Bt-Corn Resistance Management



"Remarks for the EPA/USDA Workshop on Bt Crop Resistance Management"


Mark Lipson
Organic Farming Research Foundation
June 18, 1999

Panel #1 (Refuge Design and Deployment)

I appreciate the invitation from EPA and USDA  to speak here and would like to acknowledge that they have made an effort to solicit participation from the organic sector.  Organic farmers do indeed have a stake in these issues and we expect to continue participating in the discussion and decision-making.  I suspect that there are still many misconceptions in this audience about organic agriculture, and I would have liked to address some of those issues, but we don’t have time for it today.  I have been a professional organic vegetable grower since 1983.  Over the last few years I have also been the Policy Program Director for the Organic Farming Research Foundation, working on national agricultural research policy.  You can find more information about the Foundation and its activities at www.ofrf.org.

From the perspective of an organic farmer with a policy habit on the side, it seems to me that there is basic confusion about the goal of EPA’s proposed resistance management policies.  Is the point of all this activity to actually prevent resistance or is it simply to try and delay it for a few years?  Is the assumption of eventual resistances built in?  I am not an entomologist but I have talked with a number of them, and every single one I have spoken with believes strongly that target pest resistance and loss of efficacy is only a matter of “when it will happen,” and not, “if it will happen.”   Yet, the EPA staff has stated clearly to me, “EPA is committed to preserving the Bt genes.”  I thought that meant having a meaningful program for preventing resistance, but I am not sure that is actually the case.

If there is an assumption that the Bt toxins will inevitably lose their efficacy through massive expression in transformed crops, this is unacceptable to the organic community.  This objection is based not just on direct self-interest, but also on general grounds of sound science policy. 

Microbial Bt spray products are important in organic management, and they are especially crucial in transitional systems.  As OFRF has documented in its National Organic Growers’ Survey, Bt-spray formulations are organic growers’ single most important off-farm input for insect pest management (1). For nine upper-Midwest states, the most recent National Survey results indicated that 25 percent (.25) of certified organic growers in these states use Bt “frequently” or “occasionally.”  For certified organic field crop producers in this region, the number is 20 percent, for organic fruit crops it is 52 percent, and for vegetable operations in this area 48 percent of the growers use Bt frequently or occasionally (2).

Given the obvious importance of Bt formulations to a wide range of organic growers in all regions of the country, a definitive commitment to preventing stable resistances, AND a high probability of success in doing so, are BOTH essential preconditions to the further use of these crops.  The uncertainties expressed in the scientific literature and policy papers do not encourage confidence that either of these requirements will be met, let alone both of them.

On the policy level, the language of the EPA/USDA Position Paper for this meeting is conspicuously ambivalent.  The Position Paper describes the structured refuge/high dose strategy as a “philosophy”  in other words a belief system, with the stress apparently on the “belief” part.  It goes on to say that if both conditions are met (effectively structured refuge AND high-dose expression), this approach, “has the potential to delay the development of resistance.”(3)  (My emphases).  To me, these carefully tentative statements raise the question of who is taking accountability for the efficacy of this strategy.  Is EPA taking on the liability for this scheme working?  Are the registrants responsible?  What tangible commitments, if any, are being made here?

On a scientific level, of course, many questions are still being raised about the efficacy of the IRM strategies.   One particular example I would like to note is an issue identified in the October, 1998 Supplement of the NC-205 Research Committee, regarding impacts on natural enemies.  The Committee states that,

Less attention has been paid to the potential effects of Bt corn on natural enemies in agricultural ecosystems…[T]his technology has the potential to have widespread and lasting impacts on beneficial insects...These effects could ripple through other crops and habitats in unpredictable ways…[I]t is unclear if 20-30% refuge is sufficient to mitigate negative impacts on natural enemies...(4)

This is not about concern for Monarch butterflies as an aesthetic value, as some of you might dismiss it.  This is about potentially undermining the ecological foundations of pest management in organic systems, as well as more mainstream bio-intensive integrated pest management (IPM) programs. The most basic tenet of resistance management is using multiple methods of control.  The NC-205 has identified here a significant risk to the most elegant, widest-ranging and lowest-cost system of pest management, but no consideration is being given to this in the policy statements or the proposed IRM plans.

On a practical level, the theoretical nuances of refugia design seem somewhat beside the point.   Despite the verbal commitments being made to “grower practicality,” organic growers that I have talked to are deeply skeptical about implementation of IRM plans. What they are seeing and hearing from their neighbors stirs a great deal of doubt about the willingness of growers to comply with refuge recommendations.   In some coffee shop discussions the idea of planting refuges to encourage target pest survival reportedly does not even pass the “laugh test.”  The magnitude of grower reluctance to implement this strategy is probably being greatly underestimated or simply discounted.

These are just a couple pieces of the evidence which suggest very strongly to me that there is neither a strong commitment to preventing target pest resistance in the Bt-crops, nor a high probability of success in maintaining pest susceptibility based on the so-called “high dose/structured refuge” philosophy. 


Remarks for Panel #3  Monitoring and Remediation
(Based on advance questions posed to speakers by EPA staff.)

Question: What should be the goals of IRM monitoring programs?

Within the context of an overall resistance prevention policy, the basic goal of monitoring programs must be to identify trends in susceptibility, on fine-grained scales of both time and geography.  That is, monitoring programs must be designed to provide rapid feedback on changes in susceptibility, and to show the patterns of these changes in detail on the landscape.          

In addition to this primary goal, there are at least two very important corollary goals for monitoring. The first corollary is to provide useful feedback to all participants about the performance of IRM methods.  Monitoring programs must be more than just a fire alarm that goes off when susceptibility has already begun to collapse.  Monitoring should be a tool to evaluate and improve IRM practices.

The second corollary is even more important.  The sampling and monitoring programs must be designed to contribute to basic knowledge of insect ecology, and to the optimization of Integrated Pest Management practices.  If the IRM monitoring efforts are not designed to be scientifically and administratively complementary to these wider efforts, then they likely will be competitive.  This would be tragically shortsighted, and would further compound the overall failure to utilize and improve the application of non-pesticidal, biological pest control. 

Question: What techniques should be used for resistance monitoring programs?

The method with the most precision  (apparently Dr. Siegfried’s F2 screen) should be the basis for a comprehensive national program, but that should not be the only monitoring system.  It is essential that monitoring be conducted by everybody, from the individual grower, to the county extension agents, to state university personnel.  

Question: What is an appropriate geographic frequency for sampling sites?

I think the order of magnitude should be close to one sampling program per county where the Bt crops are being commercially grown.  Resistance is likely to spread rapidly from just a few areas.  (Note also the finding of the NC-205 Committee in the October ’98 Supplement, regarding high levels of genetic isolation in ECB populations.)  (5)  If we are committed to preventing resistance, then a very fine scale of monitoring is essential to providing corrective action before it is too late.

If the idea of remedial action is being taken seriously (and I’m not at all sure that it is), it must be realized that the density of sampling sites will have a large effect on determining the geographical scope of remedial programs when a loss of susceptibility is detected.  If there are 500 miles between sampling sites, the common sense presumption has to be that you would impose remedial actions in at least a 250-mile radius around an isolated resistance “outbreak.”  Simply put, more sampling would mean more precision in applying the hypothetical remedial actions.

Question: What remedial actions should be taken in cases of confirmed resistance?

In this discussion so far, “remedial action” is a misnomer.  I have heard and read  general descriptions of plans for changing pest management methods when resistance is detected, but I have not seen any suggestions for actually reversing a loss of susceptibility in target pest populations.  As far as I can tell, the concept of remedial action is mostly a fig leaf for the fact that we don’t know what we will do when resistance begins occurring.  EPA should require much more specific detail and justification in this area in order to consider continuing the registrations.

I would like to suggest two areas of “reparatory” action to be implemented when resistance emerges.  First, someone will need to compensate organic growers and others if there is a loss of efficacy for the microbial spray formulations of Bt.  I realize that such a loss of efficacy is not necessarily going to be an outcome of resistance to the plant-expressed Bt toxins, but it may be, and someone is going to have to be accountable if this does happen.  As the saying goes, “if it’s a manageable risk, it’s an insurable risk.”  Indemnification for the loss of Bt as a tool in organic and IPM systems should be a required aspect of registration, perhaps in the form of a performance bond posted by the registrants.

Lastly, when the Bt toxins are used up and thrown away, the most significant needed action will be investment in non-pesticidal, ecologically based systems of agricultural production.  A fraction of the public investment made in developing and mitigating the Bt crops will produce vastly greater returns in pesticide use reduction, with comparable yields and other benefits.  The lack of such research investment (along with the associated historical disparagement of alternative systems) is the main limiting factor in their improvement and adoption.  Reformation of our agricultural research and extension systems should be the main corrective action taken when the inevitable ecological consequences of recombinant pesticidal crops come to pass.


Notes:

  1. Walz, E. Final Results of the Third Biennial National Organic Farmers’ Survey.  Organic Farming Research Foundation, Santa Cruz.  1999.  Page 80.

  2. Walz, E.  Unpublished regional breakout of data from the OFRF National Organic Farmers’ Survey.

  3. U.S. Environmental Protection Agency, Office of Pesticide Programs. “EPA and USDA Position Paper on Insect Resistance Management in Bt Crops.” June, 1999. Page 3. http://www.epa.gov/pesticides/biopesticides/otherdocs/Bt_ position_paper_618.htm

  4. NC-205 Regional Research Committee.  “Supplement to: Bt Corn & European Corn Borer: Long-Term Success Through Resistance Management, NCR-602.”  October 1998.  Page 6.

  5. Ibid., p. 5.


    Organic Farming Research Foundation
    Mark Lipson, Policy Program Director
    ph: 831-426-4006 or -6606; fax: 831-426-6670
    PO Box 440, Santa Cruz, CA 95061
    http://www.ofrf.org/policy/index.html

    ** NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is distributed for research and educational purposes only. **



Last Updated on 6/30/99
By Karen Lutz
Email: karen@biotech-info.net

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