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GENETICALLY MODIFIED (GM) CROPS.
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Discusses the importance of GM crops to worldwide farming.... More...
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Paper Abstract:
Discusses the importance of GM crops to worldwide farming. Division among people regarding use of GM plants. Benefits vs. ecological disasters. Safety issue. Review of recent studies on use of GM plants in the farm setting. Goal of GM crops toreduce need for pesticides. Harm to beneficial organisms.

Paper Introduction:
Introduction: According to an article in Scientific America, genetically Modified (GM) crops are becoming an important part of worldwide farming with approximately 109 million acres under cultivation (Brown, 2001). However, most of the farmland is in the US (68%) and Argentina (23%), and the most common GM crops are soybean (36%), corn (7%), cotton (16%), and canola (11%). GM varieties are a major proportion of the total production of soybeans (58%) and corn (23%)(James, 2000). The development and use of GM plants has divided people into 2 groups. One group believes GM plants offer benefits for both increased production of food and fiber, and decreased use of pesticides and herbicides. The opposing group believes GM plants will cause ecological disaster by inadvertently killing

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The opponents to GM say the refugees are too small orpoorly designed to offer protection from forming resistance (Brown, 2 1).Scientific Speculations: The author of this review article refrained from speculation and usedevidence from scientific studies to show if there was data to support thevarying claims by supporters of both sides of the issue. Researchers are now attempting field studies to repeat the Bt pollenexperiment under more typical farming conditions. Dr. Allison Power, from Cornell, has shown that gene flow from virus-resistant GM plants offers some reason for concern. However, there areanecdotal reports from Canada of GM canola escaping from fields, invadingnearby wheat fields, and acting like "weeds" (Brown, 2 1). A fewstudies from the US Department of Agriculture indicate the major benefit ofherbicide-tolerate GM crops is the use of more benign, general-purposeherbicides. These experiments, however, were conducted in the laboratory ratherthan a natural setting. Introduction: According to an article in Scientific America, genetically Modified(GM) crops are becoming an important part of worldwide farming withapproximately 1 9 million acres under cultivation (Brown, 2 1). However,measuring environmental harm of GM crops is even more difficult thanmeasuring possible benefits.Harm to Beneficial Organisms The most alarming claim about GM plants was the allegation that Btpollen could kill beneficial non-target insects. Thesefindings have led some scientists at the EPA to conclude that the evidencesuggests that Bt corn pose no harm to monarch larvae. However, Bt modifiedcorn and potato crops do not show this large reduction because they needfewer sprayings than cotton (non-GM cotton require 7-14 sprayings pergrowing season) and the pests fluctuate in number from year to year (brown,2 1). A 1998 Swiss study ofgreen lacewing caterpillars showed they were more likely to die aftereating European corn-borer caterpillars that had eaten Bt corn rather thannormal corn, and Dr. John Losey at Cornell found that Monarch butterflylarvae would die if fed milkweed (their primary food source) dusted with Btcorn pollen (Brown, 2 1). The author estimates the current annual USuse of pesticides at 971 million pounds. Do GM crops pose a threat of introducing new genes into closely related weed species?, and . Theopposing group believes GM plants will cause ecological disaster byinadvertently killing beneficial organisms and producing "superweeds"(Brown, 2 1). For example, soybean growers can use glyphosate herbicides,which are less toxic and have faster degradation after use (Brown, 2 1). This could have thepotential of causing wild oats to out compete the wild grasses (Brown,2 1). The author wastrying to stop the usual speculation that accompanies stories about GMcrops and only presented scientifically supported data.Values and Opinions: The value of this article is very high due to its rigid compliance tothe rules of science that something is only "known" once there isscientific data to support it. For example, wild cotton occurs throughout Mexico, andwild corn occurs in South America (Brown, 2 1).Possibility of Crop Failure An expected result of GM crops is the pressure on pest species toevolve and overcome this protection. These refuges will cause any insects that have acquired resistanceto dilute their genes by mating with non-resistant individuals (Brown,2 1). This gene makes a crystallineprotein toxic to some insects (e.g., caterpillars and beetles), butharmless to others. To negate this biological pressure,GM companies suggest that farmers set aside areas of field and grow non-GMcrops. Research is needed to assess this important factorsince the environmental benefits will probably vary depending on the GMplant grown and location (Brown, 2 1). Much of the debate rests on the perception of safety and both groupsfeel strongly in their opinions; however, to date there have been fewscientific studies to test the ecological impacts or benefits, if any, ofthese plants. Insect-resistant GM crops are produced by inserting a gene from thesoil bacterium Bacillus thuringiensis (Bt). A 1 -year study by Crawley et. al (2 1) found no evidence of superweeds beingproduced by GM potatoes, beets, corn or canola. Bt modified cotton has allowed the greatest drop in pesticide use.According to the US Environmental Protection Agency (EPA), during 1999,growers of Bt cotton sprayed 21% less insecticide. This article discusses the important issues of this debateand presents a review of the results from recent studies on the use of GMplants in the farm setting (Brown, 2 1).Facts: The author's methodology in presenting the evidence for this reviewis to pose four basic questions: . Monsanto reports that about 9 % of the farmers abide by the refugerequirements, and after 5 years, there have been no occurrences of Btresistant insects. The author never gave opinions as to herfeelings for either side of the issue and presented a balanced report ofthe current data. Therefore, theEPA has ordered seed companies not to sell GM cottonseed in these tworegions (Brown, 2 1). The opponents of GM crops assert that there are actuallyenvironmental harms, rather than benefits, from these crops. The debate is over the resultingconsequences of gene transfer (Brown, 2 1). GM varieties are a major proportion of the total production ofsoybeans (58%) and corn (23%)(James, 2 ). The important question, therefore, is how much Bt toxin is harmful tonon-target insects. References Brown, Kathryn, 2 1, Seeds of Concern, Scientific American, 284(4),52-57. (Brown, 2 1) The author then attempts to answer each question using "peer-reviewed"articles or results from reputable researchers in the various scientificfields.Pesticide Use Herbicide and insecticide residue on food crops is a very importantissue for consumers and a reduction in the amount or strength of thesechemicals would be beneficial. Preliminary results fromthe studies indicate that the two most common Bt corn (Novartis andMonsanto) plants do expose butterfly larvae to Bt pollen but the exposureis too low to be toxic (Brown, 2 1). Crawley, et al., 2 1, Transgenic Crops in Natural Habitats, Nature,4 9, 682-683. In the U.S., the dire results of Bt or virus resistant GM crops donot appear to be an issue since no close relatives exist in the regionswhere they are cultivated. Although, the environmental benefits of GM crops may be indirect,farmers see a direct benefit by reducing the frequency and complexity ofpesticide spraying, and also sometimes increasing crop yield. Do GM crops pose a threat of sudden crop failure due to pests and weeds evolving immunity? Do GM crops cause the inadvertent death of beneficial organisms?, . 21. GM plants can be separated into twobroad categories: herbicide resistant (74% of GM plants) and insectresistant (19% of GM plants) (James, 2 ). James, Clive, 2 , Global Status Of Commercialized Transgenic Crops:2 , ISAAA Briefs No. Do GM crops allow the use of smaller amounts or less harmful herbicides and pesticides?, . This does not givethe opponents of GM food any assurance and they still claim that not enoughevidence is known to make a definitive statement as to the harm to non-target animals (Brown, 2 1).Potential of Producing Superweed Another concern is the potential flow of genes by cross-pollinationbetween GM plants and wild "weedy" relatives, which would produce"superweeds" free from pests and herbicides. One group believes GM plants offer benefits for both increased productionof food and fiber, and decreased use of pesticides and herbicides. Outside the US, it is not as easy to separate the GM crops from theirweedy relatives. The development and use of GM plants has divided people into 2 groups. The primary goal of GM crops isto reduce the need for pesticides. Scientists alreadyacknowledge that this will occur. Losey's laboratory experiments had the larvaeeating more Bt pollen than would be found in the wild. However,most of the farmland is in the US (68%) and Argentina (23%), and the mostcommon GM crops are soybean (36%), corn (7%), cotton (16%), and canola(11%). The only exception is wild cotton that grows insouthern Florida and Hawaii, which is similar to GM cotton. Assessing the environmentalbenefits of using GM crops is difficult due to a lack of peer-reviewedstudies on this issue. The US EPA estimates that no observable harm can bedetected at consumption levels of 15 pollen grains/cm2 of leaf surface.Measurement of milkweed plants grown near Bt corn in Maryland, Nebraska andOntario found levels of Bt pollen ranging from 6 to 78 pollen/cm2. Power's laboratorywork has shown that wild oats, a close relative of cultivated oats, canobtain resistance to the barley yellow dwarf virus. To date there is no evidence of GM crops producing superweeds.

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