July 31, 2009

The Honeybee Waggle Warning

Scientists have discovered that honeybees warn each other of dangerous flowers that might be harboring predators in wait.

This warning system was found by planting dead bees on flowers and observing how other bees respond to the sign of danger.

The bees did not just avoid the flowers; they also went on to communicate the threat to the hive through their famous waggle dance.

The discovery is published in the journal Animal Behavior.

Honeybees provide the most fascinating example of insect behavior.

Like other social insects, honey bees live in societies where survival is contingent upon mutual cooperation and division of labor.

Though it might seem silly, the honeybee waggle dance is quite a sophisticated method of communicating.

Over 40 years ago, biologists found meaning in the complex dance performed when foraging bees return to the hive.

Upon their return with pollen and nectar, the worker bee performs a demonstrative dance on the comb. If the source is relatively distant from the hive, the dance takes the form of a figure-eight.

The angle of the straight run, or "waggle," from vertical is equal to the angle from the hive between the sun and the food source. If the flowers are 45 degrees to the right of the sun, the dance will be oriented 45 degrees to right of vertical. The distance of the straight waggle run is also proportional to the distance from the hive to the source.

The bees repeat their expressive moves several times.

Now, scientists Kevin Abbott and Reuven Dukas of McMaster University in Hamilton, Ontario, Canada have found that the waggle dance packs far more information for others in the colony than just where to find good food.

The team trained honeybees to visit two artificial flowers that had the same concentration of food, leaving one of the flowers untouched as a "safe" place for the bees.

They other flower had two dead bees planted on them in plain sight of the arriving bees, but not to where it could hinder their foraging.

The scientists then recorded whether and how the bees engaged in the waggle dance upon their return to other members of the hive.

Bees that were returning from safe flowers performed an average of 20 to 30 more waggle dances than those who had visited the more threatening flowers.

This information suggests that there is recognition that some flowers present a higher level of risk for being killed or eaten by predators, such as crab spiders or other spider species that commonly hide and launch a surprise attack on visiting bees.

The most impressive part of the entire experiment is that they factor this information into what they communicate to their fellow hive-mates in order to protect them from impending danger.


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