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Daily News Archive
From August 7, 2001

Researchers Discover Clues to Pesticide Resistance

Genetic mechanisms used by the tobacco budworm moth and a type of roundworm to elude the toxic effects of the most widely used biologically produced pesticide were pinpointed by two separate research teams, according to a Reuters article. The discovery could inspire ways to keep bugs in check without resorting to synthetic chemicals.

Bt, Bacillus thuringiensis, is a naturally occurring biological pesticide widely used by organic farmers and a least-toxic alternative to chemical pesticides. It acts by inflicting intestinal damage on crop pests. Insects and worms adapt to Bt, developing resistance, as they do with man-made chemical pesticides and render it ineffective.

"By actually understanding how resistance takes place, we can develop strategies to combat it," said Raffi Aroian, a biologist at the University of California at San Diego who led one of the research teams. "But the first step toward that is understanding at the molecular level how this happens."

Aroian's team studied mutant genes discovered in the roundworm Caenorhabditis elegans that confer resistance to a particular Bt toxin, cloned one of the five mutant genes, and compared differences in the proteins produced by the mutant gene and the corresponding normal gene. The comparison showed that the roundworms' Bt toxin resistance stemmed from the loss of an enzyme that adds carbohydrates to proteins and fats. Researchers from Clemson University in South Carolina, North Carolina State University and the University of Melbourne in Australia also identified a gene in the tobacco budworm moth that confers high levels of Bt resistance in the moth.

"This is a first step to understanding the development of Bt resistance by insect pests," said Clemson biologist Linda Gahan, who led the study. "This discovery will open the door for other researchers and monitoring governmental agencies to assess resistance mechanisms and management strategies in insect pests."

To view the full article, see http://www.planetark.org/dailynewsstory.cfm?newsid=11902&newsdate=06-Aug-2001