Sunday, April 28, 2013

Criminal Bumblebees

Bee Behaviour

An article in The Economist says that there exist some bumblebees that act as criminals, stealing nectar from flowering plants without giving anything in return, namely, without pollinating the flower
Nectar robbery, in which a bumblebee carves a hole in the side of a flower as a bank robber might cut his way into a vault, was discovered by Charles Darwin. This technique lets bees get at the nectar of flowers whose shapes have evolved to encourage their pollination by insects with long tongues, which can reach down narrow tubes.
Some bumblebees do have such tongues. But some do not. Short-tongued bees are, however, unwilling to deny themselves the bounty of nectar inside these flowers. Hence the hole-cutting. By breaking in in this way, though, a bumblebee nullifies the 100m-year-old pact between flowering plants and insects: that the plant feeds the insect in exchange for the insect pollinating the plant.
The question about nectar robbery that has intrigued biologists from Darwin onwards is whether the behaviour is innate or learnt. Darwin, though he originated the idea that many behaviour patterns are products of evolution by natural selection, suspected that it is learnt. Insects, in other words, can copy what other insects get up to. Only now, though, has somebody proved that this is true.
The observations were made by David Goulson (then at the University of Stirling, now at the University of Sussex), and his colleagues. To test his ideas he had to go from Britain to Switzerland, for only there could he find a flower of the correct shape to conduct the study.
His crucial observation was that when the flowers of an alpine plant called the yellow rattle are robbed, the entry holes—because of the structure of the flower—tend to be unambiguously on either the right-hand side or the left-hand side. Moreover, preliminary observation suggested that the holes in flowers in a single meadow are often all made on the same side. This led him to speculate that bumblebees in a particular area do indeed learn the art of nectar robbery from one another, and then copy the technique with such fidelity that they always attack a flower from the same side.
This is an interesting finding in that it shows that such behaviour is passed on to other bees, who learn how to essentially get something for free. This type of thinking and action is, of course, common to many humans, who often show little hesitation or moral qualms in taking and not giving anything back in return, even though they gain the sweet nectar of the gods.

You can read the rest of the article at [The Economist]

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