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Is GM corn killing monarch butterflies?

Broadcast Date: Oct. 8, 2000

The colourful black and orange insect has become an unlikely symbol in the debate over genetically modified food. An explosive study published in the journal Nature has sent the world aflutter. It suggests that GM corn could be harmful to the monarch butterfly, reports CBC's Kelly Crowe. The Cornell University research and subsequent studies looked at pollen from a strain of corn that had been genetically modified to produce a pesticide. That pollen seems to be killing monarch caterpillars.

While environmentalists point to the study as proof of GM food's harmful effects, scientists, including the study's authors, warn against jumping to conclusions about the preliminary studies.

Is GM corn killing monarch butterflies?

• Dr. John Losey, the entomologist from Cornell University in Ithica, N.Y., who was the lead author of the original study, wrote on the university's website that: "Pollen from Bt corn could represent a serious risk to populations of monarchs and other butterflies, but we can't predict how serious the risk is until we have a lot more data. And we can't forget that Bt corn and other transgenic crops have a huge potential for reducing pesticide use and increasing yields." (May 1999)

• The study showed that monarch larvae that were fed milkweed leaves artificially coated with Bt corn pollen ate less, grew slower and suffered a higher death rate than larvae that consumed milkweed leaves free of Bt corn pollen.

• Some scientists, including University of Guelph's Mark Sears, told CBC's Bob McDonald that in actual field conditions the risks associated with genetically modified corn are minimal. Sears warned against blowing John Losey's original study out of proportion, and called for further research.

• Linda S. Rayor, who co-authored the Nature study, said the considerable media attention may be due to the monarchs themselves. Although monarchs are not an endangered species, the pretty butterflies have become a poster child for naturalists and conservationists.

Is GM corn killing monarch butterflies?

Medium: Television

Program: Sunday Report

Broadcast Date: Oct. 8, 2000

Reporter: Kelly Crowe

Duration: 2:40

Last updated:
May 27, 2008