January 14, 2009

Abrahamson works with students Nate and Matt Keller in Bucknell's greenhouse

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By Julia Ferrante

LEWISBURG, Pa. – Each year in early December, when temperatures start dipping into the 20s, and frost almost permanently covers the ground, Warren Abrahamson sets out on a collecting trip.

Unlike many biologists, who collect the insects they study during the balmy months of spring, the Bucknell University biology professor has chosen creatures that make themselves known during the coldest months in the northeast. Gall flies, gall beetles and gall wasps, so named for the bubble-like "galls" they form on the stems of goldenrod, seek out this plant as a protective home for their eggs in one of the more unusual relationships in nature.

Abrahamson and his collaborators collect the galls in winter, when the insects are in their larval stage, so they may observe them as they emerge as adult insects in the spring. "The larval offspring of insects feed on the plants, stimulating them to make tumor-like growths called galls," Abrahamson said. "It's an insect that lives inside and takes resources from a plant."

Abrahamson has been studying the gall fly and its interaction with goldenrod for 36 years and received more than $2 million from the National Science Foundation and other sources for his laboratory at Bucknell. He will be recognized as an American Association for the Advancement of Science (AAAS) Fellow next month for his extensive research in this area as well as his work to promote prescribed burns in central Florida to control wildfires and to preserve fragile land in central Pennsylvania.

Teaching science in the real world
The nonprofit organization, which is dedicated to the advancement of science worldwide, in November selected 486 fellows, recognizing them for their outstanding research and teaching. Abrahamson was chosen for "distinguished contributions to the field of biology, particularly for discoveries about evolutionary ecology and plant-insect interactions," according to organization officials. The AAAS Fellows will be honored at the organization's annual meeting Feb. 14 in Chicago.

Abrahamson, who became the first and only David Burpee Professor of Biology at Bucknell in 1983, also is the first professor at the University to be named an AAAS Fellow. He credited Bucknell with supporting his research through the endowment and with giving students the opportunity to assist him. 

"Bucknell made a huge investment in me," Abrahamson said. "To me, this is really neat, because I think it crystallizes the significance of having endowed chairs and of supporting young faculty. We have successfully competed with higher level research institutions for grants. The fact that this has been done with students is significant."

Abrahamson has published 142 papers and two books. Nearly a third of the papers are co-authored by post-doctoral fellows, masters-level and undergraduate students, giving them exposure to "science in the real world," he said. Abrahamson co-authored a book, Evolutionary Ecology Across Three Tropic Levels: Goldenrods, Gallmakers & Natural Enemies, (Princeton University Press, 1997) with Arthur E. Weis, who was a Burpee and NSF post-doctoral fellow at Bucknell for three years.

Studying the gall fly and its interaction with its host plant, the goldenrod, can help biologists understand how plants and animals interact and adapt to natural predators. Such information could help farmers protect crops and assist ecologists in removing invasive plants.

Ducking predators
Abrahamson and his collaborators have discovered several protective mechanisms or genetic mutations in goldenrod, including its practice of "ducking" or hanging its bud down, presumably to hide from the gall fly and prevent it from forming its gall. Abrahamson and a collaborator, Michael J. Wise, who also was a Burpee and NSF post-doctoral fellow at Bucknell, recently published a paper about the so-called "candy cane" goldenrod in Ecology magazine.

"The attack levels are significantly lower on stems that duck," Abrahamson said. "The fun part is we didn't know much about that when we got started 36 years ago. Goldenrod is a plant that is able to tolerate being eaten with varying impacts. One gall fly and ball gall reduce a goldenrod’s seed out by nearly 50 percent. Plants, herbivores and natural enemies of herbivores are unrelated but are evolving in response to one other. We are studying their interaction."

Abrahamson and his collaborators also have discovered that some goldenrod plants develop a higher tolerance to their predators. Others produce terpenes, an odor that is toxic to insects that feed on them.

"We are using a multitude of approaches, including genetics, behavior and ecology, to study how the interaction works and how the plant defends itself, how insects find plants and how natural enemies have evolved in respect to the gall fly," he said. "All of that helps us to understand evolutionary ecology of the interaction. We're looking at ecological interactions and how they evolve, how specialization occurs, how biodiversity is created on this earth. We mammals are a tiny part of the diversity, but insects and plants represent the vast majority of the biodiversity described on earth."

Land management
Also during his tenure at Bucknell, Abrahamson and his students studied how fire affects the interactions of plants and animals in central Florida and together published more than 40 papers on the subject. He and a colleague were largely responsible for bringing about prescribed burns in the Lake Wales ridge area of Florida as a way of controlling wildfires. During the 1970s, fire suppression was the key method, but that allowed thick brush to build up over the years, providing abundant fuel for rampant wildfires. 

Abrahamson also has been involved in the preservation of land in the Merrill W. Linn Land & Waterways Conservancy, the Montandon Marsh and Dale's Ridge hiking trail, providing scientific analysis about endangered vegetation and the ecosystem.

Contact: Division of Communications

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