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 DunAg & Applied Economics, UW-Madison

March 14, 2011 Minneapolis, MN

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

Source: Hutchison et al. (2010)

% Acres Triple Stack Bt Corn in 2009(Based on Biotech Endorsement Crop Insurance)

> 40%

30%-40%

20-30%

10%-20%

< 10%

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

Bt Corn Adoption Rate by State

0%

10%

20%

30%

40%

50%

60%

70%

80%

1995 1997 1999 2001 2003 2005 2007 2009

Bt C

orn

Adop

tion

Rat

e

ILMNWIIANE

ECB Population Data 1940 to 2009

0

50

100

150

200

250

300

350

400

450

1940 1950 1960 1970 1980 1990 2000 2010

2nd

Gen

r. EC

B la

rvae

/100

pla

nts

WIILMN

ECB Population Data Since 1990

0

50

100

150

200

250

300

350

400

450

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

2nd

Gen

r. EC

B la

rvae

/100

pla

nts

WIILMN

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

Cumulative Benefits MN, WI, IL

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

1995 1997 1999 2001 2003 2005 2007 2009

Cum

ulat

ive

Ben

efit

($ M

illio

n)

Btnon-BtTotal

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

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

1995 1997 1999 2001 2003 2005 2007 2009

Cum

ulat

ive

Bene

fits (

$ M

illio

n)

Non-BtBt + TechTotal

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

%Q Elasticity %P P3% -0.40 -7.5% -0.533% -0.33 -9.1% -0.643% -0.25 -12.0% -0.845% -0.40 -12.5% -0.885% -0.33 -15.2% -1.065% -0.25 -20.0% -1.40

Higher corn prices means more corn acres (less CRP, pasture and cereals)

Working on broader model for more definitive estimate of price effects

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

“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

Insect Resistance to Bt Toxin Populations with confirmed field resistance

to Bt toxin in a Bt crop1. Fall Armyworm (Spodoptera frugiperda) in

Puerto Rico to Cry1F in Bt corn2. Stem Borer (Busseola fusca) in South Africa

to Cry1Ab I Bt corn3. Cotton Bollworm (Helicoverpa zea) in AR/MS

to Cry1Ac in Bt cotton4. Cotton Bollworm (Helicoverpa armigera) in

China to Cry1Ac in Bt cotton More in lab and others in non-GM uses

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”

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

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

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

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?

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

RIDL Graphics (Alphey et al. 2007)

F2: Lw x ww

50% Lw, all females die

50% ww, all females liveF3: Same outcome

F1

Figure 1 in Alphey et al. (2007)

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

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

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”

0% refuge

10% refuge

Preliminary Economic Analysis

Revenue minus costs from Bt and non-Bt crop and for releasing RIDL insects

Revenue = PY[b(1 – b) + (1 – b)(1 – n)] Cost = K + bT + Cridl(dN) P = price, Y = pest free yield, b = % Bt = % 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)

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

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?

Questions and Comments

Paul D. MitchellUW-Madison Ag & Applied EconomicsOffice: (608) 265-6514Cell: (608) 320-1162Email: pdmitchell@wisc.edu

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.