Bt corn poses little risk to monarchs

Four of the five Bt corn products marketed in the U.S. do not pose threats to monarch butterflies because they express very low levels of the Bt toxin in pollen, a U.S. Department of Agriculture scientist reported Thursday at a meeting of the agency's advisory committee on biotechnology. The research was prompted by a study that suggested that the caterpillars, which subsist exclusively on milkweed leaves, could be killed when they encounter corn pollen that contains Bt (see BioCentury May 24 and Nov. 8, 1999).

Rick Hellmich, a researcher at USDA's Agricultural Research Service, said that feeding tests indicated that exposure to the amounts of pollen that fall in corn fields using four Bt corn products has almost no effect on monarchs and the amount that falls two meters from the field had absolutely no effect. ...