A research article published by the scientists of the Chinese Academy of Agricultural Sciences in the 28-5-2010 issue of "Science" shows that nature has once again outwitted Bt cotton.
Bollworm is the major pest affecting cotton and most of the pesticides used in cotton cultivation is used to control the bollworm. Scientists discovered that Bacillus thuringiensis (Bt), a bacterium which occurs naturally in the soil produces a toxin which kills bollworm larvae. By genetically modifying the cotton plant by splicing Bt genes into the cotton DNA, the cotton plant itself can be made to produce this toxin and the scientists had hoped that such cotton can be grown without application of pesticides thus saving huge costs to the farmers. Attracted by the promise of greater profits, thousands of farmers have switched over to Bt-cotton and Monsanto, the holder of the Bt-cotton patent expects that in 2-3 years, 80% of India's cotton production will be of the Bt variety.
But it is very difficult to beat nature. Monsanto admitted in March, 2010 that in Gujrat, the bollworm has now become resistant to the Bt-toxin. This means that Bt-cotton can not kill the bollworm by itself and hence still needs pesticide application.
China provides much larger data on Bt-cotton than India. It has been cultivating Bt-cotton since 1997 and now more than 95% of China's production of cotton is of the genetically modified variety. In the study published in "Science", researchers from CAAS found that with the spread of Bt-cotton, previously harmless insects called mirid bugs have now become major pests. To control the mirid bugs, Bt-cotton farmers are now using more pesticides than farmers growing conventional cotton and their profits have disappeared. In what is a major worry, these mirid bugs are not only devouring cotton plants, but are also destroying other crops such as apples, grapes, pears and dates.
K.N.Ramachandra, Mysore Grahakara Parishat