SEX, LIES, AND HERBICIDES March 2000 Nature Biotechnology Volume 18, Number 3 241 Guy della-Cioppa & Mary Callan http://www.nature.com/cgi-taf/DynaPage.taf?file=/nbt/journal/v18/n3/full/nbt 0300_241.html Procreation may, according to these authors, sometimes appear unnatural, can frequently be hazardous, and when performed in public, is almost always controversial. Such is the case even in plants, where the GMO (genetically modified organism) issue in Europe has been beaten to death editorially from every possible angle. Although the anti-GMO camp consists of many well-intentioned individuals who have been helpful in addressing other environmental issues (saving marine mammals, for example), unfortunately, they are seriously misguided with respect to GM crop technology. The authors write that they recently attended Agbiotech '99* and sat through the Sunday evening session that featured two speculative talks on the ecological risks of GMO release. The speakers proposed either a three-year moratorium (Brian Johnson, English Nature), or irrevocable banning (Benedikt Haerlin, Greenpeace), of GM crop releases into the environment. The Greenpeace viewpoint is that GM crops pose long-term evolutionary risks to the planet that are potentially irreversible and that cannot be assessed scientifically (somewhat akin to the uncertainties that the wide genetic cross giving rise to a nectarine might pose). The authors say they would argue that new varieties of traditionally bred hybrids are released in large numbers worldwide every year and the long-term evolutionary consequences are equally unknown. Greenpeace's solution to food shortages in developing countries is to encourage farmers to adopt more labor-intensive, organic farming practices rather than use the tools of modern biotechnology to increase crop yields (in other words, just work longer and harder). We won't debate these arguments because they are of a geopolitical and philosophical nature unknown to us: they would require that we grant legitimacy to the belief that scientifically unwarranted concerns for environmental safety take absolute precedent over providing a population with the means to feed itself. The authors say that plant breeders have heard these apocalyptic scenarios before when introducing traditionally bred hybrid crops. Hybrid crops represent, after all, nothing more than GM crops with thousands (as opposed to just one or two) of new genes. As a case in point, famed horticulturist Luther Burbank produced an 1893 book entitled New creations in fruits and flowers that described hundreds of new hybrid plant species. Burbank was immediately denounced by groups who claimed that only God could "create" a new plant. Once the controversy subsided, "New creations" made Burbank internationally famous and by 1901 Burbank plums and Burbank potatoes were introduced coast-to-coast to the delight of consumers. Ultimately, the popular press lauded his accomplishments in advancing the new science of plant breeding and in increasing the world's food supply (the authors argue that history will shortly be repeating itself here). In his talk, "Birds, bugs, and biotechnology, where do we go from here," Brian Johnson, however, presented entirely new scientific concepts (at least to us). He argued against the release of GM herbicide-tolerant (GMHT) and GM insect-resistant (GMIR) crops, his central thesis being that these types of crops will damage the "natural" biodiversity of UK farmland. The authors disagree entirely with his conclusions, and believe in fact that he inadvertently made compelling arguments in support of why these types of GM crops should be released onto UK farmlands. The majority of the UK land surface is used for agricultural production (current estimates 75%). Farming techniques have advanced significantly over the past 50 years in the UK, with increasing dependence on mechanization and chemical pesticides to increase crop yields. Thus, there is nothing inherently "natural" about UK farmland biodiversity after a century of intensive crop production using modern monocultural practices. Johnson decries the recent decline in UK farmland bird and butterfly populations (7080% drop) as evidence that modern agriculture results in damage to native flora and fauna, and specifically blames the use of "more efficient" herbicides. The authors own reading of a recent British bird census1, conducted between 1971 and 1995, reports a population decline in 24 of 40 species known to breed on farmland. That would imply, then, that the remaining 16 species studied have either remained stable or actually increased in population. To truly prove Johnson's assertion, data from a census of non-farmland bird populations and non-farmland species diversity in their native environments should be included by comparison. None were, preventing a logical argument. These wildlife diversity declines on farmland are likely due to a complex combination of variables that include habitat destruction (e.g., hedgerow removal to increase field size), shifting of habitats, wide-scale use of environmentally persistent crop chemicals. Johnson argues that more efficient herbicides are especially troubling and that GMHT crops would increase their use on UK farmlands. By more efficient herbicides, we assume he means broad-spectrum, post-emergent herbicides that effectively control all weed species (what would be the advantage to the grower of using a less efficient herbicide)? Farmers in general optimize their fields for survival and reproduction of the crop rather than the competing weed species. That is, however, precisely the reason why GMHT crops that are tolerant to broad-spectrum herbicides (such as glyphosate) should be widely adopted. Indeed, the best argument for GMHT crops came from Johnson himself when he lamented the fact the UK farmers currently use up to eight different herbicides to control weeds in sugarbeet (pre- and post-emergent, environmentally persistent chemistries, with multiple modes of action). Why use such an intensive chemical onslaught on UK soil and weed biodiversity when safe, clean, and environmentally friendly GMHT technology can be used? Herbicide usage in-season is reduced overall in glyphosate-tolerant GMHT crops (there would be no need for 8 different herbicide applications), and glyphosate is virtually non-toxic to mammals, fish, and invertebrates (the rat oral LD50 is 5 g/Kg; ref 2). Furthermore, yield increases in the GMHT crop of interest would allow UK farmers to increase set-asides and hedgerows and thus adopt the farmland "refuge strategy" that was proposed by Johnson. Genetic engineering aside, our global village has become increasingly smaller over the past millennium, ever since man has guided himself by the stars to navigate across oceans, be they of water or of scientific wonder. As soon as we invented tools enabling us to travel farther than we could run, we have forced genes to mix, both our own and those of the portable ecosystems we've dragged along to sustain us. We argue that now we can have far more certain control over what genes go where. At least in plants, in public.
*Agbiotech '99: Biotechnology and World Agriculture, November 1416, 1999, London.
REFERENCES 1.http://www.environment.detr.gov.uk/acre/wildlife/01.htm. The commercial use of genetically modified crops in the United Kingdom. 2.MSDS: EPA Regulation No. 2392637 PN: 6042.
English home English index Japanese Contents Japanese home