NEWS : GM cotton’s resistance under strain

| Monday , March 8 , 2010 |

OUR SPECIAL CORRESPONDENT

New Delhi, March 7: Pink bollworms in India have turned resistant to a set of genetically modified cotton plants, the crop biotechnology company Mahyco-Monsanto has announced, describing it as the world’s first emergence of insect resistance to GM cotton.   The company said its scientists had detected unusual survival of pink bollworms in first-generation single-protein GM cotton plants during field monitoring of the 2009 cotton crop in four districts of Gujarat.   Tests have confirmed resistance to the Cry1Ac protein — the bacterial protein in the GM cotton which is expected to kill the bollworms — in Amreli, Bhavnagar, Junagarh, and Rajkot, the company said in a statement.   If the findings are confirmed, they would mark the first insect resistance to GM cotton in the world. India introduced GM cotton eight years ago, but it is grown in 11 other countries, none of which have reported resistance so far despite longer periods of cultivation in some of them. Even the US which has cultivated GM cotton for more than 13 years has not reported resistance yet.   But two senior government entomologists have questioned the methodology and the conclusions drawn by Mahyco-Monsanto. “The unusual survival of bollworms in the cotton by itself need not be surprising. This is not the standard method of monitoring resistance,” said Keshav Kranthi, a crop protection specialist and acting director of the Central Institute of Cotton Research, Nagpur. Kranthi said India is the only country in the world where GM cotton is hybrid and under Mendelian rules of gene segregation the Cry1Ac gene will be absent in 25 per cent of the seeds that form on the first generation plants.   “If the levels of insect infestation is low, farmers won’t notice, but at high infestation levels, survival of the insects will become apparent,” Kranthi said. “So the survival is not something dramatic.”   Mahyco-Monsanto said while the gene segregation argument is “scientifically correct”, bollworm larvae have been controlled “very well” prior to this incidence by the Cry1Ac cotton.   “We have not come across significant damage due to pink bollworm earlier,” the company said. Laboratory tests on the surviving larvae show “they could survive concentrations that will kill susceptible larvae”.   Some scientists are also questioning the conclusion of resistance after tests on larvae surviving GM cotton fields. In a bollworm population, one entomologist said, there is likely to be a small proportion with the capacity to survive the Cry1Ac protein toxin.   “Laboratory tests on them would obviously show them as resistant. But standard resistance monitoring should involve larvae picked up from conventional cotton fields,” Kranthi said. The second entomologist who requested anonymity said he would agree with Kranthi.   But the company said its methodology is based on good science. “We based our conclusions on the judgement of recognised resistance experts who employed accepted scientific methods,” it said. “Resistance is natural and expected,” the company said.   The company said it has reported its findings to a government panel responsible for approving GM products. It has also said that no insect resistance has been observed in its second generation GM cotton containing two proteins — Cry1Ac and Cry2Ab.   The crops with additional Cry2Ab protein would be more effective than plants with Cry1Ac alone. “The stacking of genes is a standard process called gene pyramiding to deal with possibility of resistance,” said a senior crop scientist.   Mahyco-Monsanto said that single protein Cry1Ac cotton continues to control bollworms pests other than pink bollworm in the four districts of Gujarat. And no insect resistance in any of India’s cotton growing states has been observed with the second generation GM cotton.   “The findings are an important reminder to Indian farmers,” the company said. When cultivating GM cotton, farmers are expected to plant non-GM cotton as refuge around the GM cotton to delay the risk resistance, regularly scout fields for insect presence, and use insecticide sprays only when needed.   But Kranthi said more independent tests would be required to confirm that pink bollworms have indeed turned resistant to the single protein GM cotton. “Our own studies so far do not indicate resistance,” he said.   SOURCE : http://www.telegraphindia.com/1100308/jsp/nation/story_12190630.jsp