Solving the RIDL of Sustainable Bt Corn Use: Stepping Off the Biotechnology Treadmill

1. Solving the RIDL of Sustainable Bt Corn Use: Stepping Off the Biotechnology Treadmill Trends in Corn IPM Research: NCB ESA Symposium Paul D. Mitchell and Zhe Dun Ag & Applied Economics, UW-Madison March 14, 2011 Minneapolis, MN

2. Overview • Benefits and impacts of Bt corn • Biotechnology Treadmill, IRM and the need for resistance mitigation research • Genetic Pest Management • Release of Insects carrying a Dominant Lethal (RIDL) • Preliminary exploratory model results

3. Source: Hutchison et al. (2010)

4. % Acres Triple Stack Bt Corn in 2009(Based on Biotech Endorsement Crop Insurance) > 40% 30%-40% 20-30% 10%-20% < 10%

5. Source: http://www.ers.usda.gov/briefing/biotechnology/chapter1.htm

6. Bt Corn Adoption Rate by State

7. ECB Population Data 1940 to 2009

8. ECB Population Data Since 1990

9. Bt Corn in the USA • $2.5 billion cumulative Bt corn benefit for Bt acres in MN, WI, IL, IA & NE since 1996 • $1.7 billion cumulative Bt corn tech fees paid for Bt corn in MN, WI, IL, IA & NE since 1996 • Widespread planting of Bt corn has suppressed the European corn borer (Ostrinia nubilalis: ECB) population in Midwest • $4.3 billion cumulative Bt corn benefit for non-Bt acres in MN, WI, IL, IA & NE since 1996 • 63% of Bt benefit to farmers went to non-Bt acres due to ECB suppression • $920 million annual average for farmers (2007-2009), rising to $1.05 billion once include tech fees

10. Cumulative Benefits MN, WI, IL

11. With Tech Fee, Total Cumulative Benefit about $8.5 Billion in MN, WI, IL, IA, and NE, with Bt and Non-Bt Each about Half

12. Price Effects of Bt corn • Bt corn has increased corn supply and so reduced market price of corn: • 10-25% lower corn prices due to Bt corn • With a base price $7/bu, means $0.50 to $1.40/bu • Higher corn prices means more corn acres (less CRP, pasture and cereals) • Working on broader model for more definitive estimate of price effects

13. Main Point • Bt corn is popular • Bt corn is valuable • Bt corn farmers • Seed/Biotech companies • Non-Bt corn farmers • Consumers • Environment • Losing Bt corn more costly than many realize

14. “Biotechnology Treadmill” and Insect Resistance Management • High-dose/Refuge strategy for delaying insect resistance to Bt crops • Successful? Compare Bt crops to RR crops • Recent changes to lower refuge amounts, seed mixtures and pyramided traits • Has IRM become riskier? Onstad et al. (2011) • Can only avert the inevitable for so long • IRM goal has always been to delay resistance, not to prevent resistance • IRM only slows speed of the biotechnology treadmill – it does not stop the treadmill

15. Insect Resistance to Bt Toxin • Populations with confirmed field resistance to Bt toxin in a Bt crop • Fall Armyworm (Spodoptera frugiperda) in Puerto Rico to Cry1F in Bt corn • Stem Borer (Busseola fusca) in South Africa to Cry1Ab I Bt corn • Cotton Bollworm (Helicoverpa zea) in AR/MS to Cry1Ac in Bt cotton • Cotton Bollworm (Helicoverpa armigera) in China to Cry1Ac in Bt cotton • More in lab and others in non-GM uses

16. Resistance Mitigation • Product Registration in US requires remedial action plans once field resistance confirmed • Use of alternative modes (chemical, cultural) that year and in subsequent years • End sales of product in the area • Used in Puerto Rico for FAW • Develop “Case-Specific” Mitigation Action Plan • Really no details except “potentially including layering of technologies”

17. Trends in Corn IPM Research: Resistance Mitigation Research • Little research on Resistance Mitigation for chemical insecticides or for Bt crops • Most practices and plans rely on mixing and/or rotating modes of action and use of synergists • Goal is to reduce survival of resistant insects • Doesn’t stop the treadmill, just slows it down • More research now is a good idea, to get ready for problems with Bt crops (and other MOA) • Cost to register new pesticides quite high and growing, harder to find new modes of action • Larry Buschman’s presentation: Oviposition deterrence

18. Trends in Corn IPM Research: Resistance Mitigation Research • Which strategies are most effective for mitigating resistance under what conditions? • Which strategies are most economical for mitigating resistance under what conditions? • Are there new strategies that we can use? • Is it possible to stop the “biotechnology treadmill” and have sustainable Bt use? • Start addressing these questions, before we lose some valuable Bt crop technologies

19. Trends in Corn IPM Research: Genetic Pest Management (Gould 2008) • Sterile Insect Technique (SIT): beginning of genetic methods for managing pests • Irradiate males so progeny die as eggs, then release enough to swamp native male population • SIT successes: screw worm, Medfly, etc. • More sophisticated methods explored theoretically & implemented on small scales • Vanderplank and tsetse fly in Tanzania • Several explore “underdominance” systems • No practical applications of these to SIT

20. Trends in Corn IPM Research: Genetic Pest Management (Gould 2008) • Molecular biology developed new methods: • Medea Element: ZZmale x ZMfemale normally gives pM = 25% allele frequency, but with Medea Element, only ZM survive, so pM≈ 50% • Link to other genes to drive useful alleles to higher frequencies in population: • Focus on insect-vectored diseases: drive refractory gene into insect population • Reduce fitness of pest populations • Why not Bt susceptibility?

21. Trends in Corn IPM Research: RIDL Release of Insects carrying a Dominant Lethal • Series of papers associated with Luke Alphey starting in 2000 in Science • RIDL: release homozygous dominant lethal (LL) into population of wild types (ww) • RIDLmales(LL) x Wildfemale(ww) • F1: all Lw so 100% F1 females die • F2: Lw x ww so 50% F2 females die • F3: Lw x ww so 50% F3 females die

22. RIDL Graphics (Alphey et al. 2007) F2: Lw x ww 50% Lw, all females die 50% ww, all females live F3: Same outcome F1 Figure 1 in Alphey et al. (2007)

23. Trends in Corn IPM Research: RIDL • SIT: release males causing fatality of progeny, but does not introgress useful genes • RIDL: Use L alone to manage population, but with smaller release rates than SIT • Alternative: Link desired allele(s) to the L allele and introgress useful genes • Insect vectored disease refractory genes • Oxitec (Alphey) transgenic mosquito releases in Caribbean in Sept 2009 for Dengue Fever • Bt toxin susceptibility: JEE 2007, 2009

24. RIDL for Sustainable Bt Corn Use(Alphey et al. 2007, 2009) • Theoretically, use RIDL to get any desired resistance allele frequency and population • Choose refuge % and RIDL release ratio, based on pest ecology, population dynamics, and genetic parameters • Can step off the “Biotechnology Treadmill” • No economics in the analysis

25. Preliminary Exploratory Model • Building Alphey et al. model to replicate results and then do new work • Basic model working • Bt and non-Bt patches, random mating, relative fitness, dominance, etc. • Start at 10% resistance allele frequency (i.e., field resistance observed) • Only releasing ss adults, not LLss adults • Not true RIDL yet, just mass release • “Mass Released Refuge”

27. 0% refuge

28. 10% refuge

29. Preliminary Economic Analysis • Revenue minus costs from Bt and non-Bt crop and for releasing RIDL insects • Revenue = PY[b(1 – lb) + (1 – b)(1 – ln)] • Cost = K + bT + Cridl(dN) • P = price, Y = pest free yield, b = % Bt • l = % yield loss, Subscript b for Bt, n for non Bt, depends on pest population on each • K = cost, T = tech fee • Cd(dN) = cost per RIDL insect (convex)

33. Preliminary Results • Conceptually, can use mass release for sustainable management of pest population and resistance • Pulsed release of ss/RIDL insects • Initially knock down resistance, then use RIDL to manage population • Threshold (when) and how many to release depend on biological and economic parameters • Lower optimal release ratio than for SIT • Pulsing comparable to Onstad’s presentation idea of using Bt corn every 2 or 3 years instead of continuously • Many practical and technical issues to address

34. Some of the Questions to Address • What is the cost to raise enough ECB or CRW for mass release? • What is cost to engineer RIDL ECB/CRW? • How do we mass release ECB/CRW? Aerially? On the ground? Spacing? • What are the legal, social, ethical issues for releasing ss CRW/ECB? What about transgenic RIDL adults? • Is RIDL more economical for managing resistance mitigation?

35. Questions and Comments Paul D. Mitchell UW-Madison Ag & Applied Economics Office: (608) 265-6514 Cell: (608) 320-1162 Email: pdmitchell@wisc.edu

36. References • Gould, F. 2008. Broadening the application of evolutionarily based genetic pest management. Evolution 62(2):500-510. • Alphey et al. 2007. Managing Insecticide Resistance by Mass Release of Engineered Insects. J. Econ. Entomol. 100(5):1642-1649. • Alphey et al. 2009. Combining Pest Control and Resistance Management: Synergy of Engineered Insects With Bt Crops. J. Econ. Entomol. 102(2):717-732. • Thomas et al. 2000. Insect population control using a dominant repressible lethal genetic system. Science 287:2474-2476. • GM Mosquito Trial Alarms Opponents, Strains Ties in Gates-Funded Project. Science 330:1030-1031.