Michael Schirber
Date: 27 May 2005 Time: 06:29 AM ET
Scientists have long marveled over the dance of the bee. A little jitterbug seems to reveal to coworkers the location of a distant meal. But how and whether the dance really works has remained controversial.
A new study
confirms the dancing is a form of communication.
Bees outfitted
with tracking devices responded to the wiggling of one of their fellow
foragers, who had just returned to the hive from some newfound bee vittles.?
The dance, which is performed on one of the honeycomb walls, is not an exact
language, but it gets the job done.
The central
element of the choreography is a shimmy, or waggle, along a straight line. For
emphasis, the bee repeats this move several times by circling around in a
figure-8 pattern. The angle that the shimmy makes in relation to an imaginary
vertical line is the direction to the food source with respect to the sun.
For example, a
waggle dance pointing towards 3 o'clock is bee talk for: "Hey, there's
food 90 degrees to the right of the Sun."
A solar
compass
This solar
compass in honeybees was originally observed in the 1960s by the Nobel Prize
winner Karl von Frisch. Later, it was noticed that the number of waggles in one
figure-8 corresponds to the distance to the meal.
These remarkable
relations have been supported by other experiments, including one in which a
mechanical bee danced for the hive and the real bees responded. But there have
remained doubts as to whether the other bees could actually decipher the
dancer's message.
"The dance
isn't a trivial demonstration, but an abstract code," says J. R. Riley of
Rothamsted Research, UK.
One complication
is that hives are dark and cramped, so other bees - called "recruits"
- do not see the full pattern as human observers do. Furthermore, recruits tend
to take longer to find the food than would be expected.
"Flying
directly, it should only take them a minute or so, but they often don't find
the feeder for 5 or 10 minutes," Riley told LiveScience.
And sometimes
they never find it. For this reason, some scientists have speculated that the
waggle dance merely excites other bees, which then fly out of the hive
searching for a scent trail left by the returning bee.
Making a
beeline
To solve the
controversy, Riley and colleagues strapped radar transponders to 19 dance
spectators. The flight paths show that the bees make a beeline to the vicinity
of the food source, but then fly around in a looping search pattern. Only two
of the radar-tracked recruits actually found the food.
Apparently, the
dance gives incomplete instructions, and the bees rely on odors, colors, and
other clues to hone in on the final location. Still, the dance gets them pretty
close. On average, the recruits came within 18 feet of the food before
switching to search mode.
"This was
in spite of considerable wind drift which would have pushed them off course if
they had not compensated," Riley said.
To further
investigate bee-havior, the team moved some recruits several hundred yards away
from the hive and then released them. The displaced bees flew the prescribed
direction and distance - where they found nothing because their starting point
was off.
This is the most
definitive proof that recruited bees read the waggle dance, since the
transplanted bees chose the foretold trajectory without any of the possible
other cues - odors (bees have a strong sense of smell), landscape, other bees -
that might exist along the true hive-to-feeder route.
The work was
described earlier this month in the journal Nature.
Source of Article: http://www.livescience.com
Post a Comment