Science Article

IT SMELLS, it buzzes, it even dances like a honeybee. In a field in Germany, RoboBee is making its first attempts at speaking to the insects in their own language.

Bees are famous for communicating using the waggle dance - walking forward while rapidly vibrating their rear. In the 1940s, biologist Karl von Frisch realised that the length and angle of the dance correlated with the distance and direction of the food source the bee had just visited. Since then, most apiologists have held that dancers tell their fellows where to find food.

Now Tim Landgraf of the Free University of Berlin in Germany and colleagues have programmed their foam RoboBee, to mimic the dance. RoboBee is stuck to the end of a rod attached to a computer, which determines its "dance" moves. The rod is also connected to a belt which makes it vibrate. Like a real bee, it can spin, buzz its wings, carry scents and droplets of sugar water, and give off heat.

To program RoboBee, Landgraf took high-speed video of 108 real waggle dances, and put the footage through software that analysed the dances in detail (PLoS One, DOI: 10.1371/journal.pone.0021354). The outcome is "the most detailed description so far of the waggle dance", says Christoph Grüter of the University of Sussex in Brighton, UK, who was not involved in the study.

What do real bees think of RoboBee's skills? In a field outside Berlin, Landgraf trained groups of honeybees to use a feeder, which he then closed. The bees stopped foraging and stayed in their hives. There they met RoboBee, which had been programmed with Landgraf's best guess at a waggle dance pointing to another feeder, which the bees had never visited.

The bees responded by leaving the hive, but returned to their old feeders. For now, it looks like RoboBee persuaded them to forage, but failed to communicate where to go. The team is confident RoboBee didn't just scare away the foragers, as honeybees respond to intruders by stinging, not fleeing.

Bees don't always pay attention to the waggle dance, says Grüter. He recently showed that bees become more responsive to other's waggle dances if their private food sources have dried up (Animal Behaviour, DOI: 10.1016/j.anbehav.2011.01.014). This suggests bee communication is even more sophisticated than von Frisch thought: the bees' responses depend on the circumstances.

Lars Chittka of Queen Mary, University of London says previous attempts to make waggle-dancing robots have not panned out, but he is keen to see how RoboBee's more sophisticated dancing fares. Its Achilles heel, though, may be a lack of legs: some studies suggest there is a tap-dance element to the dance.

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