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University of Virginia: GMOs destroy US ecology

The wide spread of genetically modified (GM) crops reduces the use of insecticides, but increases herbicide use, while increasing weed resistance to these chemicals, causing serious damage to the environment.

The economist Federico Siliberto headed the largest study of GM crops and the use of pesticides, which was attended by Edward Perry from the University of Kansas, David Hennessy from the University of Michigan and Jean Carlo Moschini from the University of Iowa. These four economists studied the annual data of more than 5000 soybean farmers and 5,000 corn farmers in the United States from 1998 to 2011, surpassing the scale of previous studies, which were limited to 1-2 years."

"The fact that we have processed farm data from all the states for 14 years makes this study quite exceptional," Siliberto said, "We have repeated studies of the same farmers, and can understand when they started buying GM seeds and how it affected their use of chemicals." Since 2008, GM crops make up more than 80% of the corn and soybeans grown in the United States. The two genes are introduced into the maize seeds: one kills insects, and both genes enhance resistance to glyphosate – the herbicide used in the production of GMO. The soy is embedded with only one gene that enhances resistance to glyphosate.

Not surprisingly, the corn farmers, who have used insect-resistant seeds, used much less insecticides (approximately 11.2% less) than the farmers who did not use genetically modified maize seeds. Corn farmers also used 1.3% less herbicide for a 13-year period. On the other hand, in the manufacture of soybean the use of herbicides has increased significantly: among GM farmers this usage is of 28% more than in non-GM. Siliberto believes that the reason for this is the proliferation of glyphosate-resistant weeds.

Experts and other studies suggest that the use of pesticides in the production of GM crops has increased significantly during the 1998-2011 period, the data for which were analyzed in the new study of the University of Virginia. In 2011-2016 glyphosate-resistant weeds have become a major economic problem of US farmers because of the growth of the use of chemicals and increasing spending on their purchase.

"At the beginning the herbicides use was being reduced, but after a while the farmers have started buying more chemicals, because the weeds have become resistant to herbicides," Siliberto said. According to him, the corn farmers haven't face the same level of sustainability, partly because they switched to GM crops not as quickly as compared to their peers who grow soybeans. However, this research has proved that corn and soybean farmers for the last five years have been using more of herbicides, which shows a growing problem for all farmers.

From 2006 to 2011 the percentage of area treated with glyphosate alone, was reduced from 70% to 41% for soybeans and from 40% to 19% for maize. This reduction is due to the need to combine glyphosate with other chemicals due to increased spread of glyphosate-resistant weeds. "The data show that weeds become more resistant, and farmers are forced to apply additional chemicals, increasing their number," said Siliberto.

Insects do not seem to have developed a similar stability, partly because federal regulations require farmers to organize in their fields ‘security zone’, where GM crops are not planted. Insects and worms in these areas do not develop resistance to chemicals, and, crossing the insect from the contaminated areas, it helps to slow the development of resistant genes. Despite the decline in the use of insecticides, herbicides growth is a serious problem for the environment, since large doses of chemicals are harmful to biodiversity and increase pollution of water and air.

Siliberto and his colleagues measured the overall environmental impact of changes in the use of chemicals which have resulted from the spread of GMOs, employing “factor of environmental impact” to determine the impact of chemicals on farm workers, consumers and the nature. Comparing the GMO producers and producer of environmentally friendly crops, they found only small differences in the impact on farmers and consumers. However, the spread of GM soy is associated with more negative consequences for the environment due to increased use of herbicides and pollution of local ecosystems.

Further research of “factor of environmental impact” is now carried out by independent scientists in the US and Europe with more accurate “pesticide risk tool.” In general, Siliberto said that he is surprised with the degree of increase in the use of herbicides and the influence of this on the environment. "I did not expect to see such a serious picture," he said.

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  • October 11, 2016 5:09 PM MSK