Registration Terms for CRW IRM – final version 1-26-16

The following is a listing of the new registration terms that were implemented for Bt corn 

products as part of EPA’s new Insect Resistance Management framework for corn rootworm. 

Please note that is not a complete list of all the terms and conditions for the registrations; for 

specific terms for each registered product, please consult the Pesticide Product Label System 

(PPLS; https://iaspub.epa.gov/apex/pesticides/f?p=PPLS:1). 

1) IPM

Integrated Pest Management Stewardship Program

a) [Company] must implement an IPM-based stewardship program for [PIP product]. This 

program must be designed to reduce selection pressure for CRW resistance by 

encouraging growers to engage in a multi-year crop rotation strategy involving the use of 

one or more of the following: a non-CRW host crop (e.g., soybean), pyramided Bt corn 

Plant Incorporated Protectants (PIPs), other PIP corn products with different modes of 

action, and/or non-Bt or non-CRW protected Bt corn. As part of the stewardship 

program, [company] must update the technology use guide/grower guide and other 

grower educational materials to indicate that the use of SAI with [product] is not 

recommended for control of CRW except under limited circumstances and in 

consultation with extension, crop consultants or other local experts. [For pyramided 

products add: Grower education materials should also state that SAIs should not be 

necessary for CRW control with pyramided CRW trait Bt corn product(s).] A copy of the 

revised grower educational materials must be provided to EPA by January 31, 2017. As

part of the stewardship program, [Company] must promote the ABSTC/NCGA Best 

Management Practices (BMPs) for CRW control. Implementation of the IPM strategy 

can include:

o Grower education initiatives or incentives;

o Outreach to extension and consultant groups.

b) [Company] must submit an annual report to EPA documenting activities conducted under 

the IPM stewardship program. This report must include an anonymous survey of grower 

practices, including adoption levels of the various crop rotation options (if employed) and 

other elements of the stewardship program. [Company] may combine this product with 

other registered products to submit one annual report. The report must be submitted by 

January 31st each year, beginning in 2017. The 2017 report will serve as a baseline 

unless [company] wishes to submit a separate baseline report prior to January 31, 2017.

2) Unexpected Damage Reports

Investigation of Reports of Unexpected Levels of Damage (UXD) by Corn Rootworm 

(CRW): Performance Inquiries
a) [Company] is required to investigate "performance inquiries" (i.e., reports of unexpected 

corn rootworm damage to [PIP product] corn) from growers. Fields (defined as a tract 

separated by permanent boundaries such as fences, permanent waterways, woodlands, 

croplines not subject to change because of farming practices, or other similar features) 

with unexpected damage that meet both of the criteria below must be subjected to the 

follow-up actions in part b) below:

i. The affected plants are confirmed to be [PIP product] plants (take leaf samples 

to determine the presence of the CRW-active Bt protein); and 

ii. Corn rootworm feeding caused root damage with a Node Injury Score (NTS) > 

[1.0 for single trait or 0.5 for pyramid] on at least 50% of plants surveyed in a 

transect sampling of the damaged site within the field.

b) Follow-up actions (performance inquiries). For [PIP product] fields meeting the criteria 

in part a) above, [Company] must take the following actions:

• Collect at least 250 (ideally 500 or more) CRW adult individuals from the 

damaged site within the field in question. Collections may be extended to the 

whole field, if necessary to obtain sufficient CRW adult individuals. Collected 

populations must be subjected to the steps described for "investigation of 

populations of concern" (section 3) below).

o If collections are unsuccessful, visit affected farm or field the following 

year (assuming the grower continues to be a customer and repurchases 

seed and does not rotate the field to a non-host crop) and attempt to collect 

corn rootworm adults. If beetles are not present the subsequent year, see 

section 3)(c)(3). 

• Review with the grower their CRW management practices and provide CRW 

management recommendations including an assessment of corn fields with 

similar trait(s) adjacent to the affected corn field that are managed by the same 

grower. 

• Use of single trait products containing the CRW trait in fields with unexpected 

damage in previous years should be discouraged. Recommended management 

options include, but are not limited to, the following:

o Primary option: Rotation to non-host crop (e.g., soybean)

o Secondary options:

 Use of pyramided Bt corn products with multiple CRW PIP traits

 Use of different single-CRW PIP traits (i.e., an alternative corn 

rootworm-active PIP)

 Use of non-Bt or non-corn rootworm protected corn

o Tertiary options: If additional pest management need is determined 

beyond the secondary options listed above, additional corn rootworm 

control tools (e.g., soil insecticides, seed-applied insecticides, 

chemigation) should be used
• If field(s) with UXD is/are planted to a non-host crop (e.g., soybean) the 

following year, then the area will be considered “mitigated” (as discussed in 

section 3)(c)(4) below) even if subsequent bioassay results show that the 

population was resistant. No further action will be required by [company] for the 

UXD case.

c) [Company] must submit an annual report to EPA detailing activities related to 

investigations of unexpected damage (UXD). This report will include the information 

from the most recent and previous corn growing seasons:

i. Information from the most recent season:

• The number of UXD reports investigated.

• Location (by county and state).

• CRW sampling (number and location of populations collected).

ii. Information from the previous season:

• The final disposition of UXD fields from the previous season (i.e., the 

management practices employed in response to UXD if the grower continues to 

be a customer.

• Results from bioassays conducted on CRW populations from UXD fields where 

the primary management option, rotation to non-host crop, was not used. 

iii. Grower information, such as farm addresses or other personally identifiable 

information, or other sensitive business/customer information must not be 

included in this report. This report must be submitted by November 30th each 

year.

3) Resistance Detection Assays

Investigation of Populations of Concern

a) [Company] must conduct investigations of all CRW populations collected as part of the 

performance inquiry process in section 2) above. These investigations must include the 

use of an EPA-approved bioassay to determine if sampled CRW populations are resistant 

to [PIP toxin]. Acceptable assays must be able to function as diagnostic tools capable of 

distinguishing resistant populations from susceptible ones. Unless previously approved, 

[company] must consult with EPA on their bioassay prior to its use.

b) A CRW population will be considered by EPA to be resistant to [PIP toxin] if the 

following criteria are met and additional collections and testing are not deemed to be 

necessary (based on part c) below): 

1. An initial performance inquiry investigation results in a finding of Unexpected 

Damage; and

2. Where green tissues are available and if plants are unusually stressed due to 

agronomic and/or environmental factors, Bt protein levels in affected plants are 

found to be within the documented range for that hybrid (if data are available); 

and
3. Either (A): On-plant bioassays of insect collections from the UXD fields result in 

the following two statistically relevant comparisons

i. A statistically significant difference in measures of either mortality or 

sublethal effects (growth/development) between the field population and a 

relevant susceptible control population (i.e., one that responds as a typical 

susceptible field population) on Bt corn and/or lack of a statistically 

significant difference in measures of mortality or sublethal effect between 

the field population and a resistant positive control population†; and

ii. A lack of a statistically significant difference in the same measures of the 

field population raised on Bt corn and non-Bt corn plants.

Or (B): Sublethal seedling bioassay of insect collections from the UXD fields 

result in two statistically relevant comparisons

i. A statistically significant difference in measures of sublethal effects 

(growth/development) for populations on Bt corn (normalized using 

non-Bt) seedlings between the field population and a relevant 

susceptible control population where available or historical field 

populations and/or lack of a statistically significant difference in 

measures between the field population and a resistant positive control 

population†; and 

ii. A lack of a statistically significant difference in the same measures of 

the field population raised on Bt corn seedlings and non-Bt corn 

seedlings.

Or (C): Diet-based bioassays of insect collections from the UXD fields result in 

two statistically relevant comparisons

i. A statistically significant difference in measures of lethal or sublethal

effects (growth/development) on diet containing the Bt protein 

(diagnostic concentration or concentration-response measures) between 

the field population and a relevant susceptible control population where 

available or historical field populations and/or lack of a statistically 

significant difference in measures between field population and a 

resistant positive control population†; and

ii. Either a lack of a statistically significant difference in the same measures 

of the field population exposed to diet containing the Bt protein 

(diagnostic concentration) and diet not containing the Bt protein and/or 

lack of a statistically significant difference in measures between the field 

population and a resistant positive control population, or lack of a 

statistically significant concentration and/or lack of a statistically 

significant difference in concentration response between the field and a 

resistant positive control population†

.

c) Mitigation, as detailed in section 4) below, is required for any CRW population that 

meets EPA’s resistance criteria above, unless the circumstances described below are 

applicable.

 † If a resistant positive control population is not available or accessible to [Company], [Company] must consult with 

EPA prior to initiating bioassays and work to develop an appropriate resistant positive control population.
1. To minimize the potential for incorrectly reaching a conclusion of resistance, 

another year of CRW adult collections and additional testing is needed to 

determine resistance if: 

i. The results of the bioassays are inconclusive (e.g., the results of the 

statistical analysis are unclear because of low sample sizes) or 

ii. Another reasonable explanation for the unexpected damage exists (e.g., 

high pest pressure and/or high plant stress). 

2. In these cases, [Company] and EPA will discuss and align on next steps before 

reaching any resistance conclusion. 

3. If CRW collections are not possible in the current year or subsequent year due to 

successful management practices, then no further investigation is needed. The 

population would be considered "mitigated" meaning, in this case, that the 

population is suppressed or extirpated for the UXD field. However, EPA 

recommends that [Company] continue to be vigilant in areas where CRW 

populations were successfully mitigated.

4. If a UXD field receives non-host crop (e.g., soybean) rotation the following year 

(as described in Section 2)(b) above), no additional mitigation is subsequently 

required.

4) Mitigation Action

Mitigation of CRW Populations Meeting EPA’s Resistance Criteria

a) For any CRW population found to be resistant under EPA’s criteria described in section 

3)(b) above, [Company] must take the following steps:

1. [Company] must inform EPA of the results of the bioassays as soon as possible, 

but at least within 30 days if measures are triggered.

2. The mitigation action area (MAA) is defined as the growers’ farming operation up 

to a 1⁄2 mile radius from the damaged site that produced the resistant population.

3. Within 30 days of informing EPA of the results of the bioassays, the [Company] 

must notify state extension agents and crop consultants who operate within the 

county in which resistance was identified. Information shared must include

identification of the county in which resistance was detected and trait(s) affected.

4. Within the MAA, [Company] must do the following:

i. Prior to finalizing the grower’s seed order for the following season, inform

the affected grower and other registrants that hold registrations containing 

the affected trait. [Company] must also inform neighboring growers if 

those growers are customers of [Company]. Information shared must 

include identification of the county in which resistance was detected and 

trait(s) affected;

ii. Discontinue sales/planting of single trait product containing the 

compromised trait until resistance has been demonstrated to have been 

mitigated;

iii. [Company] must monitor resistant population in the MAA, as long as 

grower remains a customer of the company, until mitigation has been 
demonstrated as described in part 5 below unless otherwise agreed with 

EPA.

iv. Require any pyramids sold by [Company] containing the compromised 

trait be planted with a 20% refuge until resistance has been demonstrated 

to have been mitigated. Other Bt registrants selling pyramided products in 

the MAA are encouraged, but cannot be required by this term of 

registration, to follow suit; 

v. For [Company]’s affected customer’s field(s), the mitigation goal is to 

control the resistant CRW population. Within the MAA [Company] shall

encourage the use of “Mitigation Practices” including: 

1. Primary option: Rotation to a non-host crop (e.g., soybean);

2. Secondary options:

a. Use of pyramided Bt corn products with multiple CRW PIP 

traits;

b. Use of different single-CRW PIP traits (i.e., an alternative 

corn rootworm-active PIP);

c. Use of non-Bt corn or non-corn rootworm protected corn 

(with/without soil-applied insecticide);

3. Tertiary options:

d. If additional pest management need is determined beyond 

the secondary options listed above, additional corn 

rootworm control tools (e.g., soil insecticides, seed-applied 

insecticides, chemigation) should be used. 

e. Use of foliar applications to control adults (when 

appropriate economic thresholds have been met) may be 

used in conjunction with one or more of the above;

5. A resistant CRW population in the MAA will be considered mitigated if one of 

the following criteria is met:

i. Corn fields within the MAA are rotated to a non-host crop (e.g. soybean) 

for one growing season.

ii. After implementation of mitigation practices (part 4.v above), resistance 

monitoring (sampling) is conducted but few CRW are found (i.e., <0.1 

adults per plant) and environmental conditions (e.g., weather) are unlikely 

to be responsible for the lack of adult CRW presence. If environmental 

conditions are a factor, then monitoring should continue for another 

season.

iii. After implementation practices (part 4.v above), resistance monitoring 

(sampling) is conducted, CRW are found and collected, and bioassays 

(section 3)(b) above) show that the population susceptibility to the 

identified trait has returned to baseline levels.

6. The mitigation actions in part 4 above can be lifted, and growers can resume the 

use of [PIP product] as a primary tool for CRW management in the MAA, only 

when [Company] demonstrates that successful mitigation as described in part 5 

above has been achieved.
b) Based on further research to understand CRW resistance to Bt PIPs, EPA will consider 

refinements to the resistance mitigation program. Such research may include 

characterizing the genetics of resistance (e.g., number of genes, functional dominance, 

mechanism of resistance, and cross-resistance) and the biology of resistant insects (e.g., 

fitness in the presence and absence of the product), and other control tactics.

5) Annual Reporting

The following annual reports must be submitted.

X) IPM Stewardship Program (CRW toxins only): Activities conducted under the IPM 

stewardship program, including an anonymous survey of grower practices, adoption levels of the 

various crop rotation options (if employed) and other elements of the stewardship program, on or 

before January 31st of each year.

X) Unexpected Damage Investigations (CRW toxins only): Activities related to investigations of 

unexpected damage (UXD), including number and location of UXD cases, insect sampling, 

bioassays, and final disposition of UXD fields from the most recent and previous corn growing 

seasons, on or before November 30th of each year.