CHESTERVILLE —Canada’s state-of-the-art corn producers can look forward to cultivating their personal libraries with the second edition of A Grower’s Handbook, Controlling Insect Pests with Bt Technology.
Released last month by The Canadian Corn Pest Coalition (CCPC), the 21-page colour handbook is available from seed suppliers and the CCPC web site at www.cornpest.ca. It lays out the techniques for complying with federal on-farm insect resistance management (IRM) regulations that growers must follow in the hope of preventing future insect resistance to genetically modified Bt corn varieties.
As a working group comprised of government, seed industry, research and producer representatives, the CCPC was consulted by the Canadian Food Inspection Agency in drawing up the special regulations that have been in place since the general debut of Bt corn in the Canadian marketplace in the late 1990s.
That development coincided with the release of the handbook’s first edition in 1999, according to CCPC co-chair Dr. Mark Sears, who says the latest update reflects the availability of new Bt hybrids aimed at Corn Rootworm (CRW). The more established varieties target European Corn Borer (ECB). All are considered Bt corn, fortified with genes from Bacillus thuringiensis, a common soil bacteria, which causes tissues in the corn plant to create crystal proteins fatal to the larvae of the bugs in question but non-toxic to invertebrates, including humans.
But just as insects have proven their ability to develop resistance to conventional insecticides, the industry and the scientific community are concerned they could eventually adapt to Bt corn, too. But Sears, an entomologist and professor in the Department of Environmental said that, so far, there is no documented evidence of insect resistance developing against Bt corn in North America. The CCPC wants to keep it that way for at least another 15 to 20 years, he said.
"Each member of the CCPC is committed to setting up and managing new pest management technologies for corn in order to extend their effectiveness. Our main focus is encouraging farmers to adopt pro-active stewardship of Bt corn technology for ECB and CRW control."
He told the AgriNews, "The long-term vision of all of this is we would like these products to last a while ... We’ve developed methodologies that are easily practiced by growers. We’re not asking them to go to the moon."
A key requirement involves the 20-percent rule: Each farmer’s total acreage of corn must comprise a "refuge" of at least 20-percent non-Bt corn. The idea is that susceptible bugs will continue to grow into adulthood within the refuge, staying in the breeding pool and making it harder for resistance to emerge.
There’s a number of techniques, spelled out in the handbook, for laying out refuge plots, and information related to other regulatory details.
Sears admitted that no one really knows how quickly resistance might emerge if the 20-percent rule, which applies to growers everywhere in North America, were simply eliminated. "You’d be playing with fire," he suggested.
While there are no "corn police," seed companies are supposed to enforce the rules by refusing to sell farmers more Bt corn than they can legally plant, he said.
According to a 2003 study conducted by the CCPC, more than 80 percent of Canada’s growers comply with CFIA requirements and implement sound IRM strategies on their farms.
Bt corn comprises 35 percent of all corn grown in Canada. The new varieties aimed at Corn Rootworm are considered to have more limited application in Canada, where European Corn Borer is considered a bigger problem. "Stacked" varieties lethal to both ECB and CRW are currently available in the U.S., but not yet in this country, Sears said.