|Keywords:||Latin America/Caribbean; Disease/pest resistance; Biosafety/Foodsafety; Genetic engineering.|
|Correct citation:||Hruska, A.J. (1996), "Transgenic Crops in Central American Agriculture." Biotechnology and Development Monitor, No. 29, p. 79.|
Transgenic crops are likely to enter Central America in the coming years, either legally or illegally. Unfortunately, with a few exceptions, the region is uninformed of the potential benefits and risks of this new technology. Besides, no appropriate recommendations, policies, or regulations about the use of these crops have been developed. In May 1996, a workshop in Honduras focused on information, analysis and recommendations on the use of transgenic crops in Central America, with an emphasis on Bacillus thuringiensis transgenic varieties.
Transgenic canola, maize, cotton, potato, soya bean, squash and tomato
varieties are available commercially in North America. Some of these crops
are already widely cultivated. For example, 40 per cent of the cotton planted
in the USA in 1996 consists of transgenic varieties. A large part of the
transgenic crops are expressing genes from Bacillus thuringiensis
(Bt) for the production of crystal proteins in plant tissues to resist
insects. The workshop concentrated on transgenic Bt crops which are of
commercial importance in Central America.
In the USA, Bt transgenic crops have reached the market after several years of regulatory review and public discussions concerning biosafety and durability. This evaluation process is only about to start in the Central American countries. Nevertheless, it is likely that Bt varieties have already been planted in Central America, even if they have not been registered and regulated.
The introduction of Bt crops into Central America may have a positive impact, most importantly the potential reduction in chemical insecticide use. Cotton, for example, has received traditionally high levels of insecticide applications of which the high economic, environmental and human health costs have been well documented. In fact, the availability of Bt cotton may permit the reintroduction of the crop into those parts of the region that have stopped producing cotton due to the high costs of insecticides.
A second potential benefit of transgenic Bt crops in Central America is the ease of their implementation. In most countries in the region, agricultural extension services have faced budget cuts or complete elimination, making the extension of new technologies difficult, especially among resource-poor farmers. In the case of transgenic crops, no new practices need to be learned for the basic use of the technology. The whole technology is 'all in the seed.' Therefore the only challenge is to get the seed into the hands of farmers.
Disadvantages and threats
Several uncertainties, potential disadvantages and threats were addressed during the workshop:
Food safety and acceptability. Do Central Americans want to eat maize that has Bt toxins? Despite the fact that the food safety issue has been reviewed and the use of Bt crops have been approved in the USA, Central Americans, like Europeans and Japanese, are sceptical about statements that transgenic crops do not represent a threat to their health.
The cost of transgenic crops. In the USA, the private US company Monsanto charges an average premium of US$ 80 per ha. for its Bt seed potatoes. Given the average cost of chemical insect control of US$ 155 per ha., Bt potatoes should be economically viable in the USA. Likewise, Monsanto charges US$ 80 per ha. extra for its Bt cotton seed. The estimated savings due to reduced insecticide use are US$ 130 per ha., again making Bt cotton seed economically feasible.
Companies have not yet begun to commercialize Bt crops in Central America, so no information exists on extra seed costs. Given the small markets and perceived low returns, it is not clear whether the foreign companies will ever commercialize Bt transgenic crops in the region. If commercialization pushes through, the costs should be competitive with the price of existing control tactics.
Gene flow and genetic erosion. Possibly the greatest ecological hazard of transgenic crops in Central America is the creation of new weeds and the erosion of genetic diversity due to the exchange of genetic material between transgenic crops and their native wild relatives. A recent study by Mikkelsen has shown that inserted genes can move rapidly into wild weedy relatives, and thus create new weedy species. The possible gene flow between maize and teosinte is of great concern in Mexico, and has recently been studied by the International Centre for the Improvement of Maize and Wheat (CIMMYT). This report recommends that quantitative studies be carried out on the potential gene flow to the maize genus Zea before liberating transgenic maize varieties, and that experimentations with transgenic crops take place under the strictest security measures to prevent gene flow.
Development of resistance. A big concern in the USA is the potential rapid development of resistance in pest populations to the Bt toxin. This would not only lead to the ineffectiveness of transgenic Bt plants, but would also result in the loss of sprayed Bt toxins, currently the most effective and widely used biological pesticide. A rapid development of resistance to Bt would leave farmers with fewer options for sustainable pest management.
Due to these concerns, regulatory agencies in the USA require the application of Bt crops to be accompanied by a resistance management system (see also the article of Mark E. Whalon and Deborah L. Norris). Farmers have to sign an agreement which obliges them to follow proper resistance management, as well as to allow company representatives onto their fields to inspect compliance. The effectiveness of these resistance management plans in the USA is still unknown. To date, no appropriate resistance management system exists in Central America. But even if one were available, it is unlikely that it could be successfully enforced.
In general, Bt sprays are not as widely used in Central America as in the USA. But in export vegetable crops, the sprays are applied because of pesticide residue standards in the importing countries. Therefore, maintaining Bt sprays as a means of sustainable pest management could be of economic importance.
Adaptation to the physical environment. Obviously, the Bt plant varieties developed for North America are usually not appropriate for use in Central America for two reasons. Firstly, it is not likely that the variety itself is adapted to the physical climate. However, this problem could be solved by outcrossing the Bt genes into locally adapted varieties. Secondly, Bt toxins are often very specific to certain species of insects. Consequently, toxins expressed in Bt crops developed for the North American market are not necessarily toxic to pests prevalent in Central America. For example, the most important lepidopteran pest in maize in the USA is the European Corn Borer (Ostrinia nubilalis), which does not occur in Central America. In this region, the main lepidopteran pests are the fall armyworm (Spodoptera frugiperda) and the neotropical stem borer (Diatraea lineolata). Although these pests do occur in parts of the USA, they are not of significant importance. The Bt maize presently developed for the US market is effective against the European corn borer, but not against the fall army worm or the neotropical stem borer.
Intellectual property right. Many of the genes which confer beneficial properties originate in developing countries. But since the development and patenting of the processes, genes and final products takes place in developed countries, there is little chance that developing countries will benefit from the economic value of the genes. Workshop participants mentioned that legal agreements between companies and governments or communities should be developed to ensure that at least part of the financial benefits return to the countries and communities of origin.
Rational use of transgenics
Even if transgenic crops have not yet been commercialized in Central America, there is little to stop farmers from introducing a few bags of seeds to the region. In a few generations of outcrossing, the Bt genes can be transferred to local varieties. Thus, any debate about barring entry into the region has probably already been overtaken by events. It is important to recognize this fact immediately. Several suggestions were put forward at the workshop:
Department of Crop Protection, Panamerican Agricultural College (Zamorano), PO Box 93, Tegucigalpa, Honduras. Phone (+504) 766150/50; Fax (+504) 766242; E-mail firstname.lastname@example.org
The proceedings of the regional workshop "Transgenic Bacillus thuringiensis Crops in Mesoamerican Agriculture: Present and Future" will be published in both English and Spanish by Zamorano Academic Press in early 1997. Address: Libreria, Zamorano, PO Box 93, Teguciglpa, Honduras; Price: US$ 20 (specify English or Spanish version).
T.R. Mikkelsen, B. Andersen and R.B. Jorgensen (1996), "The Risk of Crop Transgene Spread." Nature No. 380, p.31.
J.A. Serratos, M.C. Wilcox and F. Castillo (1996), Flujo Genético entre Maíz Criollo, Maíz Mejorado y Teocintle: Implicaciones para el maíz transgénico. El Batan, Mexico: International Centre for the Improvement of Maize and Wheat (CIMMYT).
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