GIVEN a choice between two different flower beds, how can honeybees hunting for nectar be sure they鈥檝e chosen the best patch? A new computer model may provide the answer, as well as insights into the workings of a 鈥渉ive mind鈥� that could be used to guide swarms of robots.
Within a bee colony, two different types of bee handle nectar: foragers go out to collect it from flowers, and receivers unload it from the foragers and store it in honeycomb. The forager then leaves the hive to hunt for more.
Different foragers from a single hive visit more than one separate source of nectar 鈥� so how can an individual forager be sure it鈥檚 going to the best one? While bees can communicate with each other using complicated waggle dances, 鈥渢hese only show where a source is 鈥� not how good it is鈥�, says Ronald Thenius of the University of Graz in Austria.
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Thenius believes the foragers may be picking up clues about the quality of sources from their interactions with receivers. If some foragers have found a bountiful new source, the receivers have more work to do, so average unloading times across all foragers increase. This delay might suggest the existence of a better nectar source than the one a given forager has been visiting. Similarly, receivers are sometimes already half-full from another bee鈥檚 nectar when a new forager arrives, so a forager needs to unload to more than one receiver. If this occurs more frequently, it may also suggest that a richer nectar source has been found.
To test this hypothesis, Thenius鈥檚 team built a computer simulation of a hive containing 5000 independent virtual bees. Each forager started out visiting one of two different flower patches, but would switch destinations if it had to wait too long to be unloaded or was being serviced by too many receivers.
The results, presented at the Artificial Life IX conference in Winchester, UK, last week were promising. The virtual bees moved to the better nectar source at similar rates and in similar proportions to those observed for real bees. 鈥淚t鈥檚 like a new pub has opened with cheap beer: everyone鈥檚 trying to find it,鈥� says Thenius. 鈥淭he hive can gain up to 20 per cent more nectar this way.鈥�
The idea that bees glean information from the number of unloadings is new, says Francis Rietnieks, a bee expert at the University of Sussex in the UK, but it needs to be verified in the field. 鈥淚f their simulation suggests a novel means of information transfer, ideally they will devise a suitable experiment that can test the model鈥檚 predictions,鈥� he says.
Thenius says the work could prove useful in controlling swarms of tiny robots for sensing and surveillance applications. Such robots could use a similar method of incidental communication to arrive at group decisions that could maximise resources. The system would be robust because it would rely on very simple observations, he notes.
