Bee Warned

Bees have a great deal to cope with. The vagaries of the weather and limited flowering seasons of their food plants are enough to keep them busy without the mites and diseases that they get from time to time, let alone having to cope with predators.

Hornets like bees, that is, to eat. The European honeybee lives in large colonies, but the Asian honeybee lives in smaller more mobile colonies. It co-evolved with the hornet and has developed a strategy for dealing with them. Tan et al report on this in the Journal of Animal Behaviour (1,2).

Hornets like to swoop down and abduct an unsuspecting worker bee for lunch. Now the Asian honeybees are quite vigilant and if an incoming hornet is spotted a large number of them at the colony entrance shake their abdomens wildly so the hornet sees this seething mass and thinks better of its escapade and high tails it to somewhere else.

The bee's warning is not an idle threat. It alerts the hornet to a mass of bees that know it’s there. If it presses home its attack, the bees cluster around it very tightly so that it is immobilized and with the press of bees, its temperature increases and it becomes too hot and expires.

So all those wagging tails tell it to buzz off as it has a better chance of overheating than overeating.

The investigators used tethered hornets and butterflies to test the bee’s reaction. They found it was hornet specific as the bees ignored butterflies. The European honeybee has failed to evolve the same procedure and can get picked of by swooping hornets. 
  2. K. Tan, Z. Wang, H. Li, S. Yang, Z. Hu, G. Kastlberger & B.P, Oldroyd, J Anim. Behav. ,(2012).

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