Tuesday, April 1, 2014

Western corn rootworm develops resistance to bt corn!

Adult corn rootworm beetle on a corn plant. Image: Sarah Zukoff/Flickr

Named for pesticide producing Bacillus thuringiensis gene it contains, this genetically modified corn accounts for nearly 3 quarters of the US corn crop.  Concern about the reliability of it to repel pests without forcing resistances has recently been raised with the growing problem of an insect called western corn rootworm.  Over the past few years this insect has rapidly evolved resistances to the bt corn, causing serious damage to crops.

Effect of refugia on pesticide efficacy
One of the main reasons that this resistance it believed to have occurred is that farmers are not implementing properly large crop refuge areas.  Crop refuge areas are areas of crop that are not planted with bt corn and are designed to limit the evolution of resistances.  It might seem counter intuitive to only protect some of the crop, but by maintaining an environment that is not so evolutionary demanding as to only let the bt resistant bugs live, it effectively limits evolution.

-Anne Drury

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