Optimum AcreMax Bt Corn Seed Blends . 

Biopesticides Registration Action Document

BIOPESTICIDES REGISTRATION ACTION DOCUMENT

Optimum® AcreMaxTM B.t. Corn Seed Blends 

U.S. Environmental Protection Agency (EPA) 

 Office of Pesticide Programs 

Biopesticides and Pollution Prevention Division (BPPD) 

April 30, 2010
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TABLE OF CONTENTS

I. BACKGROUND ...................................................................................................... 3

II. INSECT RESISTANCE MANAGEMENT................................................................. 5

III. BENEFITS............................................................................................................... 9

IV. REGULATORY RATIONALE.............................................................................. 10

V. TERMS AND CONDITIONS OF THE REGISTRATION(S) ................................... 14

REFERENCES ............................................................................................................. 29
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 I. BACKGROUND 

Active Ingredients: 

Bacillus thuringiensis Cry34Ab1 and Cry35Ab1 proteins and the genetic material 

necessary for their production (plasmid insert PHP 17662) in Event DAS-59122-7 corn 

Bacillus thuringiensis Cry1F protein and the genetic material necessary for its 

production (plasmid insert PHI8999) in Event TC1507 corn 

Trade & Other Names: 

HERCULEX® I => Cry1F Corn 

HERCULEX® RW (Rootworm) => Cry34/35Ab1 Corn 

 

HERCULEX® XTRA => Cry1F + Cry34/35Ab1 Corn 

Optimum® AcreMaxTM 1 (OAM 1) => Seed Blend of 90% HERCULEX® XTRA 

and 10% HERCULEX® I 

OAM RW => Seed Blend of 90% HERCULEX® RW and 10% Non-B.t. Corn 

OPP Chemical Codes: 006490 (Cry34/35Ab1 corn) and 006481 (Cry 1F corn) 

Type of Pesticide: Plant-Incorporated Protectants (PIPs) 

Product Profile: 

HERCULEX® I

The registration for Cry1F Event TC1507 (Event DAS-01507-1), also known as 

HERCULEX® I, was first granted by the Agency on May 18, 2001. HERCULEX® I 

expresses the Cry1F insecticidal crystal protein as well as the PAT (phosphinothrin 

acetyl transferase) protein, which confers tolerance to the herbicidal active ingredient 

glufosinate-ammonium. Cry1F is efficacious against lepidopteran pests, and the primary 

target pest of HERCULEX® I is the European corn borer (ECB, Ostrinia nubilalis); 

other target pests are corn earworm (CEW, Helicoverpa zea), southwestern cornborer 

(SWCB, Diatrea grandiosella), fall armyworm (FAW, Spodoptera frugiperda), western 

bean cutworm (WBCW, Richia albicosta), and black cutworm (BCW, Agrotis ipsilon). 

The main target pests for which insect resistance management (IRM) requirements apply 

are ECB, CEW, and SWCB. 
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HERCULEX® RW

The registration for Event DAS-59122-7, also known as HERCULEX® RW, was granted 

by the Agency in August, 2005. HERCULEX® RW expresses B.t. toxins Cry34Ab1 and 

Cry35Ab1, which are efficacious against coleopteran pests. The primary target pests of 

HERCULEX® RW are western corn rootworm and northern corn rootworm (CRW, 

Diabrotica species). Maize containing Event 59122-7 has been modified to express the 

PAT protein, which confers tolerance to gluphosinate-aluminum herbicide. 

HERCULEX® XTRA

The registration for HERCULEX® XTRA (Event TC1507 x DAS59122-7) was granted 

in October 2005. HERCULEX® XTRA is the result of a conventional breeding cross 

between HERCULEX® I and HERCULEX® RW and is considered a stacked PIP 

because it targets two different kinds of pests (Lepidoptera and Coleoptera) and contains 

two separate PIP active ingredients. 

OAM 1: EPA File Symbol 29964-A

In February, 2008, Pioneer Hi-Bred International, Inc. submitted an application to 

register Optimum® AcreMaxTM 1 Insect Protection, a new blended seed product that 

contains two different kinds of seeds of the already registered products HERCULEX® 

XTRA and HERCULEX® I. The new product incorporates the CRW refuge into the 

seed bag. The seed blend percentage was amended to 90% HERCULEX® XTRA and 

10% HERCULEX® I. 

OAM RW: EPA File Symbol 29964-RN

In November 2009, Pioneer Hi-Bred International, Inc. submitted an application to 

register Optimum® AcreMaxTM RW Insect Protection, a seed blend consisting of 90% 

HERCULEX® RW and 10% non-B.t. Corn. The new product incorporates the CRW 

refuge into the seed bag and also can serve as a refuge for the Cry1F portion of OAM 1. 

Pioneer’s Projected Use in 2010, 2011, and 2012

Pioneer’s forecast for OAM 1 U.S. acreage in the 2010, 2011, and 2012 growing seasons 

is listed below. Pioneer states that “[t]hese estimates have been divided into highpressure areas for corn rootworm (i.e., the Red Zone) and non-Red Zone acres (i.e., the 

remaining U.S. corn acreage outside the Red Zone). The Red Zone is defined by Pioneer 

as 90 counties that have a 100% chance of corn rootworm infestation in any given year. 

These counties are primarily located in northeastern Illinois, northwestern Indiana and, to 

a lesser extent, southeastern Wisconsin and southwestern Michigan. Because of the 

strong selection pressure present in the Red Zone, it is considered a potential area for 

corn rootworm resistance to develop. The percentages are based on general USDA 

acreage projections, which project a total of 90 million corn acres in the U.S. in 2010, 

2011, and 2012.” 

 
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Growing season Red Zone geography Non-Red Zone geography 

2010 ~0.077% ~0.042% 

2011 ~5.8% ~8.2% 

2012 ~8% ~12% 

II. INSECT RESISTANCE MANAGEMENT 

FIFRA Scientific Advisory Panel (SAP)

Pioneer/Dupont's initial registration application for OAM 1 consisted of a seed blend of 

95% HERCULEX® XTRA and 5% [3.5% (±1.5)] HERCULEX® I. The HERCULEX® 

I was intended to serve as the IRM refuge for the corn rootworm active component of 

HERCULEX® XTRA. The proposed seed blend strategy and reduction in refuge from 

20% to 2% to 5% represented a significant paradigm shift for the B.t. IRM strategy that 

has been employed for over 15 years. BPPD conducted a risk assessment and presented 

preliminary conclusions to the Scientific Advisory Panel for peer review on February 23 

to 24, 2009. 

The SAP (2009) expressed concern about the proposed refuge reduction. The Panel 

concluded that there was no compelling evidence, either in the data provided by Pioneer 

or in the public literature, to support a 5% blended refuge for this particular product. The 

Panel noted, however, that the biology of the corn rootworm makes it susceptible to 

successful control and mitigation by a seed blend methodology, if the refuge is of 

sufficient size. 

Current Submissions

OAM 1 is a blended seed product that contains 90% HERCULEX® XTRA seeds 

(Cry34/35Ab1 x Cry1F) and 10% HERCULEX® I seeds (Cry1F). 

OAM RW is a blended seed product that contains 90% HERCULEX® RW seeds 

(Cry34/35Ab1) and 10% non-B.t. Corn. 

Seed Blending

Pioneer submitted information and analyses supporting their claim that refuge plants will 

be randomly distributed throughout the field, including information indicating that the 

expected error of mixing the refuge seed is ±1.5% (using the seed mixing technology 

described in their submission) and that the standard deviation for planting the correct 

percentage of refuge is ±1%. 
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IRM Modeling

EPA Model Description 

EPA'S POPGEN (Population Genetics) simulation models are a series of generalized, 

flexible population genetics modeling systems modeling the evolution of resistance to 

conventional pesticides and transgenic crops. The programs are capable of simulating 

complex landscapes that vary spatially as well as temporally over the course of a growing 

season. 

POPGEN-D 

The deterministic model POPGEN-D is a relatively simple frequency-based model that 

incorporates non-compliance estimates, non-random mating in refuge fields, and larval 

movement. The model permits modeling of both block refuges and blended seed-mixture 

refuges. 

POPGEN-S2 

The stochastic model POPGEN-S2 is a modification of an earlier stochastic, spatially 

explicit, dual locus, simulation model designed to evaluate the development of resistance 

in crop pests to insecticides. (Caprio et al 2006). 

 

POPGEN-SM 

The stochastic model POPGEN-SM is a modification of an earlier stochastic, spatially 

explicit, dual locus, simulation model designed to evaluate development of resistance in 

crop pests to insecticides and incorporating multi loci. (Caprio et al 2006). 

To incorporate uncertainty in the parameters used in the deterministic model, 

distributions, based on data for the lowest and maximum possible values, were developed 

as well as a most likely value. These values were used in PERT distributions based on a 

beta distribution with the most likely value weighted by 4 (Vose 2001). 

5% Seed Blend

Subsequent to the February 2009, FIFRA Scientific Advisory Panel meeting, Pioneer 

submitted revised modeling that incorporated new corn rootworm movement data. EPA 

fully evaluated this modeling, including assessing the new corn rootworm movement 

data. In addition, using the POPGEN model developed by EPA ORD, EPA conducted an 

independent modeling analysis of Pioneer's proposed seed blend using both deterministic 

and stochastic models. EPA concluded that a number of critical input parameters to the 

Pioneer modeling were not supported by data or were inadequate to support a rational 

basis for regulatory decisionmaking. Therefore, BPPD concluded that the results of the 

Pioneer modeling indicating that the proposed 5% seed blend is superior to a 20% block 

refuge deployment strategy for OAM 1 and corn rootworm were not scientifically 
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supported. 

EPA had concerns regarding Pioneer's assumptions about short range insect dispersal 

because the data (Nowatzki et al. 2003) were limited, and were derived from only one 

location in the cornbelt. This was a critical factor because the adult insect dispersal input 

is a sensitive parameter for modeling the durability of block refuges. Parameter inputs 

representing a shorter dispersal range lowered the resulting effectiveness of a block 

refuge. Using a range of representative parameter values and assumptions to predict the 

durability of a 20% block refuge versus Pioneer's proposed 5% blended refuge, EPA's 

deterministic modeling showed that the predicted durability for the 20% block refuge was 

superior to a 5% seed blend strategy (11.95 years vs. 8.1 years). 

In addition to the 5% seed blend, EPA modeled other blend percentages for comparison. 

A 10% seed blend was predicted to have a durability of 11.3 years, which was slightly 

less durable (5.4%) relative to a 20% block refuge based on EPA's assumptions. EPA 

concluded, however, that these results were of limited actual utility because a number of 

parameter inputs to the original Pioneer model did not reflect actual variability and/or 

uncertainty. Therefore, to assess the current application for a 10% blended refuge, EPA 

conducted modeling using a range of representative input parameters. 

10% Seed Blend 

In the latest modeling, EPA incorporated uncertainty by using probabilistic distributions 

of critical data that we determined to be variable and/or uncertain. The distributions were 

developed based on acceptable data for the minimum, maximum, and most likely, 

possible values. These values were developed as PERT distributions. Each model was 

run 2,000 times, and each run utilized input parameters drawn from the PERT 

distributions. "Resistance" was defined as the resistance allele exceeding 50%, and EPA 

measured the mean, 25th, and 75th percentiles of the time to "resistance." EPA also 

determined the proportion of simulations where the time to resistance exceeded 11 years. 

 (The SAP has advised that 15 years with no resistance is a reasonable goal for an IRM 

program applicable to a single-gene toxin. The Cry34/35 transgenic toxin has been in 

use for four years. Therefore, we believe it relevant to assess how many of the model 

runs indicate that either the 20% block or the 10% blend will delay development of 

resistance for 11 or more years.) The data from these model simulations indicate 

comparative durability values of 11.3 years for the 10% blended refuge and 20.2 years 

for the 20% block refuge. Thus, the 10% blend was 45% less durable than the 20% block 

refuge currently required for single trait CRW PIPs. 
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IRM Refuge Compliance

Critical to an assessment of the likely efficacy of an IRM mitigation program is the level 

of compliance with that program. Data received by EPA from the Agricultural 

Biotechnology Stewardship Technical Committee (ABSTC) indicate that compliance 

with the paradigmatic 20% block refuge requirement for most B.t. corn crops has been 

steadily decreasing. As noted by a number of commenters, this decreased compliance 

increases the risk of resistance development (see, e.g., Complacency on the Farm, CSPI 

2009, and Impact of Genetically Engineered Crops on Farm Sustainability in the United 

States, NAS 2010). 

For the 2002 to 2008 planting seasons, ABSTC reported refuge compliance either as ‘all 

compliant' (i.e., always planting a 20% refuge, within the proper distance) or 'out-ofcompliance’ (i.e., not having either a 20% refuge, or having the refuge not located 

exactly where required, or neither). In 2007 and 2008, ABSTC began to also report if 

growers at least planted a 15% refuge or/and if most of a grower's B.t. fields met the 

refuge distance requirement. (Reporting these additional data reflects that there may be 

degrees of noncompliance, for example, a grower may be inadvertently out of compliance 

with distance requirements by a degree that does not materially affect the efficacy of the 

refuge. Also, while, admittedly, a 15% refuge is not compliant with a 20% refuge 

requirement, it has a much different field impact than does a 0% refuge.) 

The graphs below compare "out of compliance" versus "almost compliant" data. The 

upper graph is adjusted for ‘almost compliant’ growers in 2007 to 2008; the lower graph 

is the compiled out-of-compliance data from the ABSTC for 2007 and 2008. These data 

indicate that the unadjusted "out-of-compliance" values may not accurately reflect the 

actual impact of growers who are, technically, not compliant with the refuge 

requirements. Therefore, it may be that the "out of compliance" numbers reported 

recently may indicate a greater degree of risk of resistance developing than is actually the 

case. 
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ECB CRW ECB/CRW Stacks

2002 86

2003 92

2004 91

2005 92 93

2006 89 89 78

2007 89 86 82

2008 86 84 81

ECB CRW ECB/CRW Stacks

2002 86

2003 92

2004 91

2005 92 93

2006 89 89 78

2007 80 80 70

2008 78 74 72

Compliance with Refuge Requirements 

(20% from 2002-2006; >15% refuge planted; info only available for 2007/2008)

65

70

75

80

85

90

95

100

2001 2002 2003 2004 2005 2006 2007 2008 2009

Planting Season

% Compliance

ECB CRW ECB/CRW Stacks

Compliance with Refuge Requirements 

(20% refuge planted in all years)

65

70

75

80

85

90

95

100

2001 2002 2003 2004 2005 2006 2007 2008 2009

Planting Season

% Compliance

ECB CRW ECB/CRW Stacks

III.BENEFITS 

We expect OAM 1 to have the following benefits: (1) Reduced pesticide use in the 

refuge. Currently, the 20% block refuge may be sprayed with pesticide to mitigate pest 

damage. The blended in-field refuge will not be sprayable. (2) Significantly less 

complicated refuge deployment for the corn rootworm active ingredient. Currently, to be 

fully compliant with the refuge requirements, growers must accurately calculate 20% of 

the field, accurately determine the proper distance for the refuge field, and properly plant 

the required acreage in the correct location. Moreover, there are temporal concerns, as 

the refuge field must be planted at, essentially, the same time as the yield field so that 

emergence of refuge rootworms is contemporaneous with emergence of field rootworms. 

Anecdotal reports from growers make clear that meeting each of these requirements can 

be challenging in the actual on-farm environment. A product with the refuge blended 

with the field seed will ease deployment of the rootworm refuge. (3) Increased grower 

compliance with IRM requirements for the corn rootworm active ingredient. A seed 
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blend product incorporating an effective refuge in the seed bag would lead to 100% 

grower compliance for planting a refuge. This is a significant benefit, although perhaps 

not as great as the raw data on refuge compliance might suggest. 

In addition, indirect benefits of introducing Optimum® AcreMaxTM 1 may include 

reduced energy consumption for manufacture, transport, and application of chemical 

insecticides; reduced waste streams arising from pesticide manufacture; reduced disposal 

of pesticide waste containers; and reduced residues from pesticide applications. 

Efficacy and Yield Benefits

Pioneer conducted a two year study (2006 to 2007) to assess efficacy and yield benefits 

of a blended seed refuge. The purpose of the study was to determine the effects of a 

blended refuge approach on field standability, root ratings, and yield (three effects 

measured at each treatment level). The 2006 experiment was replicated at eight different 

locations in a randomized block design with four replicates for all five treatments. The 

treatments were: (1) untreated control; (2) conventional seed treated with P1250; (3) 

100% HXRW (HERCULEX® RW) seed treated with P250; (4) 10% seed mix of 

conventional seed treated with P250 and 90% HXRW seed treated with P250; and (5) 

20% seed mix of conventional seed treated with P1250 and 80% HXRW seed treated 

with P250. During July 2006, five roots per plot were randomly selected, root damaged 

scored using the Iowa State 0-3 node injury scoring, and yield determined at end of the 

growing season. Under low insect pressure, Pioneer reports little difference in node 

injury or yields between treatments (no data provided). Under high insect pressure, all 

HXRW treatments had approximately equal grain yield and node injury and the 10% and 

20% seed blends were equivalent to the control of 100% HXRW maize. 

In 2007, the study was repeated with the addition of HX1 (HERCULEX® I) as refuge 

seed (treated with P250 and P1250). BPPD did not see statistically significant 

differences between node injury, % root lodging, and grain yields between any of the 

HXX (HERCULEX® XTRA) treatments except with respect to node for the 20% refuge 

with P250. 

IV. REGULATORY RATIONALE 

Section 3(c)(7)(A) of FIFRA provides for the registration or amendment of a pesticide 

when the pesticide and proposed use “...are identical or substantially similar to any 

currently registered pesticide and use thereof, or differ only in ways that would not 

significantly increase the risk of unreasonable adverse effects on the environment, and 

(ii) approving the registration or amendment in the manner proposed by the applicant 

would not significantly increase the risk of any unreasonable adverse effect on the 

environment.” Unreasonable adverse effects on the environment are defined under 

Section 2(bb) of FIFRA as “... any unreasonable risk to man or the environment, taking 

into account the economic, social, and environmental costs and benefits of the use of any 

pesticide...” Thus, pursuant to Section 3(c)(7)(A), EPA may conditionally register a 
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pesticide if (1) the pesticide and its proposed use are identical or substantially similar to a 

currently registered pesticide; or (2) the pesticide and its proposed use differ only in ways 

that would not significantly increase the risk of unreasonable adverse effects; and (3) 

approving the registration would not significantly increase the risk of any unreasonable 

adverse effect. 

We find that OAM 1 and OAM RW meet criteria (2) and (3) of Section 3(c)(7)(A) for a 

time-limited registration to expire September 30, 2010. Optimum® AcreMaxTM 1 is a 

seed blend consisting of two currently registered products, 90% HERCULEX® XTRA 

and 10% HERCULEX® I. Optimum® AcreMaxTM RW is a seed blend consisting of an 

already registered product and non-PIP corn, 90% HERCULEX® RW and 10% non-B.t.

Corn. Thus, both products are substantially similar to already registered PIPs in 

composition and use site (field corn). These products do not meet criteria (1), however, 

because the proposed use of OAM 1 and OAM RW that achieves the insect resistance 

management refuge via a seed mix rather than a block refuge is not substantially similar 

to any currently registered pesticide. Having the refuge in the bag of seeds is a novel 

approach. 

We determine, however, that each of these products meets criteria (2) as, when used in 

accordance with the terms and conditions of a time-limited registration set to expire 

September 30, 2010, neither would significantly increase the risk of unreasonable 

adverse effects on the environment. Since OAM 1 and OAM RW are substantially 

similar to already registered PIPs in composition and use site, EPA’s consideration of 

whether these new products would significantly increase the risk of any unreasonable 

adverse effect on the environment is limited to the change in insect resistance 

management refuge deployment and percentage, i.e., a 10% seed blend in the bag versus 

a 20% block refuge. The unreasonable adverse effect of concern is the development of 

resistance to Cry34/35Ab1 in corn. Thus, we consider: (1) how does the registration of 

OAM 1 and OAM RW contribute to the development of corn rootworm resistance to 

Cry34/35Ab1 corn; (2) should this resistance develop, what risk does it pose to man or 

the environment; and (3) taking into account the economic, social, and environmental 

costs and benefits, does this risk constitute an unreasonable adverse effect? 

The Risk of OAM 1 and OAM RW Registrations Causing CRW Resistance to 

Cry34/35Ab1

The modeling used by EPA to assess IRM strategies utilizes comparative simulation 

models. The model durability outputs, years to resistance, is intended to be used for 

comparative purposes to evaluate different refuge options on a relative basis. The 

durability outputs that EPA has determined for the proposed 90% CRW protected 

seed/10% non-CRW protected seed blend, and a 20% block refuge are 11.3 years to 

resistance, and 20.2 years to resistance, respectively. Thus, our analysis indicates that, as 

modeled, the proposed seed blend is 45% less durable on a comparative basis than the 

20% block refuge currently required for single trait CRW PIPs . 

Besides the currently registered Pioneer PIPs, Cry34/35Ab1 corn is registered in a 
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number of other B.t. corn PIPs, including multi-CRW B.t. toxin products, by Monsanto 

and Dow AgroSciences. Should resistance develop to Cry34/35 in a OAM 1 seed blend, 

these other products could be adversely affected including potential loss of efficacy and 

viability as CRW control tools. We note, in particular, the recent statement of the 

National Research Council to the effect that “. . . results from simulation models and 

small-scale laboratory experiments indicate that the evolution of resistance to two-toxin 

cultivars is accelerated when plants that produce two B.t. toxins are grown near plants 

that produce just one toxin.” National Academy of Sciences, Impact of Genetically 

Engineered Crops on Farm Sustainability in the United States, 2-37 (2010). Based on 

our current assessment, we conclude that significant acreage of a 10% seed blend with a 

single, non-high dose mode of action such as Cry 34/35Ab1 likely increases the risk of 

resistance for all B.t. corn products containing Cry34/35Ab1. But, the current timelimited registration will not likely increase the risk of resistance to Cry34/35Ab1. 

Pioneer projects that the time-limited registrations being granted for the 2010 growing 

season will result in planting on only approximately 0.042% of acres of non-Red Zone 

geography corn acres; and only on approximately 0.077% of Red-Zone geography corn 

acres. In the context of 90 million acres of corn planted in the United States annually, we 

conclude that plantings on such limited acreage will not have effects on CRW resistance 

development. 

Should Resistance Develop, What Risk Does it Pose to Man or the Environment, and 

What Economic and Social Costs?

Should Cry34/35Ab1 resistance develop, there would be an increase in conventional 

chemical insecticide use for U.S. corn production. Although there are other CRW 

controlling PIPs in the marketplace and under development, Cry34/35Ab1 resistance 

would not only impact OAM 1 and OAM RW, but also HERCULEX® RW, 

HERCULEX® XTRA, and GenuityTM SmartStaxTM. Increased use of conventional 

insecticides would increase impacts on the environment and man. There would also be 

indirect impacts in increased consumption for manufacture, transport, and application of 

chemical insecticides; increased waste streams arising from pesticide manufacture; and 

increased disposal of pesticide waste containers and residues from pesticide applications. 

What are the Economic, Social, and Environmental Benefits of OAM 1 and OAM 

RW?

Both OAM 1 and OAM RW have been determined by EPA to be efficacious in their 

control of corn rootworm. 

OAM 1 and OAM RW should increase grower compliance with CRW refuge 

requirements by providing a novel and effective way of simplifying the refuge 

deployment process for growers as the corn rootworm refuge is deployed as a seed blend 

rather than a separate block in the field. 

OAM 1 and OAM RW should also reduce the insecticide use in the CRW refuge and in 

the CRW-PIP fields. Currently, corn rootworm PIP products require insecticide 
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treatment of the PIP acreage, even if economic thresholds are not reached. This use of 

insecticides solely to support the management of resistance has been required if aerial 

insecticides are applied to the refuge for control of CRW adults or if pests other than 

adult corn rootworms are treated with CRW-labeled insecticide on the refuge acres when 

adult corn rootworms are present. OAM 1 and OAM RW would reduce this IRM based 

use of insecticides. Indirect benefits of decreased insecticide use include reduced energy 

consumption for manufacture, transport, and application of chemical insecticides; 

reduced waste streams arising from pesticide manufacture; reduced disposal of pesticide 

waste containers and residues from pesticide applications. 

OAM 1 and OAM RW should benefit growers by simplifying the planting process. 

Registration Decision for 2010 Growing Season

We conclude that OAM 1 and OAM RW meet the criteria for registration under FIFRA 

Section 3(c)(7)(A). Our assessment supports the determination that these products are 

not likely to contribute towards the development of resistance of CRW to Cry34/35Ab1 

during period of the time-limited registration in effect for the 2010 growing season. Our 

assessment of the likely impacts concerning ease of use, increased grower compliance, 

efficacy, and reduced insecticide use coupled with our determination that OAM 1 and 

OAM RW are not likely to increase the risk of resistance of CRW to Cry34/35Ab1 

developing during the 2010 growing season support the conclusion that the criteria under 

FIFRA Section 3(c)(7)(A) are met such that registration of OAM 1 and OAM RW will 

not pose a risk of unreasonable adverse effects on the environment during this period. 

On October 1, 2009, EPA announced a new policy to provide a more meaningful 

opportunity for the public to participate on major registration decisions before they occur. 

According to this new policy, EPA intends to provide a public comment period prior to 

making a registration decision for, at minimum, the following types of applications: new 

active ingredients; first food use; first outdoor use; first residential use; and other actions 

for which the Agency anticipates that there will be significant public interest. 

Notwithstanding that the current actions on OAM 1 and OAM RW qualify as "actions for 

which the Agency anticipates that there will be significant public interest," EPA believes 

that it is in the best interests of the public and the environment to issue the registrations 

for OAM 1 and OAM RW without delay. The PRIA (Pesticide Registration 

Improvement Act) deadline date of May 1, 2010, is sufficiently late in the growing 

season that a 30-day delay would lessen the likelihood that significant acreage of these 

products could be planted in 2010. Given the potential benefits attendant to the blended 

refuge concept, EPA concludes that it is in the best interests of the public and the 

environment to issue the registrations for OAM 1 and OAM RW without delay for 2010 

growing season. The registration is only effective for the current growing season. 

Therefore, consistent with the Agency’s policy for making certain registration actions 

more transparent, EPA is issuing these time-limited registrations with an initial period to 

expire September 30, 2010, and, concurrent with their issuance, providing a 30-day 

public comment period on the time-limited registrations. EPA is registering this product 
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as a time-limited registration, with the understanding that public comments could bring to 

light new information or concerns that could inform EPA’s initial decision. Any 

subsequent action taken on these registrations will be informed by any information 

received during the public comment period. 

Proposed Registration Decisions for 2011 and 2012 Growing Seasons 

We have also preliminarily concluded that our modeling analysis combined with the 

Pioneer sales projections for the 2011 and 2012 growing seasons support continued 

registration of OAM 1 and OAM RW for 2011 and 2012. We note that Pioneer predicts 

acreage to increase up to 8% of the Red Zone and 12% of the non-Red Zone. EPA 

invites comments during the 30-day comment period on the preliminary decision to 

register OAM 1 and OAM RW for the 2011 to 2012 growing seasons. Important to this 

preliminary decision is the fact that Pioneer has committed to the following additional 

elements of the IRM plan applicable to OAM 1 and OAM RW regarding insect resistance 

monitoring, remedial action should resistance be detected, and the refuge assurance 

program. These are all listed in detail in the terms and conditions of the OAM 1 and 

OAM RW registrations. 

V. TERMS AND CONDITIONS OF THE REGISTRATION(S) 

OAM 1

1) Submit and/or cite all data required for registration/ registration review of your 

product under FIFRA section 3(c)(5) when the Agency requires all registrants of similar 

products to submit such 

data. 

2) The subject registration will automatically expire on midnight September 30, 2010. 

3) The subject registration will be limited to a seed mix of TC1507 (Cry1F) xDAS59122-7 (Cry34Ab1/Cry35Ab1) corn seed blended with not less than 10% TC1507 

(Cry1F) corn seed. 

4) Submit or cite all data required to support the Herculex XTRA and the Herculex I 

plant-incorporated protectant products within the timeframes required by the terms and 

conditions of EPA Registration Numbers 29964-3 and 29964-5. 
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5) The subject registration will be limited to Submit the following data in the timeframes 

listed: 

Study Type Required Data Due Date 

Insect Resistance 

Management 

Pioneer must provide the Agency with a copy of the 

grower agreement, associated stewardship documents, 

and written description of a system, which assures that 

growers will sign grower agreements and persons 

purchasing OAM1 corn will annually affirm that they are 

contractually bound to comply with requirements of the 

insect resistance management (IRM) program. 

90 days from 

the date of 

registration 

Insect Resistance 

Management 

Pioneer must implement an enhanced resistance 

monitoring plan for OAM1. Pioneer must provide the 

Agency with a baseline (benchmark) study that shows 

the susceptibility of western corn rootworm populations 

(WCRW) in the Sublethal Seedling Assay prior to the 

large-scale introduction of OAM1. Although northern 

corn rootworm (NCRW) is difficult to rear, Pioneer must 

attempt to obtain benchmark susceptibility data using the 

Sublethal Seedling Assay for NCRW as well. 

12/1/2010 for 

WCRW 

12/1/11 for 

NCRW 

Insect Resistance 

Management 

Pioneer must submit a detailed OAM1-specific resistance 

monitoring and remedial action plan, including an 

analysis to determine the expected field performance 

criteria for OAM1 products so that unexpected damage 

can be benchmarked. Pioneer will update the plan by 

12/1/2012, if needed, based on continued field evaluation 

of OAM1 performance. 

12/1/2010 

6) Pioneer must commit to do the following Insect Resistance Management Program for 

OAM1. 

The required IRM program for OAM1 corn must have the following elements: 

Requirements relating to creation of a lepidopteran refuge (consisting of corn that does not 

contain any Bt trait for lepidopteran control) in conjunction with the planting of any acreage of 

OAM1 corn; 

Requirements for Pioneer to prepare and require OAM1 users to sign “grower agreements,” 

which impose binding contractual obligation on the grower to comply with the refuge 

requirements; 

Requirements regarding programs to educate growers about IRM requirements; 

Requirements regarding programs to evaluate and promote growers’ compliance with IRM 

requirements; 
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Requirements regarding programs to evaluate whether there are statistically significant and 

biologically relevant changes in target insect susceptibility to Cry1F and Cry34Ab1/Cry35Ab1 

proteins in the target insects; 

Requirements regarding a “remedial action plan,” which contains measures Pioneer would take 

in the event that any field-relevant insect resistance was detected as well as to report on activity 

under the plan to EPA; 

Annual reports on units sold by state (units sold by county level will be made available to the 

Agency upon request), IRM grower agreements results, and the compliance assurance program 

including the educational program on or before January 31st of each year, beginning in 2011. 

a) Refuge requirements for OAM1 

Because the refuge for corn rootworm is blended in each bag or box of OAM1 seed, no 

additional corn rootworm refuge is required. A refuge must be planted for corn borers. The 

refuge must be planted with corn hybrids that do not contain Bt technologies for the control of 

corn borers. Refuge options are based on the planting of OAM1 in cotton or non-cotton growing 

regions and insect pressure present in those locations. The refuge sizes for these regions are 

either 50% in cotton-growing regions (i.e., 50 acres of corn that does not contain Bt technology 

for the control of corn borers for every 50 acres of OAM1) or 20% in non-cotton growing 

regions (i.e., 20 acres of corn that does not contain Bt technology for the control of corn borers 

for every 80 acres of OAM1). Refuge planting options include: separate fields, blocks within 

fields (e.g., along the edges or headlands), and strips across the field. Cotton-growing regions 

consist of the following states Alabama, Arkansas, Georgia, Florida, Louisiana, North Carolina, 

Mississippi, South Carolina, Oklahoma(only the counties of Beckham, Caddo, Comanche, 

Custer, Greer, Harmon, Jackson, Kay, Kiowa, Tillman, Washita), Tennessee (only the counties 

of Carroll, Chester, Crockett, Dyer, Fayette, Franklin, Gibson, Hardeman, Hardin, Haywood, 

Lake, Lauderdale, Lincoln, Madison, Obion, Rutherford, Shelby, and Tipton), Texas (except the 

counties of Carson, Dallam, Hansford, Hartley, Hutchinson, Lipscomb, Moore, Ochiltree, 

Roberts, and Sherman), Virginia (only the counties of Dinwiddie, Franklin City, Greensville, Isle 

of Wight, Northampton, Southampton, Suffolk City, Surrey, Sussex) and Missouri (only the 

counties of Dunkin, New Madrid, Pemiscot, Scott and Stoddard. 

External refuges must be planted within 1⁄2 mile. If perimeter or in-field strips are implemented, 

the strips must be at least 4 consecutive rows wide. The refuge can be protected from 

lepidopteran damage by use of non-Bt insecticides if the population of one or more of the target 

lepidopteran pests of OAM1 in the refuge exceeds economic thresholds. Economic thresholds 

will be determined using methods recommended by local or regional professionals (e.g., 

Extension Service agents, crop consultants). 

b) Grower Agreement for OAM1 Corn 

1. Persons purchasing OAM1 corn must sign a grower agreement. The term 

“grower agreement” refers to any grower purchase contract, license agreement, or 

similar legal document. 
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2. The grower agreement and/or specific stewardship documents referenced in the 

grower agreement must clearly set forth the terms of the current IRM program. 

By signing the grower agreement, a grower must be contractually bound to 

comply with the requirements of the IRM program. 

3. Pioneer must implement a system (equivalent to what is already approved for 

previously registered Pioneer Bt corn products), which is reasonably likely to 

assure that persons purchasing OAM1 corn will affirm annually that they are 

contractually bound to comply with the requirements of the IRM program. A 

description of the system must be submitted to EPA within 90 days from the date 

of registration. 

4. Pioneer must use a grower agreement and must submit to EPA, within 90 days 

from the date of registration, a copy of that agreement and any specific 

stewardship documents referenced in the grower agreement. If Pioneer wishes to 

change any part of the grower agreement or any specific stewardship documents 

referenced in the grower agreement that would affect either the content of the 

IRM program or the legal enforceability of the provisions of the agreement 

relating to the IRM program, 30 days prior to implementing a proposed change, 

Pioneer must submit to EPA the text of such changes to ensure it is consistent 

with the terms and conditions of this registration. 

5. Pioneer shall maintain records of all OAM1 corn grower agreements for a period 

of three years from December 31st of the year in which the agreement was signed. 

6. Beginning on January 31, 2011 and annually thereafter, Pioneer shall provide 

EPA with a report on the number of units of OAM1 corn seed shipped and not 

returned, and the number of such units that were sold to persons who have signed 

grower agreements. The report shall cover the time frame of a twelve-month 

period. Note: The first report shall contain the specified information from the 

time frame starting with the date of registration and extending through the 2010 

growing season. 

7. Pioneer must allow a review of the grower agreements and grower agreement 

records by EPA or by a State pesticide regulatory agency if the State agency can 

demonstrate that confidential business information, including names, personal 

information, and grower license number, will be protected. 

c) IRM Education and IRM Compliance Monitoring Program for OAM1 Corn 

1. Pioneer must design and implement a comprehensive, ongoing IRM education 

program designed to convey to OAM1 corn users the importance of complying 

with the IRM program. The education program shall involve the use of multiple 

media, e.g. face-to-face meetings, mailing written materials, EPA-reviewed 
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language on IRM requirements on the bag or bag tag, and electronic 

communications such as by internet, radio, or television commercials. Copies of 

the materials will be provided to EPA for their records. The program shall 

involve at least one written communication annually to each OAM1 corn user 

separate from the grower technical guide. The communication shall inform the 

user of the current IRM requirements and specifically the need to plant a 

lepidopteran refuge. Pioneer shall coordinate its education program with the 

educational efforts of other registrants and other organizations, such as the 

National Corn Growers Association and state extension programs. 

2. Pioneer must conduct targeted, on-farm compliance assessments for growers who 

purchase OAM1 seed to ensure growers are compliant with the requirement of a 

20% refuge for lepidopteran pests. For the 2010 growing season, Pioneer must 

conduct at least 500 on-farm assessments or roughly half the number of 

assessments that Pioneer will contribute to the 2010 Agricultural Biotechnology 

Stewardship Technical Committee (ABSTC) compliance assurance program 

assessment for corn borer and stacked products. Beginning in 2011 and annually 

thereafter, Pioneer will target twice the number of on-farm assessments for 

OAM1 as Pioneer conducts for corn borer and stacked products on an annual 

basis. The table below reflects the relative number of on-farm assessments for 

OAM1 based on Pioneer’s contribution to the ABSTC compliance assurance 

program report and is subject to change with time as appropriate. 

Number of on-farm assessments conducted by Pioneer 

Products Year: 2010 

Year: 2011, 

annually 

thereafter 

Corn Borer and Stacked 

Products 1000 750-1000 

OAM1 500 1500-2000 

Total 1500 2250-3000 

Pioneer must provide a report to EPA summarizing the OAM1 compliance assurance 

program activities and results for the prior year and plans for the OAM1 compliance 

assurance program for the current year, January 31, 2011 and annually thereafter. 

3. Annually, Pioneer shall revise, and expand as necessary, its education program to 

take into account the information collected through the compliance survey and 

from other sources. The changes shall address aspects of grower compliance that 

are not sufficiently high. 

4. Beginning January 31, 2011, Pioneer must provide a report to EPA summarizing 

the activities it carried out under its education program for the prior year. 
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Annually thereafter, Pioneer must provide EPA any substantive changes to its 

grower education activities as part of the overall IRM compliance assurance 

program report. Pioneer must either submit a separate report or contribute to the 

report from the industry working group, ABSTC. 

d) Insect Resistance Monitoring for OAM1 Corn 

In addition to the existing two-pronged approach to insect resistance monitoring (monitoring 

insect populations using the diet bioassay and investigations of field reports) that currently takes 

place for Cry34/35 for Herculex Rootworm Insect Protection (29964-4) and Herculex Xtra Insect 

Protection (29964-5), Pioneer must also conduct enhanced monitoring using the Sublethal 

Seedling Assay as a complement to the diet bioassay method. Pioneer must submit a detailed 

OAM1/OAMRW-specific resistance monitoring plan to the Agency by December 1, 2010. 

With respect to the implementation of the Sublethal Seedling Assay: 

1. Pioneer must monitor for resistance and or changes in target pest susceptibility that will 

lead to increased injury potential in western and northern corn rootworm feeding on the 

rootworm component of OAM1 products. Sampling must be focused in the four regions 

of highest risk of resistance development: Region – 1 (Illinois, Indiana); Region 2 (Iowa, 

Missouri), Region 3 (Nebraska and Kansas), Region 4 (Minnesota, South Dakota and 

Wisconsin). 

2. Pioneer must provide the EPA its detailed western corn rootworm resistance monitoring 

plan for approval by December 1, 2010 and its northern corn rootworm resistance 

monitoring plan for approval by December 1, 2011. These plans will include baseline 

(benchmark) susceptibility data and an enhanced annual resistance monitoring plan. The 

reports will contain: 

• Sampling scheme: annual collection should target a range of 16-20 western 

and/or northern rootworm populations (4-5 per region), with a minimum 

number of 2,000 beetles collected per population. 

• Bioassay methodology (precision, detection level, etc.). Pioneer must 

bioassay a target of 3000 larvae on 59122 plants for each population. 

• A description of how monitoring results relate to and are predictive of 

changes in field efficacy, and change in injury potential to DAS-59122-7 

constituting product failure and development of a remedial action plan. 

3. Pioneer will provide the EPA with an annual OAM1 resistance monitoring report by 

August 31st of each year beginning with 2011 for western corn rootworm and 2012 for 

northern corn rootworm, reporting on populations collected the previous year. 

In addition to screening of wide-area corn rootworm populations as outlined above, for 

the second prong of resistance monitoring Pioneer must investigate grower, extension 

specialist or consultant reports of less-than-expected efficacy or field performance of 

OAM1 products. 

e) Remedial Action Plan for Corn Rootworm and OAM1 Corn 
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The remedial action plan is designed as a tiered approach for mitigating western and northern 

corn rootworm resistance development specifically due to the commercialization of OAM1 corn. 

The following program summary describes, in order of events, the steps that must be taken to 

implement a remedial action plan if resistance to target pests is confirmed. 

Pioneer will complete a benchmark study of susceptibility of western corn rootworm using the 

Sublethal Seedling Assay and analyze field efficacy data to set a benchmark for expected levels 

of damage to finalize the OAM1 remedial action plan by December 1, 2010, so that decision 

points regarding crop damage and target pest resistance are established, and a remedial action 

plan can be initiated when needed. Although northern corn rootworm is difficult to rear in the 

laboratory, Pioneer will attempt to complete a benchmark study for susceptibility of northern 

corn rootworm using the Sublethal Seedling Assay. 

1. Suspected Resistance from Population Monitoring 

Definition of Suspected Resistance - Resistance will be suspected if investigations of target pest 

injury potential to OAM1 maize from the Sublethal Seedling Assay show that: 

• Injury potential of a target pest population obtained as part of the annual insect 

monitoring program has increased to a level representative of product failure in 

field conditions; 

• The seeds used in the investigation of this population’s injury potential contain 

Cry34/Cry35Ab1 at levels representative of (and in the same genetic background 

as) the benchmark study; and 

• The change in injury potential has been documented as a heritable characteristic 

of the target pest population and not a result of experimental error. 

If resistance is "suspected", Pioneer will inform growers in the area of the potential benefit of 

augmenting CRW control such as adulticide treatment and/or crop rotation or use of soil or seedapplied insecticides at rates providing corn rootworm control the following year. These 

measures are intended to educate growers of the potential for change in efficacy, reduce the 

possibility of grower loss from change in efficacy and reduce potentially resistant insects 

contributing to the following year's pest population. 

2. Confirmed Resistance from Population Monitoring 

Definition of Confirmed Resistance - Resistance will be confirmed if all of the following criteria 

are met by progeny from a subsequent rootworm population collected from the area of 

"suspected resistance" the following year: 

• Injury potential of the subsequent field-collected rootworm population feeding on 

plants containing DAS-59122-7 remains at a level likely to produce repeated 

product failure in field conditions; 

• The change in injury potential has been documented as a heritable characteristic 

of the target pest population; 

• Greenhouse node-injury evaluation confirms product failure; 

• Subsequent populations collected from the area and assayed show that the results 
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are repeatable; and 

• Continued monitoring of the area suggests that the change is spreading. 

3. Suspected Resistance – Investigation of Field Reports 

The registrant will follow up on grower, extension specialist or consultant reports of unexpected 

product performance due to corn rootworm species listed on the label. The registrants will 

instruct its customers to contact them if such incidents occur. The registrants will investigate all 

such reports submitted to the company or the company’s representatives. 

• Confirm the corn in question is rootworm-active Bt corn; 

• Confirm the field in question contains the correct blend rate of refuge corn; 

• Confirm that species not susceptible to the protein are not responsible for the 

damage, that no climatic or cultural reasons could be responsible for the 

damage, and that all other reasonable causes based on historical experience 

for the observed root damage have been ruled out; 

• If not due to other reasons, the registrant will conduct a thorough investigation 

of the factors known to affect the manifestation of corn rootworm feeding 

damage. 

• If the investigation fails to rule out target pest resistance as the cause, 

resistance is suspected. 

If resistance is "suspected", Pioneer will inform growers in the area of the potential benefit of 

augmenting CRW control such as adulticide treatment, crop rotation the following year or use of 

soil or seed insecticides the following year. These measures are intended to educate growers of 

the potential for change in efficacy, reduce the possibility of grower loss from change in efficacy 

and reduce potentially resistant insects contributing to the following year's pest population. 

Pioneer will collect insects as soon as possible from the area for laboratory studies to test for 

resistance by comparing with benchmark susceptibility data. These studies will be performed 

following the same laboratory protocols as used for the benchmark determination and monitoring 

programs. 

4. Confirmed Resistance – Investigation of Field Reports 

• Injury potential of the field-collected rootworm population feeding on plants 

containing DAS-59122-7 remains at a level likely to produce repeated product 

failure in field conditions; 

• Subsequent populations collected from the area and assayed show that the results 

are repeatable; 

• The change in injury potential has been documented as a heritable characteristic 

of the target pest population; 

• Greenhouse node-injury evaluation confirms product failure; and

• Continued monitoring of the area suggests that the change is spreading.

5. Remedial Action 
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When resistance is "confirmed", the following steps will be taken: 

• The EPA will receive notification within 30 days of confirmed resistance; 

• Affected customers and Extension specialists will be notified about confirmed 

resistance; 

• Affected customers and Extension specialists will be encouraged to implement 

alternative CRW control measures such as adulticide treatment, crop rotation the 

following year, or use of soil or seed insecticides the following year; 

• Pioneer and EPA will jointly determine the extent of the mitigation needed and 

determine whether sales should be stopped on an appropriate geographic (i.e., 

county or regional) basis; and 

• Pioneer will develop a case-specific resistance mitigation action plan within 90 

days according to the characteristics of the resistance event and local agronomic 

needs. Pioneer will consult with appropriate stakeholders in the development of 

the action plan, and the details of such a plan shall be approved by the EPA prior 

to implementation. The resistance management plan could include such measures 

layering additional technologies in future OAM1 products. 

f) Remedial Action Plan for lepidopteran pests and OAM1 Corn 

When field resistance is confirmed (as defined above), the following steps will he taken by the 

registrant: 

• EPA will receive notification within 30 days of resistance confirmation; 

• Affected customers and extension agents will be notified about confirmed resistance 

within 30 days; 

• Monitoring will be increased in the affected area and local target pest populations will be 

sampled annually to determine the extent and impact of resistance; 

• If appropriate (depending on the resistant pest species, the extent of resistance, the timing of 

resistance, and the nature of resistance, and the availability of suitable alternative control 

measures) , alternative control measures will be employed to reduce or control target pest 

populations in the affected area. Alternative control measures may include advising customers 

and extension agents in the affected area to incorporate crop residues into the soil following 

harvest to minimize the possibility of over-wintering insects, and/or applications of chemical 

insecticides; 

• Unless otherwise agreed with EPA, stop sale and distribution of the relevant 

lepidopteran-active Bt corn hybrids in the affected area immediately until an effective 

local mitigation plan approved by EPA has been implemented; 

• The registrant will develop a case-specific resistance management action plan within 90 days 

according to the characteristics of the resistance event and local agronomic needs. The registrant 
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will consult with appropriate stakeholders in the development of the action plan. and the details 

of such a plan shall be approved by EPA prior to implementation; 

• Notify affected part ies (e .g. growers, consultants, extension agents, seed distributors, 

university cooperators and state/ federal authorities as appropriate) in the region of the 

resistance situation and approved action plan; and 

• In subsequent growing seasons, maintain sales suspension and alternative resistance 

management strategies in the affected region(s) for the Bt corn hybrids that are affected 

by the resistant population until an EPA-approved local resistance management plan is in 

place to mitigate the resistance. 

A report on results of resistance monitoring and investigations of damage reports must be 

submitted to the Agency annually by August 31st each year for the duration of the conditional 

registration. 

g) Refuge Assurance Program for OAM1 Corn 

Pioneer must implement a Blended Seed Refuge Assurance Program designed to ensure OAM1 

products are formulated with the appropriate rate of refuge seeds. The program must include the 

following four elements: 

1. Trait purity check on seed lots prior to blending; 

2. ISO 9000 Standard Operating Procedures for the blending process; 

3. Calibration of blending equipment; and 

4. Records and data retention records for seed blend products. 

• Calibration records - Pioneer will retain documentation for a specified period of 

time on the equipment calibration including the procedure, when it was conducted 

and the results. 

• Blend proportion records (weight and kernel based) - Pioneer will retain 

documentation for a specified period of time on the kernel per pound data of the 

components, the calculations to determine the proportions based on weight and 

the actual weights that are blended together to make up an OAM1 product by seed 

lot. 

All records must be maintained at the Pioneer blending facility and must be available for the 

EPA review upon request. 

h) Annual Reporting Requirements for OAM1 Corn 

1. Annual Sales: reported and summed by state (county level data available by 

request) January 31st each year, beginning in 2011; 

2. Grower Agreements: number of units of OAM1 corn seed shipped or sold 

and not returned, and the number of such units that were sold to persons who 

have signed grower agreements, January 31st each year, beginning in 2011; 

3. Grower Education: substantive changes to education program completed 
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previous year, January 31st each year, beginning in 2011; 

4. Compliance Assurance Program: compliance assurance program activities 

and results for the prior year and plans for the compliance assurance program 

for the current year, January 31st each year, beginning in 2011; 

5. Compliance Survey Results: results of annual surveys for the prior year and 

survey plans for the current year; full report January 31st each year, beginning 

in 2011; 

6. Insect Resistance Monitoring Results: results of monitoring and 

investigations of damage reports, August 31st each year, beginning in 2011 for 

western corn rootworm and 2012 for northern corn rootworm. 

OAM RW

1) Submit and/or cite all data required for registration/ registration review of your product under 

FIFRA section 3(c)(5) when the Agency requires all registrants of similar products to submit 

such 

data. 

2) The subject registration will automatically expire on midnight September 30, 2010. 

3) Submit or cite all data required to support the Herculex RW plant-incorporated protectant 

products within the timeframes required by the terms and conditions of EPA Registration 

Number 29964-4. 

4) The subject registration will be limited to a seed mix of DAS-59122-7 (Cry34Ab1/Cry35Ab1) 

corn seed blended with not less than 10% non-Bt corn seed. 

Because OAMRW controls corn rootworm pests and contains an integrated corn rootworm 

refuge, no additional refuge is required. When a grower plants a bag of OAMRW, all refuge 

requirements are fully and automatically met for this product. Therefore, grower agreements 

(demonstrating persons purchasing OAMRW corn will annually affirm that they are 

contractually bound to comply with requirements of the insect resistance management (IRM) 

program) and other associated stewardship documents are neither necessary nor required. 

Targeted on-farm compliance assessments are neither necessary nor required for OAMRW 

because the refuge is automatically implemented when planting this product. 

OAMRW may be used as the Lepidopteran refuge for OAM1. In this case, on-farm assessments 

to ensure that the Lepidopteran refuge is planted and placed appropriately would be covered by 

OAM1 grower education, targeted on-farm assessments and stewardship documents. 
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5) Submit the following data in the timeframes listed: 

Study Type Required Data Due Date 

 

Insect Resistance 

Management 

Pioneer must implement an enhanced resistance 

monitoring plan for OAMRW. Pioneer must provide the 

Agency with a baseline (benchmark) study that shows 

the susceptibility of western corn rootworm populations 

(WCRW) in the Sublethal Seedling Assay prior to the 

large-scale introduction of OAMRW. Although northern 

corn rootworm (NCRW) is difficult to rear, Pioneer must 

attempt to obtain benchmark susceptibility data for 

NCRW as well. 

12/1/2010 for 

WCRW 

12/1/11 for 

NCRW 

Insect Resistance 

Management 

Pioneer must submit a detailed OAMRW-specific 

resistance monitoring and remedial action plan, including 

an analysis to determine the expected field performance 

criteria for OAMRW products so that unexpected 

damage can be benchmarked. Pioneer will update the 

plan by 12/1/2012, if needed, based on continued field 

evaluation of OAM1 performance. 

12/1/2010 

 

6) Pioneer must commit to do the following Insect Resistance Management Program for 

OAMRW. 

The required IRM program for OAMRW corn must have the following elements: 

Requirements regarding programs to evaluate whether there are statistically significant and 

biologically relevant changes in target insect susceptibility to Cry34Ab1/Cry35Ab1 proteins in 

the target insects; 

Requirements regarding a “remedial action plan,” which contains measures Pioneer would take 

in the event that any field-relevant insect resistance was detected as well as to report on activity 

under the plan to EPA; 

Annual reports on units sold by state (units sold by county level will be made available to the 

Agency upon request) on or before January 31st of each year, beginning in 2011. 

a) Insect Resistance Monitoring for OAMRW Corn 

In addition to the existing two-pronged approach to insect resistance monitoring (monitoring 

insect populations using the diet bioassay and investigations of field reports) that currently takes 

place for Cry34/35 for Herculex Rootworm (29964-4), Pioneer must also conduct enhanced 

monitoring using the Sublethal Seedling Assay as a complement to the diet bioassay method. 

Pioneer must submit a detailed OAM1/OAMRW-specific resistance monitoring plan to the 

Agency by December 1, 2010. 

With respect to the implementation of the Sublethal Seedling Assay: 
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1. Pioneer must monitor for resistance and or changes in target pest susceptibility 

that will lead to increased injury potential in western and northern corn rootworm 

feeding on the rootworm component of OAMRW products. Sampling must be 

focused in the four regions of highest risk of resistance development: Region – 1 

(Illinois, Indiana); Region 2 (Iowa, Missouri), Region 3 (Nebraska and Kansas), 

Region 4 (Minnesota, South Dakota and Wisconsin). 

2. Pioneer must provide the EPA its detailed western corn rootworm resistance 

monitoring plan for approval by December 1, 2010 and its northern corn 

rootworm resistance monitoring plan for approval by December 1, 2011. These 

plans will include baseline (benchmark) susceptibility data and an enhanced 

annual resistance monitoring plan. The reports will contain: 

• Sampling scheme: annual collection should target a range of 16-20 western 

and/or northern rootworm populations (4-5 per region), with a minimum 

number of 2,000 beetles collected per population. 

• Bioassay methodology (precision, detection level, etc.). Pioneer must 

bioassay a target of 3000 larvae on 59122 plants for each population. 

• A description of how monitoring results relate to and are predictive of 

changes in field efficacy, and change in injury potential to DAS-59122-7 

constituting product failure and development of a remedial action plan. 

3. Pioneer will provide the EPA with an annual OAMRW resistance monitoring 

report by August 31st of each year beginning with 2011 for western corn 

rootworm and 2012 for northern corn rootworm, reporting on populations 

collected the previous year. 

In addition to screening of wide-area corn rootworm populations as outlined above, for the 

second prong of resistance monitoring Pioneer must investigate grower, extension specialist or 

consultant reports of less-than-expected efficacy or field performance of OAMRW products. 

b) Remedial Action Plan for Corn Rootworm and OAMRW Corn 

The remedial action plan is designed as a tiered approach for mitigating western and northern 

corn rootworm resistance development specifically due to the commercialization of OAMRW 

corn. The following program summary describes, in order of events, the steps that must be taken 

to implement a remedial action plan if resistance to target pests is confirmed. 

Pioneer will complete a benchmark study of susceptibility of western corn rootworm using the 

Sublethal Seedling Assay and analyze field efficacy data to set a benchmark for expected levels 

of damage to finalize the OAMRW remedial action plan by December 1, 2010, so that decision 

points regarding crop damage and target pest resistance are established, and a remedial action 

plan can be initiated when needed. Although northern corn rootworm is difficult to rear in the 

laboratory, Pioneer will attempt to complete a benchmark study for susceptibility of northern 

corn rootworm using the Sublethal Seedling Assay as well. 
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1. Suspected Resistance from Population Monitoring 

Definition of Suspected Resistance - Resistance will be suspected if investigations of target pest 

injury potential to OAMRW maize from the Sublethal Seedling Assay show that: 

• Injury potential of a target pest population obtained as part of the annual insect 

monitoring program has increased to a level representative of product failure in 

field conditions; 

• The seeds used in the investigation of this population’s injury potential contain 

Cry34/Cry35Ab1 at levels representative of (and in the same genetic background 

as) the benchmark study; and 

• The change in injury potential has been documented as a heritable characteristic 

of the target pest population and not a result of experimental error. 

If resistance is "suspected", Pioneer will inform growers in the area of the potential benefit of 

augmenting CRW control such as adulticide treatment and/or crop rotation or use of soil or seedapplied insecticides at rates providing corn rootworm control the following year. These 

measures are intended to educate growers of the potential for change in efficacy, reduce the 

possibility of grower loss from change in efficacy and reduce potentially resistant insects 

contributing to the following year's pest population. 

2. Confirmed Resistance from Population Monitoring 

Definition of Confirmed Resistance - Resistance will be confirmed if all of the following criteria 

are met by progeny from a subsequent rootworm population collected from the area of 

"suspected 

resistance" the following year: 

• Injury potential of the subsequent field-collected rootworm population feeding on 

plants containing DAS-59122-7 remains at a level likely to produce repeated 

product failure in field conditions; 

• The change in injury potential has been documented as a heritable characteristic 

of the target pest population; 

• Greenhouse node-injury evaluation confirms product failure; 

• Subsequent populations collected from the area and assayed show that the results 

are repeatable; and 

• Continued monitoring of the area suggests that the change is spreading. 

3. Suspected Resistance – Investigation of Field Reports 

The registrant will follow up on grower, extension specialist or consultant reports of unexpected 

product performance due to corn rootworm species listed on the label. The registrants will 

instruct its customers to contact them if such incidents occur. The registrants will investigate all 

such reports submitted to the company or the company’s representatives. 

• Confirm the corn in question is rootworm-active Bt corn; 

• Confirm the field in question contains the correct blend rate of refuge corn; 
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• Confirm that species not susceptible to the protein are not responsible for the 

damage, that no climatic or cultural reasons could be responsible for the 

damage, and that all other reasonable causes based on historical experience 

for the observed root damage have been ruled out; 

• If not due to other reasons, the registrant will conduct a thorough investigation 

of the factors known to affect the manifestation of corn rootworm feeding 

damage. 

• If the investigation fails to rule out target pest resistance as the cause, 

resistance is suspected. 

If resistance is "suspected", Pioneer will inform growers in the area of the potential benefit of 

augmenting CRW control such as adulticide treatment, crop rotation the following year or use of 

soil or seed insecticides the following year. These measures are intended to educate growers of 

the potential for change in efficacy, reduce the possibility of grower loss from change in efficacy 

and reduce potentially resistant insects contributing to the following year's pest population. 

Pioneer will collect insects as soon as possible from the area for laboratory studies to test for 

resistance by comparing with benchmark susceptibility data. These studies will be performed 

following the same laboratory protocols as used for the benchmark determination and monitoring 

programs. 

4. Confirmed Resistance – Investigation of Field Reports 

• Injury potential of the field-collected rootworm population feeding on plants 

containing DAS-59122-7 remains at a level likely to produce repeated product 

failure in field conditions; 

• Subsequent populations collected from the area and assayed show that the results 

are repeatable; 

• The change in injury potential has been documented as a heritable characteristic 

of the target pest population; 

• Greenhouse node-injury evaluation confirms product failure; and

• Continued monitoring of the area suggests that the change is spreading.

5. Remedial Action 

When resistance is "confirmed", the following steps will be taken: 

• The EPA will receive notification within 30 days of confirmed resistance; 

• Affected customers and Extension specialists will be notified about confirmed 

resistance; 

• Affected customers and Extension specialists will be encouraged to implement 

alternative CRW control measures such as adulticide treatment, crop rotation the 

following year, or use of soil or seed insecticides the following year; 

• Pioneer and EPA will jointly determine the extent of the mitigation needed and 

determine whether sales should be stopped on an appropriate geographic (i.e., 

county or regional) basis; and 

• Pioneer will develop a case-specific resistance mitigation action plan within 90 
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days according to the characteristics of the resistance event and local agronomic 

needs. Pioneer will consult with appropriate stakeholders in the development of 

the action plan, and the details of such a plan shall be approved by the EPA prior 

to implementation. The resistance management plan could include such measures 

layering additional technologies in future OAMRW products. 

c) Refuge Assurance Program for OAMRW Corn 

Pioneer must implement a Blended Seed Refuge Assurance Program designed to ensure 

OAMRW products are formulated with the appropriate rate of refuge seeds. The program must 

include the following four elements: 

1. Trait purity check on seed lots prior to blending; 

2. ISO 9000 Standard Operating Procedures for the blending process; 

3. Calibration of blending equipment; and 

4. Records and data retention records for seed blend products. 

• Calibration records - Pioneer will retain documentation for a specified period of 

time on the equipment calibration including the procedure, when it was conducted 

and the results. 

• Blend proportion records (weight and kernel based) - Pioneer will retain 

documentation for a specified period of time on the kernel per pound data of the 

components, the calculations to determine the proportions based on weight and 

the actual weights that are blended together to make up an OAMRW product by 

seed lot. 

All records must be maintained at the Pioneer blending facility and must be available for the 

EPA review upon request. 

d) Annual Reporting Requirements for OAMRW Corn 

1. Annual Sales: reported and summed by state (county level data available by 

request) January 31st each year, beginning in 2011; 

2. Insect Resistance Monitoring Results: results of monitoring and investigations of 

damage reports, August 31st each year, beginning in 2011 for western corn 

rootworm and 2012 for northern corn rootworm. 

REFERENCES

Bailey, L., R. Binning, L. Higgins, D. Langer, R. Layton, S. Lefko, T. Nowatzki, E. Owens, 

and T. Rood. 2008. Trait Durability Plan for Optimum® AcreMaxTM1 Insect Protection 

Following Commercialization. Unpublished report submitted to the US EPA (MRID 473567-

09). 

Caprio, MA, T Nowatzki, B Siegfried, LJ Meinke, RJ Wright & LD Chandler. 2006. Assessing 

the Risk of Resistance to Aerial Applications of Methyl-Parathion in the Western Corn 
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Rootworm. Journal of Economic Entomology, Vol. 99(2): 483-493 

Caprio, M. A., D. Sumerford & S. Sims. 2006b. Evaluating transgenic plants for suitability in 

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rootworm (Coleoptera: Chrysomeldiae). Environmental Entomology, Vol. 15: 620-625 

Davis, P. and S. MacIntosh. 2008. Benefits Document of Optimum® AcreMaxTM 1 Insect 

Protection. Unpublished report submitted by Pioneer Hi-Breed International, Inc. to the US 

EPA (MRID 473567-10). 

EPA MRID No. 47339601 Bailey, L. (2008) 2007 Insect Resistance Management Compliance 

Assurance Program Report for Corn Borer-Protected Bt corn, Corn Rootworm-Protected Bt corn, 

and Corn Borer/ Corn Rootworm-Protected Stacked Bt corn. Project Number: CAP/2007. 

Unpublished study prepared by Agricultural Biotechnology Stewardship Technical Committee. 

17 p. 

EPA MRID No.47356701 Lefko, S.; Binning, R. (2008) Characterization of Instar-Specific 

Response and Larval Recovery of Western Corn Rootworm Exposed to 59122 Maize. Project 

Number: PHI/2005/053.Unpublished study prepared by Pioneer Hi-Bred International, Inc. 

34 p. 

EPA MRID No.47356702 Lefko, S.; Binning, R. (2008) Effect of Off-Type Seeds on the 

Precision of Sublethal Corn Rootworm Seedling Assay Results. Project Number: PHI/2006/042. 

 Unpublished study prepared by Pioneer Hi-Bred International, Inc. 13 p. 

EPA MRID No.47356703 Lefko, S.; Diehn, S. (2008) An Observational Study Characterizing 

the Relative Quantity and Distribution of Cry34Ab1 and Cry35Ab1 Insecticidal Proteins in 

Roots of Maize Containing Event DAS-59122-7. Project Number: PHI/2006/119. Unpublished 

study 

prepared by Pioneer Hi-Bred International, Inc. 22 p. 

EPA MRID No.47356704 Lefko, S.; Binning, R. (2008) Quantifying the Concentration of 

Cry34Ab1 and Cry35Ab1 in 59122 Maize Grown in the Sublethal Corn Rootworm Seedling 

Assay System. Project Number: PHI/2006/171. Unpublished study prepared by Pioneer HiBred 

International, Inc. 11 p. 

EPA MRID No.47356705 Nowatzki, T. ; Thompson, S.; Peters, M. (2008) Field Measures of 

Adult Corn Rootworm (Coleoptera: Chrysomelidae) Production When Refuge is Deployed as a 

Seed Blend with DAS-59122-7 Maize. Project Number: PHI/2007/075. Unpublished study 

prepared by Pioneer Hi-Bred International, Inc. 57 p. 
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EPA MRID No.47356706 Nowatzki, T.; Meinke, L. (2008) Impact of Western and Northern 

Corn Rootworm Larval Exposure to DAS-59122-7 in a Block Planting and a Seed Blend on Life 

History Traits of Adults. Project Number: PHI/2007/076. Unpublished study prepared by 

Pioneer 

Hi-Bred International, Inc. and University of Nebraska-Lincoln. 31 p. 

EPA MRID No.47356707 Lefko, S.; Binning, R. (2008) Investigating the Effect of Insecticidal 

Proteins Cry34/35Ab1 on Western Corn Rootworm Host Searching Behavior. Project Number: 

PHI/2007/126. Unpublished study prepared by Pioneer Hi-Bred International, Inc. 17 p. 

EPA MRID No.47356710 Davis, P.; MacIntosh, S. (2008) Benefits Document for Optimum 

AcreMax 1 Insect Protection. Project Number: PHI/2007/145. Unpublished study prepared by 

Pioneer Hi-Bred International, Inc. 21 p. 

EPA MRID No.47663301 Bailey, L. (2009) 2008 Insect Resistance Management Compliance 

Assurance Program Report for Corn Borer-Protected Bt Corn, Corn Rootworm-Protected Bt 

Corn, and Corn Borer/Corn Rootworm-Protected Stacked Bt Corn. Project Number: CAP/2008. 

 Unpublished study prepared by Agricultural Biotechnology Stewardship Techn. Committee. 15 

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EPA MRID No.47683801 Binning, R.; Langer, D. (2009) Additional Responses for "Pioneer's 

Benefit Documentation in Support of a Sec(3) Product Registration for Optimum AcreMax 1 

Insect Protection, also Known as Stack Herculex XTRA (Cry34/35Ab1 + Cry1F) with Herculex 

I (Cry1F, Refuge Seed for CRW) [MRID 473567-10 and Supplemental Data]": Final Report. 

Project Number: PHI/2009/026. Unpublished study prepared by Pioneer Hi-Bred International, 

Inc. 11 p. 

EPA MRID No. 48076501 Dreyer, C.; Gutsche, A.; Hubbard, N.; et al. (2010) Addendum to 

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PHI/2009/099. Unpublished study prepared by Pioneer Hi-Bred International Inc. 33 p. 

EPA MRID No.47871001 Pan, Z.; Onstad, D.; Stanley, B.; et al. (2009) A Spatially Explicit 

Computer Simulation Study of Corn Rootworm, Diabrotica spp. [Coleoptera: Chrysomelidae]: 

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