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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 (006490, 006481) Fact sheet Draft October 19, 2010 13:37

Related Information
Information related to this page:

Issued: January 30, 2002

Reason for Issuance: Registration

Date Issued: December 2005

On This Page

  1. Description of the Plant-Incorporated Protectant
  2. Background
  3. Science Assessment
  4. Terms and Conditions of the Registration
  5. Additional Contact Information

  1. Description of the Plant-Incorporated Protectant

  2. Background

    3. EPA has conditionally registered Mycogen Seeds c/o Dow AgroSciences LLC and Pioneer Hi-Bred International’s new products containing Bacillus thuringiensis Cry34Ab1 and Cry35Ab1 proteins and the genetic material necessary for their production (plasmid insert PHP 17662) in Event DAS-59122-7 corn and Bacillus thuringiensis Cry1F protein and the genetic material necessary for its production (plasmid insert PHI8999) in Event TC1507 corn.

    Herculex XTRA corn was developed through conventional breeding of a corn line containing Event TC1507 (Herculex I), which expresses the Cry1F (truncated) and PAT proteins and a corn line containing Event DAS-59122-7, which expresses the Cry34Ab1, Cry35Ab1, and PAT proteins. These Herculex XTRA products are considered stacked PIPs, because they target two different kinds of pests and contains two separate PIP active ingredients. Herculex XTRA is intended to provide protection against certain lepidopteran corn pests and certain coleopteran corn rootworm pests.

    Tolerance exemptions covering these plant-incorporated protectants are found under 40 CFR Part 174.457 (Bacillus thuringiensis Cry34Ab1 and Cry35Ab1 proteins and the genetic material necessary for their production in corn) and 40 CFR Part 180.1217 (Bacillus thuringiensis Cry1F protein and the genetic material necessary for its production in corn).

  3. Science Assessment

    4. Product Characterization

    Southern blot analysis data demonstrated that Herculex XTRA corn contains the cry1F, cry34Ab1, cry35Ab1, and pat genes and that there were no alterations or rearrangements in the inserts from the conventional cross.

    Protein expression level data from various corn tissues were provided for the stacked corn product and compared to expression levels in corn tissues containing the individual traits and expression levels are similar to those for corn tissues containing the individual traits.

    Human Health Assessment

    The data generated for the Cry1F, Cry34Ab1, Cry35Ab1, and PAT proteins individually support the food safety determination for the stacked trait corn since the mode of action for these proteins does not suggest an enhanced activity when they are combined.

    Although no synergistic effect has been observed with the Cry1F, Cry34Ab1, and Cry35Ab1 proteins combined, an acute oral toxicity study in mice on an equimolar mixture of the proteins was submitted. No treatment-related adverse effects were observed.

    Environmental Assessment

    From all of the required and voluntarily developed indicator and host range species test data on Cry1F, Cry34/35Ab1, and Cry1FxCry34/35Ab1 corn, the Agency concludes that the levels of Cry1FxCry34/35Ab1 protein in Herculex? XTRA corn will not pose unreasonable adverse effects to corn field flora and fauna. Available data also indicate that there should be minimal short-term accumulation of Cry1FxCry34/35Ab1 protein in agricultural soil. No evidence of synergy between the lepidopteran-active and coleopteran-active insecticidal proteins expressed by Herculex? XTRA corn was found in laboratory studies of target and non-target insects evaluated for this registration. Endangered/threatened species assessments conducted in support of individual trait (Herculex I and Herculex? RW) registrations were sufficient to demonstrate a no "may effect" finding for the stacked product (EPA 2001, 2005). In conclusion, Herculex? XTRA is projected to control certain lepidopteran and certain coleopteran pests in field corn without concerns of risk to non-target organisms.

    Insect Resistance Management

    Dow and Pioneer have submitted an acceptable IRM plan for Herculex XTRA, subject to the comments below. Submitted information indicates that Herculex XTRA likely expresses a "high dose" for ECB and slightly less than a high dose for CRW (identical to the dose profiles for Herculex I and Herculex Rootworm, respectively). The core elements of the IRM plan consist of a 20% non-Bt corn refuge and options for separate lepidopteran and coleopteran refuges or a combined refuge design.

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  4. Terms and Conditions of the Registration

    1. The subject registrations will automatically expire on midnight October 15, 2008.


    2. The subject registration will be limited to Cry1F [Bacillus thuringiensis Cry1F protein and the genetic material necessary for its production (plasmid insert PHI8999) in Event TC1507 corn] X Cry34/35Ab1 [Bacillus thuringiensis Cry34Ab1 and Cry35Ab1 proteins and the genetic material necessary for their production (plasmid insert PHP17662) in Event DAS-59122-7 corn] corn for use in field corn.


    3. Submit/cite all data required for registration of this product under FIFRA § 3(c)(5) when the Agency requires registrants of similar products to submit such data.


    4. Submit all data required to support the individual plant-incorporated protectants in Event TC1507 (Herculex I) and Event DAS-59122-7 (Herculex Rootworm) corn. In the event that the Agency concludes Cry34/35Ab1 (Herculex Rootworm) studies do not sufficiently demonstrate a lack of long range adverse effects, additional data with Herculex? XTRA corn must be submitted. This data may include


      1. laboratory toxicity testing with Orius insidiosus (minute pirate bug),


      2. laboratory toxicity testing with a carabid (ground beetle),


      3. long range effects testing on invertebrate populations in the field, and


      4. long range soil persistence testing.


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    5. You must commit to do the following Insect Resistance Management Program:
      6.

      The required IRM program for Cry1FxCry34/35Ab1 corn has the following elements:

      1. Requirements relating to creation of a refuge for both the Cry1F and Cry34/35Ab1 components that meets the requirements of the individual traits. The refuge for both traits may be combined by planting non-Bt corn as the refuge, or the refuge for each trait may be planted separately. In the latter case, corn rootworm-resistant Bt corn may be planted in the lepidopteran refuge for the Cry1F component and lepidopteran-resistant Bt corn may be planted in the corn rootworm refuge for the Cry34/35Ab1 component.


      2. Requirements for the registrants to prepare and require Bt corn users to sign grower agreements which impose binding contractual obligations on the grower to comply with the refuge requirements;


      3. Requirements for the registrants to develop, implement, and report to EPA on programs to educate growers about IRM requirements;


      4. Requirements for the registrants to develop, implement, and report to EPA on programs to evaluate and promote growers= compliance with IRM requirements (the Cry1F x Cry34/35Ab1 Compliance Assurance Program (CAP) must integrate with the Cry1 and Cry34/35Ab1 CAPs);


      5. Requirements for the registrants to develop, implement, and report to EPA on programs to evaluate whether there are statistically significant and biologically relevant changes in target insect susceptibility to Cry1F and Cry34/35Ab1 proteins in the target insects;


      6. Requirements for the registrants to develop, and if triggered, to implement a remedial action plan which would contain measures the registrants would take in the event that any insect resistance was detected as well as to report on activity under the plan to EPA;


      7. Submit 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, compliance assurance program including the education program, on or before January 31st each year, and for resistance monitoring, on or before April 30th each year for Cry1F and on or before August 31st each for Cry34/35Ab1, beginning in 2007.

        8. 5a. Refuge Requirements

        The use of Cry1F x Cry34/35Ab1 corn requires accompanying refuge corn for both the Cry1F and Cry34/35Ab1 components that meets the requirements of the individual traits, described below. Therefuge for both traits may be combined by planting non-Bt corn as the refuge (see C. below), or the refuge for each trait may be planted separately (see A. and B. below).

        For the separate refuges, corn rootworm-resistant Bt corn (e.g., Herculex RW) may be planted in the lepidopteran refuge for the Cry1F component and lepidopteran-resistant Bt corn (e.g, Herculex I) may be planted in the corn rootworm refuge for the Cry34/35Ab1 component. Depending on cropping practices, pest problems, and pest management options employed on any given farm, growers may need to choose different refuge arrangements for different fields. Possible options include: two refuge blocks (one for rootworm, one for Lepidoptera) can be planted within one field, or strips can be used for either refuge. Alternatively, a block of Herculex RW corn can serve as an in-field lepidopteran refuge for one field planted to Cry1F X Cry34/35Ab1 and an external lepidopteran refuge for separate fields planted to Cry1F X Cry34/35Ab1, while the rootworm refuge is planted as Herculex I corn in an external adjacent field. In all options, size and management of each individual refuge must be followed as described in A. and B. below.

        Other refuge designs and combinations are permissible as long as in all cases the size and management of each refuge are described in A., B., and C., below.

        1. Lepidopteran refuge for the Cry1F component.
          2.

          1. Refuge size, Corn-Growing Areas (= corn belt and other non corn/cotton-growing regions). The use of Cry1F x Cry34/35Ab1 corn requires an accompanying 20% refuge consisting of non-Bt corn or non-lepidopteran resistant Bt corn.


          2. Refuge size, (Corn/Cotton-growing areas). * The use Cry1F x Cry34/35Ab1 corn requires an accompanying 50% refuge consisting of non-Bt corn or non-lepidopteran resistant Bt corn.


          3. Refuge location.
            • The lepidopteran refuge can be planted in a separate field not more than ½ mile (1/4 mile preferred) of the Cry1F x Cry34/35Ab1 field.
            • The lepidopteran refuge can be planted within the Cry1F x Cry34/35Ab1 field as blocks (e.g. along the edges or headlands)
            • The lepidopteran refuge can be planted within the Cry1F x Cry34/35Ab1 field as strips across the field at least four rows wide (six preferred)


          4. Refuge management.

            5. Insecticide treatments for control of European corn borer, corn earworm, southwestern corn borer, fall armyworm, black cutworm,western bean cutworm, lesser corn stalk borer, sugarcane borer and southern corn stalk borer may be applied only if economic thresholds are reached for one or more of these target pests. Economic thresholds will be determined using methods recommended by local or regional professionals (e.g. Extension Service Agents, crop consultants). Microbial Bt insecticides must not be applied to lepidopteran resistant refuges.

            Cotton growing areas 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, Stoddard).

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        2. Corn rootworm refuge for the Cry34/35Ab1 component.

          1. Refuge size. The use of Cry1F x Cry34/35Ab1 corn requires an accompanying 20% refuge consisting of non-Bt corn or non-corn rootworm-resistant Bt corn.


          2. Refuge location. The rootworm refuge is required to be planted within or adjacent (e.g. across the road) to the Cry1F x Cry34/35Ab1 corn field.


          3. Refuge management options. The rootworm refuge can be managed in such a way that there is little or no yield loss to rootworms, but must be managed in a way that it is sufficiently productive of susceptible rootworm adults.
            • The in-field rootworm refuge options may be planted as a single block or as a series of strips measuring at least four (4) crop rows wide.
            • Seed mixtures of Cry1F x Cry34/35Ab1 and rootworm refuge corn are not permitted.
            • If the rootworm refuge is planted on rotated ground, then Cry1F x Cry34/35Ab1 corn must also be planted on rotated ground.
            • If the rootworm refuge is planted in continuous corn, the Cry1F x Cry34/35Ab1 field may be planted on either continuous or rotated land (option encouraged where WCRW rotation-resistant biotype may be present).
            • Application of soil insecticide is permitted in the rootworm refuge.
            • Seed treatment is permitted in the rootworm refuge, either at a rate for rootworm protection or at a rate for controlling secondary soil pests.
            • If aerial insecticides are applied to the rootworm refuge for control of CRW adults, the same treatment must also be applied in the same time-frame to Cry1F x Cry34/35Ab1 corn.
            • Pests other than adult corn rootworms can be treated on the rootworm refuge acres without treating the Cry1F x Cry34/35Ab1 acres only if treatment occurs when adult corn rootworms are not present or if a pesticide without activity against adult corn rootworms is used. Pests on the Cry1F x Cry34/35Ab1 acres can be treated as needed without having to treat the rootworm refuge.
            • The rootworm refuge can be planted to any corn hybrid that does not express PIPs for rootworm control (e.g. lepidopteran-protected Bt corn, herbicide-tolerant corn, or conventional corn).
            • The rootworm refuge and Cry1F x Cry34/35Ab1 corn should be sown on the same day, or with the shortest window possible between planting dates, to ensure that corn root development is similar among varieties.
            • Growers are encouraged to plant the rootworm refuge in the same location each year, as it allows the rootworm population to remain high and the durability of the trait is extended. This option may be preferable to growers who wish to only think of their refuge design once and for growers who grow continuous corn. However, for those growers who need to employ crop rotation, a fixed refuge would be impractical.


        3. For the combined refuge option (i.e. the lepidopteran refuge combined with the rootworm refuge by planting non-Bt corn), the refuge must be planted and managed such that it is consistent with the requirements of the two individual traits, as follows


          1. Refuge size shall be 20% in corn-growing areas and 50% in cotton-growing areas (see list labeled with " * " under A).


          2. Refuge location. The combined refuge is required to be planted within or adjacent (e.g. across the road) to the Cry1F x Cry34/35Ab1 corn field.


          3. Refuge management options
            • The in-field refuge options must be planted as a single block or as a series of strips measuring at least four (4) rows wide (six rows preferred).
            • Seed mixtures of Cry1F x Cry34/35Ab1 and refuge corn are not permitted.
            • If the combined refuge is planted on rotated ground, then the Cry1F x Cry34/35Ab1 corn must also be planted on rotated ground.
            • If the combined refuge is planted on continuous corn, the Cry1F x Cry34/35Ab1 field may be planted on either continuous or rotated land (option encouraged where WCRW rotation-resistant biotype may be present).
            • Application of soil insecticide for corn rootworm control is permitted in the combined refuge.
            • Seed treatment is permitted in the combined refuge, either at a rate for rootworm protection or at a rate for controlling secondary soil pests.
            • If aerial insecticides are applied to the combined refuge for control of CRW adults, the same treatment must also be applied in the same timeframe to Cry1F x Cry34/35Ab1 corn.
            • Insecticide treatments in the combined refuge for control of European corn borer, corn earworm, southwestern corn borer, fall armyworm, black cutworm, western bean cutworm, sugarcane borer, lesser corn stalk borer, or southern corn stalk borer may be applied only if economic thresholds are reached for one or more of these target pests. Economic thresholds will be determined using methods recommended by local or regional professionals (e.g. Extension Service Agents, crop consultants). These pests can be treated with CRW-labeled insecticide on the combined refuge acres without treating the Cry1F x Cry34/35Ab1 acres only if treatment occurs when adults corn rootworms are not present. Microbial Bt insecticides must not be applied to the common refuges.
            • Pests other than adult corn rootworms can be treated with CRW-labeled insecticide on the combined refuge acres without treating the Cry1F x Cry34/35Ab1 acres only if treatment occurs when adults corn rootworms are not present. Pests on the Cry1F x Cry34/35Ab1 acres can be treated as needed without having to treat the refuge.
            • The combined refuge can be planted to any corn hybrid that does not express PIPs for lepidopteran or rootworm control (i.e. herbicide tolerant corn or conventional corn).
            • The combined refuge and Cry1F x Cry34/35Ab1 corn should be sown on the same day, or with the shortest window possible between planting dates, to ensure that corn root development is similar among varieties.

              The description of the refuge requirements in the grower guide must be consistent with the preceding requirements.

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        5b. Grower Agreements

        1. Persons purchasing the Bt corn product must sign a grower agreement. The term "grower agreement" refers to any grower purchase contract, license agreement, or similar legal document.


        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. The registrant must develop a system (equivalent to what is already approved for Cry1F Bt corn) which is reasonably likely to assure that persons purchasing the Bt corn product will affirm annually that they are contractually bound to comply with the requirements of the IRM program. The proposed system will be submitted to EPA by January 31, 2006.


        4. The registrant must use grower agreements and submit to EPA by January 31, 2006 a copy of that agreement and any specific stewardship documents referenced in the grower agreement. If the registrants wish 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, thirty days prior to implementing a proposed change, the registrant must submit to EPA the text of such changes to ensure that it is consistent with the terms and conditions of the amendment.


        5. The registrant must establish a system (equivalent to what is already approved for Cry1F Bt Corn) which is reasonably likely to assure that persons purchasing the Bt corn sign grower agreement(s), and must provide by January 31, 2006 a written description of that system.


        6. The registrant shall maintain records of all Bt corn grower agreements for a period of three years from December 31st of the year in which the agreement was signed.


        7. Beginning on January 31, 2007 and annually thereafter, the registrant shall provide EPA with a report showing the number of units of its Cry1F x Cry34/35Ab1 corn seeds sold or 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 the twelve-month period covering the prior August through July.


        8. The registrant 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.

        5c. IRM Education and IRM Compliance Monitoring Programs

        1. The registrants must implement a comprehensive, ongoing IRM education program designed to convey to Bt Cry34/35Ab1 corn users the importance of complying with the IRM program. The program shall include information encouraging Bt Cry1F x Cry34/35Ab1 corn users to pursue optional elements of the IRM program relating to refuge configuration and proximity to Bt Cry1F x Cry34/35Ab1 corn fields. The education program shall involve the use of multiple media, e.g. face-to-face meetings, mailing written materials, EPA reviewed 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 its records for the first year of commercialization (2006 growing season) by January 31, 2007. The program shall involve at least one written communication annually to each Bt Cry1F x Cry34/35Ab1 corn user separate from the grower technical guide. The communication shall inform the user of the current IRM requirements. The registrants shall coordinate their education programs with educational efforts of other registrants and other organizations, such as the National Corn Grower Association and state extension programs.


        2. Annually, the registrant shall revise, and expand as necessary, its education program to take into account the information collected through the compliance survey required under paragraph 6] and from other sources. The changes shall address aspects of grower compliance that are not sufficiently high.


        3. Beginning January 31, 2008 and annually thereafter, the registrant must provide EPA any substantive changes to its grower education activities as part of the overall IRM compliance assurance program report. The required features of the compliance assurance program are described in paragraphs 4]-15] below.


        4. The registrant must design and implement an ongoing IRM compliance assurance program designed to evaluate the extent to which growers purchasing its Cry1F x Cry34/35Ab1 Bt corn product are complying with the IRM program and that takes such actions as are reasonably needed to assure that growers who have not complied with the program either do so in the future or lose their access to the Cry1F x Cry34/35Ab1 Bt corn product. The registrant shall coordinate with other Bt corn registrants in designing and implementing its compliance assurance program and integrate the Cry1F x Cry34/35Ab1 CAP with the Cry1 CAPs. The registrant must prepare and submit by January 31, 2006 a written description of their compliance assurance program including a summary of the program implemented in the 2006 growing season. Other required features of the program are described in paragraphs 5] - 15] below.


        5. The registrant must establish and publicize a “phased compliance approach,” i.e., a guidance document that indicates how the registrant will address instances of non-compliance with the terms of the IRM program and general criteria for choosing among options for responding to any non-compliant growers. The options shall include withdrawal of the right to purchase Cry1F x Cry34/35Ab1Bt corn for an individual grower or for all growers in a specific region. An individual grower found to be significantly out of compliance two years in a row would be denied sales of the product the next year. Similarly, seed dealers who are not fulfilling their obligations to inform/educate growers of their IRM obligations will lose their opportunity to sell Cry1F x Cry34/35Ab1Bt corn.


        6. The IRM compliance assurance program shall include an annual survey conducted by an independent third party of a statistically representative sample of Cry1F x Cry34/35Ab1Bt corn growers who plant the vast majority of all corn in the U.S. and in areas in which the selection intensity is greatest The survey shall consider only those growers who plant 200 or more acres of corn in the Corn-Belt and who plant 100 or more acres of corn in corn-cotton areas. The survey shall measure the degree of compliance with the IRM program by growers in different regions of the country and consider the potential impact of non-response. The sample size and geographical resolution may be adjusted annually, based upon input from the independent marketing research firm and academic scientists, to allow analysis of compliance behavior within regions or between regions. The sample size must provide a reasonable sensitivity for comparing results across the U.S.


        7. The survey shall be designed to provide an understanding of any difficulties growers encounter in implementing IRM requirements. An analysis of the survey results must include the reasons, extent, and potential biological significance of any implementation deviations.


        8. The survey shall be designed to obtain grower feedback on the usefulness of specific educational tools and initiatives.


        9. The registrant shall provide a written summary of the results of the prior year's survey (together with a description of the regions, the methodology used, and the supporting data) to EPA by January 31 of each year, beginning with 2007. The registrant shall confer with EPA on the design and content of the survey prior to its implementation.


        10. Annually, the registrant shall revise, and expand as necessary, its compliance assurance program to take into account the information collected through the compliance survey required under paragraphs 6] through 8] and from other sources. The changes shall address aspects of grower compliance that are not sufficiently high. The registrant must confer with the Agency prior to adopting any significant changes.


        11. The registrant shall conduct an annual on-farm assessment program. The registrant shall train its representatives who make on-farm visits with Cry1F x Cry34/35Ab1Bt corn growers to perform assessments of compliance with IRM requirements. There is no minimum corn acreage size for this program. Therefore, growers will be selected for this program from across all farm sizes. In the event that any of these visits result in the identification of a grower who is not in compliance with the IRM program, the registrant shall take appropriate action, consistent with its "phased compliance approach," to promote compliance.


        12. The registrant shall carry out a program for investigating legitimate “tips and complaints” that its growers are not in compliance with the IRM program. Whenever an investigation results in the identification of a grower who is not in compliance with the IRM program, the registrant shall take appropriate action, consistent with its “phased compliance approach.”


        13. If a grower, who purchases Cry1F x Cry34/35Ab1Bt corn for planting, was specifically identified as not being in compliance during the previous year, the registrant shall visit with the grower and evaluate whether that the grower is in compliance with the IRM program for the current year.


        14. Beginning January 31, 2007 and annually thereafter, the registrants shall provide a report to EPA summarizing the activities carried out under their compliance assurance program for the prior year including changes to the grower education program, and the plans for the compliance assurance program during the current year. The report will include information regarding grower interactions (including, but not limited to, third-party grower survey, on-farm visitation program, verified tips and complaints, education programs (e.g., grower meetings and letters), the extent of non-compliance, corrective measures to address the non-compliance (phased-compliance program), and any follow-up actions taken.


        15. The registrant and the seed corn dealers for the registrant must allow a review of the compliance records by EPA or by a State pesticide regulatory agency if the State agency can demonstrate that confidential business information, including the names, personal information, and grower license number of the growers will be protected.

        5d. Insect Resistance Monitoring

        The Agency is imposing the following conditions for this product:

        A report on results of Cry1F resistance monitoring and investigations of damage reports must be submitted to the Agency annually by April 31st each year for the duration of the conditional registration. You must provide EPA with an annual Cry34/35Ab1 resistance monitoring report by August 31st of each year beginning with 2008, reporting on populations collected the previous year.

        Cry1 F

        1. The registrants will monitor for resistance and/or trends in increased tolerance for Ostrinia nubilalis (European corn borer), Diatraea grandiosella (Southwestern corn borer), and/or Helicoverpa zea (corn earworm). Sampling should be focused in those areas in which there is the highest risk of resistance development. The ABSTC has identified four regions for its compliance and monitoring programs.


        2. The registrant shall provide to EPA a description of its Cry1F resistance monitoring plan by January 31, 2006. The description shall include: sampling (number of locations and samples per locations), sampling methodology, bioassay methodology, standardization procedures, detection technique and sensitivity, and the statistical analysis of the probability of detecting resistance.


        3. 3) The registrant must follow up on grower, extension specialist or consultant reports of less than expected results or control failures for the target lepidopteran pests Ostrinia nubilalis (ECB), Diatraea grandiosella (SWCB), Helicoverpa zea (CEW/CBW), Spodoptera frugiperda (FAW), Agrotis ipsilon (BCW), and Richia albicosta (WBCW),
          Sugar cane borer Diatraea saccharalis; southern corn stalk borer, Diatraea crambidoides; lesser corn stalk borer, Elasmopalpus lignosellus. The registrant will instruct its customers (growers and seed distributors) to contact them (e.g., via a toll free customer service number) if incidents of unexpected levels of damage occurs from these target pests. The registrant will investigate all damage reports submitted to the company or the company=s representatives. See Remedial Action Plans section below.

          4. Cry34/35Ab1

          The registrant must monitor for Cry34Ab1/35Ab1 resistance and/or trends in increased tolerance for corn rootworm. Sampling should be focused in those areas in which there is the highest risk of resistance development.

          1. The registrant must provide EPA its resistance monitoring plan for approval. A preliminary plan must be submitted to the Agency by January 31, 2006 consisting of a description of the steps to be taken to establish corn rootworm baseline sensitivity and damage guidelines. A detailed resistance monitoring plan must be submitted to the Agency for review by January 31, 2008. This plan must include: baseline sensitivity data, sampling (number of locations, samples per locations), sampling methodology and life-stage sampled, bioassay methodology, standardization procedures (including QA/QC provisions), detection technique and sensitivity, the statistical analysis of the probability of detecting resistance, and an interim description of rootworm damage guidelines.


          2. The registrant must develop and validate an appropriate discriminating or diagnostic dose assay by January 31, 2010. Further the registrant must provide BPPD with a detailed explanation and validation (steps for) of the "high-throughput diagnostic screen" if it is to be considered an acceptable diagnostic dose assay.


          3. The registrant must finalize rootworm damage guidelines and submit these to BPPD by January 31, 2010 should the registration be extended.


          4. The registrant must follow-up on grower, extension specialist or consultant reports of unexpected damage or control failures for corn rootworm.

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        5e. Remedial Action Plans

        Cry1F

        A Remedial Action Plan covering both suspected and confirmed resistance for European corn borer, corn earworm, and southwestern corn borer follows. If resistance involves any of these three target pests, the registrant must implement this Remedial Action Plan. The registrant must obtain approval from EPA before modifying the Remedial Action Plan for Lepidopteran-Protected Corn.

        Remedial Action Plan for Responding to Resistance in European Corn Borer Corn Earworm and/or Southwestern Corn Borer (October 15, 2001)

        1. Definitions

          2. Suspected resistance

          EPA defines "suspected" resistance to mean, in the case of reported product failure, that: the corn in question has been confirmed to be Bt corn

          • the seed used had the proper percentage of corn expressing Bt protein;
          • the relevant plant tissues are expressing the expected level of Bt protein; and it has been ruled out that species not susceptible to the protein could be responsible for the damage, that no climatic or cultural reasons could be responsible for the damage, and that other reasonable causes for the observed product failure have been ruled out. The Agency does not interpret "suspected resistance" to mean grower reports of possible control failures, nor does the Agency intend that extensive field studies and testing to confirm scientifically insect resistance be completed before responsive measures are undertaken.

          If resistance is “suspected,” the registrant must instruct growers to do the following:

          • Use alternate control measures to control the pest suspected of resistance to Bt corn in the affected region.
          • Destroy crop residues in the affected region immediately after harvest (i.e. within one month) with a technique appropriate for local production practices to minimize the possibility of resistant insects overwintering and contributing to the next season's pest population.

          Confirmed Resistance

          The registrant assumes responsibility for the implementation of resistance mitigation actions undertaken in response to the occurrence of resistance during the growing season. When resistance has been confirmed, the registrant must immediately stop sale and distribution of Bt corn in the remedial action zone (may be less than a single county, single county, or multiple counties) where the resistance has been shown until an effective local mitigation plan approved by EPA has been implemented.

          A resistance event becomes confirmed if the progeny of the sampled ECB, CEW, or SWCB population would exhibit all of the following characteristics in bioassays initiated with neonates:

          1. If there is > 30% survival and > 25% leaf area damaged in a 5-day bioassay using Cry1Ab-positive or Cry1F-positive leaf tissue under controlled laboratory conditions.


          2. If standardized laboratory bioassays using diagnostic doses for ECB (Marçon et al. 2000), SWCB (Trisyono and Chippendale 1999), or CEW/CBW (USDA/ARS/SIMRU, unpublished) demonstrate resistance has a genetic basis and survivorship in excess of 1% (gene frequency of population ?0.1).


          3. If an LC50 in a standard Cry1Ab or Cry1F diet bioassay exceeds the upper limit of the 95% confidence interval of the standard unselected laboratory population LC50 for susceptible ECB, SWCB, or CEW populations, as established by the ongoing baseline monitoring program.

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        2. Remedial Action

          3. The registrant assumes responsibility for the implementation of resistance mitigation actions undertaken in response to the occurrence of resistance during the growing season. In cases of "confirmed" resistance, the following strategy for Cry1Ab and/or Cry1F Bt corn hybrids:

          The registrant will report all instances of confirmed pest resistance, as defined above, to the Agency within 30 days. Upon identification of a confirmed instance of resistance, registrants will take the following immediate mitigation measures:

          1. Notify customers and extension agents in the affected area,


          2. Require to customers and extension agents in the affected area the use of alternative control measures to reduce or control the local target pest population,


          3. Where appropriate, require to customers and extension agents in the affected area that crop residues be incorporated into the soil following harvest, to minimize the possibility of overwintering insects.


          4. Immediately stop sale and distribution of Bt corn in the remedial action zone (may be a single or multiple counties) where the resistance has been shown until an effective local mitigation plan approved by EPA has been implemented.


          Within 90 days of a confirmed instance of pest resistance, as defined above, registrants will:

          1. Notify the Agency of the immediate mitigation measures that were implemented,


          2. Submit to the Agency a proposed long-term resistance management action plan for the affected area,


          3. Submit to the Agency a proposed long-term resistance management action plan for the affected area,


          4. Implement an action plan that is approved by EPA and that consists of some or all the following elements, as warranted:


            1. Informing customers and extension agents in the affected area of pest resistance,


            2. Increasing monitoring in the affected area, and ensuring that local target pest populations are sampled on an annual basis,


            3. Recommending alternative measures to reduce or control target pest populations in the affected area,


            4. Implementing intensified local IRM measures in the affected area based on the latest research results. The implementation of such measures will be coordinated by the Agency with other registrants; and


            5. The implementation of the remedial action strategy will be coordinated by the Agency with other registrants and stakeholders.


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          For mitigation of resistance in the growing season(s) following a confirmed resistance incident(s), use of the following procedures:

          1. Maintenance of the sales suspension of all Bt corn hybrids (with the same protein or similar Bt proteins as the Bt corn hybrids with the resistant population) in the affected region would remain in place until an EPA-approved local resistance management plan is in place to mitigate resistance in the affected region(s).


          2. The development and recommendation of alternative resistance management strategies for controlling the resistant pest(s) on corn in the affected region.


          3. Notification of all relevant personnel (e.g., growers, consultants, extension agents, seed distributors, processors, university cooperators, and state/federal authorities) in the affected region of the resistance situation.

      Cry34/35Ab1

      The remedial action plan is designed as a tiered approach for mitigating WCRW, NCRW, and MCRW resistance development to the Cry34/35Ab1 protein. 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. However, the levels of "expected" damage cannot be identified until baseline sensitivity is determined. EPA requires that the registrants establish the baseline sensitivity by January 31, 2008, so that expected levels of crop damage and target pest resistance can be established, and a remedial action plan initiated when needed.

      1. Definition of Suspected Resistance: Resistance will be suspected if investigations of unexpected damage reports show that:


        1. implicated corn plant roots were expressing Cry34/35Ab1 proteins at the expected levels;
        2. the seed used was not mixed with non-Cry34/35Ab1 seed;
        3. alternative causes of damage or lodging, such as non-target pest insect species, weather, physical damage, larval movement from alternate hosts, planting errors, and other reasonable causes for the observations, have been ruled out;
        4. the level of damage exceeds guidelines for expected damage.

        If resistance is "suspected", the registrant will instruct affected growers to use alternate pest control measures such as adulticide treatment, crop rotation the following year, or use of soil or seed insecticides the following year. These measures are intended to reduce the possibility of potentially resistant insects contributing to the following year's pest population.

      2. Confirmation of Resistance: Resistance will be confirmed if all of the following criteria are met by progeny from the target pest species sampled from the area of "suspected resistance":


        1. the proportion of larvae that can feed and survive on Cry34/35Ab1 roots from neonate to adult is significantly higher than the baseline proportion (currently being established);
        2. the LC50 of the test population exceeds the upper limit of the 95% confidence interval for the LC50 of a standard unselected population, and/or survival in the diagnostic assay is significantly greater than that of a standard unselected population, as established by the ongoing baseline monitoring program;
        3. the ability to survive is heritable;
        4. Cry34/35Ab1 plant assays determine that damage caused by surviving insects would exceed economic thresholds;
        5. if subsequent collections in the affected field area demonstrate similar bioassay results.


      3. Response to Confirmed Resistance: When resistance is "confirmed", the following steps will be taken:


        1. EPA will receive notification within 30 days of confirming resistance;
        2. affected customers and extension agents will be notified about confirmed resistance;
        3. affected customers and extension agents will be encouraged to employ alternative CRW control measures;
        4. sale and distribution of Cry34/35Ab1 corn in the affected area will cease immediately;
        5. a long-term resistance management action plan will be devised according to the characteristics of the resistance event and local agronomic needs.

  5. Additional Contact Information

Ombudsman, Biopesticides and Pollution Prevention Division (7511P)
Office of Pesticide Programs
Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460

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