Superweeds and Superpests

The use of genetically modified crops was intended to reduce the need for herbicides to control weeds and insecticides to control pest insects. However, The New York Times reports that instead herbicide use increased over 16 years, while insecticide use decreased somewhat. The widespread use of a single herbicide glyphosate, sold under Monsanto’s brand name Roundup, has resulted in the evolution of a number of glyphosate-resistant weeds. The Times piece, http://green.blogs.nytimes.com/2012/10/05/the-legacy-of-pesticides-superweeds-and-superpests/?src=rechp, describes different approaches to the use of these genetically modified organisms. “Roundup Ready” corn, soybeans, and cotton seeds were planted on 1.37 billion acres from 1996 to 2011. The GMO plants, tolerant of the herbicide glyphosate, were supposed to reduce or eliminate the need to till fields and reduce the need for harsher chemicals. The use of these GMOs was supposed to also save money and be less stressful on the environment. As glyphosate-resistant weeds increased, increases in the use of glyphosate slowed; and in 2010 the National Research Council warned that, “Eventually, repeated use will render glyphosate ineffective.”

Those deploying the genetically modified seed containing the Bt gene producing toxins from the soil bacterium Bacillus thuringiensis recognized the potential for evolving resistant insects, and they took precautions. They required that a percentage of non-Bt seed be planted with Bt crops to ensure that some insects susceptible to the Bt toxin survive to mate with survivors of the Bt crops. Otherwise, surviving pest insect populations could become increasingly resistant to the Bt toxin with each generation. The mechanism for ecological harm from chemical pesticides was described by Rachel Carson in Silent Spring 50 years ago: “First, many of these chemicals are indiscriminate, killing not only pest but also the predators and parasites that help to keep them at bay. Second, surviving pest populations become increasingly resistant to the applied toxins with each generation, as those most susceptible to the toxins die off. It’s natural selection in overdrive.” Today’s photo: applying herbicide to control grasses in GMO soybeans.

--Richard

GMO Safety Questioned

I recently spoke with knowledgeable individuals from Europe, Africa, and Asia about their concerns with genetically modified crops grown in the United States. I explained that GMOs, genetically modified organisms, have been in use for nearly two decades, and we have been assured they are safe. Genetic modification involves inserting genetic material from one species into another to produce new properties. Current GMO technology has two purposes: pesticide production and herbicide resistance.  The first technology, “Bt,” inserts genetic material from Bacillus thuringiensis bacterium into plants to produce bacterial toxins to kill insects. The second technology involves creating “Roundup-Ready” crops resistant to the herbicide glyphosate, the active ingredient in the broadleaf week killer Roundup.

An article published in Mother Earth News, “The Threats from Genetically Modified Foods,” http://www.motherearthnews.com/sustainable-farming/genetically-modified-foods-zm0z12amzmat.aspx, points to possible health risks. Though we have been told by the makers of GMO seed and glyphosate of their safety, the article strongly questions this. It explains that the manufacturers make it nearly impossible for independent scientists to study genetically modified seeds. Researchers point to possible risks to human health with Bt crops causing damage to the small intestines and glyphosate causing malformations in animals. Also, glyphosate causes damage to wetlands through run-off, and causes soil damage. Researchers state that glyphosate “can significantly increase the severity of various plant diseases, impair plant defense to pathogens and disease, and immobilize soil and plant nutrients, rendering them unavailable for plant use.” These researchers also warn that glyphosate “may have dire consequences for agriculture such as rendering soils infertile, crops nonproductive and plants less nutritious.” Glyphosate herbicide can lead to disease and toxins in plants including toxin levels in straw high enough to make cattle and pigs infertile. In another GMO technology, “rBST,” genetically modified cattle growth hormone is injected into dairy cattle to increase milk production, resulting in high levels of a milk protein that increases the risk of breast, colon, and prostate cancer. Surely, GMO crops deserve independent scientific investigation. Photo: GMO Corn.

--Richard

Are GMOs Safe?

The recently reported study of a significant Indiana honey bee kill that was traced to the insecticide clothianidin drew questions about the crops involved. The study followed the flow of a systemic insecticide, coated onto corn seed, from crops and the surrounding soil to the bees and their hives. The study by Krupke et al. is published in the Public Library of Science at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029268. Several readers questioned the safety of the treated crop, genetically modified, or GMO, corn. A large percentage of grain and food crops grown in the United States involve plants known as genetically modified organisms, crops that have been modified to have desirable traits either by altering the plant’s genes or by introducing genetic material from other organisms. Most crop GMOs accomplish two purposes: The first is to provide resistance in the crop plants to herbicides used to control competing weeds and grasses, and the second is to allow the crop plants to control insect pests. Genetically modified crops are tested for safety to beneficial insects, like honey bees, and for livestock and humans that consume the crops. While testing and observation continue, genetically modified crops appear to be safe. GMO grains have a history of safe use over a number of years. Researchers find no connection between GMO crops and honey bee Colony Collapse Disorder.

GMO crops also offer a number of advantages for modern agriculture. Crops resistant to specific herbicides, like glyphosate, can be grown weed-free by spraying the entire field. Weeds are killed, but the crop is not damaged. Glyphosate-resistant crops are often known as “Roundup Ready.” The use of genetically modified crops can reduce the need for mechanical cultivation, saving labor, fuel, and soil moisture by employing no-till practices. Also, GMO crop plantings often reduce the need for insecticides such as clothianidin. In today’s photo greater white-fronted geese, “specklebellies,” wintering in the Arkansas Delta, forage in a harvested soybean field. The Delta is seeing increased numbers of migratory waterfowl.

--Richard