Sunday, 8 July 2012

We've found genetic shortcuts to better crops, but there's a risk

By Tom Beal, Arizona Daily Star
Development of a better breed of cotton was a long, slow process for scientists with the U.S. Department of Agriculture and the University of Arizona, as detailed in today's "100 Days of Science" feature about Pima cotton in the Arizona Daily Star.
More recent development of a bug-resistant cotton was speeded by the ability to find and modify the genetic makeup of plants, in this case to insert a naturally-occuring pesticide into the strain of upland cotton now most commonly grown in Arizona.
It led to the eradication of the pink bollworm in Arizona, but it took more than genetic manipulation to do that.
I wrote about the campaign in November 2010:
The (pink bollworm) moth was the target of a novel approach to pest eradication, which paired seed that had been genetically altered to produce a natural toxin called Bt, or Bacillus thuringiensis, with the release of sterile moths to guard against growth of an insect population resistant to the engineered seed.
That four-year assault reduced the pink bollworm population to essentially zero, says a research paper published this month in the journal Nature Biotechnology.
It's good news for farmers and beneficial to society at large, said University of Arizona entomologist Bruce Tabashnik. Growers have been able to virtually eliminate pesticide spraying on cotton crops in Arizona, he said.
The efficacy of Bt seed is nothing new, said Tabashnik, an author of the paper.
Tabashnik also sounded a note of caution.
Worldwide, nearly 500 million acres are planted in Bt cotton and corn. It has proven effective in warding off pests, but some of Tabashnik's studies have raised concerns about the development of resistance by the insects it is supposed to kill.
No pesticide is 100 percent effective, and resistant insects can mate with each other to create a pest population that isn't killed by the Bt toxins.

More recently, Tabashnik and other scientists have raised concerns about Bt corn, citing reports that the Western corn rootworm has developed resistance to Bt.
The Associated Press reported in January:
If rootworms do become resistant to Bt corn, it "could become the most economically damaging example of insect resistance to a genetically modified crop in the U.S.," said Bruce Tabashnik, an entomologist at the University of Arizona. "It's a pest of great economic significance - a billion-dollar pest."
Original Article here

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