VOA慢速英語(yǔ)：為什么蚊子會(huì)叮你？

蚊子有種驚人的能力，能夠遠(yuǎn)遠(yuǎn)地嗅到人類(lèi)，然后直接飛到他們的皮膚上。遺憾的是，蚊子叮咬的后果不僅僅是癢，一些蚊子還會(huì)傳播一些很?chē)?yán)重的疾病，包括登革熱、黃熱和瘧疾。

Mosquitoes need blood to survive and their favorite target is humans. Scientists find out why these insects prefer some people's skin more than others.

Over one million people worldwide die from these mosquito-borne diseaseseach year. New research now shows how mosquitos choose who to bite.

世界上每年有超過(guò)一百多萬(wàn)人民死于這些蚊子叮咬帶來(lái)的疾病。一項(xiàng)新的研究顯示了蚊子是如何選擇叮咬目標(biāo)的。

Mosquitoes need blood to survive. They are attracted to human skin andbreath. They smell the carbon dioxide gas -- which all mammals breathe out. This gas is how mosquitoes know that a warm-blooded creature is nearby.

蚊子靠血液生存。它們受人類(lèi)皮膚和呼吸吸引。它們能夠嗅到所有哺乳動(dòng)物呼出的二氧化碳?xì)怏w。這種氣體就是蚊子是如何察覺(jué)附近有溫血?jiǎng)游锎嬖诘脑颉?/p>

But mosquitoes also use their eyes and sense of touch. Michael Dickinson is a professor at the California Institute of Technology. His research shows howthese small insects, with even smaller brains, use three senses to find ablood meal.

但是蚊子也會(huì)用它們的視覺(jué)和觸覺(jué)。米歇爾·迪金森是加州理工學(xué)院的一名教授。他的一項(xiàng)調(diào)查顯示，這些小昆蟲(chóng)是如何用它們更小的腦袋和三種知覺(jué)發(fā)現(xiàn)血液大餐的。

"We suspected from research that we had been doing on fruit flies that visionmight play a very large and underappreciated role in allowing the mosquitoto really home in on the potential host target."

“根據(jù)我們對(duì)果蠅調(diào)查，我們懷疑視覺(jué)在蚊子找到潛在的目標(biāo)寄主中很可能起很大的但不受重視的作用。”

Michael Dickinson's team used plumes – material that rises into the air -- ofcarbon dioxide gas into a wind tunnel. They then used cameras to record themosquitoes. The insects followed the plume.

邁克爾·迪金森的研究小組用一種能夠飛到空中的羽毛飛進(jìn)二氧化碳?xì)怏w風(fēng)道。他們接著用相機(jī)記錄這些蚊子。蚊子跟著羽毛飛行。

Then, the scientists placed dark objects on the lighter colored floor and wallsof the tunnel. Mr. Dickinson said, at first, the mosquitoes showed no interest in the objects at all.

后來(lái)，科學(xué)家們?cè)陬伾^淺的風(fēng)道的地板上和墻上放置深色物體。迪金森說(shuō)，剛開(kāi)始，這些蚊子對(duì)這些物體一點(diǎn)也不感興趣。

"What was quite striking and quite surprising is that the mosquitos fly backand forth for hours--these are hungry females--and they completely ignore theobjects on the floor and wall of the tunnel. But the moment that they get a hit of CO2, they change their behavior quite dramatically and now would becomeattracted to these little visual blobs."

真正驚訝的是有蚊子來(lái)來(lái)回回地飛了幾個(gè)小時(shí)，這些都是饑餓的母蚊子，它們完全忽視管道里的地板上和墻壁上的物體。但是一旦它們問(wèn)到了二氧化碳的味道，它們立刻行為大變，對(duì)那些物體立馬有了興趣。

This suggested to the researchers that a mosquito’s sense of smell is moreimportant in the search for food. Once mosquitoes catch a smell of a humanor animal, they also follow visual cues.

這項(xiàng)研究表明，蚊子在尋找食物時(shí)嗅覺(jué)比視覺(jué)更重要。一旦蚊子問(wèn)到了人類(lèi)或者動(dòng)物的味道，它們也會(huì)有視覺(jué)線索。

"This really makes a lot of sense because if the mosquitoes were distractedby every visual object in their world, they would just waste all their time. Thiscase, they only start paying attention when their nose tells them that theremight be a host nearby."

這真的很有意義，因?yàn)槿绻米颖凰鼈兪澜缰忻恳晃矬w分心，它們只是在浪費(fèi)時(shí)間。在這種情況下，它們一旦嗅到有可能是寄主的味道，才開(kāi)始集中注意力。

This process happens several times over the course of a mosquito's flight.Michael Dickinson explains.

這種情況在蚊子爭(zhēng)斗的過(guò)程中時(shí)有發(fā)生。邁克爾·迪金森解釋道，

"What some of the details of our experiments indicated is that it's very hard tofool them over the long run. They will always get their man or woman overtime because they'll just keep repeating this strategy until they find a yummymeal. "

我們這項(xiàng)實(shí)驗(yàn)中一些細(xì)節(jié)顯示，很難長(zhǎng)時(shí)間欺騙蚊子，它們永遠(yuǎn)會(huì)得到它們的寄主，因?yàn)樵谡业窖捍蟛颓?，它們?huì)一直重復(fù)這種策略。

Matt DeGennaro is a scientist at Florida International University. He saysunderstanding a mosquito’s way of finding its host could help prevent thoseinsects from biting. He is working to create genetic changes that affect themosquito's sense of smell.

馬特是佛羅里達(dá)國(guó)際大學(xué)的一名科學(xué)家。他表示，研究蚊子如何找到宿主的方式能夠幫助防止被這些蚊子叮咬。他正在致力于改變影響蚊子嗅覺(jué)的基因。

"We need to know which genes control this process at all these differentstages. And then we can use that knowledge to design a new perfume thatcould block the mosquito's sensation of us or could trigger certain receptorsthat signal danger to the mosquito and then cause them to stay away."

我們需要知道在不同的階段哪些基因控制這個(gè)過(guò)程。我們可以運(yùn)用這種知識(shí)來(lái)設(shè)計(jì)一款新式香水，防止蚊子感覺(jué)到我們，或者向蚊子發(fā)出危險(xiǎn)信號(hào)，趕它們走開(kāi)。

The study, published in Current Biology, details the steps of the mosquito'sflight so that we may one day have a fighting chance against the biting insect.

這次研究發(fā)表在《現(xiàn)代生物》雜志上，詳細(xì)的記載了蚊子的飛行，因此我們可能有一天有機(jī)會(huì)反擊這些咬人的昆蟲(chóng)。

I’m Marsha James.

瑪莎·詹姆斯為您播報(bào)。

Maia Pujara reported this story from Washington. Marsha James adapted it for Learning English. Caty Weaver was the editor.

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Words in This Story

host– n. an animal or plant in which another animal or plant lives and gets itsfood or protection

underappreciated– adj. not given the respect or thanks that is deserved

plume– n. something (such as smoke, steam, or water) that rises into the airin a tall, thin shape

blob – n. something that does not have a regular shape

cue – n. something that suggests the nature of what is being seen, smelled, heard etc.

yummy – adj. very pleasing to the taste

trigger– v. to cause something to start or happen

receptor – n. a nerve ending that senses changes in light, temperature,pressure, and causes the body to react in a particular way