Controversies Regarding Transgenic Crops Escalate

October 4, 1999
On an almost daily basis, the media are filled with reports about transgenic crops and the growing concerns among the general public about this new technology. During the summer, we read stories about the potential threat of Bt-corn pollen to monarch butterfly populations. Although one study revealed that monarch butterfly caterpillars could be killed by Bt corn under laboratory (and likely not realistic) conditions, the real threat to monarch butterflies in the "real world" is unknown. Indeed, the scientist who conducted the study reported that his findings were preliminary. Unfortunately, much of the media chose to ignore that part of the published article in order to sensationalize the negative results.

The most recent controversy has to do with the announcements of some countries and companies that food products made from genetically modified crops should be labeled as such. These announcements prompted some major grain exporters to announce that they wanted genetically modified crops separated from "normal" crops before shipment to their elevators. Consequently, Bt corn must be segregated from non-Bt corn before it can be delivered to these elevators. And therein lies a problem.

Even before Bt corn was available commercially, university, government, and industry scientists began developing insect resistance management plans that could be implemented by growers when Bt corn was available for planting. Based on all scientific data available for use in simulation models, scientists determined that the best resistance management plan would rely on a high dose/refuge strategy. Theoretically, the high dose would kill 100 percent of the target insects. Realistically, however, scientists believed that some insects (assumed to be very few) that fed on Bt corn might already carry a gene for resistance and survive. Therefore, the resistance management strategy had to include some way to make certain that rare resistant individuals would mix and mate with susceptible individuals. Thus arose the need for non-Bt corn refuges that would "supply" the susceptible individuals.

The objective of these resistance management plans was to slow down, or possibly prevent, the development of resistance to Bt in target insects, most notably European corn borers. Opponents of transgenic crops, and of Bt corn more specifically, were most concerned about development of resistance among pest insects and the potential negative impact that might have on the use of Bt-based insecticides such as DiPel. Objective scientists and corn growers were concerned about this, too. And after much effort, dialog, and consensus building, virtually all parties agreed on a minimum of 20 percent non-Bt corn refuge. In addition, to make certain that European corn borers would mix and mate, scientists agreed that the non-Bt corn refuge had to be planted near Bt corn. Fields of non-Bt corn adjacent to fields of Bt corn were acceptable as refuges, but most people agreed that a better mix of the corn borer population would occur if the refuge was planted within the Bt cornfield, either in a block or in strips throughout the field.

Extension entomologists at land-grant universities and industry scientists have been spreading the message about the importance of growers' demonstrating good stewardship of Bt corn by planting non-Bt corn refuges. For the most part, corn growers agreed that preservation of the technology was important, and they willingly followed the suggestion to implement resistance management strategies. They dutifully planted non-Bt corn next to or within Bt cornfields to establish the recommended refuges. In other words, they did the right thing.

And then came the announcements that Bt corn had to be segregated from non-Bt corn before delivery to some elevators. However, in order to make certain that pollen from Bt corn will not "contaminate" non-Bt corn, they have to plant non-Bt corn and Bt corn far apart. Obviously, this defeats the purpose of resistance management. In other words, corn growers cannot segregate Bt corn from non-Bt corn and implement insect resistance management strategies.

In our opinion, the effort by the scientific community to address a major concern (insect resistance) is being completely ignored by the major grain exporters who are forcing farmers to segregate their grain. Basically, the message is, "We don't care about insect resistance management." In fact, the companies are ignoring scientific recommendations in deference to unfounded hysteria. And there is no scientific evidence that Bt is a threat to human health.

Ultimately, farmers suffer the most. They are doing what they think is right (planting non-Bt corn refuges next to or within Bt cornfields), and then they find out that this practice might be a problem when they want to take their grain to an elevator. If a non-Bt corn refuge was planted within a Bt cornfield, the grain from the entire field must be considered Bt corn. Some companies have offered premiums for nontransgenic crops. And some elevators will not accept transgenic crops, so Bt corn growers might have to pay additional transportation costs to locate an elevator that will accept Bt corn. The result is that growers who planted Bt corn and non-Bt corn refuges will suffer economically at a time when crop prices aren't very good anyway. It's a "Catch 22" for many growers.

It is a shame that media hype has so much more power than solid science. We hope that the controversies over transgenic crops can be discussed objectively, rather than subjectively. Without reasonable dialog about this issue, regulations and restrictions will arise from rhetoric.--Kevin Steffey, Mike Gray

Author: Kevin Steffey Mike Gray