“The biological bases of the bee dance have actually been explored quite thoroughly through the works of Austrian behavior researcher Karl von Frisch,” Menzel says. Not long after World War II, von Frisch (1886–1982) discovered something that practically all schoolchildren still learn today in biology class: After returning to the hive, bees that have swarmed out of the hive use dance to tell other worker bees where they can find food, and whether the food offered is good. But although von Frisch received many awards, including a Nobel Prize in 1973 for his discoveries regarding this kind of communication among bees, there are still skeptics who believe the bee dance is just a flight of fancy. If von Frisch was right: How do bees receive signals in the dark interior of a beehive? And which ones are important?
Using a robot bee sounds far-fetched, but Menzel and Rojas have been friends and research colleagues for more than 18 years – and nothing seems impossible. Still, the project, started in 2007, was not exactly simple to choreograph. To fool the real bees, the scientists dug deep into their bag of tricks. Noises made by dancing bees come from a tiny speaker above the robot. The fluttering of the wings – transmitted from outside by rods – is triggered by a motor like the kind that makes a cell phone vibrate. Scents given off by dancing bees are blown into the hive from above.
The robot can even offer a food sample if other bees follow its dance – just like a real live bee. The robo-bee even has the same body temperature as a real one, since the researchers built a heating system into its body. An astrocompass was programmed for the robot’s dance. The main point of all these functions in terms of the experiments is that they can be turned on and off individually. Since 2011, the robot bee has been able to dance a description of the location of a food source that the scientists have set up several hundred meters away. Experiments got under way in the summer, in an area in Klein Lüben, Brandenburg. To perform their experiments, the researchers glued tiny numbers to the bodies of bees in the hive, set up a food source, coded the information about where it was located, and sent the robot bee into the hive to do its dance.
While the experiment was in progress, one researcher observed the hive, which had been lit with red light, which bees cannot see. Bees that followed the dance and swarmed out were identified by number, caught when exiting the hive, and equipped with a miniature antenna that does not hinder their flight. Outdoors, researchers used a special radar unit to continuously monitor the bees. Many of the bees instructed by the robot did in fact reach their destination.
Rojas and Menzel are pleased at these preliminary results. “We eliminated most of the disruptive factors,” Rojas says. “There are bees that follow the dance – although there are still many that notice that something is amiss.” To Menzel, the fact that the bees can reach a destination based on a location description communicated through the robot’s dance is “clear evidence that it works.” If the scientists can now manage to prove that bees do not look for flowers the way people have generally thought they do, instead following specific instructions encoded in the bee dance, as Karl von Frisch believed, it would be more than merely a scientific success for Menzel. He knew von Frisch, the father of bee research, personally.