Global Insect Resistance Management

Worldwide, insects are a major cause of crop damage and yield loss, requiring farmers to often make multiple applications of chemical pesticides to combat insect pests. To protect the yield potential of plants and significantly decrease pesticides use, insect-resistant traits in transgenic plants using Bt(Bacillus thuringiensis) were developed.

Crops with a Bt trait have been modified to produce a protein that is toxic to various forms of insect larvae. Bt proteins have long been used as topical sprays in conventional and organic agriculture because they are effective and can be used safely. Crops that are genetically engineered to carry the Bt trait allow farmers to protect their crops while eliminating or significantly decreasing the amount of pesticides sprayed.

Monsanto’s Bt corn and cotton products will sustain less damage from some of the most troublesome lepidopteran pests, but they will not control all insect pests in the crop. Therefore, it is important to understand that, in some cases, severe infestations of target and/or non-target insects may occur and require additional control measures. 

The best way for growers to preserve the benefits and insect protection of Bacillus thuringiensis (Bt) technology is to incorporate Integrated Pest Management (IPM) practices and to develop and implement Insect Resistance Management (IRM). The IRM plan is used to decrease the likelihood of an insect developing the ability to survive pesticide application or the ingestion of transgenic crops containing the Bt trait. Every grower of a Monsanto Bt corn or cotton product must comply with licensing terms and must have an Insect Resistance Management (IRM) plan.

Integrated Pest Management Practices
Around the world, growers of Monsanto Bt corn and cotton products have found them to be highly compatible with their goals of integrated pest management (IPM). Growers can enhance the sustainability of their cotton and corn agricultural systems by following recommended IPM practices, including cultural and biological control tactics, and appropriate use of pest thresholds and sampling. These latter measures are not only important for non-Bt refuge acres, but are equally important for detecting and controlling non-target pests that exceed established thresholds on Bt crops. Recommended IPM practices commonly adopted by growers of Bt crops include:

  • Employing regular, appropriate scouting techniques and treatment decisions, especially during periods of heavy or sustained pest presence.
  • Consulting a local crop advisor or extension specialist for the most up-to-date pest control information.
  • Selecting insecticide treatments that have minimal negative impact on beneficial insects, which are conserved by Bt-protected crops and contribute to insect pest control.
  • Selecting cultivars well-adapted to their local ecology and giving appropriate attention to the impact of crop maturity and timing of harvest on pest severity.
  • Using recommended cultural control methods to reduce pest overwintering, such as crop rotation and other soil management practices.


Insect Resistance Management Plans
The goal of an IRM plan for Bt crops is to decrease the likelihood of an insect population becoming resistant to a Bt train, and a key component of any IRM plan is planting a refuge. A refuge is simply a block or strip of the same crop that does not contain a Bt trait. The lack of exposure to the Bt protein in refuges means that there will be susceptible insects nearby to mate with any rare resistant insects that may emerge from the biotech crop. To help reduce the risk of insects developing resistance, the refuge should be planted with a similar hybrid/variety, close to, and at the same time as, the crop containing Bt technologies.

In the United States, refuge is required by the Environmental Protection Agency (EPA) when planting Bt products. For more information on refuge, please visit our Refuge Requirements.

To help ensure compliance, growers can try the IRM Refuge Calculator. It's a tool designed for growers to help illustrate the appropriate refuge calculation, the quantity of standard seed bags to purchase for both trait and refuge and possible planting configurations for planting certain corn products in the United States.

Monsanto’s Ongoing IRM Efforts

  • Monsanto takes IRM and the stewardship of our products very seriously. In addition to the actions that can be taken by growers, we are focused on:
  • Continually working to increase overall awareness of the need for, and adoption of, strong IRM programs through our Monsanto seed dealers, as well as the academic community.
  • Carefully evaluating the need for – and practicality of – updating our BMPs or agronomic recommendations as new scientific data becomes available.  Updates may include information tailored to local growing conditions, refuge compliance, scouting techniques, the addition of soil-applied insecticides, maturity and harvest schedules, soil management practices, crop rotation, and adoption of products with dual modes of action. 
  • Expanding our offering of multi-gene corn hybrids and cotton varieties that provide dual modes of action and increase protection for growers.  We encourage farmers to begin trying these seeds with greater protection as the product line expands in their area. 
  • Researching and developing other genes in our pipeline so that we can continue to deliver products with new and increased modes of action.
  • Continuing multi-year, wide-scale monitoring of insect populations in the United States and abroad.
  • Actively investigating claims of insect resistance. 
  • Conducting thorough, generational studies on sample insect populations as appropriate to determine if stable and inherited resistance is present.
  • Monitoring and studying the occasional performance issues in fields with very high insect population densities that exceed control thresholds. 


Insect Resistance Management Documents

Grower Licensing Documents


To learn more about Monsanto’s commitment to the stewardship of corn rootworm-protected traits, visit our Corn Rootworm Management section.