Non-target Pests Not Harmed By Bt Bacterium, Studies Suggest

Two entomology studies find no negative effects of Bt on non-target insects

Published on: Feb 4, 2014

GM crops containing the bacterium Bacillus thuringiensis have no effect on a wide range of non-target species, two studies published in entomology journals show.

The studies, one published in the February 2014 issue of Environmental Entomology, and the other in the February 2014 issue of the Journal of Economic Entomology, show that Bt crops have no negative effects on two beneficial insect predators or on a beneficial entomopathogenic nematode.

For the first study, researchers took caterpillars that were known to be resistant to Bt proteins and fed them Bt maize and Bt cotton.

Two entomology studies find no negative effects of Bt on non-target insects
Two entomology studies find no negative effects of Bt on non-target insects

Researchers then fed the caterpillars to two common, beneficial, predatory insects — insidious flower bugs and big-eyed bugs — for two generations and compared them to another group of predators that consumed caterpillars fed on non-Bt plants.

The researchers found that the survival, development, adult mass, fecundity, and fertility of the insect predators in both groups were similar, regardless of whether they consumed caterpillars that fed on Bt plants or non-Bt plants.

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"This research demonstrates that the current Bt proteins used in corn and cotton crops globally do not harm Geocoris punctipes or Orius insidious, two important insect predators that help suppress pest populations on corn, cotton, and many other crops," said Dr. Anthony Shelton, a professor of entomology at Cornell University and one of the co-authors.

"By using caterpillars resistant to the Bt proteins in this study, we were able to remove any 'host quality effects' that might have led to spurious misinterpretation of the results. This work demonstrated that the caterpillars consumed the Bt proteins, and the predators consumed the Bt proteins when they fed on the caterpillars, but they did not suffer any harm even over multiple generations," Shelton noted.