While at Davis, Amdam met professor Robert Page, who was breeding honeybee strains distinguished by whether the worker bees were more likely to collect pollen or nectar. Besides their differing collecting habits, the strains possessed various other physiological and sense-related traits, but researchers did not understand how these suites of traits emerged.

In 2004, Page came to ASU as director of the School of Life Sciences. Amdam followed him to ASU in 2005. Together, Amdam and Page theorized that foraging behavior could have something to do with reproductive differences in the worker bees of the two strains.

"Worker bees--which are exclusively female--are considered to be 'facultatively sterile,' meaning that when a queen is present, they do not lay eggs," Amdam said. "However, if the queen is removed, some of these females develop their ovaries and lay eggs."

Foraging for pollen is a maternal reproductive behavior in solitary species of bees, while non-reproductive solitary bees feed mostly on nectar. Amdam wondered if similar relationships were present in the highly social worker bees. She noticed that a certain protein--called vitellogenin--associated with a bee's reproductive status was more common in the strain of bees that preferred to forage for pollen (identified by Amdam as the high pollen-hoarding strain). Low levels of this protein were associated with bees that foraged mostly for nectar (the low pollen-hoarding strain).

Using that as a foundation, Amdam and Page hypothesized that that the high pollen-hoarding strain of social worker bees, although non-reproductive, represented the maternal, reproductive state of its solitary ancestors, who presumably foraged for pollen when reproductively active. By contrast, the low pollen-hoarding strain of worker bees represented the state of those same ancestors when they were not reprodu
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Contact: Skip Derra
skip.derra@asu.edu
480-965-4823
Arizona State University
4-Jan-2006