On Monsanto's Application to Register Bt Corn Targeted at Corn Rootworms

Comments to EPA on Docket No. OPP-30487

20mar00

Comments to the Environmental Protection Agency on Monsanto's Application to Register Bt Corn Targeted at Corn Rootworms Jane Rissler, Ph.D.
Margaret Mellon, Ph.D., J.D.
Union of Concerned Scientists

The Union of Concerned Scientists (UCS) is grateful for the opportunity to present comments to the Environmental Protection Agency (EPA) on an application from Monsanto Company to register a new genetically engineered pesticidal plant product. UCS is a nonprofit, public-interest group advocating the transition to a sustainable food system.

Background

Application to register Bt corn targeted at corn rootworm.

EPA is seeking public comment on an application from Monsanto Company to register Bt corn engineered to produce the Cry3Bb insecticidal protein from Bacillus thuringiensis to control corn rootworms (Federal Register 64:71753-4, 12/22/99). Genetically engineered pesticidal plants must be registered under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) before they can be commercialized. These comments are submitted in response to Monsanto's request for registration.

The registration application is the first for a Bt-corn variety engineered to control beetles. All Bt-corn varieties currently on the market contain Bt toxins which are specific for moths, in particular, the European corn borer. Thus far, only one commercialized crop -- Monsanto's Bt potato -- contains a beetle-specific Bt toxin.

Corn rootworm.

The insect, which is actually a complex of four kinds of rootworms in three species of Diabrotica beetles, is one of the Corn Belt's worst insect pests, accounting for an estimated $650 million to $1 billion annually in yield losses and control costs in the United States (Gray, 1999; Tollefson and Levine, 1999). Corn rootworms do just as their name implies -- they feed on corn roots and as a result interfere with the plant's ability to absorb water and nutrients and to remain upright.

Two of the four rootworms -- the northern and western -- cause the most damage in the Corn Belt (Tollefson and Levine, 1999). The other two -- the southern and Mexican -- also cause losses though over a smaller range. The southern corn root worm, while widely distributed east from the Rocky Mountains, is primarily a problem in coastal Texas and Louisiana (Drees, 1999). In the United States, the Mexican corn rootworm is generally limited to Texas and Oklahoma (Stewart, 1999).

Until the adoption of corn monoculture in the Midwest, beginning about 50 years ago, corn rootworms were minor pests. In fields devoted only to corn year after year, large populations of rootworms build up -- leading to the use of huge amounts of insecticides. According to the Handbook of Corn Insects (Sutter, 1999) nearly 90 percent of continuous-corn acres are treated with soil insecticides.

Many farmers control the corn rootworm through crop rotations. Rotations -- even the simple two-crop corn/soybean rotation -- worked in areas harboring northern and western corn rootworms because they feed almost exclusively on corn and adult females lay eggs almost exclusively in corn fields. As a result, in a corn/soybean rotation, eggs deposited in a corn field in the fall would hatch into larvae in the spring-but they would starve to death with only soybean roots for food in the action center

In the last few years, however, the corn/soybean rotation, which along with continuous corn has become a mainstay of midwestern farmers, has failed to control corn rootworm in some areas. Two adaptations in corn rootworm appear to account for the failure (Drees et al., 1999). First, some western corn rootworm females have begun laying eggs in soybean fields in the fall. Then, in the spring, when the field is rotated to corn, the larvae hatch and begin feeding on the corn roots. Second, an increasing number of northern corn rootworms exhibit an extended egg diapause, that is, eggs, rather than hatching the first spring after they are laid, may pass through two or several winters before they hatch. Some of these worms may fortuitously encounter corn when they emerge.

Comments and Recommendations

1. EPA should postpone consideration of Monsanto's application to register rootworm-protected Bt corn until it has analyzed data submitted under the company's experimental use permit.

EPA should not act on Monsanto's registration application before it has reviewed data submitted under the company's experimental use permit (EUP) (Federal Register 64:68681-2, 12/8/99), which was announced only two weeks in advance of the registration application. Under the EUP, Monsanto expects to plant well over a thousand acres of rootworm-protected Bt corn for testing and seed increase purposes (Monsanto, 1999b). Because some of the testing will generate data supporting the application for registration (Monsanto, 1999a), it would be premature for the Agency to make a decision on registration before it has those data in hand.

2. EPA should turn down all registrations of transgenic pesticidal plants, including the rootworm-targeted Bt corn, until it has in place a comprehensive, scientifically rigorous program for assessing the ecological risks of the new crops.

The Agency has yet to develop a strong program to ensure that all potential environmental impacts of Bt crops are fully evaluated before the crops are grown at commercial scale. For its reviews of Bt crops thus far, the Agency has relied, to a great extent, on protocols and methodology developed for assessing the ecological effects of microbial pesticides.

Late last year, after its failure to identify publicly the potential effects of Bt-corn pollen on monarch butterflies, the Agency took a significant step towards a program tailored for transgenic crops. In response to requests from the public interest community (UCS et al., 1999), the Agency convened a meeting of a Scientific Advisory Panel (SAP) on December 8, 1999, to discuss the Agency's current approach and future plans for characterizing engineered plant pesticides and evaluating their nontarget effects.

The report of that panel confirms the weakness of EPA's current program, citing, for example, the need for a new paradigm, different from that used for microbial pesticides, to evaluate plant pesticides (EPA SAP, 2000, p. 14); improved data requirements for nontarget insect testing (EPA SAP, 2000, p. 11); more field scouting data to evaluate potential exposures of nontarget organisms to plant toxins (EPA SAP, 2000, p. 11); more information on cross pollination and weedy relatives of crops to define data requirements for impacts of transgene flow (EPA SAP, 2000, p. 12); and detailed recommendations to applicants on experimental design and data analysis (EPA SAP, 2000, p. 17).

The Agency's new program must also take into account the growing body of research on the ecological implications of engineered crops. In a series of recent publications, Angelika Hilbeck and her co-workers have reported indirect effects of plants producing the corn-borer-targeted Bt toxin in laboratory studies (Hilbeck, Baumgartner et al., 1998; Hilbeck, Moar et al., 1998; Hilbeck et al., 1999). Their work suggests that the Bt toxin, mediated through the European corn borer, may have harmful effects on green lacewings, which are predators of the corn borer. Other studies in Guenther Stotzky's laboratory raise important issues about the fate and impacts of Bt toxins in soil ecosystems (Saxena et al., 1999 and references therein). Based on years of research on the environmental impacts of genetically engineered organisms, Donegan and Seidler (1999 and references therein) also raise concerns in a recent article about the effects of transgenic pesticidal plants on plant and soil microbial communities and processes.

3. EPA should turn down Monsanto's application until the Agency requires, receives, and assesses data appropriate for addressing the potential environmental impacts of the rootworm-targeted Bt corn.

If the Agency chooses to go ahead absent a revamped risk assessment program, it must still defer a decision on Monsanto's application until it is able to evaluate fully the potential risks of the new Bt corn. This means that the Agency must develop new, tailored data requirements, which when fulfilled, will allow a comprehensive look at the environmental implications of planting the new Bt corn on millions of acres of US farmland. Those requirements must reflect, as noted above, the advice offered by the December SAP and recent risk research. In particular, the Agency must address the daunting challenge of assessing the soil ecosystem effects of Bt-toxin-containing exudates from Bt-corn roots. Though Monsanto submitted hundreds of pages of information in its registration application, the company will need to do substantially more research and testing under new Agency protocols to provide the data that will be needed for a comprehensive ecological risk assessment.

4. EPA should turn down Monsanto's application because it does not contain a comprehensive, workable resistance management plan for the rootworm-targeted Bt corn.

Beginning in 1995, EPA approved Bt cotton, Bt potato, and several Bt-corn varieties -- all lacking comprehensive resistance management plans. We urge the Agency to take a different course now to preserve the valuable Bt toxins for many, many years. EPA should delay the registration of rootworm-targeted Bt corn, and any other Bt crops, until strong, comprehensive resistance management plans are in place.

Commercializing Cry3Bb Bt corn without workable resistance management plans practically guarantees a rapid evolution of resistance in corn rootworms -- and a loss of Bt as a viable control for these pests. Rootworms are notoriously adaptable, having evolved resistance to a variety of insecticides and a cultural control method (Gray, 2000). Even with sound resistance management plans in place, resistance to Bt toxins will develop eventually (Gray, 2000).

Monsanto has made only preliminary strokes on the resistance-management drawing board -- and is years away from filling in the details. The company's submission to EPA reveals significant gaps in every area of research critical to a sound plan: pest biology and ecology, the high dose/refuge strategy, and monitoring and mitigation methods (Monsanto, 1999a). For example, the company offers no convincing data on a cornerstone of a strong plan-that the Bt corn consistently produces a high dose of Cry3Bb toxin under a variety of field conditions (Monsanto, 1999a, pp. 78-80). Nor is the company even close to having the data needed to define either the spatial configuration or the size of refuges-another key component of a comprehensive plan (Monsanto, 1999a, pp. 80-81).

We urge EPA to consider a recent proposal by Michael Gray, a University of Illinois corn rootworm expert, which could be an important new component of mandatory resistance management plans. Dr. Gray suggests restricting the use of rootworm-targeted Bt corn to fields where a need for rootworm control can be documented (Gray, 2000). Because adults lay eggs that overwinter in fields and hatch in the spring into root-eating larvae, entomologists can estimate expected rootworm damage in the spring by counting late-summer adults. As a result, depending on the predictive capability of the surveys (which are controversial), farmers may know by fall whether they are likely to have a substantial problem the next year and therefore whether rootworm-targeted Bt corn would be beneficial.

Under the prescriptive approach suggested by Dr. Gray, only farmers with survey results predicting economic thresholds of corn rootworms would be allowed to plant the new corn (Gray, 2000). Prohibiting the use of Bt corn on the almost 50 percent of continuous-corn fields lacking economically important populations of rootworms would reduce the acreage planted in engineered corn, resulting in large refuges of nonBt corn (Gray, 2000) to provide susceptible insects for mating with resistant ones emerging from Bt corn.

5. Any assessment of the benefits of the rootworm-protected Bt corn must include a comparison with nonchemical, alternative rootworm-control methods, such as long crop rotations.

To the extent that a benefits assessment plays a role in EPA's decisions concerning rootworm-targeted Bt corn, UCS urges the Agency to compare the benefits of the new product to the full range of alternative rootworm-control methods, including crop rotation.

Monsanto's submission, comparing the new corn only with synthetic chemical insecticides, finds that its new product "offers a significant advantage over existing pest control strategies, and is clearly in the public good" (Monsanto, 1999a, p. 39). The company expects this product to significantly reduce the use of chemical insecticides in corn.

Rather than follow Monsanto's narrow view of "existing pest control strategies" the Agency should compare the new corn to the other prominent, existing control method-crop rotation. The Agency should determine the value of the decades-long use of the two-crop rotation and evaluate the benefits of adding a third and fourth crop to the rotation to control rootworms.

6. EPA should convene specific subpanels of the SAP for advice on the complex technical issues raised by the rootworm-targeted Bt-corn registration.

As indicated above, Monsanto's application to register rootworm-targeted Bt corn raises a number of complex scientific issues on a new Bt crop. UCS urges EPA to convene special subcommittees of the SAP to advise it on the full range of technical issues presented by this application.

References Cited

Donegan, K.K. and R. J. Seidler. 1999. Effects of transgenic plants on soil and plant microorganisms. Recent Res. Devel. Microbiology 3:415-24.

Drees, B.M. 1999. Southern corn rootworm (spotted cucumber beetle). Page 63 in Handbook of Corn Insects, K.L. Steffey et al., eds., Entomological Society of America, Lanham, Md.

Drees, B.M., E. Levine, J.W. Stewart, G.R. Sutter, and J.J. Tollefson. 1999. Corn rootworms. Page 66 in Handbook of Corn Insects, K.L. Steffey et al., eds., Entomological Society of America, Lanham, Md.

Environmental Protection Agency Scientific Advisory Panel. 2000. Characterization and non-target organism data requirements for protein plant-pesticides. SAP Report No. 99-06A dated February 4, 2000, of December 8, 1999, FIFRA SAP meeting, Arlington, Va.

Gray, M.E. 2000. Prescriptive use of transgenic hybrids for corn rootworms: an ominous cloud on the horizon? Proceedings of Year 2000 Crop Protection Technology Conference, University of Illinois at Champaign-Urbana, January 2000; www.biotech-info.net/mgray.pdf .

Hilbeck A., M. Baumgartner, P.M. Fried, and F. Bigler. 1998. Effects of transgenic Bacillus thuringiensis corn-fed prey on mortality and development time of immature Chrysoperla carnea (Neuroptera: Chrysopidae). Environmental Entomology 27:480-87.

Hilbeck, A, W.J. Moar, M. Pusztai-Carey, A. Filippini, and F. Bigler. 1998. Toxicity of the Bacillus thuringiensis Cry1Ab toxin to the predator Chrysoperla carnea (Neuroptera: Chrysopidae). Environmental Entomology 27:1255-63.

Hilbeck, A, W.J. Moar, M. Pusztai-Carey, A. Filippini, and F. Bigler. 1999. Prey-mediated effects of Cry1Ab toxin and protoxin and Cry2A protoxin on the predator Chrysoperla carnea. Entomologia Experimentalis et Applicata 91:305-16. 1999.

Monsanto, 1999a. Administrative materials in support of the registration of the plant-expressed protectant, Bacillus thuringiensis corn rootworm control protein, as produced in corn (Zea mays L.) and the amendment to the previous request for exemption from the requirement of a tolerance, PP 7F4888. Submitted to EPA, August 19, 1999. St. Louis, Mo.

Monsanto, 1999b. Administrative materials in support of an application for an experimental use permit for genetically enhanced corn developed from vector ZMIR13L, producing a protein that provides control of corn rootworm (Diabrotica spp.). Submitted to EPA, November 15, 1999. St. Louis, Mo.

Saxena, D., S. Flores, and G. Stotzky. 1999. Insecticidal toxin in root exudates from Bt corn. Nature 402:480, December 2, 1999; www.biotech-info.net/risks.html#soil .

Stewart, J.W. 1999. Mexican corn rootworm. Pages 61-2 in Handbook of Corn Insects, K.L. Steffey et al., eds., Entomological Society of America, Lanham, Md.

Sutter, G.R. 1999. Western corn rootworm. Pages 64-5 in Handbook of Corn Insects, K.L. Steffey et al., eds., Entomological Society of America, Lanham, Md.

Tollefson, J.J. and E. Levine. 1999. Northern corn rootworm. Pages 62-3 in Handbook of Corn Insects, K.L. Steffey et al., eds., Entomological Society of America, Lanham, Md.

Union of Concerned Scientists, National Wildlife Federation, Sierra Club, Natural Resources Defense Council, Arizona-Sonora Desert Museum, and Defenders of Wildlife. 1999. Letter to EPA: Toxic Bt -corn pollen and the monarch butterfly. August 10, 1999. Washington, D.C.; www.ucsusa.org/agriculture/browner.aug11.html

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