Butterflies on Bt Corn Not at Risk in Nature

An investigation on the possible effects of Bt maize pollen on two butterfly species "Little Fox" and "Peacock" was conducted by Mechtchild Schuppener of the RWTH Aachen, Germany. Bt corn produces Bt toxins that are specifically effective against the corn borer pest, a moth. It was then assumed that other species of butterflies are also sensitive to the Bt protein.

A feeding experiment was conducted in the laboratory for laboratory-bred butterflies. At 200 to 300 pollen grains per square centimeter, the first effects of Bt pollen diet was observed and manifested by a decrease in pollen consumption. Increasing pollen grains to 1,000 pollen grains per square centimeter resulted to high mortality compared with the conventional maize pollen.

Another study was conducted in the field to determine the amount of corn pollen that land on the food plants of butterflies under natural conditions. Pollen traps in the form of stinging nettle, Urtica dioica – plants with stinging hairs on stems and leaves were placed at different distances from the corn field. As might be expected, the highest amount of pollen at 150 pollen grains per square centimeters - one fifth of the lethal amount of protein, were found in the pollen traps directly at the field edge. The amounts of pollen, which resulted in the laboratory to an increased mortality of larvae, could therefore not be detected in the wild.

See the news in German at http://www.biosicherheit.de/presse/1353.schmetterlinge-bt-mais.html