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Gene is shown to guide social lives of honeybees

March 10, 2007|Robert Lee Hotz | Times Staff Writer

As the epitome of sociability, the honeybee is a living engine of selfless domesticity, caretaking colonies of kin that have fascinated generations of behaviorists.

Like any employee climbing the corporate ladder, honeybee workers go through changes in behavior with each new assignment in the hive, transforming from housebound nest nurses into field explorers that may travel more than 550 miles in a lifetime in search of pollen and nectar.

Yet much of this complicated social life is coordinated by the activity of a single gene, researchers at Arizona State University in Tempe and UC Davis reported this week in PLoS Biology, published by the Public Library of Science.

The new finding demonstrates how powerfully biology can orchestrate complex social behavior, the researchers said.

"We showed that this one protein made by this gene controls several very important traits for worker behavior, including the division of labor," said senior author Gro Amdam of Arizona State, who studies honeybees to understand the evolution of behavior.

The gene makes a protein called vitellogenin, a reproductive biochemical crucial for the formation of yolks in many egg-laying insects. By using gene-silencing techniques, the researchers created bees that expressed higher or lower levels of the protein.

The level of vitellogenin, the researchers concluded, controlled when worker bees started foraging. (All workers are female.) It also affected whether they preferred seeking pollen or nectar for the hive. Higher levels of the protein early in the bee's life favored pollen, and lower levels favored nectar, Amdam said. The protein levels also affected life span. The higher the level, the longer the worker bees lived.

The research reinforces the idea that the evolution of community is founded on the basic molecular biology of reproduction, with those genes and proteins being used as building blocks to assemble ever more complex behavior.

"They are affecting the sensory system of the animal in a new way, from which emerges social behavior," said Robert Page, director of Arizona State's School of Life Sciences.

"We can look into social behavior that originated 65 million years ago and see the footprints of evolution."

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