India: Bt cotton toxic, bollworms seek new hosts

The agricultural gains by Bt cotton farmers seems to be at the cost of other farmers. The bollworm, which the Bt cotton is resistant to, has now found new hosts in other varieties of plants, putting them at risk.

Bt cotton is poisonous for the cotton bollworm and it cannot survive on its leaves. So the insect, which belongs to the butterfly family, has migrated to non-Bt plants such as tomato, pigeon pea, chickpea, sorghum and maize.

The agricultural loss, which cotton growers suffered earlier, is now being experienced by farmers growing food crops. This has led to increase in the use of pesticides by non-Bt cotton farmers to reduce the additional loss.

There are no reports of reduction in the population of cotton bollworm and this indicates that it has adapted to non-Bt cotton crops to lay eggs and populate its species.

There have been no scientific studies on the additional loss to farmers growing other crops. However, field observations show that the shifting of bollworm from Bt cotton to food crops has resulted in farmers losing at least 20 per cent of their yield. Thanks to the pest migration, the bollworm has found a continuous life, from one season to another, said M.A. Qayyum, who has conducted field research studies on Bt cotton for about a decade now.

Dr P.V. Satheesh, national convener of Southern Act-ion on Genetic Engineering, said that given a choice between cotton and red gram, the bollworm prefers red gram. “If you control the pest using Bt technology, it will find new sources of food to survive. We have to assess the damage caused to other crops with the shift in plant hosts,” he said.

Red gram seems to be the most affected crop with the shift in the pest’s preference. Earlier, farmers used to grow a few layers of red gram along with cotton to detract the attention of the bollworm from cotton to red gram. Farmers stopped this practice after the introduction of Bt cotton.