VOA慢速英语 2008 0512a

Development Report - Secret of DEET Could Lead to New Insect Products
Scientists finally discover how the world's most widely used insecticide works. Transcript¹ of radio broadcast:
11 May 2008

This is the VOA Special English Development Report.
　

DEET molecules2

There are new findings about an old method for keeping away insects. Scientists have uncovered the molecular³ workings of DEET.

DEET is the most widely used product for preventing insect bites. The scientists say their findings could lead to better insecticide products.

Fifty years ago, the United States Army and the Department of Agriculture developed DEET to protect soldiers from disease-carrying insects. Since then, it has been used to guard against blood-sucking insects, like mosquitoes carrying malaria⁴. DEET has been shown to work on almost all insects, including ticks, which spread Lyme disease.

Until recently, no one had explained exactly how the product keeps insects away from skin. Some people thought that because DEET’s strong smell is not pleasing to human beings, it also smelled bad to insects. But the new study shows that DEET temporarily interferes⁵ with an insect’s ability to smell.

Leslie Vosshall is a professor of neurogenetics at Rockefeller University in New York. She was the lead investigator⁶ of the study.

Her team carried out experiments with mosquitoes and fruit flies. She says they discovered proteins in the antennae⁷ of both insects that identify several smells. The antennae help the insects identify smells, including those of human breath and sweat. As a result, the insects are able to identify human beings as food.

Professor Vosshall says DEET works by stopping some of the smell proteins, or receptors, in the antennae. When insects come in contact with DEET, they are no longer able to guide themselves to their target. She says the insects do not bite people wearing DEET because they cannot smell them. Other studies have suggested that DEET affects the smelling abilities of insects. But the new study is the first to identify DEET’s molecular targets.

DEET is widely used and found in more than one hundred products. It is not considered dangerous when placed on clothing and unprotected arms and legs. But DEET is not advised for young children, especially those under two months old. Concerns about possible health risks have led scientists to work on improvements.

Professor Vosshall says the new information about DEET could help in the development of other, safer products. She says such products could even be used on babies.

And that's the VOA Special English Development Report, written by Brianna Blake.

　

1 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

2 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

3 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

4 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

5 interferes   

vi. 妨碍，冲突，干涉

参考例句：

• The noise interferes with my work. 这噪音妨碍我的工作。
• That interferes with my plan. 那干扰了我的计划。

6 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

7 antennae   

n.天线；触角

参考例句：

• Sometimes a creature uses a pair of antennae to swim.有时某些动物使用其一对触须来游泳。
• Cuba's government said that Cubans found watching American television on clandestine antennae would face three years in jail.古巴政府说那些用秘密天线收看美国电视的古巴人将面临三年监禁。