
New Pheromone Creates Buzz About the Clout of Older Bees
Midnite Bee-Beekeeper's: New Pheromone Creates Buzz About the Clout of Older Bees
ARTICLES
New Pheromone Creates Buzz About the Clout of Older Bees
A recent discovery unveils the chemical secret that gives old bees the authority
to keep young bees home babysitting instead of going out on the town. A hard-to-detect
pheromone explains a phenomenon Michigan State University entomologist Zachary
Huang published 12 years ago that somehow older forager bees exert influence
over the younger nurse bees in a hive, keeping them grounded until they are
more mature, and thus more ready to handle the demands of buzzing about.
The work that identifies the chemical, Regulation of Behavioral Maturation
in Honey Bees by a New Primer Pheromone is publishing in Proceedings of the
National Academy of Science Biological Sciences, Population Biology, Early Edition
the week of Nov. 29.
If the older ones dont keep them in check, the young ones can mature too
quickly, Huang said. Its kind of the same thing as with people, you need
the elders to check on the young, even if the young are physically able to go
out on their own, its not the best situation for anybody and now we know how
it works.
Huang worked with a team that spanned from the United States, France and Canada
to explain how the bees kept an exquisitely consistent balance between the ones
that go out to collect nectar and pollen and defend the hive, and those that
stay home and nurture the larvae.
Huang had documented that this balance is controlled by the elder bees, those
that typically spend the final one to three weeks of their five-week lifespan
out in the field. Experiments showed that if a significant number of forager
bees didnt come home, the young nurse bees would mature ahead of schedule and
head out to become foragers themselves.
If the older bees were kept inside more than usual as in an extended rain
shower fewer young bees would mature, but instead stick to brood care. But
the question was always, why? Pheromones are a chemical signal emitted by animals,
insects and humans.
Some, called releaser pheromones, are like a quick conversation that changes
behavior, such as those that inspire sexual attraction. Since releasers change
behaviors immediately, they historically have been easier to identify. Hundreds
of releaser pheromones have been chemically identified, whereas only four (including
this new one) have been identified as primer pheromones.
Primer pheromones are more difficult to work with because they imparts behavioral
changes in a much longer time scale, taking days or sometimes weeks to see an
effect. Huang and his associates spent years futilely searching for a primer
pheromone.
After many dead ends, the group came upon a crucial difference between forager
bees and nurse bees:Forager bees carry a mother load of a chemical called ethyl
oleate in the abdominal reservoir in which they store nectar. That, Huang said,
led them to identify ethyl oleate as another kind of pheromone called primer
pheromone.
Forager bees load up on ethyl oleate when theyre buzzing about gathering
food, but dont digest it. The forager bees feed the chemical to the worker
bees, and the ethyl oleate keeps them in a teenage state, sort of like being
grounded to watch the younger siblings.
As the old bees die off, the chemical no longer is fed to nurse bees. Eliminate
ethyl oleate and the bees mature into foragers. This provides clear insight
into how a bee colony works, said Gene Robinson, G. William Arends professor
of integrative biology and director of the neuroscience program at the University
of Illinois at Champaign-Urbana. Whats most impressive about a honey bee colony
is it is able to respond to changing conditions and alter its division of labor.
When you think of that type of flexibility and adaptability, you immediately
think, whos in charge? People from many scientific and engineering endeavors
are fascinated by localized decentralized decision making. Huang said the system
makes sense for the health of the hive.
Young bees those in the first two to three weeks of life are biologically
better suited for brood care, thanks to some boosted blood protein. Bees forced
out too early arent great navigators, and since foraging is dangerous, they
risk dying before their time. Our idea has never been disproved, but the lack
of mechanism drove me crazy, said Huang. Now we know the specific chemical
that controls the behavior of honey bees for the good of the whole population.
In addition to Huang and Robinson, the papers authors are Isabelle Leoncini,
Yves Le Conte, Didier Crauser, Guy Costagliola and Jean-Marc Bcard, of the
National Institute of Agricultural Research in Avignon, France; Mianwei Wang,
Erika Plettner and Keith Slessor of Simon Fraser University in Burnaby, Canada;
and Amy Toth of the University of Illinois at Urbana-Champaign. The research
was funded by the National Institute of Health. Huangs research also is supported
by the Michigan Agricultural Experiment Station