September 5, 2008

Bees Remember, Learn From Near Death Experiences

In a study of real bees in an artificial setting, scientists found that bees that have been captured by predators tend to learn from their previous experience and become more cautious in their subsequent foraging trips.

Crab spiders pose a great threat to the lives of bees, butterflies and other pollinating insects. The predators have the ability to change color to match that of a flower while it sits and waits for a bumblebee to fly into its trap.

However, Dr Thomas Ings and Professor Lars Chittka from the Queen Mary University in London found that bees that survive becoming the next prey of a crab spider tend to learn from this experience and adapt their behavior accordingly.

Researchers designed an artificial meadow of yellow flowers stocked with robotic crab spiders equipped with two remote-controlled foam pincers.

"The bees behave very much as they do in nature: they go from one flower to the other as they empty it of food," said Dr Ings.

The bees were introduced to a meadow containing well hidden (yellow) or highly visible (white) spiders.

"We thought it would be more difficult for the bees to learn to avoid camouflaged spiders," explained Dr Ings.

"However, the bees learned to avoid both types of spider equally well - and very quickly," he said.

Scientists noticed that bees became increasingly aware of the possible dangers lurking within certain flowers.

"When they come in to inspect flowers, they spend a little bit longer hovering in front of them when they know a camouflaged spider is present," said Dr Ings.

What's more, the bees did not forget which flowers posed the highest threats even one day later. In fact, the next day bees rejected all yellow flowers "“ even those without spiders.

The bees that detected the highly visible (white) spiders did not change their flight behavior.

"Surprisingly, our findings suggest that there is no apparent benefit to the spider in being camouflaged, at least in terms of prey capture rates. Spider camouflage didn't increase the chances of a bumblebee being captured, or reduce the rate at which the bees learnt to avoid predators. But our results did show that the bees which encountered camouflaged spiders were worse off in terms of reduced foraging efficiency," Dr Ings said.


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