US EPA warns GM maize could be losing its edge
Sep. 12, 2012
Following on from its Memo in November last year, when the United States Environmental Protection Agency announced that it had confirmed root worm – a common pest in the US maize belt – had developed resistance to genetically modified crops, the agency last month suggested the GM seed could be losing its effectiveness in the face of emerging resistance.
In the United States, cultivation of GM seeds is widespread, with many engineered to produce a toxin, Cry3bB1, (which comes from Bacillus thuringiensis, a soil-dwelling bacteria, known as Bt) to kill insect pests. However, in addition to concerns about health and environmental effects of widespread cultivation of Bt crops, insect resistance is now becoming a hot topic.
The EPA suggested on 31st August that “There is mounting evidence raising concerns that insect resistance is developing in parts of the corn belt,” after a study by researchers at the University of Illinois uncovered evidence of resistant root worms on two farms. In August, University of Illinois entomologist Mike Gray announced that rootworms collected last year in fields in North-Western Illinois had been shown to be resistant to the Cry3Bb1 protein.
He said reports of resistance had been made as early as 2009, when, following increased rootworm damage in Iowa, Iowa State University entomologist Aaron Gassmann confirmed the presence of resistant pests.
In November 2011, heightened root worm activity across four US states led the EPA to suggest that Bt maize may be losing its effectiveness and that resistance may have developed in these areas. Since that time others have also claimed resistant rootworms are causing problems in the Midwest. The EPA said last winter that Monsanto’s efforts to monitor for resistance had been “inadequate.”
Monsanto responded that the study’s findings did not confirm resistance in the field. The company maintains that resistance needs to be proven by further studies, but said it was working with the EPA to address the situation.
However, Professor Bruce Potter, a pest management specialist at the University of Minnesota, said the problem is an inherent flaw in the current approach to pest management. He stated, "We're not going to make this go away. We're stuck with managing this problem. Instead of making things easier, we've just made corn rootworm management harder and a heck of a lot more expensive."
Resistance: Inherent flaw or comeuppance for irresponsible greed?
Farmers who grow Bt maize are supposed to plant a ‘refuge’ of non-resistant maize to prevent resistance from developing. The ‘refuge’ works by ensuring resistance is bred out of root worms when those who have been exposed to the toxins mate with worms which have not from the conventional variety.
However, it would appear that, driven by an eagerness to capitalise on high prices, some farmers have not grown refuges or have avoided rotating crops, another method said to hamper the development of resistance.
University of Illinois’ Mike gray said, “In every case where we’ve had Bt Cry3Bb1 fail, the growers had been in continuous corn [maize] for a long time, six, seven, eight years in a row. They had utilized that same trait every year. That’s a recipe for a problem.” He advised farmers to, “Consider a long-term integrated approach. Mix it up. Manage the population. Don’t rely on the same technology over and over.”
Missouri-based agribusiness Monsanto is facing pressure in other areas of its GM empire; its patented seeds which have been engineered to resist applications of herbicide glyphosate , sold by Monsanto as Round-Up, are also being blighted by herbicide tolerant weeds. Resistant weeds are now thought to affect over 20 million acres across the US.
Studies have shown that herbicide tolerant crops have led to significant increases in the use of damaging herbicides since they were made commercially available in the nineties.
Maize prices rose to record levels this year on the back of the United States’ worst drought in over fifty years, which has affected yields in the US’s maize growing regions. Globally, the country is the largest exporter of maize.
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