchers wrote, “appear to have identified the hornet’s Achilles heel.”
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