Benefits of a variety of genetically modified cotton are not restricted to fields where it is planted, but extend to nearby conventional crops, scientists have found.

The GM cotton, which is engineered to make its own biological insecticide, reduces pest populations significantly in neighbouring fields.

A ten-year study of the GM cotton variety in China, led by Kong-Ming Wu, of the Chinese Academy of Agricultural Sciences in Beijing, has suggested that its widespread adoption was responsible for a dramatic long-term decline in damage from the cotton bollworm, the biggest pest threat to the crop.

The GM cotton is modified to produce a natural bacterial insecticide called Bacillus thuringiensis (Bt). It is highly toxic to the larvae of moths and butterflies, while leaving other insects unharmed. In the study, which is published in the journal Science, researchers found that populations of the cotton bollworm fell significantly with the introduction of Bt cotton.

Julian Little, of the Agricultural Bio-technology Commission, which represents GM companies, said: “It is time that anti-GM groups acknowledge the very real benefits that this technology can bring to the developing world.”

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