VOA慢速英语2014 科学家们寻找新的方法来对付蚊子

AS IT IS 2014-05-25 Scientists Search for New Ways to Stop Mosquitoes 科学家们寻找新的方法来对付蚊子

The sound of a mosquito can mean trouble in many parts of the world.  The bite of a mosquito can be deadly. Today, we will hear about some of the diseases these insects carry and what scientists are doing to help protect people.

We begin with one of the most common diseases linked to mosquitoes: malaria¹.  The World Health Organization estimates that almost 630,000 people died from malaria and malaria-related causes in 2012.  Most of these cases were in African countries south of the Sahara Desert. 

In the United States, scientists are seeking new ways to fight malaria.  A group of California researchers is working to develop more effective and less costly² ways to protect people from mosquitoes.  The researchers work at the University of California Riverside.  They are investigating mosquitoes’ sense of smell.  They found the insects use the same receptor for identifying carbon dioxide in human breath as they do for the smell of our skin.  

Anandasankar Ray is leading the investigation³.  He says scientists tested more than a million chemical compounds until they found a substance called Ethyl pyruvate.  He says Ethyl pyruvate makes the mosquito’s receptor inactive.

“When we apply Ethyl pyruvate to a human arm and offer it to the mosquitoes -- hungry mosquitoes in a cage -- then very few of the mosquitoes are attracted to the human arm because only a few of them are able to smell it out.”

Genevieve Tauxe is a member of the UC Riverside research team.  She says it was not easy to find the neurons, or nerve cells, that recognize both the smell of human breath and skin.  She describes a device the researchers are using to examine mosquitos.

“With this apparatus⁴, we’re able to insert a very small electrode into the part of the mosquito's nose, effectively, where it’s olfactory⁵ neurons are and where the smell is happening.”

The scientists use these instruments to look for the signals that a mosquito's neurons send to its brain when it finds an interesting smell.  Computer screen images show when the sense is strong or weak. 

Anandasankar Ray says a product based on Ethyl pyruvate may cost less to manufacture than DEET, the most effective chemical treatment now in use.  He says DEET is too costly for most people who live in areas affected⁶ by malaria. 

“Perhaps by finding odors that can attack other target receptors, we will be able to improve upon DEET and finally have the next generation of insect behavior control products.”

The scientists believe they will soon be able to find a way to manufacture less costly and more effective products for the fight against mosquitoes.  

I'm Jonathan Evans in Washington.

1 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。

2 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

3 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。

4 apparatus   

n.装置，器械；器具，设备

参考例句：

• The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
• They had a very refined apparatus.他们有一套非常精良的设备。

5 olfactory   

adj.嗅觉的

参考例句：

• He is to develop a sensor to substitute for the olfactory abilities of dogs.克罗克将研制一种传感器用以代替狗的嗅觉功能。
• Based on these findings, Keller suspects that each person has an olfactory blind spot.根据这些发现，凯勒推断，每个人都有一个嗅觉盲区。

6 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。