Back in 1996, Bt corn caused a revolution in the corn industry by solving the problem of corn rootworms. However, over the years the rootworms have evolved to build immunity to the Bt corn variant.
Bt corn is essentially an engineered seed which comes with a specific strain of a protein. This protein is able to target and eliminate the corn rootworms. As soon as a rootworm eats the corn, the protein in the corn causes a lethal infection to take place in the worm’s body. This results in the death of the worm.
Currently, Bt corn accounts for 75% of the total corn production around the U.S. However, it has recently been discovered that the rootworm has been able to evolve and build immunity against the Bt corn. As a result, the rootworm is back and eating at the corn crops.
Typically, some Bt corn plants produce less amount of the toxic protein. This low dose may kill some rootworms but some survive and become more immune to the protein as a result. To counter this, farmers are advised to keep ‘refuges’ near their crops. These refuges comprise of land cultivated with simple corn, with no toxic protein.
As a result, the rootworms in this area develop no immunity towards the Bt corn. And when evolved rootworms from Bt corn fly to this area, they mate with low-immunity rootworms. This helps ensure that the rootworm population wouldn’t developed a full-blown deficiency against the cure.
This solution should have worked fine. But according to reports, most farmers simply ignored this essential task. Not only that, they continued to ignore despite repeated warnings in the recent past that the corn rootworms are developing immunity. Sadly, with no effective alternative right now, farmers will inevitably use more chemicals to counter the rootworms.
Source: PNAS
Courtesy: The Verge
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