What's the Story with Corn Rootworm Technology?

K. Sauer 9/12/2011

Key Points:

The USDA has previously estimated the damage caused by corn rootworms and costs associated with controlling them typically total $1 billion annually.

Farmers have various ways of managing corn rootworm pressure, one of which is using Bt traits on their farms.

There are geographical pockets of heavy rootworm infestation, but we have not seen resistance develop to our rootworm-traited products in the field.

Recent headlines have questioned the performance of Monsanto’s corn rootworm-protected technologies in some areas of the U.S. Corn Belt. So, we're providing education about the pest and related management practices.

What is corn rootworm?

Each year, U.S. corn yields are adversely impacted by a number of insect pests. One of the country’s most devastating pests is the corn rootworm family. There are several types of rootworm, including the northern corn rootworm, the western corn rootworm and the Mexican corn rootworm.

The corn rootworm does its damage as a larva – the immature stage of the insect. After mating in the late summer, adult corn rootworms lay their eggs in the soil, depositing them in cornfields in many regions. The eggs survive the winter underground and hatch in the spring, when the larvae then feed on the roots of young corn plants in farmers’ fields. Rootworm larval feeding inhibits the corn plant's ability to take up water and nutrients, decreases its ability to develop and remain upright, and – ultimately – leads to possible yield loss, depending on the damage inflicted on the roots by the feeding pests and the growing conditions.

Because of its impact, the corn rootworm has earned the nickname the “billion-dollar bug.” The U.S. Department of Agriculture (USDA) has previously estimated the damage caused by the pest and costs associated with controlling it typically total $1 billion annually – including approximately $800 million in yield loss and $200 million in treatment expenses.

How do farmers manage corn rootworm?

Growers limit corn rootworm damage primarily through one of the following methods, or a combination thereof:

  • Crop rotation to soybeans or another non-host crop
  • The use of soil- or foliar-applied insecticides to manage larvae and adults, respectively
  • The use of different single and dual mode-of-action (pyramided) Bt-trait products

Is Monsanto seeing resistance to Bt-corn products?

We take all performance claims of our products seriously, and we actively work with farmers who report these incidents to better understand what they are seeing and provide them with recommendations for their farm. Monsanto has not seen resistance develop to our rootworm-traited products in the field.

We're continuing to see our portfolio of corn-rootworm products demonstrate an outstanding level of performance and grower satisfaction across tens of millions of U.S. acres. Field monitoring of these products, which we have conducted since the introduction of Bt traits last decade, show corn rootworm-protected hybrids deliver superior performance on greater than 99 percent of all acres planted to the technology in the U.S.

Recent headlines unfortunately overlook the fact that farmers have routinely faced areas with high populations of rootworms for years, even prior to the introduction of insect-protection trait technologies.

Today, there are geographical pockets of heavy rootworm infestation in areas where there’s a long history of corn-on-corn plantings. In these areas, farmers see intense rootworm pressure that can overwhelm the plants, leading to damage and some surviving insects. This is not something that is specific to any commercial product category, and farmers in these areas work to effectively manage this problem in their fields every year.

Where can I learn more?