Bees lock up invaders and throw away the key
19/05/2001 - James Randerson - http://www.newscientist.com/
AFRICAN honeybees have devised a bizarre but highly effective tactic for dealing with unwanted guests--they lock them up in prison cells inside their hives. This penal policy keeps a lid on the parasites and, if necessary, buys the colony time to escape.
Peter Neumann of the University of Halle-Wittenberg in Germany and colleagues studied how bees in South Africa defend themselves against the small hive beetle Aethina tumida, which is about half the size of a bee. The beetle raids the bees' food reserves and eats their larvae.
The beetle is "built like a tank", and the bees have little success tackling invaders directly, says Neumann. Instead, they literally imprison the beetles in small cracks within the hive, a tactic involving sophisticated teamwork called "social encapsulation". "While some bees build the prison, others continuously guard the beetles to prevent escape," says Neumann. The jailhouse is made from tree-resin collected by the bees, and building can take up to four days.
Hive beetles are rarely a serious threat to African honeybees because they deal with them so efficiently. In one instance, Neumann found that a colony of bees managed to imprison over 200 beetles, although the colony did eventually abandon its nest after the heavy infestation. The results will be published in a future issue of Naturwissenschaften.
In the US, however, honeybees are at the mercy of the beetle invaders, which were accidently introduced to the country 3 to 5 years ago. "It has become a major honeybee pest in the US," says Neumann. "Once colonies from European stock are infested they are basically doomed, because these bees lack the behavioural resistance mechanisms of African honeybees."
Read the original paper : Newscientist
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