This is the VOA Special English Agriculture Report.
are a traditional threat to cotton crops. Young ones feed on the boll, the part
of the cotton plant that contains the seeds.
A bacterium known as Bt is able
to kill bollworms and some other pests. Bt is short for Bacillus thuringiensis.
It was discovered in the early twentieth century. Farmers began using Bt as a natural
Then, in the nineteen nineties, researchers found a way
to grow cotton plants that contain a Bt gene. The genetically modified cotton
plant produces toxins that kill bollworms. Farmers around the world are now
growing an estimated fourteen million hectares of Bt cotton.
Cotton bollworms also attack other crops. But
scientists in China recently reported that Bt cotton may help suppress bollworm
in other crops growing nearby.
study involved crops grown in six provinces of northern China between nineteen
ninety-two and two thousand seven. The study area contained three million
hectares of cotton and twenty-two million hectares of corn, peanuts, soybeans
The researchers say the study suggested
that Bt cotton not only controls bollworm on the transgenic cotton, but also
may reduce its presence on other crops. And that reduction, they say, may
decrease the need for insecticide sprays in general.
the researchers also pointed out concerns. They say bollworms could develop
resistance to the cotton plants designed to resist them. And they noted that
insects called mirids have become "key pests" of cotton in China.
They said this is because of a decrease in pesticide use made possible by Bt
researchers say they do not believe that Bt cotton alone can solve all insect
problems. Instead, they say farmers in China should consider it just one part
of pest management systems.
Wu of the Chinese Academy of Agricultural Sciences in Beijing led the study. The
findings appeared in Science magazine.
British group, the Institute of Science in Society, said the findings were
presented in a way that could mislead readers. The group noted that the only part
of the study available online at no cost, a short abstract, said nothing about the
that’s the VOA Special English Agriculture Report, written by Jerilyn Watson
with additional reporting by Jessica Berman. I’m Bob Doughty.