Growing gains

Published: Thursday 15 May 2003

genetically modified (gm) crops threatening biodiversity? Not really, if the results of a small-scale trial being conducted in Denmark are to be trusted. The tests suggest that engineered sugar beet is more beneficial to wildlife than its conventional counterpart. In their experiments in Jutland from 1999 to 2001, ecologists Beate Strandberg and Marianne Bruus Pedersen compared the environmental impact of conventional beet with that of the gm variety. The beet was modified to make it resistant to the herbicide glyphosate. The genetic tinkering prevents the crop from being damaged when the herbicide is sprayed in the fields on a large scale.

Critics of gm technology have argued that the widespread use of herbicides in the fields of gm crops affects the biodiversity by killing many weed species before they can produce seeds. But contrary to these claims, the Danes found that the gm beet farms had more weeds than fields of conventional crops. " gm plots were also richer in insects and other arthropods, providing more food for birds than conventional ones," says Strandberg, who works at Denmark's National Environmental Research Institute.

However, Strandberg warns that weeds may not be as bountiful if glyphosate is sprayed year after year. Furthermore, the use of gm beet might favour some weeds such as dwarf nettles, which are harder for the herbicide to kill, over weeds such as meadow grass that succumb quickly. This could have unpredictable effects on farmland biodiversity.

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