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)

Updated August 4 , 2010Optimum AcreMax B.t. Corn Seed Blends Page 2 of 23

Biopesticides Registration Action Document 

### TABLE OF CONTENTS I. OVERVIEW ................................ ................ ERROR! BOOKMARK NOT DEFINED. 3 II. INSECT RESISTA NCE MA NA GEMENT ................................ ................................ . 6 III. BENEFITS ................................ ................................ ................................ ............. 10 IV. REGULATORY RATIONA LE ................................ ................................ .............. 12 V. REFERENCES ................................ ................................ ................................ ....... 1 9Optimum AcreMax B.t. Corn Seed Blends Page 3 of 23

Biopesticides Registration Action Document I. OVERVIEW A. BAC KGROUND On April 30, 2010, EPA conditionally registered the plant - incorporated protectant product s , Optimum® AcreMaxTM 1 (OAM 1 ), a seed blend of 90% HERCULEX® XTRA and 10% HERCULEX® I, and OAM RW, a seed blend of 90% HERCULEX® RW and 10% Non -B.t. Corn. T hese registrations will expire on September 30, 2010. The Agency determined that the use of these pesticide products is in the public interest and that their use during the limited time of the registration would not cause an y unreasonable adverse effects on the environment. The registrant for both products is Pioneer Hi - Bred International, Inc. (Pioneer). OAM1 is the first registered B.t. corn product to incorporate a "blended" refuge; i.e., the OAM1 product requires a 10% refuge for corn rootworm, and the corn rootworm refuge seed is sold within the same seed bag as the B.t. corn rootworm product. (OAM1 also requires a separate 20% refuge for lepidopteran pests, and that refuge is in the form of a structured refuge that is sold separatel y). On October 1, 2009, EPA announced a new policy to provide a more meaningful opportunit y 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 reg istration decision for, at minimum, the following t ypes of applications: new active ingredients; first food uses; first outdoor uses; first residential uses; and other actions for which the Agency anticipates that there will be significant public interest. Consistent with the policy of making registration actions more transparent, the proposed amendments to the expiring OAM1 and O AM RW corn products are subject to a 30 - day comment period because the Agency believes, given past experiences with PIPs in gen eral, these actions are of significant public interest. While a final decision on amending the expiring OA M 1 and O AM RW corn products is contingent upon review and consideration of public comments received, the Agency believes that, based on all data submi tted in support of the expiring OA M 1 and O AM RW corn registrations, it is in the best interest of the public and the environment to amend the currentl y existing OA M 1 and O AM RW registrations b y extending the current expiration dates to September 30, 201 2 . The basis for this preliminary decision can be found in the risk assessment s for the expiring OA M 1 and O AM RW , and our responses to comments on the original OAM1 and OAM RW registrations, all of which are set forth in this Biopesticides Registration Action Document (BRAD). In addition to the expiring OA M 1 and O AM RW corn products, there are other Bt corn PIPs, expressing different proteins effective in controlling various lepidopteran and coleopteran pests, that expire in 2010, and for which the associ ated registrants have formally requested an extension to the current expiration dates. Therefore, within the same docket ( EPA - HQ - OPP 2010 - 0607) as this document, the following information is also available for public examination: ● Cry 1F and Cry 1Ab BRAD  C ry 3Bb1 BRAD ● Cry 34/35Ab1 BRAD ● mCry 3A BRAD ● Optimum® AcreMaxTM B . t . Seed Blends BRAD ● Current Registration Terms and Conditions for Bt Corn Registrations Set to Expire in 2010Optimum AcreMax B.t. Corn Seed Blends Page 4 of 23

Biopesticides Registration Action Document ● Proposed Registration Terms and Conditions for Bt Corn Registrations Se t to Expire in 2010 EPA has made the preliminary decision to amend the registrations of twent y - two (22) expiring Bt corn PIP registrations to extend the expiration dates. We have conducted comprehensive assessments of each of these registrations, considering all toxicity and environmental effects data, data from insect resistance monitoring, and insect resistance refuge compliance reports, received and obtained since the last comprehensive evaluation of these products in 2001. Based upon our comprehensive assessment, we have reached significant conclusions regarding the positive environmental impact of Bt corn PIPs, and we are proposing several actions to strengthen the insect resistance management requirements to ensure continued success in the prevention of the evolution of resistance in target pests. Since the commercialization of Bt crops, there have been a significant number of published field studies that, combined with the post - registration field studies required to be submitted to the Agency , have d emonstrated that non - target invertebrates are generall y more abundant in Bt cotton and Bt corn fields than in non - transgenic fields managed with chemical insecticides. Thus, these published and registrant - produced studies demonstrate that, not only are the Bt crops not causing an y unreasonable adverse effects in the environment, but, arthropod prevalence and diversity is greater in Bt crop fields. Although no effects have been observed in the environment, the Agency

is requiring additional aquatic invertebr ate data in light of published laboratory studies showing reduced growth in shredding caddis flies exposed to Cry 1A protein corn litter. To strengthen insect resistance management of these corn PIPs and to address reports that compliance with the mandated refuge requirements has been decreasing, EPA is proposing to require enhanced compliance assurance programs (CAPs), and a phased requirement for seed bag labeling that clearl y shows the refuge requirements. Also, g iven the increasing variet y of PIP pro ducts and combinations, and the differing risk of resistance evolution that the various products represent, we are proposing to grant registrations for the corn PIP products for different timeframes, based on assessments of their likelihood of forestalling the evolution of insect resistance. We are registering differing categories of products for differing time periods to reflect the assessed level of risk of resistance posed b y the various corn PIP products. The scheme that we propose to follow will includ e registration periods generall y of five, eight, and twelve ye ars; with the possibility

of a fifteen - ye ar registration period for products that are demonstrated to meet specified criteria. We retain, however, the discretion to register products for time periods differing from these defaults where circumstances warrant . In the case of OAM1 and OAM RW, we are proposing to register these products for two y ears . B. U SE PROFILE Active Ingredients : Bacillus thuringiensis Cry34Ab1 and Cry 35Ab1 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 PHI 8999) in Event TC1507 cornOptimum AcreMax B.t. Corn Seed Blends Page 5 of 23

Biopesticides Registration Action Document Trade & Othe r Names: HERCULEX® I = > Cry1F Corn HERCULEX® RW (Rootworm) = > Cry 34/35Ab1 Corn HERCULEX® XTRA = > Cry 1F + Cry 34/35Ab1 Corn Optimum® AcreMaxTM 1 ( OAM1 ) = > 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 Code s : 006490 (Cry 34/35Ab1 corn) and 006481 (Cry 1F corn) Type of Pesticide: Plant - Incorporated Prot ectants (PIPs) Product Prof

i le : HERCULEX® I The registration for Cry 1F Event TC1507 (Event DAS - 01507 - 1), also known as HERCULEX® I, was first granted b y the Agency on May 18, 2001 . HERCULEX® I expresses the Cry 1F insecticidal cry stal protein as well as the PAT (phosphinothrin acet yltransferase) protein , which confers tolerance to the herbicidal active ingredient glufosinate - ammonium . Cry 1F 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 arm yworm (FAW, Spodoptera frugiperda ), western bean cutworm (WBCW, Richia albicosta ), and black cutworm (BCW, Ag rotis ipsilon ) . The main target pests for which insect resistance management ( IRM ) requirements appl y are ECB, CEW, and SWCB. HERCULEX® RW The registration for Event DAS - 59122 - 7, also known as HERCULEX® RW , was granted b y the Agency in August, 2005 . HER CULEX® RW expresses B.t. toxins Cry34Ab1 and Cry 35Ab1, 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 conv entional 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 . OAM1 : 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 twoOptimum AcreMax B.t. Corn Seed Blends Page 6 of 23

Biopesticides Registration Action Document 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 percenta ge 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% HE RCULEX® RW and 10% non -B.t. Corn . The new product incorporates the CRW refuge into the seed bag and also can serve a s a refuge for the Cry 1F portion of OAM1 . Pioneer’s Projected Use in 2010, 2011, and 2012 Pioneer’s forecast for OAM1 U.S . acreage in the 2010, 2011 , and 2012 growing seasons is listed below. Pioneer states that “[t]hese estimates have been divided into high - pressure areas for corn rootworm (i.e., the Red Zone) and non - Red Zone acres (i.e., the remaining U.S. corn acr eage outside the Red Z one). 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 Il linois, northwestern Indiana and, to a lesser extent, southeastern Wisc onsin 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 b ased on general USDA acreage projections, which project a t otal of 90 million corn acres in the U.S. in 2010, 2011 , and 2012. ” Growing season Red Zone geography Non - Red Zone geography 2010 ~0.077% ~0.042% 2011 ~5.8% ~8.2% 2012 ~8% ~12% Pioneer provided information to EPA indicating that the total OAM1 acre s planted in 2010 was 34,804 , which is less than originall y projected . (Rood 2010) . Pioneer has not changed the initial projections for 2011 and 2012. II. INSECT RESISTANCE MANAGEMENT FI FRA Scientific Advisory Panel (SAP) Pioneer/Dupont 's initial reg istration application for OAM1 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 co rn rootworm active component of HERCULEX® XTRA . Th e proposed seed blend str ategy 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 Adviso ry

Panel for peer review on February 23 to 24, 2009 . The SAP (2009) expressed concern about the propos ed refuge reduction. The Panel concluded that there was no compelling evidence , either in the data provided b y Pioneer or in the public literature, to support a 5% blended refuge for this particular product . T he 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.Optimum AcreMax B.t. Corn Seed Blends Page 7 of 23

Biopesticides Registration Action Document Ad hoc members of the SAP commented on EPA's grant of the OAM1 registration for 2010. These members noted that the 2009 SAP had voiced concerns on the simultaneous approval of a blended and reduced refuge for corn rootworm, and stated that EPA "ignored" the 2009 SAP's general conclusion to retain a 20% refuge while research continues. In granting a registration for sale and distribution of OAM1 for the 2010 growing season, EPA did consider and rel y upon the advice of the SAP. Pioneer's initial application sought approval for a 2.5 % blended refuge and that is what EPA took before the SAP. Concerns raised b y the SAP were a major factor in wh y the Agency

did not approve the 2.5% blended refuge proposal. Moreover, the concerns raised by the SAP, and other comment ers, are a significant factor in certain of the unique terms and conditions that EPA is placing on the OAM1 registration for 2011

– 2012. The ad hoc members also commented that the SAP's concerns regarding Pioneer's h ypothesis concerning mode of action we re not addressed. EPA did not specifically address the SAP's recommendation on the mod e of action h ypothesis because that hy pothesis did not play

a role in our decision. EPA similarly has concerns as to the validity of the mode of action h ypothesis and d id not in any way factor this h ypothesis in our decision. Current Submission s OAM1 is a blended seed product that contains 90% HERCULEX® XTRA seeds (Cry 34/35Ab1 x Cry 1F) and 10% HERCULEX® I seeds (Cry 1F). OAM RW is a blended seed product that contain s 90% HERCULEX® RW seeds (Cry 34/35Ab1) and 10% non -B.t. Corn . Seed Blending Pioneer submitted information and anal ys es 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% . IRM Modeling EPA Model Description EPA'S POPGEN (Po pulation Genetics) simulation models are a series of generalized, flexible population genetics modeling s ys tems modeling the evolution of resistance to conventional pesticides and transgenic crops. The programs are capable of simulating complex landscapes that vary spatiall y 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 larv al movement. The model permits modeling of both block refuges and blended seed - mixture refuges.Optimum AcreMax B.t. Corn Seed Blends Page 8 of 23

Biopesticides Registration Action Document 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 develop ed 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 b y 4 (Vose 2001). Dr. David Onstad of the University of Illinois commented that it was difficult to underst and EPA's modeling because insufficient detail on the design and inputs was included in the docket for the initial registration. We recognized that it would have been useful to place more information on the modeling in the docket. Unfortunately , this inf ormation was not ready for release at the start of the comment period. We supplement ed the docket with additional information on the model and model inputs during the comment period . Dr. Onstad also suggested that EPA's modeling efforts should be more tr ansparent and should include more explicit explanation of how the modeling was conducted. We hope that the additional information provided to the docket addressed the concerns regarding transparency . Also, EPA will convene a public meeting of the SAP to evaluate these models in earl y December. We urge all interested parties to participate and submit comments at that time. Additional information on this meeting of the SAP will be available within the normal time frame. 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 analy sis 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 deploy ment str ateg y for OAM1 and corn rootworm w ere not scientifically

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 i s a sensitive parameter for modeling the durability of block refuges . Parameter inputs representing a shorter dispersal range lowered the resulting effectiveness of a block re fuge. Using a r ang e of representative parameter values and assumptions to predict the durability of a 20% block refugeOptimum AcreMax B.t. Corn Seed Blends Page 9 of 23

Biopesticides Registration Action Document 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 ye ars 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 y ears, which was slightly less durable (5.4%) relative to a 20% block refuge based on EPA's assumptions . EPA concluded, h owever, 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 distrib utions of critical data th at 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 mod el 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, 25 th , and 75 th percentiles of the time to "resistance." EPA also determined the proportion of simulations where the time to resistance exceeded 11 ye ars. (The SAP has advised that 15 y ears with no resistance is a reasonable goal for an IRM program applicable to a single - gene toxin. The Cry 34/35 transgenic toxin has b een in use for four ye ars. 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 ye ars.) The data from these model simulations indicate comparative durability values of 11.3 years for the 10% blended refuge and 20.2 y ears for the 20% block refuge . Thus, the 10% bl end was 45% less durable than the 20% block refuge currentl y required for single trait CRW PIPs. IRM Refuge Compliance Cri tical to an assessment of the likely efficacy of an IRM mitigation program is the level of compliance with that program. Data received b y 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 d ecreased compliance increases the risk of resistance development ( see , e.g., Complacency on the Farm , CSPI2009 , and Im pact 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., alway s planting a 20% refuge , within the proper distance ) or ' out - of - compliance’ (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. fi elds met the refuge distance requirement. ( Reporting these additional data reflects that there may be degrees of noncompliance, for example, a grower may be inadvertentl y out of compliance with distance requirements b y a degree that does not materially

af fect the efficacy

of the refuge . Also, while, admittedly , a 15% refuge is notOptimum AcreMax B.t. Corn Seed Blends Page 10 of 23

Biopesticides Registration Action Document 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 accurat el y 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 a ctually the case.

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/CRWStacks III. BENEFITS We expect OAM1 to have the following benefits: (1) R educed 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) S ignificantl y less complicated refuge deploy ment for the corn rootworm active ingredient . Currently , to be fully compliant with theOptimum AcreMax B.t. Corn Seed Blends Page 11 of 23

Biopesticides Registration Action Document refuge requirements, growers must accuratel y calculate 20% of the field, accurately determine the proper distanc e 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 plant ed 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 depl oy ment of the rootworm refuge. (3) Increased grower compliance with IRM requirements for the corn rootworm active ingredient . A seed blend product incorporating an effective refuge in the seed bag would lead to 100% grower compliance for planting a refug e . 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 pest icide applications . Efficacy and Y ield B enefits Pioneer conducted a two y ear 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 fie ld 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 treat ed 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 pressur e, 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 . The Center for Science in the Public Interest (CSPI) commented that our analy sis of the benefits of OAM1 should consider overall IRM compliance, including that in the lepidopteran refuge. In addition, CSPIstated that EPA sh ould require additional conditions related to the lepidopteran refuge, such as requiring that refuge requirements be placed on seed bags, requiring that on - farm assessments be conducted by third parties, requiring growers to certify compliance annuall y, an d separating compliance data into geographic regions. EPA agrees with and is implementing a number of these suggestions. Pioneer has committed to including labeling on OAM1 seed bags indicating the size of the required refuge for lepidoptera, and this is being made a specific term of the registration. (We note that this is also being made a term of all B.t. corn registrations and that all B.t. corn registrants are required to make best efforts to implement this change on as many bags of seed as possible for the 2011 growing season, on 50% of seed bags for the 2012 growing season, and on 100% of seed bags for the 2013 growing season). EPA is also requiring that on - farm assessments for all B.t. corn registrations must be conducted by independent, third parties. Also, compliance data will be required to be submitted in a form that will permitOptimum AcreMax B.t. Corn Seed Blends Page 12 of 23

Biopesticides Registration Action Document e valuation b y geographic region. We are not, at this time, requiring that growers annually certify ex post facto that they

complied with the IRM requirements; but, that is a requirement that we will consider in the future, should the compliance picture not improve . Dow AgroSciences commented that the requirement for a separate structured lepidopteran refuge would create confusion among growers. We agree that there is the possibility of grower confusion related to the fact that there must be two separate refuges for OAM1 . Pioneer is required to conduct enhanced grower education to ensure that purchasers of OAM1 understand the lepidopteran refuge requirements. Pion eer also is responsible for 2000 independent, third party on - farm assessments to address compliance with the lepidopteran refuge requirements. Significant non - compliance with the OAM1 lepidopteran refuge requirements, if verified, could have implications for continued availability of OAM1 in 2011 and beyond . 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 , % r oot lodging, and grain yi elds between an y of the HXX (HERCULEX® XTRA ) treatments except with respect to node for the 20% refuge with P250 . IV. REGULATORY RATIONALE A. 2010 Registration Decision Section 3(c)( 7 ) (A) of FIFRA provides for the registrati on or amendment of a pesticide when the pesticide and proposed use “...are identical or substantially similar to any

currentl y registered pesticide and use thereof, or differ onl y in way s that would not significantly increase the risk of unreasonable adver se effects on the environment , and (ii) approving the registration or amendment in the manner proposed b y 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 “... an y unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of the use of an y pesticide ...” Thus, pursuant to Section 3(c)(7)(A), EP A may conditionally register a 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 onl y in ways that would not significantly incre ase the risk of unreasonable adverse effects; and (3) approving the registration would not significantl y increase the risk of an y unreasonable adverse effect. In our registration decision for the 2010 growing season, we found that OAM1 and OAM RW met cri teria (2) and (3) of Section 3(c)(7)(A) for a time - limited registration to expire September 30, 2010. Optimum Acre Max (OAM) 1 is a seed b lend consisting of two currentl y registered products, 90% Herculex Xtra and 10% Herculex I . Optimum Acre Max ( OAM ) RW is a seed blend consisting of an already registered product and non - PIP corn, 90% Herculex RW and 10% n on - B.t. c orn . Thus, both products we re found to be substantially similar to already registered PIPs in composition and use site (field corn). These p roducts d id not meet criteria (1), however, because the proposed use of OAM1 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 currentl y registered pesticide. Hav ing the refuge in the bag of seeds is a novel approach. We determine d , however, that each of these products met criteria (2) as , when used in accordance with the terms and conditions of the time - limited registration set to expire SeptemberOptimum AcreMax B.t. Corn Seed Blends Page 13 of 23

Biopesticides Registration Action Document 30, 2010, neith er would significantl y increase the risk of unreasonable adverse effect s on the environment. Since OAM1 and OAM RW are substantially similar to already

registered PIPs in composition and use site, EPA’s consideration of whether these new products would si gnificantl y increase the risk of an y unreasonable adverse effect on the environment wa s limited to the change in insect resistance management refuge deploy ment and percentage, i. e. , a 10% seed blend in the bag vers u s a 20% block refuge . The unreasonable a dverse effect of concern wa s the development of resistance to Cry 34/35Ab1 in corn . Thus, we consider ed : ( 1) how does the registration of OAM1 and OAM RW contribute to the development of corn rootworm resistance to Cry 34/35Ab1 corn ; ( 2) should this resistance develop, what risk does it pose to man or the environment ; and ( 3) taking into account the economic, social, an d environmental costs and benefits , does this risk constitute an unreasonable adverse e ff e ct ? The Risk of OAM1 and OAM RW Registrations Caus ing CRW Resistance to Cry34/35Ab1 The modeling used b y EPA to assess IRM strategies utilizes comp ar ative simulation models . The m odel durability output , ye ars to resistance , is intended to be used for comparative purposes to evaluate different refuge opt ions on a relative basis . The durability outputs that EPA determined for the proposed 90% CRW p rotected seed /10% non - CRW protected seed blend , and a 20% block refuge are 11.3 years to resistance , and 20.2 years to resistance, respectivel y. Thus, our anal ys is indicate d 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 number of other B.t. corn PIPs, including multi - CRW B.t. toxin products, by Monsanto and Dow AgroSciences . Should resistance develop to Cry 34/35 in a OAM1 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 Academ y of Sciences, Impact of Genetically Engineered Crops on Farm Sustainability in the United States, 2 - 37 (2010). Based on our assessment, we conclude d that s ignificant acreage of a 10% seed blend with a single, non - high dose mode of action such as Cry 34/35Ab1 likely

increase s the risk of resistance for all B.t. corn products containing Cry 34/35Ab1. But, the time - li mited registration expiring September 30, 2010, likel y would not increase the risk of resistance to Cry 34/35Ab1. Pioneer project ed that the time - limited registrations granted for the 2010 growing season w ould result in planting on onl y approximately 0.042 % of acres of non - Red Zone geography corn acres; and only on approximately

0.077% of Red - Zone geograph y corn acres. In the context of 90 million acres of corn planted in the United States annually , we conclude d that plantings on such limited acreage w ou l d not have effects on CRW resistance development. The ad hoc members of the SAP commented that the evolution of resistance that occurs as a result of OAM1 presence in the field will speed resistance to Cry 34/35 py ramided products. Comments from Dow Agro sciences and S yn genta also expressed concern that OAM1 would impact other PIP products and speed resistance evolution. CSPIcommented that if the registration decision was based in part on sales projections, then acreage caps should be a term of the regis tration. We appreciate the concerns of the ad hoc members of the SAP, DowOptimum AcreMax B.t. Corn Seed Blends Page 14 of 23

Biopesticides Registration Action Document Agrosciences, and S yn genta regarding the potential of OAM1 to accelerate evolution of resistance to Cry

34/35. This is a concern that we share. We took steps and imposed terms on the OAM1 registration for the 2010 growing season to address these concerns. Pioneer was required to implement an enhanced resistance monitoring plan for OAM1 that included benchmark studies showing susceptibility of the western corn rootworm populations (WCRW) in the Sublethal Seedling Assay . These studies must be submitted by December 1, 2010. Pioneer must attempt to o btain benchmark susceptibility data using the Sublethal Seedling Assay for the northern corn rootworm as well, and submit such studies by December 1, 2011. Pioneer must also submit by

December 1, 2010, a detailed OAM1 - specific resistance monitoring and remedial action plan, including an anal ys is to determine the expected field performance criteria for OAM1 products so that unexpected dam age can be benchmarked. This plan will be updated b y December 1 , 2012, if needed, based on continued field evaluation of OAM1 performance. Pioneer was also required to develop programs to evaluate whether there are statistically significant and biologica lly relevant changes in target insect susceptibility to Cry 1F and Cry 34Ab1/Cry 35Ab1 proteins in the target insects; and a remedial action plan that must set forth the specific measures Pioneer will take in the event that any field - relevant insect resistanc e is detected. While we are not requiring specific acreage caps as part of the registration for 2011 and 2012, we will closely monitor the extent of sales and plantings of OAM1 , as well as all insect monitoring data. In the event there is an y i ndication of resistance evolution, Pioneer must report that to EPA immediately . We will assess all data and information relevant to the indication of resistance evolution and, if we determine that such action is appropriate, will use our authority

under Section 6(c ) of FIFRA to suspend the registration. 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 insectici de use for U.S . corn production . Although there are other CRW controlling PIPs in the marketplace and under development, Cry 34/35Ab1 resistance would not only impact OAM1 and OAM RW, but also HERCULEX® RW, HERCULEX® XTRA , and GenuityTM SmartStaxTM . In creased use of conventional insecticides would increase impact s on the environment and man . There would also be indirect impacts in increased energy 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 OAM1 and OAM RW? Both OAM1 and OAM RW have been determined by EPA to be efficacious in their control of corn rootworm. OAM1 and OAM RW should increase grower compliance with CRW refuge requirements by providing a novel and effective way of simplifying the refuge deploy ment process for grower s as the corn rootworm refuge is deploy ed as a seed blend rather than a separate block in the field . OAM1 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 insec ticide 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 i f aerial insecticides are applied to the refuge for control of CRW adults or if p e sts other than adult corn rootworms are treated with CRW - labeledOptimum AcreMax B.t. Corn Seed Blends Page 15 of 23

Biopesticides Registration Action Document insecticide on the refuge acres when adult corn rootworms are present . OAM1 and OAM RW would reduce this IRM based use of insecticides . Indirect benefits of decreased insecticide use includ e 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 . OAM1 an d OAM RW should benefit growers by simplifying the planting process . Reg istration Decision for 2010 Growing Season We conclude d that OAM1 and OAM RW met the criteria for registration under FIFRA Section 3(c)(7)(A). Our assessment support ed the determi nation that these products are not likel y to contribute towards the development of resistance of CRW to Cry34/35Ab1 during the period of the time - limited registration in effect for the 2010 growing season . Our assessment of the likely impacts concerning e ase of use, increased grower compliance, efficacy , and reduced insecticide use coupled with our determination that OAM1 and OAM RW are not likely to increase the risk of resistance of CRW to Cry 34/35Ab1 developing during the 2010 growing season support ed the conclus ion that the criteria under FIFRA Section 3(c)(7)(A) we re met such that registration of OAM1 and OAM RW w ould not pose a risk of unreasonable adverse effects on the environment during this period . On October 1, 2009, EPA announced a new policy t o provide a more meaningful opportunit y 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 t ypes 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 ac tion s on OAM1 and OAM RW qualif y as " a ctions for which the Agency

anticipates that there will be significant public interest," EPA believe d that it wa s in the best interests of the public and the environment to issue the registration s for OAM1 and OAM RW w ithout delay . The PRIA (Pesticide Registration Improvement Act ) deadline date of M ay 1, 2010, wa s sufficiently late in the growing season that a 30 - day delay would have lessen ed the likelihood that significant a creage of these products could be planted in 2010. G iven th e potential benefits attendant to the blended refuge concep t, EPA conclude d that it was in the best interests of the public and the environment to issue the registration s for OAM1 and OAM RW without delay for 2010 growing season . The regis tration is only effective for the current growing season. Therefore, c onsistent with the Agency ’s policy for making certain registration actions more transparent, EPA issu ed th ese time - limited registration s with an initial period t o expire September 30, 2 010, and, concurrent with their issuance, provid ed a 30 - day public comment period on the time - limited registration s . EPA register ed this product as a time limited registration, with the understanding that public comments could bring to light new informati on or concerns that could inform EPA’s initial decision. Any subsequent action taken on these registrations will be informed b y an y information received during the public comment period . CSPIcommented that the public participation process for the OAM1 registration for the 2010 growing season was inadequate. CSPIbelieved that the opportunity for public comment shouldOptimum AcreMax B.t. Corn Seed Blends Page 16 of 23

Biopesticides Registration Action Document have occurred prior to the registration decision. We do not disagree with the comment. All things being equal, however, we felt that it was important to meet the PRIA due date for this action, and that taking public comment concurrent with the registration would not unfairly deprive the public of the opportunity for meaningful comment, nor deprive us of the benefit of public input. The O AM1 2010 registration was a very short, approximately

five - month , time limited registration that was only good for one growing season. Moreover, as noted in the April 30, 2010, BRAD, the timing of the registration was so late in the growing season that it precluded significant sale and planting of the product. As it happened, data submitted by Pioneer (Rood, 2010), verified that OAM1 acres for 2010 amounted to only 39,000 acres, which is less than projected in the earlier BRAD. We are pleased that we did receive meaningful comment on the April 30, 2010, registration action, and that that comment has been useful in informing the preliminary

decision that we are announcing today . The OAM1 registration that we are proposing today

contains a number of enhanc ed requirements for corn rootworm resistance management that we believe will have a propitious impact not only on this registration, but on other B.t. corn registrations as well. Finall y, comments received on the OAM1 registration played a significant rol e in EPA's deliberations on the concept of tiered time - limited registrations. As discussed below, we believe that it makes sense to make a specific connection between the risk of resistance evolving that a particular product presents and the time permitte d for the registration of that product to be in effect. Products that we determine through scientific evaluation to meet a stringent standard for protecting against the risk of resistance evolving will be eligible for a registration of up to fifteen ye ars . CSPIalso commented that EPA "stealthil y" released the OAM1 BRAD, and did not announce the comment period either in the Federal Register or b y press release. We can assure all concerned that the intent was not to be "stealthy." EPA opened the public c omment period for this action as it has done for all other actions subject to the new public participation initiative, i.e., by announcing the comment period on the Agency 's public participation webpage. This comment points out to us, however, that there are instances where more extensive efforts to publicize the initiation of a comment period and the availability

of BRADs, etc., may

be warranted. We have undertaken such efforts in conjunction with the B.t. corn registrations comment period that is starti ng today . B. Registration Decision for 2011 and 2012 Growing Seasons In the April 30 BRAD, w e preliminaril y concluded that our modeling analysis combined with the Pioneer sales projections for the 2011 and 2012 growing seasons support ed continued registration of OAM1 and OAM RW for 2011 and 2012. We note d that Pioneer predicts OAM1 and OAM RW acreage to increase up to 8% of the Red Zone and 12% of the non - Red Zone. EPA invite d comments during the 30 - day comment period on the preliminary decision to reg ister OAM1 and OAM RW for the 2011 - 2012 growing seasons. Important to this preliminary decision was the fact that Pioneer committed to additional elements that would enhance the IRM plan applicable to OAM1 and OAM RW regarding insect resistance monitoring and remedial action should resistance be detected, and the refuge assurance program. These were listed in detail in the terms and conditions of the April 30, 2010, OAM1 and OAM RW registrations. 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

currentl y registered pesticide and use thereof, or differ onl y in way s that would not significantly increase the risk of unreasonable adverse ef

fects on the environment , and (ii) approving the registration or amendment in the manner proposed b y the applicant would not significantly increase the risk of any unreasonable adverse effect on the environment.” Unreasonable adverse effects on theOptimum AcreMax B.t. Corn Seed Blends Page 17 of 23

Biopesticides Registration Action Document environment are defined under section 2(bb) of FIFRA as “... an y unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of the use of an y pesticide...” Thus, pursuant to section 3(c)(7)(A), EPA may conditionally register a 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 onl y in ways that would not significantly increase the risk of unreasonable adverse effects; and (3) approving the registration would not significantl y increase the risk of an y unreasonable adverse effect. The Agency

concludes that the following Cry 34/35Ab1 corn product registrations, set to expire Septembe r 30, 2010, and described in - depth throughout this BRAD, meet both criteria (1) and (2): (1) Optimum® AcreMaxTM 1 ( OAM1 ) => Seed Blend of 90% HERCULEX® XTRA

and 10% HERCULEX® I (2) OAM RW => Seed Blend of 90% HERCULEX® RW and 10% Non -B.t. Corn Each of these Cry 34/35Ab1 corn products are identical in both composition and use (field corn) to plant - incorporated protectants that are currently registered. Thus, criterion (1) has been fulfilled. With regard to criterion (2), the Agency maintains, a s was previously determined for the original registration of these particular products, that cultivation of Cry34/35Ab1 - containing corn will not cause unreasonable adverse effects on the environment. The conditional environmental effects data, submitted in response to terms and conditions of registration and summarized in section II(C)(2)(b) of this BRAD, strengthen the Agency ’s initial position and also confirm that long - term effects on non - target organisms are not anticipated. Lastly , the continued use of these products will likely still provide many

of the benefits as were evaluated to support the OAM1 registration for the 20 1 0 growing season (e.g., reduction in use of conventional insecticides that are highl y toxic to both humans and the environment ; inc reased compliance with CRW refuge requirements ). In conclusion, as the expiring Cry 34/35Ab1 products ( Optimum® AcreMaxTM 1 ( OAM1 ) => Seed Blend of 90% HERCULEX® XTRA and 10% HERCULEX® I; and OAM RW => Seed Blend of 90% HERCULEX® RW and 10% Non - B.t. Corn ) have met the required criteria under section 3(c)(7)(A) of FIFRA, the Agency is proposing to amend these registrations to extend their respective expiration dates as follows:

Product Nam e (EPA Reg. No.) Proposed Expiration Date OAM1 (29964 - 6) September 3 0, 2012 OAM1 R W (29964 - 10) September 30, 2012

Although data provided were satisfactory to make the determinations required by section 3(c)(7)(A) of FIFRA, they were not sufficient to support an unconditional registration under FIFRA section 3(c)(5). Additional data, specifically in relation to aquatic invertebrate testing andOptimum AcreMax B.t. Corn Seed Blends Page 18 of 23

Biopesticides Registration Action Document insect resistance management, are necessary for a finding of registrability under FIFRA section 3(c)(5) and remain as terms or conditions for the purposes of the propose d amendments. C. Period of Registration In the 2001 B.t. Corn reassessment, EPA determined that it was appropriate to amend the then existing registrations to extend the period of registration of those products to an expiration date of October 15, 2008 . All of the products being assessed at that time were efficacious against lepidopteran pests. EPA based this action on the finding that use of Cry 1Ab or Cry 1F expressed in corn will not significantly increase the risk of unreasonable adverse effects on the environment "for the limited time period of 7 additional years (to October 15, 2008)." These registrations were later amended to extend the period of registration to an expiration date of September 30, 2010. EPA subsequently granted time - limited reg istrations to products efficacious against coleopteran corn rootworm pests. For example, EPA registered Cry 3Bb1 on February 24, 2003, to May

1, 2004, and extended that registration twice, to February 24, 2008, and September 30, 2010. As set forth elsewhe re in this document, EPA's primary concern for the B.t. protected transgenic corn products is the possibility that target pests will develop resistance to one or more of the PIP toxins. Development of resistance to a B.t. toxin would be a grave adverse ef fect, and, for over 15 years, EPA has imposed stringent requirements intended to countermand the potential development of resistance. Registrants similarly have been busily

developing various products, product mixes (i.e., so - called "p yramids" and "stacks "), and resistance strategies, to maximize agronomic benefits and address resistance management issues. The result has been a vast array of product combinations and, occurring over the past couple of ye ars, a re - emergence of varying refuge requirements fo r different products. As discussed in the 2001 B.t. PIP BRAD (at IID13), the earliest B.t. corn registrations did not include mandatory

refuge requirements. There was a lack of scientific consensus as to what the appropriate refuge requirement should be, and, it was assumed that the limited market penetration of these earl y crops would be so low as to guarantee that adequate natural refuges would be available from neighboring non - B.t. corn fields. From 1995 to 1997, B.t. corn registrations included voluntary refuge requirements of 0% to 20% in the corn belt. In 1999, the ABSTC, in conjunction with the National Corn Growers Association, proposed uniform IRM requirements for B.t. corn registrations. With some modifications, this proposal, put in place for the 2000 growing season, formed the baseline IRM requirements for almost all B.t. corn registrations for the better part of a decade: farmers were required to plant a 20% refuge that could be treated for insects, or a 50% treated refuge in cotton - growing areas; all refuges to be planted within one - half mile of the B.t. corn field. These uniform requirements brought certaint y and consistency to the market after the initial period where man y B.t. corn products had different refuge requirements. Recentl y , however, as product developers have begun to conceive of products with different combinations of "p yr amided" products (i.e., products containing two or more toxins efficacious against the same pest) and "stacked" products (i.e., products combining toxins efficacious against different pests), the refuge requirements have begun to vary . For example, certain products require a 20% external refuge; some products permit a 5% external refuge; one product incorporates a 10% seed blend refuge; we have applicatio ns in process for products that propose to incorporate a 5% seed blend refuge; and other permutations are possible.Optimum AcreMax B.t. Corn Seed Blends Page 19 of 23

Biopesticides Registration Action Document Given the profusion of various toxin combinations and refuge options, we can no longer proceed on the basis that, as concerns insect resist ance management, all products are equal. It was a relativel y simple proposition when the default requirement of a 20% sprayed refuge applied to almost all of the B.t. corn crops in the market. Under those circumstances, the relative durability of product s against the development of resistance was functionall y equivalent, and, as a consequence, imposing functionally equivalent registration periods was appropriate. That is now no longer the case. As part of our continually evolving regulatory approach to the continuall y evolving product mix wrought by

developers, we think it appropriate to revise our regulatory requirements in scientifically

defensible way s to reflect the actual level of risks posed by the products that we regulate. Here, for example, whe re we've determined that a particular product, or category of products, likely

will pose less risk of insect resistance developing to a particular PIP protein, we think it appropriate to grant that particular product, or category of products, a registratio n for a period greater than that granted a corresponding product that poses a greater risk of insect resistance developing. This approach is reflective of complementary principles: first, to ensure that we appl y our limited resources to the products that pose greater risk of adverse effects to the environment; and, second, to conserve the resources that registrants and applicants must expend in amending the registrations of products that pose less risk of adverse effects to the environment. The scheme that we propose to follow will include registration periods of five, eight, and twelve ye ars; a fifteen year registration period will also be available, if adequatel y supported by our science assessment. In this scheme, (i) a product with a single PI P toxin, and a 20% external refuge, qualifies for a five year registration; (ii) a product with py ramided PIP toxins (i.e., two or more toxins with distinct, non - cross reacting modes of action), that are non - high dose (the definition for a high dose prod uct remains unchanged), with either a seed blend or external refuge, qualifies for an eight ye ar registration; (iii) a product with p yramided PIP toxins (i.e., two or more toxins with distinct, non - cross reacting modes of action), that are high - dose, with either a seed blend or external refuge, qualifies for a twelve year registration; (iv) a product with py ramided PIP toxins (i.e., two or more toxins with distinct non - cross reacting modes of actions), with either a seed blend or external refuge, that has b een determined b y EPA's science assessment to be 150% as durable as the baseline single toxin product with a 20% external refuge, would qualify

for a fifteen ye ar registration. Products determined by EPA's science assessment to be less than 100% as durabl e as the baseline single toxin product with a 20% external refuge would not qualify for a five year registration and the registration period for such products will be determined on a case - by - case basis consistent with the level of risk they pose. Similarl y, instances where other risk issues may arise, or where novel resistance concerns may be present, would also be determined on a case - by - case basis. V. REFERENCES Bailey , L., R. Binning, L. Higgins, D. Langer, R. L ay ton, 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).Optimum AcreMax B.t. Corn Seed Blends Page 20 of 23

Biopesticides Registration Action Document Caprio, MA, T Nowatzki, B Siegfried, LJ Meinke, RJ Wright & LD Chandler. 2006. Assessing the Risk of Resistance to Aerial Appli cations of Methyl-Parathion in the W estern Corn Rootworm. Journal of Economic Entomology, Vol. 99(2): 483 - 493 Caprio, M. A., D. Sumerford & S. Sims. 2006b. Evaluating transgenic plants for suitability in pest and resistance management programs, 2nd edit ion. L . L acey & H. Kaya [eds]. Field Manual of Techniques for the Application and Evaluation of Entomopathogens. Coats SA, JA Mutchmor, and JJ Tollefson. 1986. Study of migratory

flight in the western corn rootworm (Coleoptera: Chry someldiae). Envir onmental 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 B.t. corn, Corn Rootworm - Protected B.t. corn, and Corn Borer/ Corn Rootworm - Protected Stacked B.t. corn . Project Number: CAP/2007 . Unpublished study

prepared by

Agricultural Biotechnology Stewardship Technical Committee . 17 p. EPA MRID No.47356701 L efko, 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 L efko, S.; Binning, R . (2008) Effect of Off - Ty pe 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 L efko, S.; Diehn, S . (2008) An Observational Study Characterizing the Relative Quantity

and Distribution of Cry 34Ab1 and Cry 35 Ab1 Insecticidal Proteins in Roots of Maize Containing Event DAS - 59122 - 7 . Project Number: PHI/2006/119 . Unpublished study prepared b y Pioneer Hi - Bred International, Inc . 22 p. EPA MRID No.47356704 L efko, S.; Binning, R . (2008) Quantifying the Concentr ation of Cry 34Ab1 and Cry 35Ab1 in 59122 Maize Grown in the Sublethal Corn Rootworm Seedling Assay S ys tem . Project Number: PHI/2006/171 . Unpublished study prepared by

Pioneer Hi Bred International, Inc . 11 p. EPA MRID No.47356705 Nowatzki, T . ; Thompso n, S.; Peters, M . (2008) Field Measures of Adult Corn Rootworm (Coleoptera: Chry somelidae) Production When Refuge is Deployed as a Seed Blend with DAS - 59122 - 7 Maize . Project Number: PHI/2007/075 . Unpublished study prepared b y Pioneer Hi - Bred Internation al, Inc . 57 p.Optimum AcreMax B.t. Corn Seed Blends Page 21 of 23

Biopesticides Registration Action Document EPA MRID No.47356706 Nowatzki, T.; Meinke, L . (2008) Impact of Western and Northern Corn Rootworm L arval Exposure to DAS - 59122 - 7 in a Block Planting and a Seed Blend on Life History Traits of Adults . Project Number: PHI/2007/076 . Unpub lished study prepared by Pioneer Hi - Bred International, Inc . and Universit y of Nebraska - Lincoln . 31 p. EPA MRID No.47356707 L efko, S.; Binning, R . (2008) Investigating the Effect of Insecticidal Proteins Cry 34/35Ab1 on Western Corn Rootworm Host Search ing 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/20 07/145 . 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 B.t. Corn, Corn Rootworm - Protected B.t . Corn, and Corn Borer/Corn Rootworm - Protected Stacked B.t. Corn . Project Number: CAP/2008 . Unpublished study prepared by

Agricultural Biotechnology Stewardship Techn . Committee . 15 p. EPA MRID No.47683801 Binning, R.; Langer, D . (2009) Additional Re sponses 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 (Cry 34/35Ab1 + Cry 1F) with Herculex I (Cry 1F, Refuge Seed for CRW) [MRID 473567 - 10 and Suppl emental Data]": Final Report . Project Number: PHI/2009/026 . Unpublished study prepared by

Pioneer Hi - Bred International, In c . 11 p. EPA MRID No. 48076501 Drey er, C.; Gutsche, A.; Hubbard, N.; et al . (20 10 ) Addendum to MRID 47795101 Addendum to the Be nefits of Optimum AcreMax 1 . Project Number: PHI/2009/099 . Unpublished study prepared by

Pioneer Hi - Bred International Inc . 3 3 p. EPA MRID No.47871001 Pan, Z.; Onstad, D.; Stanley , B.; et al . (2009) A Spatially Explicit Computer Simulation Study of Co rn Rootworm, Diabrotica spp . [Coleoptera: Chry somelidae]: Addendum . Project Number: PHI/2009/125 . Unpublished study prepared by

Pioneer Hi - Bred International, Inc . 32 p. EPA MRID No.47887901 Rood, T.; Pan, Z.; Onstad, D.; et al . (2009) Additional Add endum to MRID 473567 - 08: A Spatially Explicit Computer Simulation Study of Corn Rootworm, Diabrotica spp . [Coleoptera: Chry somelidae]: Final Report . Project Number: PHI/2009/197, PHI/2009/125 . Unpublished study prepared by

Pioneer Hi - Bred International, In c . 32 p. EPA MRID No.47910801 Pan, Z.; Onstad, D.; Stanley , B.; et al . (2009) Third Addendum to: A Spatially

Explicit Computer Simulation Study of Corn Rootworm: Strip vs . Blended Refuge: Final Report . Project Number: PHI/2009/204, 473567/08 . Unpublished study prepared by Pioneer Hi - Bred International, Inc . 19 p. EPA Scientific Advisory

Panel . 2009 . Transmittal of meeting minutes of the FIFRA Scientific Advisory Panel meeting held February 23 - 24, 2009 on the evaluation of the resistance risks f rom using a seed mix refuge with Pioneer’s Optimum AcreMax1 corn rootworm - protected corn.Optimum AcreMax B.t. Corn Seed Blends Page 22 of 23

Biopesticides Registration Action Document Memorandum from J.E. Bailey (DFO) to Dr. D. Edwards (Director of OPP) on May 6, 2009. Grant RH and KP Seevers. 1989. L ocal and long - range movement of adult wes tern corn rootworm (Coleoptera: Chry somelidae) as evidenced by washup along southern lake Michigan shores. Envir. Entomology , Vol. 18 (2): 266 - 272 Hibbard B, personal communication with Mike Caprio, January 2010 Jaffe, G. 2009. Complacency on the Fa rm . CSPI. Meinke LJ, personal communication with Mike Caprio, January 2010 Meinke LJ, TW Sappington, DW Onstad, T Gullemaud, NJ Miller, J Komaromi, N Levay , L Furian, J Kiss, and F Toth. 2009. Western corn rootworm (Diabrotica virgifera virgifera LeCo nte) population dy

namics. Agricultural and Forest Entomology , Vol.11: 29 - 46 Naranjo SE. 1990. Comparative flight behavior of Diabrotica virgifera virgifera and Diabrotica barberi in the laboratory . Ent. Experimantalis et Aplicata, Vol. 87: 383 - 394 National Academ y of Science. 2010. The Impact of Genetically Engineered Crops on Farm Sustainability in the United States , The National Academies Press. Nowatzki TJ, N Bradley , KK Warren, S Putnam, LJ Meinke, DC Gosselin, FE Harvey , TE Hunt, and B Siegf

ried. 2003. In - field labeling of western corn rootworm adults (Coleoptera: Chry somelidae) with Rubidium. Journal of Economic Entomology , Vol. 96(6): 1750 - 1759 Ostlie K. 2009. L odging in corn: diagnosis, harvesting tips, and unexpected damage in trip le stack corn. http://blog.lib.umn.edu/efans/cropnews/2009/11/lodging - in - corn - diagnosis - harv.html Ostlie K and Gassman A. 2010. BPPD teleconference with Dr. Kenneth Ostlie (University of Minnesota) and Dr. Aaron Gassman (Iowa State University). February 4, 2010. Rood, T.A. 2010. Letter to Michael Mendelsohn providing information concerning OAM 1 and OAM RW. Scott IA, J L Spencer, TR Mabry , and E Levi ne. 2004. Influence of atmospheric conditions on high - elevation flight of Western corn rootworm (Choleoptera: Chrysomelidae). Environmental Entomology , Vol. 33(3):650 - 656 Spencer J . 2009 . Personal communication . E - mail response and summary of unpubl ished data submitted to J.C . Martinez (EPA), dated December 28 , 2009 . Van Woerkom GJ, FT Turpin, & JR Barret Jr. 1983. Wind effect on western corn rootworm (Coleoptera: Chry somelidae) flight behavior. Environmental Entomololgy , Vol 12: 196 - 200 Vose , 2000. Risk Analy sis: A quantitative guide. Wiley , New York. Witkowski JF, JC Owens, and JJ Tollefson. 1975. Diel activity and vertical flight distribution ofOptimum AcreMax B.t. Corn Seed Blends Page 23 of 23

Biopesticides Registration Action Document adult western corn rootworms in I owa cornfields. Journal of Economic Entomology , Vol. 68 : 351 - 352