Professor buzzes in with new findings
By KRISTIN YEMM
News Writer
After decades of research about bees, Notre Dame professor Harald Esch has made a discovery that will revolutionize his field of study.
In the May 31 issue of the scientific journal Nature, Esch, a professor emeritus in the University's department of biological sciences, and colleagues at the Australian National University in Canberra and the University of Wurzburg in Germany, reported that bees use subjective perceptions of how far they have flown to communicate to other bees the sites of food sources.
"Hives send out foragers, who come back and tell others where the feeding site is," said Esch. "The idea [of the research] is to find out how bees measure distance and how they transfer this information to other bees."
To accomplish this goal, Esch set up an experiment that forced forager bees to fly through a patterned, six-meter long tube to a feeding site and then back to the hive. Due to the complex designs on the inside of the tube, the bees that flew through it believed that they had traveled farther than the actual length of the tube.
"They then communicate to other bees that they've been 70 to 100 meters, when in fact it's only been six," Esch said.
This discrepancy results from the bees' use of optic flow — the environment that moves over the eyes — as a gauge of distance.
"That is the revolutionary part because many ideas were based on the idea that distance was the ground distance between the hive and the feeder, period," said Esch. "It's not, it's the experienced distance. For bees, flying across campus with all of its structures would translate to a longer distance on an open field."
These groundbreaking discoveries did not go unnoticed in the wider scientific community. After Nature published Esch's report, Science magazine bought an article about it.
"I got calls from radio stations and from the Discovery Channel, which is interested in making a documentary," said Esch.
While Esch conducted his research on bees' use of optic flow in Germany, he laid the groundwork for that experiment with work on the Notre Dame campus.
Researchers had assumed that bees measured distance based on the energy they used during flight. Esch disproved this theory by training bees to go from a hive outside his window at the Galvin Life Sciences Building to two sites on campus: one on the roof of the Hesburgh Library, the other on the ground the same distance away.
"Lifting their bodies to the top of the library required the bees to use more energy but did not affect the distance they reported," said Esch. This result gave Esch the idea that led to the research published in Nature.
Esch, who studied and the University of Munich and the University of Wurzburg before coming to Notre Dame in 1965, has been researching bees and bee communication since he was a doctorate student. After his discovery he spent the remainder of the summer in Wurzburg doing follow-up work on his optic flow research.
All News Stories for Monday, September 10, 2001
