The Cutting Edge: COMPUTING / TECHNOLOGY / INNOVATION : Bioengineered Pesticides Bad for Bugs; Are They OK for Planet?
Last summer, researchers at a New Jersey agricultural products company conducted field tests of a novel new type of genetically engineered pesticide. American Cyanamid scientists took a virus that commonly infects agricultural insect pests--autographa californica baculovirus--and added a gene from the North African scorpion that made the virus even deadlier against two especially troublesome bugs, the cabbage looper and the tobacco budworm.
The test is part of a broad effort underway among universities and agricultural products companies to use bioengineering to develop new types of pesticides. As evidence mounts that chemical pesticides can cause serious health problems--and as many agricultural pests develop resistance to the most common chemicals--genetic engineering is seen as the next great hope in pesticides.
“The promise of this technology is that it’s very specific for insect pests, and it has no effect on birds, fish or other nontarget-type organisms,” said Thomas Merriam, director of crop protection discovery at American Cyanamid. “So it’s a very safe technology from that perspective.”
But even as industry races to deploy several new types of bioengineered pest-control techniques, some scientists fear that the new products are being field-tested and commercialized before their effects are fully understood, possibly raising new, and even more serious, dangers for agriculture and the environment.
“I didn’t think enough work was done to evaluate the risk,” H. Alan Wood of the Boyce Thompson Institute for Plant Research at Cornell University said of the American Cyanamid tests in Georgia and Texas.
Wood, a noted virologist who has also tested bioengineered viruses--and whose own start-up company, AgriVirion, is a competitor of American Cyanamid--said the baculovirus tests, though approved by the Environmental Protection Agency, were done without sufficient containment safeguards, and that not enough data was gathered before the tests to know what effect the virus would have on beneficial insects.
“Their data indicated that the ability of the virus to infect the insect host had been altered,” Wood said. “So they now have an undocumented genetic change to the virus, and how many other undocumented genetic changes do they have? . . . It sets a very bad precedent.
“If you find a problem with chemicals, you just stop using it and it’s OK,” he said. “Biologicals have all this potential ecological impact far beyond those of any chemical pesticides.”
The Union of Concerned Scientists, a nonprofit scientific watchdog group, also objected to the American Cyanamid tests on the grounds that they were premature and unnecessarily risky. The group supported Wood’s recommendation to the EPA that the tests be delayed, but the regulatory body ruled that sufficient safeguards were in place.
Despite these concerns, a wide spectrum of scientists supports the new technology, and growers are anxiously awaiting the biopesticide products. American Cyanamid’s bioengineered baculovirus has been hailed by the U.S. Department of Agriculture as well as the National Wildlife Foundation because of its potential for helping to reduce--and perhaps one day eliminate--the use of toxic chemical pesticides.
Agricultural products companies are working on other biopesticide approaches as well. Although American Cyanamid technology is based on altering viruses that infect pests, others are developing genetically altered crops that can fend off pests through the production of insect-killing toxins.
The first of these new crop varieties, known as Bt crops, are engineered to produce an insect toxin taken from a naturally occurring soil bacterium called bacillus thuringiensis. Scientists have successfully spliced Bt toxin genes into a variety of crop plants, including cotton, potatoes and corn.
Mike Sund of San Diego-based Mycogen Corp., which is developing a Bt cotton variety, said, “If you rebuild the Bt gene sequence to more closely resemble a plant gene sequence, keeping intact the portion that encodes for the protein that is toxic to insects, you can trick the plant into thinking that it is a plant gene.” The plant then produces the protein toxin in its tissues, thus killing only those insects that bite into it.
Monsanto Co., a leader in agricultural bioengineering, gained federal approval last year to market a Bt potato aimed at combating the extremely troublesome Colorado potato beetle, as well as a Bt cotton variety engineered to kill the cotton bollworm, pink bollworm and tobacco budworm. Monsanto’s Bt potato and cotton products will be widely available commercially for the first time this year, and the company is also working to develop Bt corn varieties it expects to be marketing in a few years.
Robert Hollingworth, director of the Pesticide Research Center at Michigan State, said of the Bt technology: “So far, Bt biopesticides don’t look anything like as threatening as the toxicological problems that often go along with chemical pesticides. If the plant is producing these and they are relatively innocuous to human beings, you have many positive advantages in terms of human health, impact on the environment and impact on the normal parasites and predators that do a lot of insect control naturally.”
Still, not everyone is enthusiastic about Bt crops. In the case of food crops such as potatoes, the Union of Concerned Scientists have said that more work should be done to make certain the toxins introduced into the bioengineered crops do not affect human health. The scientists group has also cautioned that insects could quickly develop resistance to Bt crops, just as they have to chemical insecticides.
“With Bt, I think there will be a short-term reduction in the use of chemical insecticides, but in the long term we will not be any better off,” said Jane Rissler, a senior staff scientist at the Union of Concerned Scientists.
“Insects will develop resistance. . . . This technology is very much like chemical pesticide technology in that it brings you the short-term solutions to problems but it doesn’t solve the long-term problems of pest control or yield problems in agriculture.”
Monsanto has attempted to address such concerns with a resistance management program that is included as part of its licensing agreements with growers. The company is requiring that growers attend a three-hour training class on how to use the new technology and that they adhere to a resistance management strategy.
Farmers using Monsanto’s Bt cotton will have the option of setting aside either 25 acres of non-Bt cotton that would also be left untreated with commonly used Bt spray or four acres of cotton untreated with any insecticide for every hundred acres of Bt cotton they plant. The idea is to create refuges to preserve insects that are not Bt-resistant.
Critics say this isn’t enough and that companies are rushing Bt crops onto the market before there has been time to develop proven, dependable resistance management strategies.
“One of the problems is that there is very little experimental basis for this, and to be sure that the ‘resistance management’ strategy is likely to work, you really have to take it out in the field and try it on an experimental basis, which is expensive and time-consuming,” Hollingworth said. The companies “really feel that they have to go for a return on their investment more quickly than that. These are business decisions.”
Scientists who have voiced concerns about premature testing and marketing of bioengineered pesticides have directed their criticisms primarily at the EPA, which has granted testing approvals, rather than at the companies that developed them.
Janet Andersen, acting director of the EPA’s Biopesticides and Pollution Prevention Division, defended the agency’s procedures.
“We addressed Dr. Wood’s questions and comments and required more containment than American Cyanamid originally proposed,” she said. “He may not feel that it was enough, but we made a regulatory decision based on all the information that we had and said that the benefits of allowing the tests to go forward outweighed the risks.”
