Protein ecological safety evaluations

The needs of plant protection will compel continued innovation in the nature of transgenic plants developed using pesticidal proteins. Experience to date with plant-expressed insecticidal proteins provides guidance as to the fundamental framework for the ecological safety assessments for future products. This experience shows that assessments should rely on a core set of short-term, high-dose laboratory studies to broadly establish nontarget effects. Findings of these studies may warrant refined laboratory studies or monitoring as determined on a case-by-case basis for a given protein. A tiered strategy of testing and assessment allows for this case-by-case consideration and arrives at the appropriate stopping point for the assessment. Ecological entities of concern are the logical focus of the safety assessment. These entities are determined through a problem formulation that considers those nontarget species most likely to be sensitive to a particular protein and for which there is a reasonable likelihood of exposure as determined on the basis of biology and distribution. Therefore, exposure analysis to determine probable risk under environmentally relevant exposure scenarios is a critical facet of the ecological safety assessment.

This methodology has proven to be robust in considerations of insecticidal protein ecological safety through an appropriate consideration of risk within an ecological framework. This framework considers the nature of the plant-expressed pesticide and its deployment along with the characteristics of nontarget organisms of concern.

REFERENCES

1. Casida, J.E. and Quistad, G.B., Golden age of insecticide research: Past, present, or future? Ann. Rev. Entomol., 43, 1, 1998.

2. U.S. Department of Agriculture (USDA), Crop Production: Acreage Supplement, National Agricultural Statistics Service, Washington, D.C., http://usda.mannlib.cornell. edu/usda/current/Acre/Acre-09-12-2006.pdf, 2006, pp. 24-25 (accessed January 9, 2007).

3. International Service for the Acquisition of Agri-biotech Applications (ISAAA), Global status of commercialized biotech/GM crops: 2005, ISAAA Briefs 34-2005, http://www. isaaa.org/, 2006 (accessed January 9, 2007).

4. Estruch, J.J. et al., Vip3A, a novel Bacillus thuringiensis vegetative insecticidal protein with a wide spectrum of activities against lepidopteran insects, Proc. Natl. Acad. Sci. USA, 93, 5389, 1996.

5. Yu, C.G. et al., The Bacillus thuringiensis vegetative insecticidal protein Vip3A lyses midgut epithelium cells of susceptible insects, Appl. Environ. Microbiol., 63, 532, 1997.

6. Lee, M.K. et al., Mode of action of the Bacillus thuringiensis vegetative insecticidal protein Vip3A differs from that of Cry1Ab S-endotoxin, Appl. Environ. Microbiol., 69, 46484, 2003.

7. Blackburn, M. et al., A novel insecticidal toxin from Photorhabdus luminescens, toxin complex A (TCA), and its histopathological effects on the midgut of Manduca sexta, Appl. Environ. Microbiol., 64, 3036, 1998.

8. Bowen, D. et al., Insecticidal toxins from the bacterium Photorhabdus luminescens, Science, 280, 2129, 1998.

9. Liu D. et al., Insect resistance conferred by 283-kDa Photorhabdus luminescens protein TcdA in Arabidopsis thaliana, Nature Biotechnol., 21, 1222, 2003.

10. Wei, J.-Z. et al., Bacillus thuringiensis crystal proteins that target nematodes, Proc. Natl. Acad. Sci. USA, 100, 2760, 2003.

11. Head, G. and Dively, G.P., Impact of transgenic Bt crops on nontarget animal species, in Transgenic Crop Protection: Concepts and Strategies, Koul, O. and Dhaliwal, G.S., Eds., Science Publishers Inc., Enfield, NH, 2004.

12. O'Callaghan, M. et al., Effects of plants genetically modified for insect resistance on nontarget organisms, Annu. Rev. Entomol., 50, 271, 2005.

13. Zipf, A.E. and Rajasekaran K., Ecological impact of Bt cotton, J. New Seeds, 5, 115, 2003.

14. National Research Council (NRC), Risk Assessment in the Federal Government: Understanding the Process, National Academy Press, Washington, D.C., 1983.

15. Landis, W.G. and Yu. M., Ecological risk assessment, in Introduction To Environmental Toxicology, Lewis Publishers, Boca Raton, FL, 1999, pp. 287-314.

16. U.S. Environmental Protection Agency (EPA), Framework for Ecological Risk Assessment, Risk Assessment Forum, EPA/630/R-92/001, Washington, D.C., 1992.

17. U.S. Environmental Protection Agency (EPA), Ecological Risk Assessment Issue Papers, Risk Assessment Forum, EPA/630/R-94/009, Washington, D.C., 1994.

18. U.S. Environmental Protection Agency (EPA), Microbial Pesticide Test Guidelines: OPPTS 885.4340 — Nontarget Insect Testing, Tier I, EPA 712-C-96-336, http:// www.epa.gov/oppbppd1/biopesticides/regtools/guidelines/microbial_gdlns.htm, 1996 (accessed May 13, 2005).

19. U.S. Environmental Protection Agency (EPA), Guidelines for Ecological Risk Assessment, EPA/630/R-95/002F, Risk Assessment Forum and Office of Research and Development, Washington, D.C., 1998.

20. Society for Environmental Toxicology and Chemistry (SETAC), Aquatic Dialogue Group: Pesticide Risk Assessment and Mitigation, SETAC Foundation for Environmental Education, Pensacola, FL, 1994.

21. Dutton, A., Romeis, J. and Bigler, F., Assessing the risks of insect resistant transgenic plants on entomophagous arthropods: Bt-maize expressing Cry1Ab as a case study, BioControl, 48, 611, 2003.

22. Wilkinson, M.J., Sweet J., and Poppy G.M., Risk assessment of GM plants: Avoiding gridlock? Trends Plant Sci., 8, 2003.

23. National Research Council (NRC), Science and Judgment in Risk Assessment, National Academy Press, Washington, D.C., 1994.

24. Hellmich, R. et al., Monarch larvae sensitivity to Bacillus thuringiensis-purified proteins and pollen, Proc. Natl. Acad. Sci. USA, 98, 11925, 2001.

25. Hassan, S.A., The initiative of the IOBC/WPRS working group on pesticides and beneficial organisms, in Ecotoxicology: Pesticides and Beneficial Organisms, Haskell, P.T. and McEwen, P., Eds., Kluwer Academic, Dordrecht, The Netherlands, 1998, pp. 22-27.

26. Hassan, S.A., Standard laboratory methods to test the side-effects of pesticides, in Eco-toxicology: Pesticides and Beneficial Organisms, Haskell, P.T. and McEwen, P., Eds., Kluwer Academic, Dordrecht, The Netherlands, 1998, pp. 71-79.

27. U.S. Environmental Protection Agency (EPA), Pesticide Fact Sheet: Bacillus thuringiensis subspecies Cry1F Protein and the Genetic Material Necessary for Its Production (Plasmid Insert PHI 8999) in Corn, Office of Prevention, Pesticides, and Toxic Substances, Washington, D.C., http://www.epa.gov/pesticides/biopesticides/ingredients/ factsheets/factsheet_006481.pdf, 2001 (accessed May 3, 2004).

28. U.S. Environmental Protection Agency (EPA), Biopesticides Registration Action Document—Bacillus thuringiensis Plant-Incorporated Protectants, Office of Prevention, Pesticides, and Toxic Substances, http://www.epa.gov/pesticides/biopesticides/ pips/bt_brad.htm, 2001 (accessed May 3, 2004).

29. U.S. Environmental Protection Agency (EPA), Pesticide Fact Sheet: Bacillus thuringi-ensis Cry2Ab2 Protein and the Genetic Material Necessary for Its Production in Cotton (006487), http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/ factsheet_006487.htm, 2002 (accessed April 8, 2005).

30. U.S. Environmental Protection Agency (EPA), A Set of Scientific Issues Being Considered by the Environmental Protection Agency Regarding: Corn Rootworm Plant-incorporated Protectant Nontarget Insect and Insect Resistance Management Issues, Part A: Nontarget Issues, FIFRA Scientific Advisory Panel Meeting, Arlington, VA, August 27-29, 2002, http://www.epa.gov/scipoly/sap/atozindex/cornroot.htm, 2002 (accessed May 14,2004).

31. Canadian Food Inspection Agency (CFIA), Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits, Directive 94-08, Plant Products Directorate, Plant Biosafety Office, http://www.inspection.gc.ca/english/plaveg/bio/ dir/dir9408e.shtml, 2004 (accessed May 13, 2005).

32. European Commission (EC), Guidance Document for the Risk Assessment of Genetically Modified Plants and Derived Food and Feed, 6-7 March 2003, Health and Consumer Protection Directorate-General, http://europa.eu.int/comm/food/fs/sc/ssc/ out327_en.pdf, 2003 (accessed May 13, 2005).

33. Ministry of Agriculture, Forestry and Fisheries (MAFF), Guidelines for Application of Recombinant DNA Organisms in Agriculture, Forestry and Fisheries, the Food Industry and Other Related Industries, MAFF, Tokyo, 1989.

34. Glare, T.R., and O'Callaghan, M. Bacillus thuringiensis: Biology, Ecology and Safety, John Wiley & Sons, New York, 2000.

35. Kumar, P.A., Sharma, R.P. and Malik, V.S., The insecticidal proteins of Bacillus thuringiensis, Adv. Appl. Microbiol., 42, 1, 1997.

36. Mizuki, E. et al., Ubiquity of Bacillus thuringiensis on phylloplanes of arboreous and herbaceous plants in Japan, J. Appl. Microbiol., 86, 979, 1999.

37. Holt, J.G. et al., Bergey's Manual of Determinative Bacteriology, 9 th edition, Williams and Williams, Baltimore, 1993.

38. Crickmore, N. et al., Revision of the nomenclature for the Bacillus thuringiensis insecticidal crystal proteins, Microbiol. Mol. Biol. Rev., 62, 807, 1998.

39. Martin, P.A.W., and Travers, R.S., Worldwide abundance and distribution of Bacillus thuringiensis isolates, Applied Environ. Microbiol., 55, 2437, 1989.

40. U.S. Environmental Protection Agency (EPA), Reregistration Eligibility Decision (RED): Bacillus thuringiensis, EPA738-R-98-004, Office of Prevention, Pesticides, and Toxic Substances, Washington, D.C., 1998.

41. Schnepf, H.E. et al., Characterization of Cry34/Cry35 binary insecticidal proteins from diverse Bacillus thuringiensis stain collections, Appl. Environ. Microbiol., 71, 1765, 2005.

42. Höfte, H., and Whiteley, H.R., Insecticidal crystal protein of Bacillus thuringiensis, Microbiol. Rev, 53, 242, 1989.

43. Gill, S., Cowles, E., and Pietrantonio, P., The mode of action of Bacillus thuringiensis endotoxins, Annu. Rev. Entomol., 37, 615, 1987.

44. Chambers, J.A. et al., Isolation and characterization of a novel insecticidal crystal protein gene from Bacillus thuringiensis subsp. Aizawai, J. Bacteriol., 173, 3966, 1991.

45. Sims, S.R., Bacillus thuringiensis var. kurstaki (CryIA(c)) protein expressed in transgenic cotton: Effects on beneficial and other nontarget insects, Southwest. Entomol., 20, 493, 1995.

46. Huber, H.E., and Lüthy, P., Bacillus thuringiensis delta-endotoxin: Composition and activation, in Pathogenesis of Invertebrate Microbial Diseases, Davidson, E.D., Ed., Allanheld, Osmum and Co. Pub., Totowa, NJ, 1981.

47. Agbios, Case Studies: MON 810 Environmental Risk Assessment Case Study, http:// www.agbios.com/cstudies.php, 2005 (accessed April 8, 2005).

48. Pleasants, J. et al., Corn pollen deposition on milkweeds in and near cornfields, Proc. Natl. Acad. Sci. USA, 98, 1191, 2001.

49. Miller, J., Field assessment of the effects of a microbial pest control agent on nontarget Lepidoptera, Am. Entomol., 36, 135, 1990.

50. Johnson, K. et al., Toxicity of Bacillus thuringiensis var. kurstaki to three nontarget Lepidoptera in field studies, Environ. Entomol., 24, 288, 1995.

51. Navon, A., Control of lepidopteran pests with Bacillus thuringiensis, in Bacillus thuringiensis, an Environmental Biopesticide: Theory and Practice, Entwistle, P. et al., Eds., Wiley, New York, 1993, pp. 125-146.

52. Wagner, D. et al., Field assessment of Bacillus thuringiensis on nontarget Lepidoptera, Environ. Entomol., 25, 1444, 1996.

53. Losey, J., Rayor, L. and Carter, M., Transgenic pollen harms Monarch larvae, Nature, 399, 214, 1999.

54. Jesse, L., and Obrycki, J., Field deposition of Bt transgenic corn pollen: Lethal effects on the Monarch butterfly, Oecologia, 125, 241, 2000.

55. Oberhauser, K. et al., Temporal and spatial overlap between Monarch larvae and corn pollen, Proc. Natl. Acad. Sci. USA, 98, 11913, 2001.

56. Stanley-Horn, D. et al., Assessing the impact of Cry1Ab-expressing corn pollen on Monarch butterfly larvae in field studies, Proc. Natl. Acad. Sci. USA, 98, 11931, 2001.

57. Anderson, P.L. et al., Effects of CrylAb-expressing corn anthers on Monarch butterfly larvae, Environ. Entomol., 33, 1109, 2004.

58. Wolt, J.D. et al., A screening level approach for nontarget insect risk assessment: Transgenic Bt corn pollen and the Monarch butterfly (Lepidoptera: Danaiidae), Environ. Entomol., 32, 237, 2003.

59. Sears, M. et al., Impact of Bt corn pollen on Monarch butterfly populations: A risk assessment, Proc. Natl. Acad. Sci. USA, 98, 1193, 2001.

60. Dively, G.P. et al., Effects on Monarch butterfly larvae (Lepidoptera: Danaidae) after continuous exposure to Cry1Ab-expressing corn during anthesis, Environ. Entomol., 33, 1116, 2004.

61. Hilbeck, A. et al., Effects of transgenic Bacillus thuringiensis corn-fed prey on mortality and development time of immature Chrysoperla carnea (Neuroptera: Chrysopidae), Environ. Entomol., 27, 480, 1998.

62. Dutton, A. et al., Uptake of Bt-toxin by herbivores feeding on transgenic maize and consequences for the predator Chrysoperla carnea, Ecol. Entomol., 27, 441, 2002.

63. Head, G. et al., Cry1Ab protein levels in phytophagous insects feeding on transgenic corn: Implications for secondary exposure risk assessment, Entomol. Exp. Appl, 99, 37, 2001.

64. Raps, A. et al., Immunological analysis of phloem sap of Bacillus thurigiensis corn and of the nontarget herbivore Rhopalosiphum padi (Homoptera: Aphididae) for the presence of Cry1Ab, Molec. Ecol, 10, 525, 2001.

65. Jepson, P.C., Croft, B.A. and Pratt. G.E., Test systems to determine the ecological risks posed by toxin release from Bacillus thuringiensis genes in crop plants, Molec. Ecol., 3, 81, 1994.

66. Tapp, H. and Stotzky. G., Persistence of the insecticidal toxin from Bacillus thuringiensis subsp. Kurstaki in soil, Soil Biol. Biochem., 30, 471, 1998.

67. Saxena, D.S., Flores, S. and Stotzky, G., Insecticidal toxin in root exudates from Bt corn, Nature, 402, 480, 1999.

68. Angle, J.S., Release of transgenic plants: Biodiversity and population-level considerations, Molec. Ecol., 3, 45, 1994.

69. Sims, S.R., and Holden, L.R., Insect bioassays for determining soil degradation of Bacillus thuringiensis subsp. kurstaki Cry1A(b) protein in corn tissue, Environ. Ento-mol., 25, 659, 1996.

70. Herman, R.A., Wolt, J.D. and Halliday, W.R., Rapid degradation of the Cry1F insecticidal crystal protein in soil, J. Agric. Food Chem., 50, 7076, 2002.

71. Hopkins, D.W. and Gregorich, E.G., Detection and decay of the Bt endotoxin in soil from a field trial with genetically modified maize, Eur. J. Soil Sci., 54, 793, 2003.

72. New York Department of Environmental Conservation (NYDEC), Registration of One New Pesticide Product, Yieldgard Rootworm™ Rootworm Protection (EPA Reg. No. 524-528), Which Contains the New Active Ingredient: Bacillus thuringiensis Cry3Bb1, http://pmep.cce.cornell.edu/profiles/biopest-biocont/pip/bacillus_thur/bacil-lus_cry3Bb1_let_204.html, 2004 (accessed April 12, 2005).

73. U.S. Environmental Protection Agency (EPA), Preliminary Risk Assessment for Soil, Soil Surface and Foliar Invertebrates for Bacillus thuringiensis Cry3Bb Protein, EPA Reg. No. 524-LEI; Barcode No. D262045; Case No. 066221; Submission No. S572997, submitted by Monsanto Co. for corn containing Bacillus thuringiensis Cry3Bb protein and the genetic material necessary for its production (vector ZMIR13L), http://www. epa.gov/oscpmont/sap/2002/august/7-23-2002_overall_terr_invert_preliminary_ review_mon_863_conr.pdf, 2002 (accessed April 12, 2005).

74. U.S. Environmental Protection Agency (EPA), Bacillus thuringiensis Cry34Ab1 and Cry35Ab1 Proteins and the Genetic Material Necessary for Their Production (Plasmid Insert PHP 17662) in Event DAS-59122-7 Corn, http://epa.gov/pesticides/biopesti-cides/ingredients/tech_docs/brad_006490.pdf, 2005 (accessed January 24, 2007).

75. Kromp, B., Carabid beetles in sustainable agriculture: A review on pest control efficacy, cultivation impacts and enhancement, Agric. Ecosys. Environ., 74, 187, 1999.

76. Andersen, A., and Eltun, R., Long-term developments in the carabid and staphylinid (Carabidae and Staphylinidae) fauna during conversion from conventional to biological farming, J. Appl. Entomol., 124, 51, 2000.

77. Honek, A. and Jarosik, V., The role of crop density, seed and aphid presence in diversification of field communities of Carabidae (Coleoptera), Eur. J. Entomol., 97, 517, 2000.

78. Esau, K., and Peters, D., Carabidae collected in pitfall traps in Iowa cornfields, fence-rows, and prairies, Environ. Entomol., 4, 509, 1975.

79. Ferguson, H., and McPherson, R., Abundance and diversity of adult Carabidae in four soybean cropping systems in Virginia, J. Entomol. Sci., 20, 163, 1985.

80. Ellsbury, M. et al., Diversity and dominant species of ground beetle assemblages (Coleoptera: Carabidae) in crop rotation and chemical input systems for the northern Great Plains, Ann. Entomol. Soc. Am., 91, 619, 1998.

81. Byers, R. et al., Richness and abundance of Carabidae and Staphylinidae (Coleoptera), in northeastern dairy pastures under intensive grazing, Great Lakes Entomol., 33, 81, 2000.

82. Herman, R.A., Scherer, P.N. and Wolt., J.D., Rapid degradation of a binary, PS149B1, S-endotoxin of Bacillus thuringiensis in soil, and a novel mathematical model for fitting curve-linear decay, Environ. Entomol., 31, 208, 2002.

83. Duan J.J. et al., Evaluation of dietary effects of transgenic corn pollen expressing Cry3Bb1 protein on a nontarget ladybird beetle, Coleomegilla maculate, Entomol. Exp. Appl., 104, 271, 2002.

84. Lundgren, J.G. and Wiedenmann, R.N., Coleopteran-specific Cry3Bb toxin from trans-genic corn pollen does not affect the fitness of a nontarget species, Coleomegilla macu-lata DeGeer (Coleoptera: Coccinellidae), Environ. Entomol., 31, 1213, 2003.

85. Al-Deeb, M., and Wilde, G., Effect of Bt corn expressing the Cry3bb1 toxin for corn rootworm control on aboveground nontarget arthropods, Environ. Entomol., 32, 1164, 2003.

86. Al-Deeb, M. et al., Effect of Bt corn for corn rootworm control on nontarget soil micro-arthropods and nematodes, Environ. Entomol., 32, 859, 2003.

87. Ahmad, A., Wilde G.E., Whitworth R.J., and Zolnerowich G., Effect of corn hybrids expressing the coleopteran-specific Cry3bb1 protein for corn rootworm control on aboveground insect predators, J. Econ. Entomol., 99, 1085, 2006.

88. Head, G. et al., Cry1Ac protein levels in soil after multiple years of transgenic (Boll-gard) use: Implications for environmental risk to soil dwelling organisms, Environ. Entomol., 31, 30, 2002.

89. Ponsard, S., Gutierrez, A, and Mills, N., Effect of Bt-toxin (Cry1Ac) in transgenic cotton on the adult longevity of four heteropteran predators, Environ. Entomol., 31, 1197, 2002.

89. Liu, X.X. et al., Effects of Bt transgenic cotton lines on the cotton bollworm parasitoid Microplitis mediator in the laboratory, Biological Control, 35, 134, 2005.

90. Naranjo, S.E. and Ellsworth, P.C., Looking for Functional Nontarget Differences between Transgenic and Conventional Cottons: Implications for Biological Control, Arizona Cotton Report, University of Arizona, http://ag.arizona.edu/pubs/crops/ az1283, 2002 (accessed March 14, 2005).

91. Hardee D.D., and Bryan. W.W., Influence of Bacillus thuringiensis-transgenic and nec-tarless cotton on insect populations with emphasis on the tarnished plant bug (Heterop-tera: Miridae), J. Econ. Entomol., 90, 663, 1997.

92. Men, X. et al., Diversity of arthropod communities in transgenic Bt cotton and non-transgenic cotton agroecosystems, Environ. Entomol., 32, 270, 2003.

93. Cattaneo, M.G. et al., Farm-scale evaluation of the impacts of transgenic cotton on biodiversity, pesticide use, and yield, Proc. Natl. Acad. Sci. USA, 103, 7571, 2006.

94. Office of the Gene Technology Regulator (OGTR), Risk Assessment and Risk Management Plan: Commercial Release of Insecticidal (INGARD® Event 531) Cotton, Dir 021/2002. Woden, ACT, Australia, http://www.ogtr.gov.au/dir022.htm, 2003 (accessed March 18, 2005).

95. U.S. Department of Agriculture (USDA), Approval of Mycogen/Dow Petitions 03-036-01p and 03-036-02p Seeking Determinations of Nonregulated Status for Insect-resistant Cotton Events 281-24-236 and 3006-210-23 Genetically Engineered to Express Synthetic B.t. Cry1F and CrylAc, Respectively, Environmental Assessment and Finding of No Significant Impact, Biotechnology Regulatory Services, July 2004, 03-036-01p_com and 03-036-02p_com., http://www.aphis.usda.gov/brs/not_reg.html, 2004 (accessed March 14, 2005).

96. U.S. Environmental Protection Agency (EPA), Environmental Effects Assessment for WideStrike™, MXB-13 Cotton Line Expressing Bacillus thuringiensis var. aiza-wai Cry1F (synpro) and Bacillus thuringiensis var. kurstaki Cry1Ac (synpro) Stacked Insecticidal Crystalline Proteins as Part of Dow AgroSciences LLC Application for a FIFRA Section 3 Registration, EPA Reg. No.68467-G, http://www.epa.gov/scipoly/ sap/2004/#june, 2004 (accessed March 14, 2005).

97. Office of the Gene Technology Regulator (OGTR), Agronomic Assessment and Seed Increase of Transgenic Cottons Expressing Insecticidal Genes (cry1Ac and cry1Fa) from Bacillus thuringiensis, Dir 044/2003. Woden, ACT, Australia, http://www.ogtr. gov.au/ir/dir044.htm, 2003 (accessed April 7, 2005).

98. Wold, S. et al., In-field monitoring of beneficial insect populations in transgenic corn expressing a Bacillus thuringiensis toxin, J. Entomol. Sci., 36, 177, 2001.

99. Orr, D. and Landis D., Oviposition of European corn borer (Lepidoptera: Pyralidae) and impact of natural enemy populations in transgenic versus isogenic corn, J. Econ. Entomol., 90, 905, 1997.

100. Pilcher, C. et al., Preimaginal development, survival, and field abundance of insect predators on transgenic Bacillus thuringiensis corn, Environ. Entomol., 26, 446, 1997.

101. Jasinski, J. et al., Select nontarget arthropod abundance in transgenic and nontrans-genic field crops in Ohio, Environ. Entomol., 32, 407, 2003.

102. Gould, F., Sustainability of transgenic insecticidal cultivars: Integrating pest genetics and ecology, Annu. Rev. Entomol., 43, 701, 1998.

103. Tabashnik, B.E., and Croft, B.A., Managing pesticide resistance in crop-arthropod complexes: Interactions between biological and operational factors, Environ. Entomol., 11, 1137, 1982.

104. Gould, F., Simulation models for predicting durability of insect-resistant germplasm: A deterministic diploid, two-locus model, Environ. Entomol., 15, 1, 1986.

105. Roush, R.T., Managing pests and their resistance to Bacillus thuringiensis: Can transgenic crops be better than sprays? Biocontrol Science and Technology, 4, 501, 1994.

106. Roush, R.T., Two-toxin strategies for management of insecticidal transgenic crops: Can pyramiding succeed where pesticide mixtures have not? Phil. Trans. R. Soc. Lond. B, 353, 1777, 1998.

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