(Beyond Pesticides, August 31, 2011) Widely grown corn plants that Monsanto Co. genetically modified to thwart a voracious bug are falling prey to that very pest in Iowa cornfields, the first time a major Midwest scourge has developed resistance to a genetically modified crop. The discovery raises concerns that the biotech crops are spawning â€śsuperbugsâ€ť and calls into question EPA’s allowance of so-called plant incorporated protectants (PIPs).
Fields planted in Monsanto’s Bt corn in some areas of the Midwest are showing damage from the corn rootwormâ€”the very species targeted by Monsanto’s engineered trait. Iowa State University entomologist Aaron Gassmann, PhD has discovered that western corn rootworms in four Iowa fields have evolved and can resist the pesticide built into Monsanto’s genetically altered corn seeds. The scientist said the cases were isolated, but he did not know how widespread the problem could become. Farmers in Illinois are also seeing severe rootworm damage in fields planted in Monsanto’s Bt corn. In 2010, Monsanto acknowledged that in industrial-agriculture regions of India, where Monsanto’s Bt cotton is a dominant crop, the cotton-attacking bollworm had developed resistance.
“These are isolated cases, and it isn’t clear how widespread the problem will become,” said Dr. Gassmann in an interview. “But it is an early warning that management practices need to change.”
Monsanto became the first company to sell rootworm-resistant biotech corn to farmers in 2003. The seed contains a gene from the common soil microorganism Bacillus thuringiensis, or Bt, from which crop biotechnology has been used to mine several genes for making insecticidal proteins. One of the genes Monsanto developed makes a crystalline protein called Cry3Bb1. It rips apart the gut of the rootworm but its risk to mammals, birds, and most beneficial insects are uncertain. A study published in the May 2011 edition of the journal Reproductive Toxicology found that pregnant women and their fetuses were contaminated with pesticides and metabolites of the herbicide gluphosinate and the Cry1Ab protein of the insecticide based on Bt. Roughly one-third of the corn grown in the U.S. carries Monsanto’s Cry3Bb1 gene.
According to Dr. Gassmann, the Iowa fields in which he found rootworms resistant to the Cry3Bb1 toxin had been producing Monsanto’s Bt-expressing corn continuously for at least three years. Dr. Gassmann collected rootworm beetles from four Iowa cornfields with plant damage in 2009. Their larvae were then fed corn containing Monsanto’s Cry3Bb1 toxin. They had a survival rate three times that of control larvae that ate the same corn.
Resistance to genetically modified crops is not new. Genetically modified crop known as â€śRoundup readyâ€ť engineered to survive exposure to Monsantoâ€™s Roundup herbicide, a glyphosate-based chemical, has spawned a new generation of Round-up resistance weeds dubbed â€śsuperweeds.â€ť These weeds, immune to Roundup, have spread to millions of acres in more than 20 states in the South and Midwest. In addition to resistant weeds, heavy use of Roundup sprayed on â€śRoundup Readyâ€ť crops appear to be causing harmful changes in soil and potentially hindering yields of crops that farmers are cultivating according to scientists at the USDAâ€™s Agricultural Research Service. Growing previous Roundup Ready crops such as soy, cotton, and corn have also led to greater use of herbicides.
Threat to Organic and Sustainable Agriculture
Until insecticide-producing corn plants arrived, Midwest farmers typically tried to keep pests like the corn borer and the rootworm in check by changing what they grew in a field each year, often rotating between corn and soybeans. That way, the offspring of corn-loving insects would starve the next year. Proponents of genetically engineered crops claim they will reduce pesticide use and increase drought resistance, among other things, but studies have emerged since their widespread adoption in the 1990s that show otherwise. Insect resistance, weed resistance, and cross contamination of other crops have been documented. These impacts threaten the sustainability of agriculture. There has long been a concern that EPA’s allowance of plant incorporated protectants (PIPs) with Bt would lead to the failure of a biological tool used in organic farming systems as an alternative to highly toxic synthetic inputs. Organic farmers have expressed concern since the introduction of PIPs in 2003 that the overuse of Bt, which is inevitable when Bt is genetically engineered into every cell of a plant, will lead to insect resistance and leave many farmers without an important tool of organic agriculture. For more on genetically modified agriculture read Beyond Pesticidesâ€™ article â€śReady or Not, Genetically Engineered Crops Explode on Market.â€ś
Unfortunately, these new findings add fuel to the race among crop biotechnology rivals to locate the next generation of genes that can protect plants from insects. Scientists at Monsanto and Syngenta AG of Basel, Switzerland are already researching how to use a medical breakthrough called RNA interference to, among other things, make crops deadly for insects to eat. These insect-proof and herbicide-resistant crops have been sold as a silver bullet approach to pest management, increasing grower reliance on the technology and violating a basic tenet of pest prevention and management, which stresses the need for the nurturing of a diverse biological system instead of using single product-oriented approaches year after year that allow pests the opportunity to adapt and develop resistance.
The one sure-fire way you can avoid the genetically modified food is to buy organic or know where your food comes from. Genetically modified crops are not permitted in organic food production. Researchers are continuing to discover the environmental and health benefits of eating and growing organic food. For more information about why organic is the right choice see our Organic Food: Eating with a Conscience guide.
Source: Wall Street Journal