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Home , Plant breeding, Recombinant DNA

Genetically Engineered for Management in U.S.

Farm-Level Effects

Jorge Fernandez-Cornejo William D. McBride

Introduction

Use of crops genetically engineered with traits for pest applications, and may be more benign than management has risen dramatically since their com- required for crops without the -tolerant . mercial introduction in the mid-1990’s. Compared t Farmers using Bt crops can reduce costs with traditional selection and breeding methods, by discontinuing or decreasing applications of chemi- reduces the time to identify desir- cal targeting certain susceptible to able traits and allows a more precise alteration of a Bt such as European corn borer and the boll- plant’s traits. Seed developers are able to target a sin- worm. However, Bt crops may still require farmers to gle plant trait without the unintended characteristics use insecticides to treat other pests. Farmers planting that may occur with traditional breeding methods. The Bt crops benefit from decreased dependence on weath- most widely used pest management traits are herbicide er conditions affecting the timing and effectiveness of tolerance and resistance. Crops having herbi- insecticide applications because the Bt toxin remains cide-tolerant traits permit farmers to use herbicides active in the plant throughout the year. These that offer more effective . Insect-resistant improvements reduce losses to pests, leading to higher crops containing a derived from the soil bacteri- yields. um (Bt) produce their own toxin to protect the entire plant from certain insects. (See Despite the promise of benefits, environmental and box, “Agricultural ,” for definitions of consumer concerns may temper acceptance of agricul- terms.) tural biotechnology in the and globally (see box, “Environmental and Other Concerns”). Seed companies and claim that herbicide-tol- Moreover, although farmers may experience decreased erant and insect-resistant crops offer more effective costs and higher gross revenues from herbi- options for controlling pests, reduce chemical pesticide cide-tolerant and insect-resistant crops, there is a cost. use with consequent savings in pesticide costs, and Genetically engineered seed costs more than traditional increase crop yields. Some of the arguments put forth seed, and, in addition, farmers are usually charged a in support of these technologies are: fee to cover the development of the technology (tech- t Herbicide-tolerant genes allow crops to resist effec- nology fee). A threshold infestation level is thus tive herbicides that previously would have destroyed required for farmers to obtain economic benefits from the crop along with the targeted weeds. Although adopting herbicide-tolerant and insect-resistant crops. farmers using herbicide-tolerant crops continue to use The expected benefits from adopting these varieties chemical herbicides, these herbicides may be used at greatly depend on infestation levels, since the associat- lower application rates, require a smaller number of ed pesticide use and yield advantages of the new vari-

Economic Service/USDA Genetically Engineered Crops for Pest Management / AER-786 1 Agricultural Biotechnology: Basic Concepts and Definitions

“For thousands of years, genes have been manipulated Bt corn is genetically engineered to provide protection empirically by plant and animal who monitor against the European corn borer. their effects on specific characteristics or traits of the is the smallest structural unit of living organisms organism to improve productivity, quality, or perfor- that is able to grow and reproduce independently mance. A basic understanding of how traits are trans- (ABA). mitted was formed by in the 19th cen- tury. His experiments and concepts showed that traits Genetic engineering, very broadly, is a technique used were controlled by units of heredity called genes. to alter or move genetic material (genes) of living Extensions of his work led to the formation of applied cells. Narrower definitions are used by agencies that and breeding programs. The physical and regulate genetically engineered organisms. In the chemical of genes remained unknown until the United States, under guidelines issued by USDA’s 1950s when James Watson and Francis Crick discov- Animal and Plant Health Inspection Service, genetic ered that genes consists of a chemical known as DNA engineering is defined as “the genetic modification of (Deoxyribonucleic acid). DNA contains the informa- organisms by recombinant DNA techniques” tion to control the synthesis of and other pro- (7CFR340: 340.1), while definitions used in Europe teins that perform the basic metabolic processes of all are somewhat broader. cells. Each gene is a specific DNA sequence, and more than 100,000 different genes are found in a high- Gene stacking involves combining traits (e.g. herbi- er plant or animal . This total set of genes for cide tolerance and insect resistance) in seed. an organism (referred to as the nuclear ) is Herbicide-tolerant crops were developed to survive organized into within the cell nucleus. certain herbicides that previously would have The process by which a multicellular organism devel- destroyed the crop along with the targeted weeds. ops from a single cell through an stage into an With herbicide-tolerant crops farmers can use potent adult is ultimately controlled in the genetic informa- postemergent herbicides, providing a more effective tion of the cell and by interaction of genes and gene weed control than otherwise. The most common her- products with environmental factors” (Vodkin). bicide-tolerant crops (cotton, corn, soybeans, and Agricultural biotechnology is a collection of scientific canola) are Roundup Ready (RR) crops resistant to techniques, including genetic engineering, that are , a herbicide effective on many species of used to create, improve, or modify , animals, and grasses, broadleaf weeds, and sedges. Other genetical- microorganisms. Using conventional techniques, such ly engineered herbicide-tolerant crops include Liberty as , scientists have been working to Link (LL) corn resistant to glufosinate-ammonium, improve plants and animals for benefit for hun- and BXN cotton resistant to bromoxynil. There are dreds of years. Modern techniques now enable scien- also traditionally bred herbicide-tolerant crops, such as tists to move genes (and therefore desirable traits) in corn resistant to imidazolinone (IMI) and sethoxydim ways they could not before—and with greater ease and (SR), and soybeans resistant to sulfonylurea (STS). precision (USDA, 1999). Plant breeding involves crossing plants to produce Bt crops are genetically engineered to carry the gene varieties with particular characteristics (traits) that are from the soil bacterium Bacillus thuringiensis. The carried in the genes of the plants and passed on to produce a that is toxic when ingested future generations. by certain Lepidopteran insects. Crops containing the Transgenic plants result from the of genetic Bt gene are able to produce this toxin, thereby provid- material from another organism so that the plant will ing protection throughout the entire plant. exhibit a desired trait. Recombinant DNA techniques is genetically engineered to control (DNA formed by combining segments of DNA from budworms, bollworms, and pink bollworms. different organisms) are usually used to develop trans- genic plants.

2 Genetically Engineered Crops for Pest Management / AER-786 Economic Research Service/USDA eties vary with those levels. Therefore, farmers in pest management. Next the report presents survey regions that have a higher probability of pest infesta- information obtained from USDA’s Agricultural tions would expect greater benefits in the form of Resource Management Study (ARMS) about the extent reduced pesticide applications and higher yields. of adoption of genetically engineered cotton, corn, and soybeans (by type of technology, crop, and region). This report first establishes a context for interpreting The report then presents the results of an econometric the results by presenting information about pest man- analysis on the farm-level effects of adopting Bt cotton agement on major field crops in U.S. agriculture and and herbicide-tolerant soybeans and cotton on pesti- then summarizes previously reported studies of the cide use, crop yields, and net returns. effects on pesticide use, crop yields, and producer returns from using genetically engineered crops for

Environmental and Other Concerns

Although there are environmental benefits from using enough susceptible moths survive to mate with resis- crops with herbicide-tolerant or insect-resistant traits, tant ones (Cotton Insect Control Guide, 1997). there are some concerns about extensive use of these More recent concerns are related to popular press crops. One concern is that herbicide-tolerant crops commentaries of a letter published in the May 20 would foster farmers’ reliance on herbicides. issue of Nature (Losey et al., 1999) reporting results However, these crops may require lower application of tests showing that corn of Bt rates or fewer herbicide applications. And, in many corn killed the monarch butterfly larvae and recom- cases, these crops allow farmers to use more benign mending a comparison of “these risks with those of herbicides instead of more harmful ones and allow other pest-control tactics.” However, several scien- farmers to use them as postemergent herbicides. For tists noted that the popular press missed the subtleties example, glyphosate is considered to be environmen- of the research, and the lead author of the study tally benign (Culpepper and York, 1998; Roberts et recently declared that “it would be inappropriate to al., 1998). There could also be risks to nontarget draw any conclusions about the risk to monarch pop- insect species if Bt crops deplete of prey ulations in the field based solely on these initial species, but this is also a problem with many tradi- results” (Wipf). tional pest management systems. There are also concerns, especially in Europe, that Another concern is that extensive use of these crops with transplanted genes may cause allergic could lead to the development of insect and weed reactions. A gene from a nut inserted into another resistance. Since genetically engineered crops inter- type of , for example, might trigger allergic reac- act with the environment, concerns have been raised tions in susceptible consumers (Panos). And some about risks associated with their release. One poten- critics doubt that the body digests and assimilates tial risk is that herbicide-tolerant crops may pass their biotechnology-derived foods in the same way as tra- genes to weedy relatives, thereby making those ditional foods. But the Food and Drug weeds resistant to herbicides (Rissler and Mellon). Administration (FDA) ensures that genetically engi- Another risk is that Bt crops would promote insect neered foods reaching the marketplace are “substan- resistance to Bt. Resistant insects could make crops tially equivalent” to current foods and pose no addi- more vulnerable. This problem exists with chemical tional risk. The FDA would require a label for genet- as well, but Bt genetically engineered into ically engineered foods only if there were known a plant will persist in the environment longer than risks, as with traditionally grown foods. foliar Bt, thus shortening the time for targeted insect In addition, some believe genetic engineering inter- pests to become resistant to foliar Bt. Some agricul- feres with “nature” and “creation.” Scientists argue, tural producers, such as organic growers, rely on Bt however, that all plants are genetically modified for insect control, and, if insects become resistant, (“that is what evolution means”) either by natural these growers could lose the option of using these selection from random mutations and recombinations, products. However, the Environmental Protection by domestic breeding, or more recently by “engi- Agency (EPA) requires resistance management plans neered mutation or recombination” (Panos). to control insect resistance to Bt to ensure that

Economic Research Service/USDA Genetically Engineered Crops for Pest Management / AER-786 3