Insect Resistance Management Plan for Bt Potatoes Grown in Canada

Insect resistance management plans are required for crop plants grown in Canada that express Bacillus thuringiensis (Bt) insecticidal proteins. IRM plans are intended to delay the development of insect resistance to Bt, thereby extending the useful lifetime of this technology.

The following IRM plan for Bt potatoes was developed by a multi-stakeholder consultation group consisting of Colorado Potato Beetle (CPB) researchers, industry representatives and grower representatives. The consultation group was formed following the January 2000 Consultation on Pest Resistance Management Strategies for Bt Potatoes, to examine the scientific and practical aspects of designing an appropriate IRM plan for Bt potatoes, and to make recommendations to the CFIA on the features of a new IRM plan. The present IRM plan is intended to address some of the concerns expressed by grower representatives about previous IRM requirements, and to apply research on the biology and mobility of this significant agricultural pest.

The IRM plan requires that a "refuge" of at least 20% non-Bt potatoes be planted where Bt potatoes are grown in fields of greater than one hectare in size. The refuge is designed to provide a population of insects susceptible to Bt that are available to reproduce with potentially resistant insects which may emerge from the Bt potato field. The refuge must be located no further than 800m from the Bt crop and must not be sprayed with Bt foliar insecticides. Registered insecticides, other than the Bt foliar type may be used in the refuge when economic thresholds prescribe it, in order to control damaging populations of CPB.

The Canadian IRM Plan for Bt potatoes must be implemented by any developer that has been granted unconfined environmental release authorization of Bt potatoes. Presently, only Monsanto Canada Inc. has received food safety, feed safety and unconfined environmental release authorizations for Bt potatoes in Canada.

---

Canadian Insect Resistance Management
(IRM) Plan for Bt Potatoes

Note: This IRM plan must be implemented for any field production of Bt potatoes which exceeds one hectare in size.

Requirements

1. When Bt potato varieties are planted, at least 20% of the total potato acreage must be maintained as a "refuge"(non-Bt potato varieties that provide a Bt susceptible population of insects to interbreed with potentially resistant insects which may emerge from the Bt crop).
2. Foliar Bt applications for CPB control within the refuge are not permitted. CPB in the refuge may be treated with other insecticides registered for CPB control in potato when economic thresholds prescribe it.
3. The Refuge should be planted as close as possible to Bt potatoes, and must not be located greater than 800 m from the Bt field.
4. Growers must notify the developer authorized for unconfined environmental release of Bt potatoes if damaged plants or surviving larvae are seen in the Bt potato field. The developer is required to notify the Canadian Food Inspection Agency immediately if resistant beetles are found.

Note: Compliance with the IRM requirements for Bt potatoes will be audited by the CFIA periodically. It is the responsibility of the developer which has received unconfined environmental release authorization to have adequate systems in place to ensure grower education and compliance

Recommendations:

1. Top kill Bt potatoes prior to the non-Bt refuge potatoes to promote survival of susceptible beetles and mixing of populations.
2. Use other available methods to reduce CPB populations
   1. Rotate production so potatoes are not grown in the same field every year.
   2. If possible, use methods other than insecticides to reduce CPB populations, such as propane flaming, trench trapping, or overwintering habitat destruction.
3. Monitor for survival of CPB by scouting Bt potatoes regularly for the presence of larvae or adults.
4. When insecticides are used in the refuge, it is recommended that foliar (non-Bt, see section 2 under requirements) insecticides are used, as opposed to in-furrow insecticides, and only when populations reach damaging levels, according to local IPM recommendations.

Planting Options:

Neighbouring land planted with non-Bt potatoes may qualify as refuge as long as the applicable requirements are met, including;

1. Bt potato acreage does not exceed 80% of total potato acreage.
2. Refuge must be within 800m of Bt potato field.
3. Refuge must not be sprayed with Bt foliar insecticides.

Note: It is the responsibility of the developer to ensure that neighbouring land is maintained as a refuge by signed agreements and/or other mechanisms which obligate the compliance of the neighbour.