Bt Corn and Insect Resistance Management: What Are They?

Patti L. Anderson, Iowa State University
Richard L. Hellmich, United States Department of Agriculture

This report is from Site-Specific Management Guidelines SSMG-33 (2001): 3pp. Posted with permission.


Transgenic corn with resistance to European corn borer (ECB) has been commercially available since 1996. Inserting a gene from the soil bacterium Bacillus thuringiensis (Bt) has genetically modified the corn plant to produce a protein that is toxic to moth larvae. Bt corn is valuable because it provides yield protection, reduces ear molds, and at least in some areas of the U.S., reduces the use of chemical insecticides. Grower response to transgenic corn has been positive. Over-use of Bt corn, however, could lead to ECB becoming resistant to Bt protein. In 2000, approximately 25 percent of the total corn acreage in the U.S. contained the Bt gene. Growers must practice insect resistance management (IRM) to ensure that this technology will be available to future generations of growers.