photo: Beau/Creative Commons
An article in the latest issue of the journal Current Science raises serious questions about the long-term viability of genetically-modified Bt cotton to actually do what it's intended to do, increase pest resistance. Scientists have found for the first time bollworms not only living and surviving on GM cotton, but having offspring that can complete their full lifecycle there. Looking at two varieties of Bt cotton in commercial use, containing both single and double genes intended to be toxin to the bollworms, the scientists found that the pests were able to survive.
Report co-author Aralimarad Prabhuraj told Kolkata's The Telegraph:
We saw virtually no differences between the biology of insect populations reared on the GM cotton and the non-GM cotton ... We have indeed seen a dramatic boost to India's cotton, but we had always anticipated that at some point in time, we'll encounter pests that can withstand the modified plants. No one knew when it would happen.
This particular study did not examine whether the bollworms survived because they developed a resistance the toxin or because the toxin present in the cotton was insufficient to kill them.
Back in March of this year, however, Monsanto admitted that pink bollworms had developed resistance to Bt cotton in the Indian state of Gujarat, in plots where the single gene variety (Bollgard I) of the GM crop was planted. At that time Monsanto said that resistance in the double gene variety of Bt cotton (Bollgard II) had not been observed in India.
Since GM cotton was introduced to India, agricultural stats show that cotton production has increased from 302kg per hectare in 2002 to 567kg per hectare in 2007; it has since fallen back to 512kg/ha in 2009.
Globally, cotton is cultivated on 2.5% of the world's agricultural land, with genetically modified cotton accounting for nearly half of all the cotton grown in the world. All told, cotton consumes 16% of the world's insecticides--something which genetically-modified cotton was intended to bring down. The Organic Trade Association says that Bt cotton largely did reduce insecticide use for the past ten years, however research from China done in 2006 shows that pesticide use between GM and non-GM cotton was roughly equal.
That said, from 2002 to 2009, money spent on pesticide in India increased by nearly one-third. Research from February of this year, publicized by GM Watch links this to a growing variety of pests beginning to plague Bt cotton.
Part of the problem in bollworms developing resistance to the Bt toxin is over-cultivation of the GM crop, in the sense of planting too much of it close together and not providing so-called 'refuge' space between fields and farms.
A report earlier this year to India's environment minister Jairam Ramesh warned that "Farmers are not following the recommended refugia. With about 90 percent area under Bt cotton, bollworms can develop resistance soon. The concern needs to be addressed as a priority before it's too late."
This research has implications for GM crops more broadly: Though its introduction has been halted for now by India's environment ministry, Bt brinjal (eggplant or aubergine...) depends upon the same genes to make it resistant to pests.
Here's the original research: Survival and reproduction of natural populations of Helicoverpa armigera on Bt-cotton hybrids in Raichur, India [PDF]
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More on Genetically Modified Crops:
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