午夜福利1000集合

KILLER bees can be victims too. The hives of African honeybees, the same
subspecies as the 鈥渒iller bees鈥� now spreading across North America, have been
mysteriously disappearing in their native South Africa.

Madeleine Beekman of Sheffield University, and her colleagues at Wageningen
Agricultural University in the Netherlands found that their hives are being
invaded by Cape honeybees. It is the first time that workers have been caught
taking over the hives of other bees.

Cape bees normally live on the windswept tip of South Africa, so their queens
are quite often blown away during mating flights. In response, normally sterile
workers develop ovaries and lay fertilised eggs, without mating. Many bees do
this rarely, but in Cape bees it is part of their normal life cycle.

When beekeepers moved Cape bees north into African bee territory, the
newcomers developed a new behaviour. 鈥淭hey invade the African bee鈥檚 nests and
start laying eggs,鈥� says Beekman. 鈥淭he African bees get confused and think there
are multiple queens, so they attack and kill their own queen.鈥�

The African bees normally die. Either the Cape clones don鈥檛 forage much, or a
new Cape queen and a normal Cape colony swarm off. Sometimes the bees go off
looking for another African nest to invade, says Beekman.

This is a problem for beekeepers who prefer the African to the Cape
subspecies. 鈥淐ape bees are very irritable,鈥� says Gordon Wardell of the US
Department of Agriculture鈥檚 bee research laboratory in Tucson, Arizona. For this
reason introducing Cape bees would not help to control the African bees now
terrorising the Americas. 鈥淐ape bees are just as bad,鈥� he says.