英语听力精选进阶版 7286

科学家可能已找到对付臭虫（又称床虱）的办法。这类昆虫非常难控制，不过近期的科研结果有希望帮助科学家们研制出一系列新的、更有效的控制这一害虫的方法。

They feast on our blood while we sleep - leaving itchy, red welts as their calling card. Bedbugs are an insect that many would like to see the back of. But in North America, Europe and Australia, infestations¹ are on the rise - and our insecticides are losing their bite.

Researchers at the University of Kentucky in the US have found 14 genes² associated with resistance to these chemicals. They're causing a number of biological changes in the bedbugs. These include the development of a thicker skin that stops the poisons from penetrating³ and mutations within the insects' bodies that prevent the toxins⁴ from hitting the nervous system.

The genes linked to these changes are active in the insect's tough outer shell - creating a formidable first line of defence. These findings could help scientists to develop new insecticides that could either turn these genes off or bypass the pest's molecular⁵ shields.

But until these substances are developed, exterminators are having to resort to more primitive⁶ tactics.

Quiz 听力测验

True or False? The number of bedbugs is rising in North America, Europe and Australia.

True. Infestations are on the rise in North America, Europe and Australia.

True or False? Researchers in the US found 14 genes inside bedbugs that are resistant⁷ to insecticides.

True. Researchers at the University of Kentucky in the US have found 14 genes associated with resistance to the insecticides.

Which biological changes are caused by the 14 insecticide-resistant genes found in the bedbugs?

The changes include the development of a thicker skin that stops the poisons from penetrating and mutations within the insects' bodies that prevent the toxins from hitting the nervous system.

Why do bedbugs have a formidable first line of defence?

Because the genes linked to the biological changes are active in the insect's tough outer shell.

Glossary 词汇表

itchy 发痒的，瘙痒的

welts 红色肿块

calling card （留下来过的）标示、证据

infestations （害虫）大批出没、猖獗

insecticides 杀虫剂，杀虫药

penetrating 渗透，进入

mutations （基因）变异

toxins 毒素

formidable 强大的，难以对付的

exterminators 消除有害动物（如害虫）为职业的人

1 infestations   

n.（害虫、盗贼等）群袭，出没，横行( infestation的名词复数 )

参考例句：

• The arrival of warm weather raises the specter of disease and increased rat infestations caused by rotting garbage. 天气转暖使人们担心垃圾腐烂会引起疾病传播和鼠群猖獗。 来自《简明英汉词典》
• Piperazine citrate is the drug of choice in the treatment of Ascaris infestations. 枸橼酸哌嗪治疗蛔虫感染是最好的药物。 来自辞典例句

2 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

3 penetrating   

adj.（声音）响亮的，尖锐的adj.（气味）刺激的adj.（思想）敏锐的，有洞察力的

参考例句：

• He had an extraordinarily penetrating gaze. 他的目光有股异乎寻常的洞察力。
• He examined the man with a penetrating gaze. 他以锐利的目光仔细观察了那个人。

4 toxins   

n.毒素( toxin的名词复数 )

参考例句：

• The seas have been used as a receptacle for a range of industrial toxins. 海洋成了各种有毒工业废料的大容器。
• Most toxins are naturally excreted from the body. 大部分毒素被自然排出体外。 来自《简明英汉词典》

5 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。

6 primitive   

adj.原始的；简单的；n.原(始)人，原始事物

参考例句：

• It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
• His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。

7 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。