Field of corn.
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Yum, genetically engineered corn and cotton.

That isn’t what most people would think. (Especially the cotton bit. And especially the GMO bit.)

But a growing number of pests appear to share this sentiment. They’ve developed immunity to corn and cotton crops genetically engineered to contain the pesticide Bt, so they’re now munching away with impunity.

As of 2010, five of 13 major pest species had become largely immune to the Bt poisons in GMO corn and cotton, compared to just one species in 2005, scientists write in a paper published in the journal Nature Biotechnology.

“Three of the five cases are in the US, where farmers have planted about half of the world’s Bt crop acreage,” reports Business Standard. “[The study] indicates that in the worst cases, resistance evolved in 2 to 3 years; but in the best cases, effectiveness of Bt crops has been sustained more than 15 years.”

The scientists, who analyzed 77 studies conducted on five continents, also found that other species appear to be developing resistance.

Perhaps as alarming as the growth in the number of Bt-resistant species is the growth in the amount of land upon which Bt crops are planted. From the paper:

Click to embiggen.
Click to embiggen.
Nature Biotechnology

So not only are farmers wasting money on GMO seeds that don’t perform as advertised, but they are then spraying their crops with more insecticides to help overcome bugs’ growing resistance. Meanwhile, nobody really knows what those Bt genes are doing to other animals that eat them. Such as pigs. And us.