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Insect Resistance Management

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A Commitment to Sustaining Productivity and Profitability

Monsanto Company is committed to enhancing grower productivity and profitability through the commercialization of new seed technologies. Insect-protected crops containing Bacillus thuringiensis (Bt) technology provide significant grower benefits that require effective insect resistance management (IRM) programs. For this reason, Monsanto strongly promotes responsible product stewardship, including implementation of effective and practical IRM plans. In this fact sheet we provide basic information on insect resistance and the multiple measures that Monsanto takes to combat it.

Insect Resistance

Resistant insects inherit the ability to be less affected by a control tactic, relative to normal, susceptible insects. Resistance becomes a practical problem when the proportion of resistant insects in a field reaches sufficiently high levels that it noticeably reduces profitability of crop production. Over time, resistance has developed to most pest control tactics. However, it has been only in the past two decades that IRM programs have been aggressively developed and implemented proactively to minimize the risk of insect resistance before it has become a problem in the field.

Insect Resistance Management (IRM)

IRM comprises a mixture of approaches and tools required to prevent or delay the development of insect resistance. Proactive resistance management focuses on preserving susceptibility of the pest population, using detailed knowledge of the impacts that farming practices, crops, weeds and other components of the farm environment have on pest abundance and survival. The IRM plans for each of Monsanto’s Bt products also include extensive baseline investigations followed by yearly monitoring of target pest susceptibility, educational programs to ensure grower understanding of the plans, annual surveys of on-farm compliance, and strategies to mitigate resistance, if and when it is found.

Refuges and Their Role in IRM

Refuges provide the foundation on which IRM is based for crops containing Bt technology. Refuges function as highly productive sources of susceptible target insects in the vicinity of Bt crop fields. A refuge, in its simplest form, is simply a block or strip of the crop that does not contain a Bt technology for controlling the targeted insect pests. The susceptible insects produced in refuges mate with rare resistant insects emerging from Bt crops. This ensures that the offspring of resistant individuals remain susceptible to Bt crops, thus preserving the long-term effectiveness of Bt technology, as well as the benefits it provides to growers. Other crops and naturally-occurring plants such as weeds may also serve as important “natural” refuges for susceptible insects.

Twelve Years without Field Resistance Problems

Monsanto registered Bt cotton and Bt corn in 1996. Outstanding economic benefits drove adoption to > 50% of acreage in most areas, and > 70% in areas where yield losses from pests was greatest. Despite sustained high levels of use of Bt technology in most major cotton- and corn-producing states, no cases of field resistance have yet been documented in the continental USA. Thus, agriculture has benefitted from over a decade of use of Bt cotton and Bt corn, without resistance problems. Even with this success, Monsanto continues to invest in IRM globally, including monitoring of resistance throughout the world, so that potential resistance cases can be detected and responded to in their early stages of development, and appropriate adjustments can be made in IRM recommendations. Moreover, Monsanto is making large investments into new generations of seed technologies with reduced resistance risk, achieved by incorporation of multiple Bt toxins into crops. These will provide even better pest protection and yield enhancement, as well as tools for overcoming future resistance problems, if and when they occur.

Claims of Insect Resistance To Bt Crops

As stated above, there have been no confirmed cases of poor field performance of Bt cotton or Bt corn attributable to insect resistance. Field resistance is the criterion of relevance to agricultural producers. Resistance to Bt toxins has been isolated in the laboratory in some insect pests of cotton and corn. This has demonstrated unquestionably that some insects have the genetic potential to develop resistance. However, to result in reduced pest protection in the field insects must possess potent resistance mutations and be ecologically competitive (i.e., not have major fitness costs) and occur in an agro-ecosystem that permits their survival.

IRM strategies, most notably the maintenance of refuges and expression of effective doses of Bt toxin in plants, are specifically designed to reduce the survival of resistant pests. In this manner Monsanto’s large investments into resistance management have achieved their goal for over a decade of intensive use of Bt crops.

References

  1. 1999. EPA and USDA Position Paper On Insect Resistance Management in Bt Crops. Environmental Protection Agency. 5-27-1999. 1-15.
  2. Alexander, C. 2007. Insect Resistance Management Plans: The Farmers' Perspectives. AgBioForum. 10(1): 33-43.
  3. Banerjee, S., Martin, S. 2008. An Estimation of Producer Returns from Bt Cotton with Varying Refuge Sizes. Crop Protection. 27: 1003-1008.
  4. Bel, Y., Siqueira, H., Siegfried, B., Ferre, J., Escriche, B. 2009. Variability in the cadherin Gene in an Ostrinia nubilalis Strain Selected for Cry1Ab Resistance. Insect Biochemistry and Molecular Biology. 39: 218-223.
  5. Bommireddy, P., Leonard, B. 2008. Survivorship of Helicoverpa zea and Heliothis virescens on Cotton Plant Structures Expressing a Bacillus thuringiensis Vegetative Insecticidal Protein. Journal Economic Entomology. 101(4): 1244-1252.
  6. Bourguet, D., Desquilbet, M., Lemarie, S. 2005. Regulating Insect Resistance Management - The Case of Non-Bt Corn Refuges in the US. Journal of Environmental Management. 76(3): 210-220.
  7. Crowder, D., Onstad, D., Gray, M. 2006. Planting Transgenic Insecticidal Corn Based on Economic Thresholds: Consequences for Integrated Pest Management and Insect Resistance Management. Journal of Economic Entomology. 99(3): 899-907.
  8. Griko, N., Zhang, X., Ibrahim, M., Midboe, E., Bulla Jr., L. 2008. Susceptibility of Manduca sexta to Cry1Ab Toxin of Bacillus thuringiensis Correlates Directly to Developmental Expression of the Cadherin Receptor BT-R1. Comparative Biochemistry and Physiology Part B. 151: 59-63.
  9. Hanson, B., Shrestha, A., Shaner, D. 2009. Distribution of Glyphosate-resistant Horseweed (conyza Canadensis) and Relationship to Cropping Systems in the Central Valley of California. Weed Science. 57(1): 48-53.
  10. Head, G. 2004. Adapting Insect Resistance Management Strategies for Transgenic Bt Crops to Developing World Needs. 8th Interntional Symposium on the Biosafety of Genetically Modified Organisms, Montpellier, France. September 26-30, 2004. Pages 16-26.
  11. Head,G. 2004. Insect Resistance Management for Transgenic Bt Crops. CAST Special Publication No. 24: 66-68.
  12. Huang, F., Leonard, B., Moore, S., Cook, D., Bladwin, J., Tindall, K., Lee, D. 2008. Allele Frequency of Resistance to Bacillus thuringiensis Cry1Ab Corn in Louisiana Populations of Sugarcane Borer (Lepidoptera: Crambidae). Journal of Economic Entomology. 101(2): 492-498.
  13. Hubert, J., Nesvorna, M., Zemek, R., Stara, J., Stejskal, V. 2008. Effects of Metabolic Inhibitors on Activity of Cry1Ab Toxin to Inhibit Growth of Ephestia kuehniella Larvae. Pest Management Science. 64: 1063-1068.
  14. ISAAA. 2009. The Dawn of a New Era-Biotech Crops in India. ISAAA. 39 pages.
  15. Meinke, L., Sappington, T., Onstadt, D., Guillemaud, T., Miller, N., Komaromig, J., Levay, N., Furlan, L., Kiss, J., Toth, F. 2009. Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) Population Dynamics. Agriculture and Forest Entomology. 11: 29-46.
  16. Meissle, M., Pilz, C., Romeis, J. 2009. Susceptibility of Diabrotica virgifera virgifera (Coileoptera-Chrysomelidae) to the Entomopathogenic Fungus Metarhizium anisopliae when Feeding on Bacillus thruingiensis Cry3Bb1-Expressing Maize. Applied and Environmental Microbiology. 75(12): 3937-3943.
  17. Miller, N., Guillemaud, T., Giordano, R., Siegfried, B., Gray, M., Meinke, L., Sappington, T. 2009. Genes, Gene Flow and Adaptation of Diabrotica virgifera virgifera. Agriculture and Forest Entomology. 11: 47-60.
  18. Moser, S., Harwood, J., Obrycki, J. 2008. Larval Feeding on Hybrid and Non-Bt Corn Seedlings armonia axyridis -Coleoptera: Coccinellidae- and Coleomegilla maculata (Coleoptera: Coccinellidae). Environmental Entomology. 37(2): 525-533.
  19. Prasifka, J., Hellmich, R., Sumerford, D., Siegfried, B. 2009. Bacillus thuringiensis Resistance Influences European Corn Borer -Lepidoptera: Crambidae- Larval Behavior after Exposure to Cry1Ab. Journal Economic Entomology. 102(2): 781-787.
  20. Preston, C., Belles, D., Westra, P., Nissen, S., Ward, S. 2009. Inheritance of Resistance to the Auxinic Herbicide Dicamba in Kochia (kochia Scoparia). Weed Science 57(1): 43-47.
  21. Price, J., Hyde, J., Calvin, D. 2006. Insect Resistance Management for Bt Corn - An Assessment of Community Refuge Schemes. AgBioForum. 9(3): 129-138.
  22. Sena, J., Hernandez-Rodriguez, C., Ferre, J. 2009. Interaction of Bacillus thuringiensis Cry1 and Vip3A Proteins with Spodoptera frugiperda Midgut Binding Sites. Applied and Environmental Microbiology 75(7): 2236-2237.
  23. Spencer, J., Hibbard, B., Moeser, J., Onstad, D. 2009. Behaviour and Ecology of the Western Corn Rootworm (diabrotica Virgifera Virgifera Leconte). Agricultural and Forest Entomology 11(1): 9-27.
  24. Srinivasan, R., Yun-Che, H. 2008. Susceptibility of Major Lepidopterans to delta-endotoxins and a Formulation of Bacillus thuringiensis on Vegetable brassicas in Taiwan. Biocontrol Science and Technology 18(9): 935-939.
  25. Tyutyunov, Y., Zhadanovskaya, E., Bourguet, D., Arditi, R. 2008. Landscape Refuges Delay Resistance of the European Corn Borer to Bt-maize - A Demo-genetic Dynamic Model. Theoretical Population Biology 74: 138-145.