Corn and Biotechnology
Voluntary Refuge Program Draws Overwhelming Support

Corn producers' belief in sound environmental planning has been underlined by the results of a study showing they're overwhelmingly - and voluntarily – using insect resistance management (IRM) practices, involving Bt corn hybrid refuges.

The study of more than 1,700 producers in Ontario, Quebec and Manitoba by Stratus Agri-Marketing Inc. for the Canadian Corn Pest Coalition (CCPC) shows about 90 per cent of Canada's corn farmers have adopted two key management strategies to support the fight against European corn borer with Bt corn hybrids.

The strategies have been developed by the CCPC. First, farmers are to plant 20 per cent or more of their total corn acres to non-Bt hybrids to provide a refuge or source of corn borers that have not encountered Bt corn. Second, farmers' Bt corn plantings are to be no more than a quarter-mile away -- or closer, preferably -- from their non-Bt corn.

Growing Bt corn hybrids and non-Bt hybrids in the same field or close together reduces the potential of resistant populations of insects developing. Resistance genes present in a small number of insects are diluted with the more common susceptible conventional forms of the corn borer that emerge from the refuge, says CCPC chair Prof. Mark Sears of the University of Guelph's Department of Environmental Biology.

"The study demonstrates excellent comprehension and compliance of insect resistance management by farmers. They understand their moral and community responsibility and are practising good stewardship," says Sears. Adds Ken Hough, director of research and market development for the Ontario Corn Producers' Association: "This shows corn producers are aware of the compliance strategy for refuge, and that they view this technology as part of the future."

He says the coalition wants to know why the other 10 per cent or so haven't adopted the strategies. For example, is it because their acreage is small and they're finding the refuge requirements impractical, or some other reason?

In 2001, almost 60 per cent of all corn producers grew Bt hybrids, which contain a specific protein from the common soil bacterium Bacillus thuringiensis (Bt). It's harmless to humans and the vast majority of organisms, but when the corn borer (the larval form of a moth) eats the corn plant containing the Bt protein, the protein interferes with the insect's digestive system, and it dies.

Last year, Bt corn accounted for at least 35 per cent of the 1.4-million acres of Canadian farmland planted to corn. These hybrids are part of a growing trend towards genetically modified crops, which worldwide rose by 20 per cent last year, according to the International Service for the Acquisition of Agri-Biotech Applications (Canada grows six per cent of the world's genetically modified crops).
But like other crop protection tools, new technologies need careful management for maximum effectiveness and longevity. The CCPC – representing corn producers, researchers and extension personnel from government, industry and universities – has created an IRM strategy centred on delaying resistance. The Canadian Food Inspection Agency (CFIA) also participates. Over time, a certain proportion of insects can naturally develop resistance to any control strategy. But the onset of that problem can be delayed appreciably with strategic IRM approaches.

Bt corn manufacturers are required by law to report to the CFIA how much refuge is being maintained. It's a condition for registering the crop for sale in Canada. There is no legislation forcing farmers to maintain a refuge...but they do so anyway, says committee chair Sears, because they're concerned about insect resistance.

In fact, the CCPC study showed close to 90 per cent of producers using Bt corn hybrids had a high awareness of IRM requirements. And 87 per cent of the corn producers surveyed said they had no problem with IRM implementation, and urged the coalition to continue its monitoring, communication and education efforts, which it plans to do this year.

Coalition member Art Stirling, Government and Industry Relations Manager, Pioneer Hi-Bred, says the survey illustrates that Canadian corn producers want to do their part to maintain the effectiveness of Bt technology. "The vast majority of farmers are in compliance and don't find it difficult in their operations to do so," he says. Stirling believes producers' cooperation bodes well for the success of other new seed technologies when they come onstream; genetically engineered rootworm-resistant corn is expected next.

Editor’s Note: These results collaborate results of similar studies conducted by the University of Guelph over the previous two years, demonstrating growers’ consistent awareness and compliance with the corn borer resistance management strategies.

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