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Honeybees can smother their enemies to death by swarming them, European researchers have found.
The discovery means that bees have three ways of dispatching their enemies - by stinging, which for a bee means suicide; by raising the other creature's body temperature, or thermo-balling; and by asphyxiation.
"Here, for the first time we detail an amazing defence strategy, namely asphyxia-balling, by which Cyprian honeybees mob the hornet and smother it to death," said Gerard Arnold of the French national scientific research institute CNRS. "The domestic bee has never ceased surprising us."
Writing in the journal Current Biology, Mr Arnold and colleagues said they wanted to find out how Cyprian honeybees killed their arch enemy, the Oriental hornet.
It had been known that Asian honeybees kill their hornet enemies by thermo-balling.
A swarm of bees will cover the unfortunate insect, raising its body temperature to lethal levels.
But the Cyprian honeybees do not raise temperatures to fatal levels when they mob hornets, which prey on bees and bee larvae.
Alexandros Papachristoforou of Aristotle University of Thessaloniki, Greece, and colleagues made videos of honeybees killing hornets.
They noticed that the bees press on the insects' abdomens, so they set up an experiment to see if the bees were suffocating the hornets.
Insects breathe through openings in their exoskeletons called spiracles. These are covered by structures known as tergites where air is released.
Using tiny tweezers, the scientists propped the tergites open with miniscule pieces of plastic.
"It took much longer for honeybees to kill hornets equipped with plastic blocks than those without," the researchers wrote.
"To kill the high temperature- tolerant hornet, Cyprian honeybees have developed an alternative strategy to thermo-balling," the researchers concluded.
"They appear to have identified the hornets' Achilles' heel."
- Reuters
