-Caveat Lector- Library: The environmental risks of transgenic crops: an agroecological assessment Miguel A. Altieri Department of Environmental Science, Policy and Management, Division of Insect Biology, University of California, 201 Wellman-3112, Berkeley, CA 94720-3112, USA. Fax: (1) 510-642-7428; email [EMAIL PROTECTED] http://nature.berkeley.edu/~agroeco3 Abstract The potential risks associated with transgenic crops (especially herbicide- and insect-resistant crops) are highlighted by focusing on unexpected results following transgenic releases. These potential impacts are evaluated in the context of agroecological goals aimed at making agriculture more socially just, economically viable and ecologically sound. It is concluded that the environmental risks are serious and underplayed by the biotechnology industry. It is argued that public funding of research on transgenic crops that enhance agrochemical use and that pose environmental risks; should be ended and that ecological sustainability, alternative low-input technologies, the needs of small farmers and human health and nutrition should be pursued with greater vigour than biotechnology. Introduction Genetic engineering is an application of biotechnology involving the manipulation of DNA and the transfer of gene components between species in order to encourage replication of desired traits (OTA, 1992). Although there are many applications of genetic engineering in agriculture, the current focus of biotechnology is on developing herbicide-tolerant crops and on pest- and disease-resistant crops. Transnational corporations such as Monsanto, DuPont, Novartis, etc. which are the main proponents of biotechnology, view transgenic crops as a way to reduce dependence on inputs such as pesticides and fertilizers. What is ironic is the fact that the biorevolution is being brought forward by the same interests that promoted the first wave of agrochemically-based agriculture, but this time, by equipping each crop with new "insecticidal genes," they are promising the world safer pesticides, reduction of chemically intensive farming and a more sustainable agriculture. As long as transgenic crops follow closely the pesticide paradigm, such biotechnological products will do nothing but reinforce the pesticide treadmill in agroecosystems, thus legitimizing the concerns that many scientists have expressed regarding the possible environmental risks of genetically engineered organisms. The most serious ecological risks posed by the commercial-scale use of transgenic crops are ( Krimsky and Wrubel, 1996; Rissler and Mellon, 1996): that the spread of transgenic crops might threaten crop genetic diversity by simplifying cropping systems and promoting genetic erosion; the potential transfer of genes from herbicide-resistant crops (HRCs) to wild or semi-domesticated relatives thus creating "superweeds"; that HRC volunteers become weeds in subsequent crops; vector-mediated horizontal gene transfer and recombination to create new pathogenic bacteria; vector recombination to generate new virulent strains of virus, especially in transgenic plants engineered for viral resistance with viral genes; insect pests quickly developing resistance to crops with Bt (Bacillus thuringiensis) toxin; massive use of Bt toxin in crops unleashing potential negative interactions affecting ecological processes and non-target organisms. The above impacts of agricultural biotechnology are herein evaluated in the context of agroecological goals aimed at making agriculture more socially just, economically viable and ecologically sound (Altieri, 1996). Such evaluation is timely, given that world-wide, there have been over 1500 approvals for field testing transgenic crops (the private sector has accounted for 87% of all field tests since 1987), despite the fact that in most countries stringent procedures are not in place to deal with environmental problems that may develop when engineered plants are released into the environment (Hruska and Lara Pav�n, 1997). A main concern is that international pressures to gain markets and profits is resulting in companies releasing transgenic crops too fast, without proper consideration for the long-term impacts on people or the ecosystem (Mander and Goldsmith, 1996). Actors and research directions Most innovations in agricultural biotechnology are profit driven rather than need driven, therefore the thrust of the genetic engineering industry is not really to solve agricultural problems, but to create profitability. This statement is supported by the fact that at least 27 corporations have initiated herbicide-tolerant plant research, including the world's eight largest pesticide companies Bayer, Novartis, Zeneca, Rh�ne-Poulenc, Dow/Elanco, Monsanto, Hoescht and DuPont, and virtually all seed companies, many of which have been acquired by chemical companies (Gresshoft, 1996). In the industrialized countries from 1986-1992, 57% of all field trials to test transgenic crops involved herbicide tolerance and 46% of applicants to the USDA for field testing were chemical companies. Crops currently targeted for genetically engineered tolerance to one or more herbicides includes: lucerne, canola, cotton, maize, oats, petunia, potato, rice, sorghum, soyabean, sugarbeet, sugar cane, sunflower, tobacco, tomato, wheat and others. It is clear that by creating crops resistant to its herbicides a company can expand markets for its patented chemicals. The market for HRCs has been estimated at more than $500 million by the year 2000 (Gresshoft, 1996). Although some testing is being conducted by universities and advanced research organizations, the research agenda of such institutions is being increasingly influenced by the private sector in ways never seen in the past. While 46% of biotechnology firms support biotechnology research at universities, 33 of the 50 US states have university-industry centres for the transfer of biotechnology. The challenge for such organizations will not only be to ensure that ecologically sound aspects of biotechnology are researched and developed (N fixing, drought tolerance, etc.), but to monitor carefully and control the provision of applied non-proprietary knowledge to the private sector so as to protect that such knowledge will continue in the public domain for the benefit of all society. Biotechnology and agrobiodiversity Although biotechnology has the capacity to create a greater variety of commercial plants, the trend set forth by TNCs is to create broad international markets for a single product, thus creating the conditions for genetic uniformity in rural landscapes. In addition, patent protection and intellectual property rights espoused by GATT, inhibiting farmers from re-using, sharing and storing seeds raises the prospect that few varieties will dominate the seed market. Although a certain degree of crop uniformity may have certain economic advantages, it has two ecological drawbacks. First, history has shown that a huge area planted to a single cultivar is very vulnerable to a new, matching strain of a pathogen or pest. And, second, the widespread use of a single cultivar leads to a loss of genetic diversity (Robinson, 1996). Evidence from the Green Revolution leaves no doubt that the spread of modern varieties has been an important cause of genetic erosion, as massive government campaigns encouraged farmers to adopt MVs and to abandon many local varieties (Tripp, 1996). The uniformity caused by increasing areas sown to a smaller number of varieties is a source of increased risk for farmers, as the varieties may be more vulnerable to disease and pest attack and most of them perform poorly in marginal environments (Robinson, 1996). All the above effects are not restricted to MVs and it is expected that, given their monogenic nature and fast acreage expansion, transgenic crops will only exacerbate such effects. Environmental problems of herbicide-resistant crops According to proponents of HRCs, this technology represents an innovation that enables farmers to simplify their weed management requirements, by reducing herbicide use to post-emergence situations using a single, broad-spectrum herbicide that breaks down relatively rapidly in the soil. Herbicide candidates with such characteristics include glyphosate, bromoxynil, sulfonylurea and imidazolinones, among others. However, in actuality the use of herbicide-resistant crops is likely to increase herbicide use as well as production costs. It is also likely to cause serious environmental problems. Herbicide resistance It is well documented that when a single herbicide is used repeatedly on a crop, the chances of herbicide resistance developing in weed populations greatly increases (Holt et al., 1993). The sulfonylureas and the imidazolinones are particularly prone to the rapid evolution of resistant weeds and up to now fourteen weed species have become resistant to sulfonylurea herbicides. Cocklebur (Xanthium), an aggressive weed of soyabean and maize in the south-eastern USA has exhibited resistance to imidazolinone herbicides (Goldburg, 1992). The problem is that given industry pressures to increase herbicide sales, acreage treated with these broad-spectrum herbicides will expand, exacerbating the resistance problem. For example, it has been projected that the acreage treated with glyphosate will increase to nearly 150 million acres. Although glyphosate is considered less prone to weed resistance, the increased use of the herbicide will result in weed resistance, even if more slowly, as it has been already documented with populations of annual ryegrass (Lolium), quackgrass (Elymus repens), birdsfoot trefoil (Lotus corniculatus) and Cirsium arvense (Gill, 1995). Ecological impacts of herbicides Companies affirm that bromoxynil and glyphosate, when properly applied degrade rapidly in the soil, do not accumulate in groundwater, have no effects on non-target organisms and leaves no residues in food. There is, however, evidence that bromoxynil causes birth defects in laboratory animals, is toxic to fish and may cause cancer in humans. Because bromoxynil is absorbed dermally, and because it causes birth defects in rodents, it is likely to pose hazards to farmers and farm workers. Similarly, glyphosate has been reported to be toxic to some non-target species in the soil -both to beneficial predators such as spiders, mites, carabid and coccinellid beetles and to detritivores such as earthworms, as well as to aquatic organisms, including fish (Pimentel et al. 1989). As this herbicide is known to accumulate in fruits and tubers, suffering little metabolic degradation in plants, questions about food safety also arise. Creation of "superweeds" Although there is some concern that transgenic crops themselves might become weeds, a major ecological risk is that large scale releases of transgenic crops may promote transfer of transgenes from crops to other plants, which may then become weeds (Darmency, 1994). The biological process of concern here is introgression, that is, hybridization among distinct plant species. Evidence indicates that such genetic exchanges among wild, weed and crop plants already occur. The incidence of shattercane (Sorghum bicolor), a weedy relative of sorghum and the gene flows between maize and teosinte demonstrates the potential for crop relatives to become serious weeds. This is worrisome given that a number of US crops are grown in close proximity to sexually compatible wild relatives. There are also crops that are grown near wild/weedy plants that are not close relatives but may have some degree of cross compatibility such as the crosses of Raphanus raphanistrum � R. sativus (radish) and johnsongrass (Sorghum halepense) � Sorghum corn (Radosevich et al., 1996). Reduction of agroecosystem complexity Total weed removal via the use of broad-spectrum herbicides may lead to undesirable ecological impacts, given that an acceptable level of weed diversity in and around crop fields has been documented to play important ecological roles such as enhancement of biological insect pest control, better soil cover reducing erosion, etc. (Altieri, 1994). HRCs will most probably enhance continuous cropping by inhibiting the use of rotations and polycultures susceptible to the herbicides used with HRCs. Such impoverished, low plant diversity agroecosystems provide optimal conditions for unhampered growth of weeds, insects and diseases because many ecological niches are not filled by other organisms. Moreover, HRCs, through increased herbicide effectiveness, could further reduce plant diversity, causing shifts in weed community composition and abundance, favouring competitive species that adapt to these broad-spectrum, post emergence treatments (Radosevich et al., 1996). Environmental risks of insect-resistant crops Resistance According to the industry, the promise of transgenic crops containing Bt genes is the replacement of synthetic insecticides now used to control insect pests. Since most crops have a diversity of insect pests, insecticides will still have to be applied to control pests other than Lepidoptera not susceptible to the endotoxin expressed by the crop (Gould, 1994). On the other hand, several Lepidoptera species have been reported to develop resistance to Bt toxin in both field and laboratory tests, suggesting that major resistance problems are likely to develop in Bt crops which through the continuous expression of the toxin create a strong selection pressure (Tabashnik, 1994). Given that a diversity of different Bt-toxin genes have been isolated, biotechnologists argue that if resistance develops alternative forms of Bt toxin can be used (Kennedy and Whalon, 1995). However, because insects are likely to develop multiple resistance or cross-resistance, such a strategy is also doomed to fail (Alstad and Andow, 1995). Others, borrowing from past experience with pesticides, have proposed resistance management plans with transgenic crops, such as the use of seed mixtures and refuges (Tabashnik, 1994). Besides requiring the difficult goal of regional co-ordination between farmers, refuges have met with poor success for chemical pesticides, due to the fact that insect populations are not constrained within closed systems, and incoming insects are exposed to lower doses of the toxin as the pesticide degrades (Leibee and Capinera, 1995). Impacts on non-target organisms By keeping pest populations at extremely low levels, Bt crops can starve natural enemies as these beneficial insects need a small amount of prey to survive in the agroecosystem. Parasites would be most affected because they are more dependent on live hosts for development and survival, whereas some predators could theoretically thrive on dead or dying prey. Natural enemies could also be affected directly through intertrophic level interactions. Evidence from studies conducted in Scotland suggest that aphids were capable of sequestering the toxin from Bt crops and transferring it to its coccinellid predators, in turn affecting reproduction and longevity of the beneficial beetles (Birch et al., 1997). Sequestration of plant allelochemicals by herbivores that then affect parasitoid performance is not uncommon (Campbell and Duffey, 1979). The potential of Bt toxins moving through food chains poses serious implications for natural biocontrol in agroecosystems. Bt toxins can be incorporated into the soil through leaf materials, where they may persist for 2-3 months, resisting degradation by binding to soy clay particles while maintaining toxin activity (Palm et al., 1996). Such Bt toxins that end up in the soil and water from transgenic leaf litter may have negative impacts on soil and aquatic invertebrates and nutrient cycling processes (James, 1997), all aspects that deserve serious further inquiry. Downstream effects A major environmental consequence resulting from the massive use of Bt toxin in cotton or other crop occupying a larger area of the agricultural landscape, is that neighbouring farmers who grow crops other than cotton, but that share similar pest complexes, may end up with resistant insect populations colonizing their fields. As Lepidopteran pests that develop resistance to Bt cotton, move to adjacent fields where farmers use Bt as a microbial insecticide, may render farmers defenceless against such pests, as they lose their biological control tool (Gould, 1994). Who will be accountable for such losses? Impacts of disease-resistant crops Scientists have attempted to engineer plants for resistance to pathogenic infection by incorporating genes for viral products into the plant genome. Although the use of viral genes for resistance in crops to virus has potential benefits, there are some risks. Recombination between RNA virus and a viral RNA inside the transgenic crop could produce a new pathogen leading to more severe disease problems. Some researchers have shown that recombination occurs in transgenic plants and that under certain conditions it produces a new viral strain with altered host range (Steinbrecher, 1996). The possibility that transgenic virus-resistant plants may broaden the host range of some viruses or allow the production of new virus strains through recombination and transcapsidation demands careful further experimental investigation (Paoletti and Pimentel, 1996). The performance of field-released transgenic crops By early 1997, thirteen genetically modified crops had been deregulated by the USDA, which were already on the market or in the fields for the first time. Over 20% of the US soyabean acreage was planted with Roundup tolerant soyabean and about 400,000 acres of Maximizer Bt maize were planted in 1996. Such acreage expanded considerably in 1997 (transgenic cotton: 3.5 million acres, transgenic maize: 8.1 million acres and soyabean: 9.3 million acres) due to marketing and distribution agreements entered into by corporations and marketers (i.e. Novartis Seeds with Growmark and Mycogen Plant Sciences with Cargill). Given the speed with which products move from laboratory testing to field production are transgenic crops living to the expectations of the biotechnology industry? Table 1. Field performance of some recently released transgenic crops. 1. Bt transgenic cotton Additional insecticide sprays needed due to Bt cotton failing to control bollworms in 20,000 acres in eastern Texas The Gene Exchange, 1996; Kaiser, 1996 2. Cotton inserted with Roundup Ready gene Bolls deformed and falling off in 4000-5000 acres in Mississippi Delta Lappe and Bailey, 1997; Myerson, 1997 3. Bt corn 27% yield reduction and lower Cu foliar levels in Beltsville trial Hornick, 1997 4. Herbicide-resistant oilseed rape Pollen escaped and fertilized botanically related plants 2.5 km away in Scotland Scottish Crop Research Institute, 1996 5. Virus resistant squash Vertical resistance to two viruses and not to others transmitted by aphids Rissler, J. (Personal communication) 6. Early FLAVR-SAVR tomato varieties Did not exhibit acceptable yields and disease resistance performance Biotech Reporter, 1996 7. Roundup Ready canola Pulled off the market due to contamination with a gene that does not have regulatory approval Rance, 1997 8. Bt potatoes Aphids sequestered the Bt toxin apparently affecting coccinellid predators in negative ways Birch et al., 1997 9. Herbicide-tolerant crops Development of resistance by annual ryegrass to Roundup Gill, 1995 According to evidence presented by the Union of Concerned Scientists, there are already signals that the commercial-scale use of some transgenic crops pose serious ecological risks and do not deliver the promises of industry (Table 1). The appearance of "behavioural resistance" by bollworms in cotton, that is that the herbivore was capable of finding plant tissue areas with low Bt concentrations, raises questions not only about the adequacy of the resistance management plans being adopted, but also about the way biotechnologists underestimate the capacity of insects to overcome genetic resistance in unexpected manners (The Gene Exchange, 1996) Similarly, poor harvests of herbicide-resistant cotton due to phytotoxic effects of Roundup in 4000-5000 acres in the Mississippi Delta (New York Times, 1997) points at the erratic performance of HRCs when subjected to varying agroclimatic conditions. Monsanto claims that this is a very small and localized incident that is being used by environmentalists to overshadow the benefits that the technology brought on 800,000 acres. From an agroecological standpoint however, this incident is quite significant and merits further evaluation, since assuming that an homogenizing technology will perform well through a range of heterogeneous conditions is incorrect. Conclusions We know from the history of agriculture that plant diseases, insect pests and weeds become more severe with the development of monoculture, and that intensively managed and genetically manipulated crops soon lose genetic diversity (Altieri, 1994, Robinson, 1996). Given these facts, there is no reason to believe that resistance to transgenic crops will not evolve among insects, weeds and pathogens, as has happened with pesticides. No matter what resistance management strategies will be used, pests will adapt and overcome the agronomic constraints (Green et al., 1990). Diseases and pests have always been amplified by changes toward homogeneous agriculture. The fact that interspecific hybridization and introgression are common to species such as sunflower, maize, sorghum, oilseed rape, rice, wheat and potatoes, provides a basis to expect gene flow between transgenic crops and wild relatives to create new herbicide-resistant weeds. Despite the fact that some scientists argue that genetic engineering is not different from conventional breeding, critics of biotechnology claim that recombinant DNA technology enables new (exotic) genes into transgenic plants. Such gene transfers are mediated by vectors which are derived from disease-causing viruses or plasmids, which can breakdown species barriers so that they can shuttle genes between a wide range of species thus infecting many other organisms in the ecosystem. However, the ecological effects are not limited to pest resistance and creation of new weeds or virus strains. As argued herein, transgenic crops can produce environmental toxins that move through the food chain and also may end up in the soil and water affecting invertebrates and probably ecological processes such as nutrient cycling. Many people have argued for the creation of suitable regulation to mediate the testing and release of transgenic crops to offset environmental risks and demand a much better assessment and understanding of ecological issues associated with genetic engineering. This is crucial as many results emerging from the environmental performance of released transgenic crops suggest that in the development of "resistant crops", not only is there a need to test direct effects on the target insect or weed, but the indirect effects on the plant (i.e. growth, nutrient content, metabolic changes), soil and non-target organisms must also be evaluated. Others demand continued support for ecologically based agricultural research, arguing that the biological problems that biotechnology is aimed at can be solved using agroecological approaches. The dramatic effects of rotations and intercropping on crop health and productivity, as well as of the use of biological control agents on pest regulation have been confirmed repeatedly by scientific research (Altieri, 1994, NRC, 1996). The problem is that research at public institutions increasingly reflects the interests of private funders at the expense of public good research such as biological control, organic production systems and general agroecological techniques (Busch et al., 1990). Civil society must demand a response of who the university and other public organizations are to serve and request for more research on alternatives to biotechnology. There is also an urgent need to challenge the patent system and intellectual property rights intrinsic to the GATT which not only provide MNCs with the right to seize and patent genetic resources, but that will also accelerate the rate at which market forces already encourage monocultural cropping with genetically uniform transgenic varieties. Included amongst the various recommendations for action that NGOs, farmers' organizations and citizen groups should bring forward to local, national and international fora are the following: End public funded research on transgenic crops that enhance agrochemical use and that pose environmental risks; HRCs and other transgenic crops should be regulated as pesticides; � All transgenic food crops should be labelled as such; Increase funding for alternative agricultural technologies; Ecological sustainability, alternative low-input technologies, the needs of small farmers and human health and nutrition should be pursued with greater vigour than biotechnology; Trends set by biotechnology must be balanced by public policies and consumer choices in support of sustainability; Measures should encourage sustainable and multiple use of biodiversity at the community level, with emphasis on technologies that promote self-reliance and local control of economic resources as a means to foster a more equitable distribution of benefits. 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Union of Concerned Scientists (1996) Bt cotton fails to control bollworm. The Gene Exchange 7, 1-8. Library: The environmental risks of transgenic crops: an agroecological assessment http://binas.unido.org/binas/Library/cabi/altieri.html DECLARATION & DISCLAIMER ========== CTRL is a discussion and informational exchange list. Proselyzting propagandic screeds are not allowed. Substance�not soapboxing! These are sordid matters and 'conspiracy theory', with its many half-truths, misdirections and outright frauds is used politically by different groups with major and minor effects spread throughout the spectrum of time and thought. That being said, CTRL gives no endorsement to the validity of posts, and always suggests to readers; be wary of what you read. CTRL gives no credeence to Holocaust denial and nazi's need not apply. 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