Finally, yield performance variability exists among specialty hybrids. BT CORN is an abbreviation for the bacteria, Bacillus thuringiensis , which is found in the soil. After the insect eats Bt, the crystal dissolves to release a toxin that attacks the gut lining. Feeding stops within a few hours. The insect gut wall breaks down within 24 hours.
Bacterial spores germinate and invade the body cavity of the insect.
Over 70 different toxins are formed from Bt crystal proteins. The activity of the toxin in an insect depends on gut pH, the presence of enzymes and reducing agents, and the presence of binding sites on cell membranes. Production of the Bt protein in corn continues as long as the corn is actively growing and declines after ear fill begins. A number of questions need to be addressed regarding long term economics, since European Corn Borer outbreaks do not occur every year. In addition, special resistance management strategies may need to be developed.