After 10 years in the field, biotech corn is still under debate from some quarters. A new study from Iowa State University, released today, offers evidence that the presence of Bt corn in a field has less impact on organisms present than the nutritional quality of the corn itself. The study looked at potential impact of the presence of Bt corn on pillbugs and sowbugs, which play a key role in breaking down corn residues after harvest.
Little work has been done on the potential impact of Bt on such organisms, but other work that has shown Bt can stay in soil for a few weeks after harvest, gave rise to a look at the issue. Researchers looked at Bt lines using the Cry1Ab strain of the insect-controlling bacterium - including the Bt11 from Syngenta and the Mon810 from Monsanto.
What they found is that pillbugs and sowbugs were not impacted by the presence of Bt in the foliage they consumed. They did discover, in their work, that these decomposers were more likely to be impacted by the nutritional quality of the foliage itself, independent of biotech content.
Previous research on the impact of Bt on soil organisms involved exposing the organisms to Bt directly, which is not what would happen in "the wild." This ISU study actually fed plant material to populations of decomposers and measured weight gain of the bugs. Little Bt was found in the bugs themselves during the test, and any variance in decomposer growth was more directly related to the corn plant, not the Bt.
The researchers say more work is needed on the impact of transgenic plants on the ecosystem, but note this current study shows that the presence of Bt does not affect the survival and growth of the pillbug and sowbug species studied. They advise that the only way to study this issue is to use transgenic plant material "rather than purified protein alone."
You can read the study by clicking HERE