|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Inside JEB |
BEE'S KNEE TREMBLING TALES
kathryn{at}biologists.com
|
Although a returning forager bee looks drunk on nectar as she trembles on the honeycomb, Corrina Thom explains that the ungainly dance is far from neurotic; it's part of the complex communication system that keeps the hive running smoothly. But what provokes the bees' staggering movements wasn't quite clear. Were they trembling to catch the attention of receiver bees to help them unload their nectar cargo, or were they reporting on conditions at a profitable food source? To find out what set the bees trembling, Thom lured them to a spacious feeder, and suddenly shrank it to a fraction of the original size to see how the bees reacted. Timing how the laden bees behaved upon their return to the hive, Thom realised that instead of calling for help from receiver bees, the trembling foragers seemed to be reporting the overcrowded conditions at the feeder (p. 2111).
During their brief lives, a honeybee's role alters as it ages. After serving the hive as a cleaner and attendant to the Queen, a middle aged bee becomes a `nectar receiver', aiding returning foragers, before finally taking to the wing and foraging. But for the hive to thrive, foragers and receivers must communicate, to ensure that they work together efficiently and minimise delays. So a returning forager that's struck lucky dances, waggling their bodies, to direct other foragers to rich supplies of nectar. But what message are trembling bees communicating, and who is their message aimed at? Thom knew that overcrowding at the feeder provoked returning foragers to tremble. Were the bees commenting on conditions at the feeder, or signalling for back-up from the receivers?
Working with a team of student helpers, Thom began testing the returning insects' reactions to a congested source of nectar. First she trained foragers to feed at an artificial nectar source by slowly moving the feeder away from the hive. `If they're in a good mood they'll follow' says Thom, `but some colonies find other sources, such as flowers'; it can take days to train them. But once the hive was reliably returning to feed, Thom was ready to monitor how the bees responded to overcrowding. She replaced the spacious tray of nectar with a smaller, more congested feeder, and watched how the bees reacted.
Back at the hive, Thom timed how long the foragers waited for a receiver bee to appear, after the forager had returned from the cramped feeder. She was surprised that the bees waited no longer than if they had filled up at the spacious feeder; so overcrowding hadn't caused a backlog and delays for the returning foragers. But were waiting bees trembling to attract more receivers to help them unload? Thom timed how long it took foragers to begin performing, and found that some of the insects began trembling at the same time that other bees waggled, and most surprisingly, it didn't seem to matter whether receivers were even there to watch the performance. The ungainly dance didn't seem to be aimed at the receivers at all!
Thom believes that the foragers weren't trembling to recruit more receiver bees, she thinks that the message was aimed at other forager bees, adding extra information about the feeder's cramped conditions to the waggle dance's directions.
References
Thom, C. (2003). The tremble dance of honey
bees can be caused by hive-external foraging experience. J. Exp.
Biol. 206,2111
-2116.
Related articles in JEB:
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||
