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17 April 2014 12:48 pm ,
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Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Arrested Development Keeps Bees on Task
30 November 2004 (All day)
Honey bees are famous for their highly structured societies in which each individual plays a well-defined role. But how do they reorganize their workforce in response to changing needs? A new study shows that workers regulate the number of foragers using pheromones that arrest development in young bees.
Worker honey bees begin their lives as cell-cleaners, then advance up the ranks to become nurses and then food storers, finally graduating to foraging and colony defense at 2 to 3 weeks. The transition to foraging is associated with hormonal and structural changes in the brain and increased expression of foraging genes (ScienceNOW, 10 October 2003 ), but what triggers these changes is not known. Scientists suspected that old bees hold back the development of young bees through some chemical means, as past experiments have shown that this happens only when they can touch each other.
Isabelle Leoncini, a graduate student at the University of Avignon, France, and Gene Robinson, an entomologist at the University of Illinois, Urbana-Champaign, set out to find the mystery substance. They and their colleagues found that levels of a fatty acid compound called ethyl oleate, a component of a brood pheromone that inhibits behavioral development, were about 30 times higher in the crops (honey stomachs) of foragers than in nurses. When young worker bees ate a mixture of ethyl oleate and sugar candy, they started foraging 2 or 3 days later than did controls, the researchers report online this week in the Proceedings of the National Academy of Sciences. That delay is substantial, says Robinson, given that the bees only live 5 to 6 weeks. He and his colleagues think the foragers likely pass the pheromone to younger workers while exchanging food.
The discovery suggests a nifty mechanism for negative feedback, says Francis Ratnieks, a behavioral ecologist at the University of Sheffield, U.K. The bees most likely to receive the pheromone from the foragers are the nectar receivers, who are the next in line to become foragers, Ratnieks explains. If foragers abound in the colony--when it's raining, for example--ethyl oleate levels in the hive will be high and the development of receivers into foragers will be delayed. With fewer foragers present, levels will drop and receivers will mature more quickly. In this way, the colony can regulate the division of labor to suit changing needs and environmental conditions without any centralized control, adds Robinson.