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Corn Seed Producers Move to Avert Pesticide Resistance



   Corn Seed Producers Move to Avert Pesticide Resistance
   
   By Rick Weiss
   Washington Post Staff Writer
   Saturday, January 9, 1999; Page A04
   
   Responding to pressure from federal regulators, environmentalists and
   others, a coalition of the nation's major producers of genetically
   engineered corn seed said yesterday that they would require farmers to
   grow sizable plots of non-engineered, old-fashioned corn along with
   their new biotechnology varieties.
   
   The companies hope to allay increasing fears among scientists that
   some newly marketed varieties of gene-altered corn, which exude potent
   insecticides day in and day out, may be speeding the evolution of
   pesticide-resistant "super" insects.
   
   The announcement, which caught many farmers and others by surprise,
   was announced by an official of St. Louis-based Monsanto Co., the
   country's largest producer of gene-altered corn, at an Environmental
   Protection Agency meeting.
   
   EPA officials welcomed the coalition's plan with cautious optimism.
   "We have not had an opportunity to review the details of this
   agreement. However, we hope the final version will contain the
   elements EPA feels are required for the effective management of these
   products," Loretta Ucelli, EPA's associate administrator of public
   affairs, said in a statement.
   
   But the plan was immediately criticized as inadequate by some
   scientists and environmental activists, who noted that it calls for
   plots of non-engineered crops to be about half the size that several
   research studies have recently determined will be needed to prevent
   ecological disaster.
   
   "It's like having your doctor prescribe five pills a day to prevent a
   heart attack: It might help a little bit to take only one, but
   probably you're going to die," said Jane Rissler, senior staff
   scientist at the Union for Concerned Scientists in Washington. "These
   companies are responding to an overwhelming scientific consensus that
   they have to do something, but what they are proposing is far, far
   from what is needed."
   
   The more that insects are exposed to an insecticide, the more rapidly
   they develop resistance to that pesticide. That principle has become
   an issue as several companies have added a gene to corn that allows
   the plants to produce a steady supply of an insecticide known as bt, a
   bacterial toxin that kills European corn borers and related
   caterpillars that drill through stalks and damage ears.
   
   Growers who use the new varieties can avoid spraying bt during the
   season. But periodic spraying, though expensive and troublesome for
   growers, is in some respects more environmentally friendly. That's
   because bt breaks down quickly in sunlight, keeping exposures so brief
   that insects hardly have the opportunity to evolve strategies for
   becoming resistant to the chemical.
   
   Under constant chemical pressure from bt-exuding plants, insects have
   greater opportunity to evolve ways of being unfazed by bt.
   
   Field studies and computer modeling experiments have confirmed that
   there is a solution to the problem: Grow plots of normal corn near the
   bt plots, and don't spray those "refuges" with any bt. Without the
   pressure to develop bt resistance, insects on refuge plots tend to
   remain susceptible to the pesticide. And when those insects mate with
   their neighbors in nearby biotech plots, their susceptibility genes
   will dilute any emerging resistance in their mates.
   
   But how big do these refuges have to be? Several recent studies, which
   have been compiled into a document that EPA now relies heavily upon,
   have concluded that a refuge kept completely free of pesticides must
   be 20 percent to 30 percent the size of the engineered plot. They note
   that a refuge should be about 40 percent the size of the biotech plot
   if pesticides are to be used, since spraying can increase the odds of
   bt resistance developing.
   
   The new plan, however, calls for only 20 percent refuges, even when
   sprays are to be used, said Monsanto spokesman Dan Holman. Moreover,
   the plan offers no details about whether the refuges must be planted
   alongside the biotech plots, or can be some distance away, where
   studies suggest they would be less effective.
   
   "I think it's important that they've come up with something, even a
   compromise," said Fred Gould, an entomologist and bt expert at North
   Carolina State University in Raleigh. "But the bottom line is, 20
   percent without spraying is as low as you'd want to go."
   
   Indeed, the EPA has recently been requiring refuges about twice as big
   as what yesterday's plan proposes for newly registered varieties of bt
   corn. But previously approved varieties, including those made by the
   companies that came up with the plan, were registered by the EPA
   before the agency started insisting on refuges. That means any such
   system is voluntary for them until those registrations start to expire
   in 2002, even though they account for most of the 15 million acres of
   engineered corn now planted in this country.
   
   Holman said the coalition would release more details later, including
   how it intends to enforce the use of the refuge system among farmers.
   
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