|Keywords:||Genetic engineering; Plant breeding; Disease/pest resistance; Maize.|
|Correct citation:||Jenkins, R. (1999), "BT Crops are Unsustainable." Biotechnology and Development Monitor, No. 38, p. 24.|
Due to EPA requirements, companies such as Novartis (Switzerland)
and Monsanto (USA) have commissioned academic entomologists in the
USA to devise resistance management strategies. These strategies call for
a high expression level of Bt crops, in conjunction with the planting of
non-Bt crops, which are supposed to act as a refuge for non-resistant insects.
Through selection pressure, the strategy aims to diminish the likelihood
of dominance of Bt resistant insect populations. Monsanto was willing to
settle for a four per cent refuge if no insecticides are used, or a 25
per cent refuge, if chemical insecticides are allowed. The strategy is
based on a mathematical model of insect population behaviour, but there
is no field evidence to show that it works. Many entomologists from the
US are even arguing for bigger refuges.
To add to the controversy, at an EPA hearing in February 1998, several US entomologists claim that the Novartis Bt 176 maize does not express the Bt toxin with sufficient uniformity to meet the criteria of the high dose/refuge resistance management strategy. This implies that resistant insects are likely to become the dominant insect population more quickly with the Novartis Bt maize than with the Bt maize developed by Monsanto and others who claim to meet the resistance management requirements. Hence, the Novartis Bt maize could potentially endanger the potency of other Bt maize varieties. As a compromise, Novartis is currently recommending an even bigger 40 per cent refuge of non-Bt maize grown with Bt maize. To date, this proposal has been refused by other companies since it greatly limits the market of Bt crops and hence they would no longer be profitable to sell.
In the case of Bt maize, the EPA has publicly admitted that a single, comprehensive resistance management strategy is practically impossible since five competing companies have produced several different products, each expressing the Bt toxin differently within various parts of the plant and over the growing season. Maize stem borers could avoid high Bt toxin releases by moving for instance, from Pioneer (USA) Bt maize to Novartis Bt maize at the right time. Moreover, if the movement of resistant insects to a refuge area is high enough, these insects could pass their resistance gene to a susceptible population. Hence, to manage insect resistance to Bt crops, several strategies are required. This could be problematic to implement for large-scale agriculture, which thrives on the efficiency of uniform technology and its corresponding uniform production system.
The notion so dear to the industries that Bt crops feed the hungry, clean up the environment, and make agriculture more sustainable has no scientific basis. Bt crops are mere products in the struggle for global domination of life industries now being fought between the giants Monsanto and Novartis. Ordinary farmers worldwide will soon find out that Bt sprays no longer work, thanks to the biotechnology industries.
The author is a consultant for Genetic Resources Action International
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