Update: Bt Corn and Monarch Butterflies |
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| For the latest update on
research regarding Bt corn pollen and its affect on the Monarch
butterfly, please see: Preliminary
report on the ecological impact of Bt corn pollen on the Monarch
butterfly in Ontario. Bt corn has been modified to incorporate a gene from the bacterium Bacillus thuringiensis (Bt). The Bt provides Bt corn with a built-in control of certain insects, including the European corn borer, which accounts for annual corn yield losses of up to ten per cent. For many years, farmers have been controlling pests with a spray using that protein, and it is also widely used in organic farming. The modification with the Bt gene makes the corn’s plant tissue toxic to the larvae of the European corn borer. These larvae feed in the stalks of the plant, making them difficult to control with sprays. That’s why Bt corn has the potential to reduce pesticide use and increase yields, and thus contribute to a sustainable agriculture. Together with herbicide tolerant soya and insect resistant cotton, Bt corn is one of the most widely used commercial GM crops. Although the Bt-corn plant itself is harmless to humans and animals such as ladybirds and bees, scientists found pollen from the GM crop could have a negative effect on the larvae of monarch butterflies if it lands on milkweed – the plant on which they feed. The fact that this research was conducted in the lab and not in the field has, however, given rise to the criticism that it does not represent real field conditions. Subsequently, scientists from numerous research institutions have addressed the issue of Bt corn and monarch butterflies. In lab and field studies they analyzed the time span, in which corn plants release their pollen and the larvae of the monarch butterflies feed on milkweed, or they investigated how far the corn pollen grains actually travel. Results from this comprehensive research will help to determine whether the preliminary laboratory results hold true, when the complex interactions in the field are taken into account. In a recent report, the U.S. Environmental Protection Agency (EPA) stated that a review of all available scientific information indicated that monarch butterflies were at very little risk from Bt corn products. |
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