New Delhi, June 25: Crop-ravaging caterpillars resistant to genetically-modified BT cotton plants may proliferate in India much faster than previously believed possible, scientists have cautioned.
The genetically-modified plants are designed to produce a protein called Bacillus thuringiensis (BT) toxin that is poisonous to the caterpillar-like bollworms that feed on cotton and other crops. The government had approved BT cotton for cultivation last year.
But a new study, published in Current Science, a peer-reviewed journal of the Indian Academy of Sciences, shows that bollworms resistant to the BT toxin are lurking in at least four major cotton growing states. The bollworms acquired resistance to the BT toxin long before the introduction of BT cotton in India.
A six-member team of agricultural scientists studied bollworms from selected sites in Andhra Pradesh, Karnataka, Maharashtra and Tamil Nadu. “At all sites, we found individual bollworms that could survive even the highest concentration of the BT toxin,” said Dr Baba Fakrudin, assistant professor of biotechnology at the University of Agricultural Sciences, Dharwad.
The university has engaged in cotton research for several decades and has developed many cotton varieties.
The scientists say their findings do not mean that BT cotton will not work in India. “But the spread of resistant (boll)worms could be much faster than what it would have been in the absence of this resistance,” Fakrudin said.
Bollworms abroad have shown some level of tolerance – “native resistance” — to the BT toxin even if they have not been exposed to it. “The existence of native resistance is by itself not surprising, but we didn’t expect to find this kind of geographical variation and worms that are eight times more resistant than susceptible bollworms,” said Fakrudin.
Scientists say their findings underline the need to implement integrated pest management strategies to delay the emergence of widespread resistance.
Farmers need to rotate crops and avoid planting BT cotton on the same land year after year, and scientists need to develop novel genetically-modified plants to make it harder for the worms to develop resistance.