The adoption of transgenic, or more commonly termed genetically modified (GM) crops, has greatly transformed the crop industry. Crops resistant to the general purpose herbicide, glyphosate or Roundup, are widely available. More controversy, however, has been generated by the use of Bt-corn hybrids. These genetically engineered hybrids produce a protein derived from a soil bacteria, Bacillus thuringiensis (Bt) that is toxic to some pests but not to humans or animals.
While the biotech industry promoted Bt crops to control Lepidoptera—the order of insects that includes moths and butterflies—and thus dramatically reduce the use of synthetic insecticides, Miguel Altieri in 1999 brought attention to the issue of insect resistance. He pointed out that Lepidoptera have species that have developed resistance to the Bt toxin and that ultimately the use of Bt crops will fail. The continuous expression of the toxin in the crop will create such a strong selection pressure that resistance will be certain to develop.
To overcome the concerns for resistance development, the refuge strategy was developed. The concept is simple in design, but difficult in execution. It was first presented by US EPA in 2000 for corn borer control. It involves planting at least 20 percent of land in non-Bt corn. In cotton areas, at least 50 percent of the cotton must be non-Bt (there is also a Bt cotton). The situation is more complicated for corn rootworm Bt (a stacked trait, containing both rootworm and borer Bt, that is becoming more common).
The thinking behind the refuge is that the resistance genes will be diluted by supplying susceptible moths that can mate with the rare resistant moth. Offspring of these pairings will likely be susceptible to Bt corn. If the Bt corn rootworm is planted, the refuge should be in an adjacent field. Whereas for the corn borer, the refuge can be up to a half mile away. This is because the rootworm mating is local whereas the corn borer moth has a fairly wide range of exploration, although most recommendations prefer that the refuge for both be in the same field.
Monsanto now has a new corn seed that is a triple stacked variety for broad control of corn earworm, European corn borer, fall armyworm, southeastern corn borer, southern cornstalk borer, corn stalk borer and sugarcane borer, as well as corn rootworm. This technology has an EPA approval for a 20 percent refuge in both corn and cotton-growing areas.
The refuge compliance is voluntary, but must be monitored yearly by the major biotechnology seed producing industries. Data for 2008, reported by Gregory Jaffe of the Center for Science in the Public Interest (CSPI) and covered in The New York Times indicate a significant slippage in adherence to the refuge requirement, from a rather consistent 90 percent or above compliance in earlier years. They found:
- Only 78 percent of growers planting corn-borer-protected crops met the size requirement, and only 88 percent met the distance requirement.
- Only 74 percent of growers planting rootworm-protected crops met the size requirement, and 63 percent met the distance requirement.
- Only 72 percent of farmers growing stacked varieties of GE corn—corn protected against both corn borer and rootworm—met the size requirement and 66 percent met the distance requirement.
These are serious breaches of a contract that is made with EPA and the biotechnology companies—and with the public, who counts on the agricultural industry to live up to its stewardship obligations.
CSPI has some strong and common sense recommendations, including the removal of registration of Bt corn varieties until the companies can demonstrate a higher level of compliance; large fines or seed sales restrictions if noncompliance remains high; requiring biotech companies to pay for independent third-party assessments of compliance; and requiring bag labeling to specify refuge requirements.
Why is compliance slipping? One can only speculate. But is it a coincidence that compliance dropped when the price of corn skyrocketed in 2007-2008? At the same time, prices of inputs also increased, squeezing the farmer’s bottom line even more. The refuge requirement is expensive; seed must be segregated, pesticides that might also cause resistance cannot be used and yields on the refuge areas might suffer because of the high pest pressure.
Even more serious is the potential that organic farmers will lose the one best biological control of pests available to them; they commonly spray a mixture of Bt on crops to biologically control the Lepidoptera.