Study: GM Corn Harms Monarch Butterflies

Iowa State University researchers said today they found more evidence that pollen from bioengineered corn could be deadly for Monarch butterflies, prompting environmentalists to renew demands for tighter restrictions on the crop.

The Iowa study published in the journal Oecologia comes at a time when the U.S. Environmental Protection Agency has launched its own review of the safety of corn and cotton plants modified to contain a pest-fighting gene.

The Clinton administration has faced growing pressure during the past year from consumer and environmental groups, as well as some U.S. trading partners, who say not enough is yet known about the long-term safety of biotech crops. The seed industry and agribusiness contend that gene-spliced crops have undergone thousands of tests and pose no more safety risks than conventional crops.

Iowa State researchers John Obrycki and Laura Hansen said their research showed Monarch butterfly caterpillars were seven times more likely to die when they ate milkweed plants carrying pollen from Bt corn, compared to conventional corn.

Gene Used as Pesticide

Bt is short for bacillus thuringiensis, a naturally occurring soil bacterium that acts as a pesticide. The gene has been inserted into millions of acres of UL.S. corn and cotton plants to repel the European corn borer, bollworms and other pests.

The researchers placed potted milkweed plants in and around Bt cornfields to simulate naturally occurring conditions.

Pollen from Bt crops also drifts onto nearby plants, including those eaten by harmless insects like the Monarch. The orange and black butterflies are at greatest risk within 10 meters of Bt fields, Obrycki said in an interview.

“There exists a good possibility that we will see some mortality of Monarchs in the field,” he said. “The level and amount will depend on the timing of when the corn is shedding its pollen and when the Monarch larvae are in the fields.”

The Iowa study analyzed the impact on larvae from two types of BB corn developed by Novartis AG and sold under the brand names NatureGard and Attribute. The research built upon work by Cornell scientists who created a stir one year ago when they reported Monarch larvae died when fed relatively large amounts of Bt corn pollen in the laboratory.