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.
