A new global assessment helps scientists explain why
genetically modified crops have suppressed some pests for longer than a decade,
while others adapted in a few years.
Since 1996, farmers worldwide have planted more than 1
billion acres (400 million hectares) of genetically modified corn and cotton
that produce insecticidal proteins from the bacterium Bacillus thuringiensis,
or Bt for short.
Bt proteins, used for decades in sprays by organic farmers,
kill some devastating pests but are considered environmentally friendly and
harmless to people. However, some scientists feared that widespread use of
these proteins in genetically modified crops would spur rapid evolution of
resistance in pests.