Bt-Resistant Insects

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Bt-Resistant Insects are insects that have evolved resistance to Bt toxin, a toxin that is naturally made by a bacteria called Bacillus thuringiensis (Bt for short). Whereas Bt was an important tool of organic farmers and gardeners to deal with pests using a naturally occurring substance, it was also adopted by biotechnology companies such as Monsanto in their genetically modified crops such as Bt corn and Bt cotton. In these products, every cell of the plant manufactured Bt. With such ubiquitous exposure to Bt, by 2011, major corn pests began to evolve resistance to Bt.[1]

Resistance in Western Corn Rootworms


In July 2011, Iowa State University entomologist Aaron Gassmann reported "the first rootworms confirmed as being Bt-resistant, which he found in four of the state’s cornfields."[2] "Resistance developed in fields where the same genetically-engineered corn had been grown three years in a row."[3]


In northwestern Illinois, University of Illinois in Urbana agricultural entomologist Michael Gray is studying whether western corn rootworms collected in August 2011 in Henry and Whiteside counties are resistant to an insect-killing protein derived from Bt.[2] "The insects were collected in two fields where corn had toppled after roots were eaten by rootworms." Gray added that "planting Bt corn year after year increases the odds that the bugs will develop resistance to the insecticide... While the symptoms parallel bug resistance that’s been confirmed in Iowa, analysis of the Illinois insects won’t be complete until next year [2012], he said."[2] Since publishing his preliminary findings, Gray has been contacted by "more farmers whose Bt corn is succumbing to corn rootworms."[2]

Articles and resources

Related SourceWatch articles


  1. Clay Dillow, "Pests Are Developing Resistance to Monsanto's Engineered Supercorn," Popular Science, August 30, 2011, Accessed September 1, 2011.
  2. 2.0 2.1 2.2 2.3 Jack Kaskey, "Monsanto Corn Falls to Illinois Bugs as Investigation Widens," Bloomberg, September 2, 2011, accessed September 7, 2011.
  3. Dan Piller, "Beetle resistance reported to Monsanto BT corn," Des Moines Register, August 28, 2011, Accessed September 7, 2011.

External resources

External articles