The Monarch and the Bt Corn Controversy

I HAVE STUDIED the monarch butterfly since 1954, and it is not unusual for me to receive inquiries about the biology and conservation of this wonderful insect. None was more fateful than a phone call in September 1998 from Linda Rayor telling me of a discovery made by her and her Cornell University colleagues, John Losey and Maureen Carter that a genetically engineered strain of corn, the so-called Bt corn, produced pollen that could kill monarch caterpillars. Shortly afterwards Losey, Rayor, and I had a discussion about the implications of their study; the forces behind biotechnology are powerful ones, and it was obvious that the Cornell findings had serious scientific, political, and economic implications. Yet none of us could have predicted the firestorm that was about to descend.

This story is about how the proponents of the new genetic engineering technology distorted the scientific inquiry into the possible harmful effects of Bt corn on the monarch butterfly. In the ongoing debate over the Cornell findings, the scientific process has been spun, massaged, and manipulated by the agricultural industry, the U.S. Department of Agriculture, the U.S. Environmental Protection Agency, and elements of the North American academic community. The process disregarded international scientific standards and has helped to make science the handmaiden of industrial agriculture. As a consequence of these irregular proceedings, the monarch-Bt corn debate risks losing sight of a larger, more serious issue: the real danger that genetically engineered crops will accelerate the industrialization of agriculture, human overpopulation, and the impoverishment of biological diversity.

The findings of the Cornell scientists should not have come as a surprise, given the agricultural industry’s history of carelessness with respect to nontarget species — benign or beneficial species that are part of the natural web of life. Forty years ago Rachel Carson alerted us that the chemical industry was spreading synthetic insecticides that were killing legions of beneficial insects and the birds that ate them.

In the years following Silent Spring, some agricultural industries looked for alternatives to chemical insecticides, and agricultural entomologists tried to develop solutions that would be more specific. One was to release foreign parasites to control crop and forest pests, many of which themselves had been accidentally imported. Hundreds of species of wasps, flies, beetles, nematode worms, fungi, bacteria, and viruses were gathered across the globe and released in North America by agricultural scientists. These exotic control agents also attack many nontarget species with serious, but largely ignored, effects upon native ecosystems.

ANOTHER BIOLOGICAL APPROACH WAS TO MANIPULATE the soil bacterium Bacillus thuringiensis. The Bt bacterium secretes a protein that, when ingested by a sensitive insect, causes the larval gut to break down and a gooey, black death ensues. Industrial and academic scientists have selected numerous Bt strains that are toxic to the larvae of different groups of insects. The Bt kurstaki strain is lethal to the caterpillars of virtually all moths and butterflies and is produced in mass cultures that are harvested and sold as Dipel. Used in home gardens as a “natural” toxic powder to kill tomato hornworms and cabbage caterpillars, Dipel is also sprayed to kill gypsy moth caterpillars in the eastern deciduous forests, spruce budworms in the northern boreal forests, and tussock moth caterpillars in the western Douglas fir forests. Extensive sprayings of Dipel and its derivatives, along with repeated releases of exotic parasitic insects, have severely reduced the populations of many benign and beneficial native insects, including several of the New England silk moths renowned for their elegance and bizarre caterpillars.

The danger to nonpest species was raised to a far more sophisticated level by the new science of genetic engineering, which makes it possible to transfer genes between any species on earth. When successful, the transferred genes give the recipient species the ability to synthesize proteins that were specific to the donor species. An obvious strategy would be to insert various Bt genes into crop plants. Then as the seeds of the genetically modified strain sprout and grow, the inserted DNA would express itself in every single cell of the growing seedlings. Wonder of wonders, the roots, stems, leaves, and seeds of the plant contain the Bt toxin and are toxic to virtually all caterpillars. Agricultural companies introduced the Bt genes into several crops, including potatoes, soybeans, cotton, and corn. One major target was the European corn borer moth, an economically damaging species that is found throughout the eastern United States and southern Canada.

Before any of these genetically modified organisms (GMOs) could be used commercially, the EPA required a battery of toxicology tests. The toxins of various Bt corn strains showed no apparent adverse effects on honeybees, ladybird beetles, and a few other invertebrates. The test results, together with the fact that the toxin is inactivated in the acid milieu of mammalian guts, led U.S. regulatory agencies to judge nearly all Bt corn strains safe for human consumption and the environment. Critically, however, toxicologists ignored the potential impact on nontarget species of butterflies and moths that are the denizens of the same ecosystems in which corn is grown.

Many biologists heralded the new Bt corn technology because they believed it would mitigate the need to spray insecticidal chemicals. The corporations involved in marketing the seeds (for the most part the same ones that had developed the synthetic insecticides several decades earlier) sponsored a multimillion-dollar campaign touting them as an environmental panacea. The response was stunning: by the 1998 season, twenty-five percent of the total U.S. corn crop (of eighty million acres) was planted with Bt corn.

Genetic engineering also led to the development of numerous crop strains resistant to herbicides. It is now possible, for example, for farmers to plant “Roundup Ready” seeds of several crops — seeds that produce seedlings unaffected by Roundup spray. Roundup eliminates competing weeds, as well as nearly all native flora — including milkweeds, upon which the monarch depends. In the grassland states, nightly advertisements repeatedly promote the latest herbicide technologies. The result of such extensive use of herbicide-resistant crops is the destruction of biodiversity throughout North America and elsewhere, as millions of acres of land are converted to monoculture deserts of potatoes, soybeans, cotton, or corn.

If plants can be genetically engineered to produce their own pesticides and to resist synthetic herbicides, it is certain that crop strains can also be developed to grow in virtually any soils. Looking beneath the purported advantages of the new GMO technology to agriculture and corporate profits, an alternative view is that these corporations are converting the natural world into a biologically impoverished planet massively overpopulated by a single species: Homo sapiens. The sweeping extent of this technology can be seen in chicken factories that sit in the middle of vast cornfields, devoid of all native plants. The rich web of life that formerly occupied this prairie community has been reduced to an industrial food chain that has only three links: sunlight to corn, corn to chickens and chickens to humans.

Knowing that their findings had implications for the hot topic of genetically modified food, the Cornell scientists submitted their manuscript to the American journal Science. Before sending manuscripts out for peer review, the editors screen them, using likely audience interest as one acceptance criterion. Despite the relevance of the monarch study to a timely scientific issue, the manuscript did not pass this hurdle. With a growing realization of the magnitude of the bomb they were sitting on, Losey, Rayor, and Carter revised their manuscript and submitted it to the British journal Nature. Popular and scientific challenges to the release of genetically modified organisms into natural environments have been major press fodder in Europe, and the editors of Nature sent the paper out for peer review. It was published in May 1999.

In their article, “Transgenic Pollen Harms Monarch Larvae,” the Cornell authors asked: Could windblown corn pollen accumulate on plants that grow extensively in and adjacent to cornfields and, like conventional insecticides, inadvertently kill native insects that are not pests? To test this question, they chose the monarch as their nontarget species. Female monarchs lay eggs on wild milkweed plants, the only plants that their caterpillars can eat. In their experiment, conducted in the laboratory, the authors dusted pollen gathered from one of the Bt corn strains onto the leaves of the common milkweed. They established that caterpillars that fed on the dusted leaves ate less, grew more slowly, and suffered higher mortality than caterpillars reared on milkweed leaves dusted with pollen from a non-Bt corn strain. The scientists were circumspect about their results and stated clearly that more research was needed to determine the impact of the toxic pollen on monarchs in the natural environment.

According to a private communication, an ashen-faced president of a major biotech company marched into a board meeting shortly after the article appeared and stated, “I have only one thing to say about the Cornell publication: Bambi.” Had the scientists chosen a different insect, it is likely that few people would have responded to the Nature paper. They used the monarch, however, loved by schoolchildren, gardeners, and millions of other people throughout the world. The monarch instantly became a bête noire for the field of biotechnology. The world press latched onto the study even before the article was in print, and soon protesters wearing corn and butterfly costumes were marching in the streets.

THE AGRICULTURAL INDUSTRY’S REACTION to the news was immediate and vigorous. Criticisms belittling the Cornell study appeared widely in the U.S. and on British television. Agricultural companies launched web pages (for example, on,, and downplaying and, in some instances, ridiculing the study. The principal argument they put forward was that the benefits of using Bt corn far outweigh the environmental costs of the pesticides it replaces. Their most common assertion — that Bt corn reduces the need for other insecticides in cornfields by two orders of magnitude, a gross exaggeration — was repeated in press releases and uncritically accepted by numerous scientists. This same justification was used in articles favoring the new technology that appeared in respected journals, such as the Proceedings of the National Academy of Sciences, U.S.A.

The Cornell study mobilized the environmental community at a critical time because the earlier approval of Bt corn was about to expire, and the EPA was required to undertake a reassessment process before renewing the registration. The Union of Concerned Scientists and the Environmental Defense Fund petitioned the EPA to restrict the planting of Bt corn and to reassess the environmental risks of genetically engineered crops. The environmentalists’ initiative made it clear that further scientific study of the relationship between the monarch and Bt corn was needed before a ruling could be made. From this point on, however, scientific efforts to define that relationship would be overshadowed by the agricultural industry’s efforts to control the information on which the EPA decision would be based.

The industry’s early responses to the Cornell paper were designed to cast doubt on whether the scientists’ laboratory findings were applicable to monarch caterpillars in the field. Many statements were misleading, fanciful, and betrayed an ignorance of the monarch’s natural history. Incorrect or speculative pronouncements fed to the media included that the major geographic area of monarch reproduction lies outside the corn belt; that monarchs breed before pollen is released from the corn tassels; and that pollen release occurs over too short a time to have a major impact on the caterpillars. All these industry-released statements ignored the extensively documented literature on the monarch’s lifecycle, including information known since the nineteenth century that multiple overlapping generations of the monarch occur throughout the summer breeding range, virtually assuring that the monarch caterpillars would be widely exposed to the shedding corn pollen. Other press reports asserted that few pollen grains land on milkweed leaves, that monarchs lay most of their eggs on the undersurfaces of the leaves, that milkweed leaves have slick surfaces to which corn pollen grains will not stick, that the toxicity of the pollen grains is below the threshold that kills monarch larvae, and that one hundred times more monarchs are killed by cars and trucks than by Bt corn. The most flagrant lack of scholarship exhibited by the Bt corn proponents was their failure to cite the current scientific literature documenting that extensive monarch breeding occurs throughout the North American corn belt.

The agricultural industry’s manipulation of the press was soon made even clearer. Several corporations, including the Monsanto Company, Novartis A.G of Switzerland, and the Pioneer Hi-Bred of DuPont Company formed a soothingly named consortium, the Agricultural Biotechnology Stewardship Working Group (ABSWG). The ABSWG contacted university scientists and provided funding for studies that would address issues raised by the Cornell findings. U.S. and Canadian scientists conducted a research program during the summer of 1999, the results of which were to be presented at a scientific symposium in Chicago on November 2, hosted by the ABSWG, and also attended by representatives of the EPA and the USDA. The avowed purpose of this symposium was for the scientists to present and discuss their findings, review their methodologies, and determine through consensus what information was inconclusive or missing.

Because of the manner in which the press releases had been handled, I had an uneasy feeling about ABSWG’s symposium and how the results of the summer research would be reported there. Fortunately, a private foundation concerned about the threat of Bt corn to the monarch made it possible for me and monarch expert Myron Zalucki, of Queensland University in Australia, to attend. Our mission was to use our combined knowledge of monarch biology to make a fair and critical evaluation of the scientific content of the presentations. Because of the hurried nature of their summer research, all of the meeting participants prefaced their scientific presentations with the caveat that their data and conclusions were preliminary. Some results indicated possible major impact, others suggested minor impact, and most agreed that the current research base could not resolve the problem. Afterward, Zalucki and I concluded that the available toxicology data were inadequate and that far more field studies were needed to ascertain the extent of overlap between monarch breeding, milkweed plant distribution, and corn pollen shedding. We also recommended several specific biological questions that needed to be answered before the EPA could possibly make an informed judgment on whether to renew the registration of Bt corn.

At the meeting, Carol Yoon, a New York Times science journalist, made a stunning announcement: she had just received a fax from her Times editor indicating that a media advisory had been released earlier in the day. The headline describing the still-in-progress meeting stated: “Scientific Symposium to Show No Harm to Monarch Butterfly.” Several of the participating scientists whose studies were supported by ABSWG had apparently agreed on the contents of the misleading press statement prior to the symposium. There was now no doubt that the symposium had been co-opted by the ABSWG, and that the press was being manipulated. Yoon’s report exposing this fiasco, “No Consensus on the Effects of Engineering on Corn Crops,” was published in the Times on November 4.

A little more than a month later, on December 8, 1999, the EPA held a Scientific Advisory Panel meeting, a requirement of the EPA regulatory process leading to renewal or denial of re-registering Bt corn for commercial use. Though public comment was allowed, surprisingly few people attended the meeting. I related that the results of the Chicago meeting had been inconclusive and obfuscated by the Agricultural Biotechnology Stewardship Working Group. Another testimony, by a scientist representing one of the agricultural companies, was a vituperative commentary on both the Cornell results and another recent Nature paper documenting that Bt toxin can leach from the corn plants into the soil. A clear pattern was emerging: corporate spokespeople will attack scientists who discover any potentially adverse environmental effects of GMO crops.

Following these meetings, demands from the environmental community for further research on the impact of Bt corn on the monarch grew stronger. In the spring of 2000 the industries and the USDA jointly announced that each was allocating $100,000 for a competitive grants program to support several Bt corn and monarch butterfly research projects during the coming summer. A number of monarch scientists speculated that the paltry funding was a palliative and that the resulting research findings would be ignored in the EPA’s re-registration deliberations.

Aware that new data and more sophisticated analyses would be forthcoming, the Union of Concerned Scientists and eleven other public-interest organizations made a request to the EPA: to postpone the next Scientific Advisory Panel (SAP) meeting until more data were collected and made available to the public, including the scientists’ findings gathered over the summer of 2000. The EPA, however, held the SAP meeting on October 19, a month before the scientific symposium was scheduled to take place.

Prior to the SAP meeting, the EPA had allowed several corporations to review the agency’s preliminary assessment and suggest modifications. In addition, the EPA allowed the companies to withhold important data as confidential business information. One of the principal documents contained approximately forty deletions of so-called “proprietary” data. It was therefore impossible for the EPA panel or independent scientists to evaluate the data. Both industry and the EPA documents also ignored relevant data readily available in the scientific literature. Thus, without considering the new information that would be presented the following month, and drawing passages almost verbatim from documents prepared by industry, the EPA’s interim assessment of the risks and benefits presented to the SAP stated that “the published preliminary monarch toxicity information is not sufficient to cause undue concern of harmful widespread effects to monarch butterflies at this time.”

THE SUMMER 2000 research results were presented in November at a second Chicago symposium, attended by many of the same industry, academic, and governmental groups that had been present at the 1999 symposium. Investigations examined the toxicity of the various strains of Bt pollen, when and where monarchs feed and breed, and where they encounter the pollen. Some of the findings seemed reassuring. Toxicity studies appeared to indicate that the pollen of some strains of Bt corn was less lethal than that of others and that most of the strains currently in use may be in the less-toxic group. Several studies indicated that corn pollen does not drift very far from the cropfield, and a risk analysis using the new data predicted little effect on larvae feeding on milkweeds beyond a few meters from the edge of a field. Other studies warned of new threats. One determined Bt pollen to be toxic to later-stage monarch larvae — significant because older caterpillars had been assumed to be less sensitive than the young ones. Clarifying a contentious point of the 1999 symposium, new data fed into revised computer models now led to predictions that pollen shedding and monarch breeding happen simultaneously over wide geographic areas. This finding was made all the more important by new data showing that extensive monarch breeding occurs on milkweed growing inside cornfields. This, in turn, underscored the devastating effects that the long-term use of herbicides, and genetically manipulated organisms such as Round-up Ready crops, will have as their use totally eliminates milkweeds from the fields.

The papers presented at this symposium reflected the complexities of the Bt corn issue. Working with different methodologies even in areas where their investigations overlapped, the scientists’ findings were not easily compared. The studies, for example, used different techniques for collecting and testing pollen samples and for controlling contamination by other vegetable matter. In addition, none of the studies addressed Zalucki’s and my recommendations that toxicology tests were needed to determine whether sublethal doses of pollen ingested by larvae affect reproduction or migratory capacities of adult butterflies. In summary, despite the EPA’s interim assessment, the overall database that had been assembled through November 2000 was not adequate to resolve whether Bt pollen is a significant detriment to the monarch butterfly.

A MAJOR ISSUE that emerges from the Bt corn debate is the way in which scientific information is obtained and used in the federal regulatory process — a question with consequences far greater than the decision to register or ban Bt corn. As the handling of the monarch saga has shown, the EPA’s October 2000 decision was based on scientific information that was largely controlled by the industry and failed to measure up to even minimum standards adhered to by the international scientific community. These standards require peer review of manuscripts by independent scientists chosen by the editorial boards of scholarly scientific journals. Peer review assures that experiments are reproducible, that the data are statistically valid, that the conclusions are logically derived from the data, and that they state clearly what is and what is not resolved. This independent evaluation of scientific evidence is a sine qua non for the integrity of science. By ignoring the standard of peer-reviewed science and by relying on information supplied by the same corporations that it means to regulate, the current U.S. federal regulatory system is severely flawed.

The Bt corn issue has raised public concerns about the system by which the federal government evaluates the safety of genetically engineered products. The process that will finally determine the commercial fate of Bt corn is the same one that is applied to every one of the thousands of toxic chemical products and genetically modified organisms that fall under the jurisdiction of our nation’s regulatory system. This is the system warned of in Silent Spring. It is the system that Wendell Berry described more than thirty years ago. Will North American society ever face up to the environmental and cultural erosion caused by the cozy economic relationships of agriculture, business, government, and large segments of academia?

This Bt corn-monarch butterfly saga provides evidence that international agricultural and chemical corporations, a large segment of the academic community, and our federal regulatory agencies care not one whit about biodiversity. Sophisticated advertising, such as that by Archer Daniels Midland Company, an underwriter of nightly news broadcasts on PBS, garners public support for seemingly heroic agricultural technologies designed to feed everyone, everywhere. The same advertisement implies that the beneficent company is developing corn crops engineered to replace petroleum.

It seems certain that the profit-driven mindset of our political and corporate leaders will continue to promote biotechnology, and to fuel unsustainable human population growth with its consequent usurpation of natural habitats and their rich arrays of natural creatures, large and small.