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First published online November 14, 2008
Journal of Experimental Biology 211, i-a (2008)
Copyright © 2008 The Company of Biologists Limited
doi: 10.1242/jeb.026757
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Inside JEB |
BEES RELATE SUN MAP TO PANORAMA
kathryn{at}biologists.com
Knowing the sun's position is crucial for honeybee communication. Without this knowledge it is impossible for hive members to interpret their nest mate's famous waggle dance, where the angle that the dancing insects walk relative to vertical is the same angle that the foragers must fly relative to the sun's position to find nectar. But how do bees communicate when the sun is out of sight? According to William Towne from Kutztown University of Pennsylvania, the insects memorize the sun's position over the day, and they fall back on this memory when the weather is overcast. But for this memorized sun map to mean anything, the insects must have learned the sun's position relative to some aspect of their world that they can refer to. Towne explains that Fred Dyer first showed that bees orient their memory of the sun's position relative to their local landscape in the 1980s. Since then, most people had taken Dyer's results to mean that bees learn the sun's movements in relation to the entire landscape, until Tom Collett of Sussex University reminded Towne that there were other possibilities; such as the bees using a familiar flight path as their reference. Towne decided to retest the insects' sun maps, to see if he could tie the matter up (p. 3729).
First he had to be sure that the insects couldn't relate their sun map to any other cues, such as their flight path, so Towne and student Heather Moscrip set up a hive in a field next to a tree-lined corner. They placed a feeder adjacent to the hive so that the foragers' flight path was too short to provide a realistic reference frame for the insects' sun map. Then the duo waited for an overcast day while the bees set about learning their sun map. As soon as the clouds closed in, Towne and Moscrip picked up the hive and transported it to a field that looked identical to the first, but this time the corner was facing in the opposite direction; a mirror image. The sun was in a completely different position relative to the tree-lined corner, but the bees couldn't see it behind the clouds. After moving the feeder away from the hive until it was far enough for the insects to start waggle dancing, Towne began recording their waggle dances.
Analyzing the dance directions back in the lab, Towne quickly realised that the bees had got the feeder's position completely wrong. Thinking that they were still at the first site, the bees were dancing as if the sun was over the original field. The insects were remembering the sun's position relative to the first tree-lined corner, and not relating their dances to the sun's true position over the mirror image field. And when Towne and Moscrip repeated the experiment while moving the feeder along different compass bearings, the bees danced again as if they were in the original field. They were definitely referring their sun map to the local landscape panorama, and not to a more limited reference, such as a familiar flight path
Towne admits that he is delighted to have confirmed Dyer's original hypothesis of more than 20 years ago. Meanwhile the bees remain unphased; they knew where the sun was all along.
References
Towne, W. F. and Moscrip, H. (2008). The
connection between landscapes and the solar ephemeris in honeybees.
J. Exp. Biol. 211,3729
-3736.
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