09/1999 Steven Milloy's Junk-Science Report

09/1999 Steven Milloy's Junk-Science Report
September 1, 1999



In a scene reminiscent of a John Belushi "killer bee" skit from "Saturday Night Live," anti-technology activists dressed like butterflies in late June and demanded that European environment ministers ban the growing of genetically modified crops. "Give butterflies a chance," their banners read.

What is it about activists that makes them want to dress up like cows or vegetables or butterflies? Everybody else waits until Halloween. These folks wait for the next scientific study they can exploit into a "the sky is falling" scenario. Then they stitch up a costume and get their pictures in the paper.

This time, a laboratory study out of Cornell University was their inspiration. The study concluded that Monarch butterflies can die if they are forced to eat pollen from corn genetically enhanced with a gene from the Bacillus thuringiensis (Bt) bacteria to protect against insects.

The study gave no indication of how much pollen Monarchs would have to eat to be harmed, or whether they would actually eat the pollen if they could choose not to. It was a simple experiment that proved what entomologists already knew. Bt corn is toxic to lepidopteran insects that feed on corn, and it is not news that other moths and butterflies could be harmed if they ate Bt corn or pollen.

The author of the study, Professor John Losey, does not believe his study means curtains for the Monarch. "Our study was conducted in the laboratory and, while it raises an important issue, it would be inappropriate to draw any conclusions about the risk to Monarch populations in the field based solely on these initial results," Losey said in a June 11 interview.

Maybe the Europeans missed that interview . . . but Losey said essentially the same thing on British radio the day his study summary was released in the journal Nature. "I don't think it's a scare story, because we're showing that this is only a laboratory study. At this point, I can't see pulling back on the Bt crops because of their proven benefits weighed against potential risks," Losey told the BBC on May 20.

On the same day, he was quoted in the Associated Press, saying, "I still think the proven benefits of Bt corn outweigh the potential risks."

One of the proven benefits is that the growing of Bt crops reduces the use of chemical insecticides, and that can have a positive impact on ladybugs, lacewings, and other insects that frequent cornfields. In turn, this could have a positive downstream benefit for birds that feed on insects. In fact, anecdotal evidence suggests that farmers who have switched to Bt are seeing more birds in and around their fields.

Other scientists have weighed in on the issue as well:

  • Warren Douglas Stevens, senior curator of the Missouri Botanical Garden, suspects that in a natural setting butterflies, which apparently don't like corn pollen, would avoid eating it if they encountered it on their food source.
  • Tom Turpin, professor of entomology at Purdue University, believes there is little threat to Monarch butterflies encountering Bt pollen on milkweed, because there is very little milkweed in and around cornfields.
  • Preliminary studies have shown that corn pollen, which is fairly heavy, does not travel very far.
  • John Foster, professor of entomology at the University of Nebraska, believes automobiles pose a greater risk to Monarchs than does Bt corn.

All those scientists, and Losey himself, say more study is needed to know if butterflies in nature would ever encounter enough Bt corn pollen, during the few days a year when corn is pollinating, to cause any serious harm.

But waiting on data is not nearly as much fun as dressing up for the media. In fact, many in the media have been as guilty as the activists, dressing up this laboratory study to make it look like something it is not.


Steven Milloy is a public health specialist at the Cato Institute and publisher of the Junk Science Home Page http://www.junkscience.com.