The publication on May 20, 1999, of preliminary research by Cornell University suggesting that the use of genetically modified corn may have toxic effects on larvae of the monarch butterfly has generated a huge amount of publicity and almost as much misinformation. Groups opposing biotechnology have used the preliminary data to argue against production and trade in all genetically engineered crops regardless of the facts. Scientists are now conducting several follow-up studies examining the effects of bioengineered corn pollen on butterflies.
While a review of current research indicates that scientists have found some risk to monarch butterfly caterpillars from Bt corn pollen, very few definitive conclusions can be made at this time, according to British biologist M.J. Crawley. Crawley observes that the data gathered to date are based on preliminar laboratory studies, carried out over a comparatively short period of time under a specific set of conditions. "They do not address the issues over the entire life cycle of the insects," he says.1 Numerous scientists, industry representatives, and government officials strongly support collecting more definitive data from comprehensive field research in order to resolve what has become a burning issue in the larger biotechnological debate.
Following is a brief review of the Cornell preliminary research and ongoing research.
THE CORNELL UNIVERSITY RESEARCH
The official account of Cornell entomology professor John Losey's laboratory study was published in Nature magazine's May 20, 1999, issue under the title "Transgenic Pollen Harms Monarch Larvae."2 Losey's research investigated how pollen from genetically engineered corn (Bt corn) affects monarch caterpillars, whose exclusive food source, milkweed, frequently grows in and around corn fields. His one-page scientific correspondence in Nature outlined the methodology that he and two researchers used to compare the feeding, growth, and mortality of monarch larvae fed on milkweed leaves dusted either with Bt corn pollen or non-Bt corn pollen, or not dusted with pollen at all.
Losey reported that the larvae "reared on milkweed leaves dusted with pollen from Bt corn ate less, grew more slowly, and suffered higher mortality than larvae reared on leaves dusted with untransformed corn pollen or on leaves without pollen." He wrote: "These results have potentially profound implications for the conservation of monarch butterflies." Noting that the amount of Bt corn planted in the United States is projected to increase markedly, Losey observed that "it is imperative that we gather the data necessary to evaluate the risks associated with this new agrotechnology and to compare these risks with those posed by pesticides and other pest-control tactics." In a Cornell University press release issued on May 19, he described his research as "just the first step" and again called for more research.3 Losey reports that he has been carrying out follow-up experiments and hopes to publish his latest results this winter.4
ADDITIONAL RESEARCH
Another study frequently cited in the media is the ongoing fieldwork by entomologist John Obrycki and graduate student Laura Hansen at Iowa State University. While they have not yet published this research, the abstract they wrote for presentation at an Entomological Society of America meeting describes its focus and preliminary findings.5 Obrycki and Hansen have been investigating the potential risk that the manifestation and dispersal of Bt toxin in corn pollen poses to monarchs. The first step of their methodology was to place potted milkweed plants at several distances from the edge in both a Bt cornfield and a non-Bt field to determine pollen concentration levels. They then took milkweed leaf samples to assess the mortality of newly hatched monarch larvae exposed to either Bt corn or non-Bt corn pollen. They found that "within 48 hours, there was 19 percent mortality in the Bt corn pollen treatment compared to zero percent on non-Bt corn pollen exposed plants." In evaluating their research, Marlin Rice, an entomologist at Iowa State, writes that both the Iowa State and Cornell studies "suggest that some, but not all, monarch caterpillars may be killed when they eat Bt corn pollen." However, he says, the bottom line is that more research needs to be conducted on the effects of Bt corn on monarchs and other non-target species. 6
Another team of scientists from Iowa State, the Agricultural Research Service of the U.S. Department of Agriculture, and several other American universities is currently conducting field studies under the sponsorship of the Agricultural Biotechnology Stewardship Working Group (ABSWG). ABSWG is a consortium of biotechnology companies and associations that includes the Biotechnology Industry Organization (BIO), the American Crop Protection Association (ACPA), Monsanto Company, and Novartis Seeds Inc. Through ongoing projects focusing on milkweed distribution, pollen movement, monarch biology, and the biochemistry of Bt pollen, the researchers are studying how the pollen that is transported outside of corn fields affects butterfly larvae in their natural habitat, as they feed on milkweed plants. In a press release, BIO's vice president for food and agriculture states that the consortium's goal was to "assemble a cadre of top-flight, highly reputable and credible public researchers to answer the real questions that grew out the Cornell University laboratory study." 7 According to the executive director of ACPA's Biotechnology Committee, Leah Porter, the researchers plan to present their findings this December at the Entomology Society of America's annual meeting in Atlanta.8 At the meeting, a symposium on the Impact of Transgenic Corn Pollen on Monarch Larvae will feature the latest results of several high-profile studies.9
Also participating on the ABSWG-affiliated research team, are scientists from the Agricultural Research Service (ARS). According to an ARS information officer, the USDA scientists are continuing to conduct follow-up studies and have not yet released data from these experiments. An informal meeting to exchange information and discuss the direction of future research is planned for November 2 in Chicago. In a discussion of the Cornell study, the USDA fact sheet, "USDA and Biotechnology," reports that the department is working to identify useful follow-up information and research to better understand how monarchs and corn pollen interact in the field. The fact sheet lists a number of reasons why the effect of Bt corn pollen on monarchs may prove to be small.10 These include corn pollen's heavy weight, which may prevent it from being blown a significant distance from the field, and the monarchs' potential capacity to avoid feeding on milkweed plants dusted with Bt pollen. Overall, the document states, "USDA is committed to further research on the potential impacts of new technologies in agriculture."
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