Bacillus thuringiensis (Bt) is a biological insecticide that has activity on some moth larvae. The gene expressing the protein toxin of this insecticide has been genetically engineered into corn. In YieldGard hybrids, the protein is expressed in the grain as well as other parts of the plant, thus providing the grain with protection from larval feeding. Recent research has shown that about 75 percent fewer Indianmeal moths emerge from Bt grains in storage, and those that survive lay 90 percent fewer eggs. This means that the effectiveness of Bt grains should be superior to Bt products applied as a topical, bin, or grain treatment. However, keep in mind that Bt corn will not control weevils or other beetles.
