[Why use the BT gene to modify crops?].
Farmers are incredibly productive, but it does come at a price. There is a lot of contamination of soils and groundwater with the excess use of chemicals that are used to control weeds and insects and pests. So this was an obvious area that biotech could very quickly address issues of interest to the farming community. At that point in time, the biotech companies weren't thinking specifically of the consumer. They really were thinking of the farmer.
Last year, 55 percent of all soybeans were genetically engineered for another type of resistance gene, and this was herbicide tolerance. What this herbicide tolerance gene does is allow a far more environmentally compatible herbicide--glyphosate--to be used to control weeds. A recent report from the U.S. National Food and Ag Council in Washington has shown that using herbicide-tolerant soybeans, there was a savings of $280 million by farmers in 1998. This allowed them to use just a single herbicide. They only had to spray
if the weeds emerged. They didn't have to use multiple sprayings or pre-sprayings. Likewise, they didn't have to use complex cocktails of really pretty nasty herbicides.
Take corn and cotton. What kind of pathogens attack these crops?
The main pathogen, especially for corn, is European corn borer. That particular pathogen comes up through the stalk of the plant itself, and it's very difficult to get at because it's literally inside the stalk, and you really oftentimes don't realize you have a problem until the ears fall off. That's not very good for farmers, and there's no really good way of being able to control them right now, even using traditional chemical pesticides.
With the BT gene in the corn itself, when the larvae eat [it], they are immediately affected. If you look at the two plants--the control plant and the engineered plant--it's like night and day. The control plant is just completely infected with the European corn borer. The BT plant is completely clean.