Box: Seeds of discontent

Gabor Lövei reviewed lab experiments on the impact of biotech crops on predators of crop pests. Pictured, an assassin bug.P. SHIRK

Several scientists say they have been sharply attacked by others in the research community when they have published papers that reflect negatively on biotech crops. In October 2002, for example, David Schubert at the Salk Institute in La Jolla, California, suggested in a Commentary in Nature Biotechnology that not enough attention was being paid to the potential unintended molecular effects of inserting genes into plant cells². Almost immediately, he received a barrage of mail from around the world, he says: "I've never received such an obscene response for offering an opinion." Schubert says people complained directly to the Salk Institute, and an administrator called him into his office to say he was jeopardizing funding for his institution. "I've written hundreds of articles — some of them controversial — and never had this kind of response," he says, adding that he has given up trying to have a public discussion about the technology.

One letter¹⁵ critical of Schubert published in Nature Biotechnology and signed by 18 people, admonished: "Good scientists go astray when they leave their area of expertise to offer an opinion when they have not studied the literature." Henry Miller at the Hoover Institution in Stanford, California, also a critic of Rosi-Marshall's paper¹, told Nature that "[Schubert] is an accomplished immunologist who has no grasp on agricultural biotech whatsoever." Not true, says Schubert. "The basic technology used to make transgenic plants was invented using bacterial and animal cells, and my lab uses this technology on a daily basis," he says.

In some cases the attacks start before a paper is out. In September 2007, Bruce Tabashnik, an entomologist at the University of Arizona in Tucson, was preparing a paper showing evidence of insect resistance to Bt cotton. He got an e-mail from William Moar, an entomologist at Auburn University, Alabama, warning him that the paper's consequences would be "devastating". "Your statement ... would be all of the ammunition many special interest groups would need ... Just for a moment think 'monarch butterfly and Bt corn' and the repercussions that surrounded that fiasco," he wrote. Tabashnik's paper was published in Nature Biotechnology¹⁶. Moar, who now works for Monsanto, a maker of Bt maize (corn), based in St Louis, Missouri, criticized the paper at conferences and challenged it in Correspondence¹⁷ to the journal saying that the comparisons and conclusions that Tabashnik made were scientifically unsound and based on lab measures, whereas proof of insect resistance must ultimately come from field studies. Tabashnik says: "The rigorous analysis in our paper was based on systematic, objective analysis of all of the relevant data."

One author on Moar's letter was Anthony Shelton, an entomologist at Cornell University in Geneva, New York. He was in action again this year, challenging a review article by Gabor Lövei, an ecologist at Aarhus University in Denmark, and two co-authors. Lövei's article reviewed laboratory experiments that examined whether crops engineered to kill pests affected the predators and parasites that normally feed on those pests. They found more effects, some negative, some positive, than other reviews had reported. Lövei and his colleagues argued that their method provided a more accurate summary of the literature because it directly examined the data within published papers, rather than relying on authors' conclusions.

Environmental Entomology accepted Lövei's paper¹⁸ but, in January, three months before it was published, Shelton and three colleagues were given a proof by a colleague of one of the authors. Shelton prepared a rebuttal¹⁹ that was published days after Lövei's paper. The six-page critique called the study "negatively biased", "erroneous" and "inappropriate". For example, it says the authors didn't distinguish whether predators and parasites of insects that feed on biotech crops were affected by the toxins in the plants or by the health of their prey. Lövei and his co-authors say they hope to defend their paper in the October issue of Environmental Entomology, and will agree that the distinction would have been useful, but that it would not have changed their conclusions.

Shelton says that he and his group wanted to counteract any effect Lövei's work might have on policy, particularly as that month the European Food Safety Authority was writing up a risk assessment on unintended effects of genetically modified plants. "I could envision a regulator having this Lövei article appear on his desk and saying 'We've got to rethink approval methods'," says Shelton.

Shelton's critique was a "way over-reaction", says an editor at the Entomological Society of America, which publishes Environmental Entomology, who asked to remain anonymous. "They seem to have read it with eyes predisposed to dismiss anything reflecting poorly on GMOs [genetically modified organisms]." Shelton disagrees. "I have been critical of some aspects of genetically engineered plants and microbes in the past when I thought they were warranted, based on scientific data," he says. "I am also an editor in the Entomological Society of America and felt that our reaction was not a 'way over-reaction'." He adds that as an editor he routinely rejects papers that could be considered supportive of GMOs because of their quality. "Poor science can occur on both sides of issues."

When asked to point to a good paper that reflects negatively on biotech crops, most critics Nature spoke to said they couldn't name any. "I have seen very little substantive data that are negative towards Bt crops that can't be easily overturned," says Moar. Wayne Parrott at the University of Georgia in Athens, however, says: "There is plenty of biotech-safety research out there that has not come under attack, even when the answers are not what everyone would have liked."

E.W.