VOA慢速英语2010年-SCIENCE IN THE NEWS - Locusts（在线收听）

BOB DOUGHTY: This is SCIENCE IN THE NEWS in VOA Special English. I’m Bob Doughty.

KATHERINE COLE: And I’m Katherine Cole. Today, we will tell how some insects might prove useful against hard-to-fight diseases. We will tell about a program to protect crops from harmful insects. We also will examine a possible effect of volcanic activity long ago. And we will describe an unusual recycling program.

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BOB DOUGHTY: People have feared locusts for thousands of years. The insects can destroy whole fields of crops. And very few people like cockroaches. They eat waste. They spread their own waste and carry disease germs that threaten human health.

But, wait, there may be something good about locusts and cockroaches. At least, scientists in England think so. They performed research that may help make possible new medicines to fight bacterial diseases that resist current drugs.

KATHERINE COLE: Simon Lee led a team of experts from the University of Nottingham. His team found that locusts and cockroaches carry substances that may help kill microbes. Mr. Lee is a graduate student in the School of Veterinary Medicine and Science at Nottingham University. He presented the findings at a meeting of the Society for General Microbiology.
　
Locusts

In experiments, the scientists combined substances from the American cockroach and the desert locust. They examined this material against disease-causing bacteria. E. coli is often an innocent bacterium. But the E. coli used in this study was responsible for the disease meningitis. The team also tested the insect material on methicillin-resistant staphylococcus aureus, also known as the disease MRSA.

BOB DOUGHTY: The scientists crushed the brains of the insects and combined them. They placed the combined material with the bacteria. The material and the bacteria were kept warm in an incubator for two hours. Next, the scientists put the material into special containers. The test material was left in culture dishes overnight.

Mr. Lee tested nerve tissue from the thorax of the desert locust separately. The thorax is a body part between the throat and the abdomen.

At the end of the experiments, ninety percent of the bacteria were dead. The scientists say they recognized up to nine molecules in the tissues that appeared to have killed the bacteria. Researchers have begun to test the molecules against other infections that are difficult to treat.

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A cloud of locusts in Cancun, Mexico, in 2006

KATHERINE COLE: Farmers know that if you reduce harmful insects and diseases in your crops, you have a chance for a better harvest. Today, many farmers and experts praise integrated pest management, or IPM. IPM is a series of choices and methods to control insects, diseases and fungi.

The program provides current information on how pests live and act in the environment. A number of nongovernmental and other organizations in many countries provide education in IPM.

James Frederick works for Clemson University’s Pee Dee Research and Educational Center in South Carolina. He says one IPM method is to plant as early in the season as possible so that most of the crop will be in by the time a disease or pest arrives. Not all insects are pests. Some are helpful. IPM programs help farmers learn to identify different kinds.

BOB DOUGHTY: Another IPM method is rotating crops. Farmers do not plant the same crop season after season in the same soil. Instead, they may plant corn one season, soybeans the next, then corn again.

Professor Frederick says farmers need information about what crops are best to plant. He says that sometimes disease-resistant crops will reduce harvests. He said a last choice would be chemical control. But he suggests using management methods first.

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KATHERINE COLE: Scientists in Russia are suggesting that climate change after volcanic activity caused Neanderthals to disappear from earth. The suggestion appeared recently in the publication Current Anthropology. The Neanderthals were early relatives of human beings. They lived in Europe until about forty thousand years ago.

Scientists from the ANO Laboratory of Prehistory in Saint Petersburg did the research. They proposed that huge volcanic explosions caused the Neanderthals to die out in Western Europe. As evidence, they point to the Caucasus Mountains of southern Russia.

BOB DOUGHTY: The scientists noted discoveries made in the Mezmaiskaya Cave, a hollow area in one of the mountains. Many Neanderthal bones and objects have been found there over time. The scientists studied two separate geological layers in the cave. They believe these layers of material were from the same time as major volcanic events. That was about forty thousand to forty-five thousand years ago.

The scientists say some ash in the cave formed after a volcano exploded in what is now Italy. Another ash layer formed around the same time as a smaller volcanic explosion that is thought to have taken place in the Caucasus.

KATHERINE COLE: The scientists say the geological layers show evidence of sudden climate change. They say the layers show reduced pollen compared to surrounding layers.

The scientists say the reduction means a change to a dryer and cooler climate. They propose that the explosions caused what is known as a volcanic winter. Such an event takes place when clouds of ash block sunshine for long periods, causing loss of warmth.

The change may have destroyed the local environment. The area for hunting animals became severely limited. Animal bones disappeared from the cave about forty-five thousand years ago.

BOB DOUGHTY: The research team proposes that loss of Neanderthal life helped human beings spread out their living area.

Early modern people were in more southern and western parts of Eurasia when the volcanoes erupted. But they escaped direct effect. About two thousand years passed. Then the humans moved north. The researchers say they were able to occupy the area that once was home to Neanderthals.

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KATHERINE COLE: Finally, recycling programs usually give new life to materials like paper, metal, plastic and glass. But a program in the eastern United States is recycling shellfish to help the Chesapeake Bay.

Oysters are filter feeders. That means they help clean the water. At the same time, generation upon generation of oysters form reefs. These structures provide homes for fish and crabs. Oysters are a Chesapeake tradition. And they are good for the bay. But environmental damage and too much harvesting have cut the oyster population of the Chesapeake.
　
As part of Maryland's oyster recovery program, children learn that marine life needs to be protected

BOB DOUGHTY: An organization called the Oyster Recovery Partnership started the recycling program earlier this year. Baby oysters need to attach themselves to a shell or other hard surface as they grow. Scientists are using recycled shells as part of an oyster reproduction program.

More than fifty restaurants, seafood dealers and other businesses have joined the Oyster Shell Recycling Alliance. Two states, Maryland and Virginia, are also taking part in the program.

KATHERINE COLE: The Oyster Recovery Partnership takes away oyster shells for recycling. First the shells get washed. Then they go to the Center for Environmental Science at the University of Maryland for further processing.

The shells are placed in containers with hundreds of millions of oyster larvae. This way, the baby oysters can be raised until they have grown big enough to be moved to the Chesapeake.

BOB DOUGHTY: This year, the Oyster Recovery Partnership helped produce and plant more than four hundred fifty million baby oysters in the bay. Don Meritt heads the oyster recovery program at the University of Maryland. He says the goal is not just to increase the oyster population.

DON MERITT: “Our real goal here is to try to bring healthy oyster populations back to the Chesapeake Bay so that we can help restore a healthy Chesapeake Bay. Not just a healthy oyster population, but a healthy bay."

BOB DOUGHTY: Mr. Meritt says it will take many years of work before the Chesapeake Bay has a good supply of oysters again.

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KATHERINE COLE: This SCIENCE IN THE NEWS was written by Jerilyn Watson. June Simms was our producer. I’m Katherine Cole.

BOB DOUGHTY: And I’m Bob Doughty. You can find transcripts, MP3s and podcasts of our programs at voaspecialenglish.com. Join us again next week for more news about science in Special English on the Voice of America.