Waggle Dance Leads Bees to Nectar

BBC

Radar has helped resolve a long-standing controversy about the purpose of a strange dance performed by bees, Nature magazine reports.
The famous "waggle" dance contains information about the whereabouts of nectar, just as was originally proposed in the 1960s, scientists now claim.

The theory met with scepticism, partly because people did not believe bees could decode such a complex message.

But now radar tracking has proved they do follow waggle dance instructions.

Mysterious dance

Bee-keepers have long puzzled over the mysterious little performance, which bees stage for their hive-mates when they return home from a foraging mission.

On entering the hive after gathering nectar, a bee will run around in a tight figure of eight dance, waggling its abdomen as it does so. All the other bees gather around, apparently scrutinising the ceremonial manoeuvre.

"It is, at first sight, a rather confusing and not very organised movement," said co-author Joe Riley of Rothamsted Research, UK. "But if you watch it carefully you can recognise the very distinct and organised pattern."
It wasn't until the 1960s that a plausible explanation for the dance was proposed, by Nobel Prize winning zoologist Karl von Frisch.

He suggested that the bees are delivering a complex set of instructions about how to find a rich nectar source.

The direction the bees point while performing the dance, Professor von Frisch speculated, indicates the direction of the food source in relation to the sun; while the intensity of the waggles indicates how far away it is.

The theory was tested by setting up artificial feeding stations and monitoring whether the bees' dances did describe where the food was, according to von Frisch's rules. They did indeed, but some scientists did not believe observing bees could actually follow the instructions.

"What was questioned was whether bees could decode the dance because it seemed like a very difficult thing for them to do," Professor Riley told the BBC.

Indeed, it seemed they were not managing to decode the dance because they took much longer to reach the food source than would be expected if they were following the instructions.

This led some scientists to suggest that the waggle dance was in fact performing a much simpler task.

Professor Riley explained: "Other hypotheses were raised that suggested the dance was to attract the attention of bees in the hive, cause them to cluster around the dancing bee, and pick up the odour of the source visited.

"And then these bees would fly out of the hive and home in on the food source [using smell]."

Radar transponders

However the new tests have shown Professor von Frisch was right all along.


Professor Riley and his colleagues fixed radar transponders to bees who had watched the waggle dance, to track their route to the food source.
They found they flew straight there. To double check, bee recruits were taken to release sites 250m away from the hive. These bees flew to where the feeding site should have been had they not been displaced, showing they were following the dance instructions accurately.

"This was very strong support from the von Frisch hypothesis because in this case there was no possibility the bees were following regular routes or any odours that the dancer might have left in the air," said Professor Riley.

Professor Riley's team also discovered a possible reason for why the bees took longer than expected to actually reach the food source. They found that, although the bees flew straight to the location of the food, they were slow to home in on it.

Professor Riley thinks this might be because of the artificial - and largely odourless - feeding stations used in experiments.

Under normal circumstances, he believes, the bees would use the waggle dance to get near a fine crop of flowers, before relying on smell to actually land on them. But in the sterile laboratory environment this was harder to do.

Professor Riley believes these experiments will end debate about the function of the waggle dance.

"I can't see that there is any other explanation other than the one offered by von Frisch that could explain the bees' clear ability to travel to a destination that they've never been to before," he said. "It is a pretty convincing case to me."