Imagine a driver asked to keep track of the number of buildings, signs, and lampposts whizzing by. Now ask that driver to tell a friend how far to go based on all those landmarks. That's exactly what honeybees do by dancing certain steps when they return to the hive. Now a new study shows that if the foragers get fooled, they will pass on the faulty directions to the rest of the hive--further evidence that eyesight is the apian odometer.
Over the past several years, experiments have suggested that honeybees know how far they've gone by how much they've seen--and not, as many had thought, by the amount of energy expended on the trip. In a key experiment published in 2000, Mandyam Srinivasan and Shawu Zhang, neurobiologists at Australian National University in Canberra, Jürgen Tautz of the University of Würzburg in Germany, and their colleagues tested this idea by training bees to fly down tunnels with different patterns painted inside. They found that the bee danced longer than it should have after flying through a semicheckered tunnel that gave the bee the sense of moving past many, many objects. If the tunnel was lined with horizontal stripes, which had no vertical boundaries to signify an object being passed, the bee's dance was too short.
To see whether other bees would follow these bad directions, Srinivasan, Zhang, and Ta1tz teamed up with neurobiologist Harald Esch of the University of Notre Dame, Indiana. They first set up a tunnel lined with a complex pattern, then trained bees leaving their hive to fly through the tunnel to get to a feeder on the other side. They videotaped the bee's dance when it returned and calculated the distance communicated. The bee danced a if it had traveled 72 meters instead of 11, the true distance. The researchers then stationed themselves 35, 70, and 140 meters away from the hive for 2.5 hours and counted how often bees from the hive flew up to them in search of food. About three-quarters of the 220 bees approached the 70-meter spot looking for nectar--the distance communicated in the dance--while the remaining quarter were seen either closer or farther away.
Based on these results, "there is now no question that the way honeybees communicate distance depends on what they see," says Mark Frye, a neurobiologist at the University of California, Berkeley. The work, reported in the 31 May issue of Nature, is "another in a series of very cleverly designed experiments," he says.