A new study has found that pollen from genetically-changed corn plants can harm Monarch butterflies.
Research scientists at lowa State University confirmed results of an earlier study that examined the environmental effects of a product called B-t corn.
However,a group that represents the genetic engineering industry disputes the findings.
B-t corn was developed by a process of genetic engineering.
Genetic engineering is the technology of changing the genes of living things.
The changed gene directs the plant or other organism to do things it normally does not do.
B-t corn seeds were given a gene from a bacterium that produces a poison.
The poison kills harmful insects that eat the corn plants.
The insects cause an estimated one-thousand-million dollars in damage to corn each year.
American farmers began using B_t corn four years ago.
The plants have helped increase crop production.
They also have reduced the need for farmers to use chemicals to kill harmful insects.
Today,about one-third of all corn grown in the United States is B-t corn.
Many of the plants are grown in areas where monarch butterflies live.
Last year,Cornell University researchers reported B-t corn might be killing the caterpillars that turn into monarch butterflies.
They said pollen from the corn could blow onto other plants the insects eat.
Pollen is a reproductive substance made by plants.
Monarch caterpillars feed only on milkweed plants.Milkweed commonly grows in or near cornfields.
The Iowa State researchers collected leaves from milkweed growing near cornfields.
Pollen had blown onto the leaves.They fed the leaves to monarch caterpillars in the laboratory.
The caterpillars that ate leaves with pollen from traditional corn survived.
However,about twenty percent of the caterpillars that ate leaves with B-t pollen died.
The Biotechnology Industry Organization said twenty other unpublished studies dispute the findings.
The group says those studies have shown that B-t corn has little effect on Monarch butterflies.
The Environmental Protection Agency also is studying the possible effects of B-t corn on the environment.
The agency has announced that permits to sell B-t corn seed will be extended for another year.