No Damage to Monarch Butterfly

Contact: Ellen Ternes, Office of University Communications301-405-4626, [email protected] Dr. Galen Dively, 301 405 3913 (W) 301 441 1083 (alternate office)[email protected]

New Study Shows No Damage to Monarch Butterfly

COLLEGE PARK, Md - New findings show that the most commonly used types of genetically engineered corn have no adverse effects on Monarch butterfly larvae, according to Galen P. Dively, a University of Maryland scientist and member of the international team that has been studying the issue.

The study, released on September 14 by the Proceedings of the National Academies of Science, may put to rest the controversy over whether pollen from genetically engineered corn is killing the Monarch butterfly.

The two-year study examined the Monarch's exposure to pollen from the two major types of genetically altered corn currently in use and evaluated the toxic effects of that exposure. The study concluded that the impact on the butterfly is negligible.

Dively, an entomology professor in the University of Maryland's College of Agriculture and Natural Resources, and five other researchers from the U.S. and Canada undertook the study to answer questions that arose after a 1999 study showed that pollen from one type of genetically engineered corn could be toxic to the Monarch larvae. The U.S. Environmental Protection Agency, now deciding whether to reregister other strains of genetically engineered corn, wanted to know if they have the same effect.

The issue involves two emotionally charged leading characters - the beautiful and popular Monarch butterfly and a relatively new type of crop that has been genetically altered to repel a damaging insect.

With its flashy black-streaked wings of reddish orange, the Monarch butterfly is a remarkable insect. The only North American butterfly unable to stand freezing temperatures, the species annually flies 3000 miles from Canada to Mexico to winter over.

Along the way, the butterflies stop to breed, laying their eggs on the common milkweed, which often grows around cornfields. The larvae, or caterpillars, eat the milkweed leaves, eventually turn into butterflies, then take to the air to continue the trip their parents started. It usually takes two generations of a Monarch to complete the journey.

Enter genetically engineered corn. Also called Bt corn, this corn has been altered by transplanting into it genes of the naturally occurring bacteria Bacillus thuringienis (Bt), which produces a protein that kills the corn borer, a major corn pest. The corn borer can cut a crop's yield by as much as 20 per cent. Maryland, whose number one field crop is corn, and the surrounding states in the Delmarva peninsula have the largest corn borer population in the country.

"It's not feasible to control the corn borer with insecticide," said Dively, who works closely with Maryland farmers on pest control. "At the time the corn borer does its damage, the corn plants are so large that it is difficult to get the insecticide spray to where the corn borers are feeding.

"So this Bt corn essentially comes with a natural insecticide already in it. As the corn borer larvae eat the leaves and stalks of the Bt corn plants, they stop feeding and eventually die after several days."

Scientists agree that pollen from the Bt 176 type, which makes up only about two per cent of Bt corn now in use, can be toxic to Monarchs if too much of the pollen lands on milkweed near cornfields. The EPA will not reregister the Bt 176 type.

But the EPA wanted to make sure Bt 11 and Mon 810 corn did not pose a similar threat to the Monarch. To determine potential effects, Dively and the other researchers in Canada and the midwest measured how much corn pollen actually falls on milkweed in the Monarch's breeding areas. They then looked at the effects that amount of pollen has on the Monarch larvae.

"We put newly hatched larvae on milkweed that had the Bt pollen on it," said Dively. "We used the worse case scenario, with the Bt 11 sweet corn, which produces more pollen than field corn. After four days we found no effect on the larvae."

Other researchers in the study are based at Iowa State University, the University of Minnesota, the University of Nebraska and the University of Guelph, Ontario, Canada.

The study was funded by a pooled grant from the U.S. Department of Agriculture, the Maryland Agricultural Experiment Station, the Agricultural Biotechnology Stewardship Technical Committee -- a coalition of companies that produce genetically engineered corn -- the Canadian Food Inspection Agency, Environment Canada, the Ontario Ministry of Agriculture and the Leopold Center for Sustainable Agriculture.

The results of the study and the six papers that make up the research are available to the public through the Environmental Protection Agency and on the National Academies of Science website, http://www.pnas.org/papbyrecent.shtml. The results were originally scheduled to be released on October 1, but were published early on request from the EPA.

#No. 01173, Ternes, 9/18/01