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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