[00:00.00]本套LRC同步字幕为我爱英语屋（QQ:18469114）整理制作，祝您英语学习顺利,生活称心如意！
[00:00.50]更多LRC同步字幕资料尽在：http://shop36187450.taobao.com或http://18469114.paipai.com
[00:01.00]A new study has found that pollen from genetically-changed corn plants can harm Monarch butterflies.
[00:10.64]Research scientists at lowa State University confirmed results of an earlier study that examined the environmental effects of a product called B-t corn.
[00:26.18]However,a group that represents the genetic engineering industry disputes the findings.
[00:34.93]B-t corn was developed by a process of genetic engineering.
[00:42.11]Genetic engineering is the technology of changing the genes of living things.
[00:49.40]The changed gene directs the plant or other organism to do things it normally does not do.
[00:59.43]B-t corn seeds were given a gene from a bacterium that produces a poison.
[01:07.27]The poison kills harmful insects that eat the corn plants.
[01:14.01]The insects cause an estimated one-thousand-million dollars in damage to corn each year.
[01:22.47]American farmers began using B_t corn four years ago.
[01:29.11]The plants have helped increase crop production.
[01:33.76]They also have reduced the need for farmers to use chemicals to kill harmful insects.
[01:42.22]Today,about one-third of all corn grown in the United States is B-t corn.
[01:50.50]Many of the plants are grown in areas where monarch butterflies live.
[01:57.87]Last year,Cornell University researchers reported B-t corn might be killing the caterpillars that turn into monarch butterflies.
[02:10.80]They said pollen from the corn could blow onto other plants the insects eat.
[02:18.35]Pollen is a reproductive substance made by plants.
[02:23.55]Monarch caterpillars feed only on milkweed plants.Milkweed commonly grows in or near cornfields.
[02:34.94]The Iowa State researchers collected leaves from milkweed growing near cornfields.
[02:43.77]Pollen had blown onto the leaves.They fed the leaves to monarch caterpillars in the laboratory.
[02:52.54]The caterpillars that ate leaves with pollen from traditional corn survived.
[02:59.46]However,about twenty percent of the caterpillars that ate leaves with B-t pollen died.
[03:07.04]The Biotechnology Industry Organization said twenty other unpublished studies dispute the findings.
[03:16.29]The group says those studies have shown that B-t corn has little effect on Monarch butterflies.
[03:24.52]The Environmental Protection Agency also is studying the possible effects of B-t corn on the environment.
[03:33.53]The agency has announced that permits to sell B-t corn seed will be extended for another year.
