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.
- http://www.bbc.co.uk/nature/16981702
- K. Tan, Z. Wang, H. Li, S. Yang, Z. Hu, G. Kastlberger & B.P, Oldroyd, J Anim. Behav. ,(2012). http://dx.doi.org/10.1016/j.anbehav.2011.12.031
