蚊子是如何進化到被人類吸引的，這對未來意味著什么

蚊子是如何進化到被人類吸引的，這對未來意味著什么

Not all mosquitoes are created equal, even if it feels that way when they bite you.

并非所有的蚊子都是生而平等的，即使它們叮咬你時的感覺是一樣的。

There are about 3,500 species of mosquitoes around the world, but only a few are responsible for spreading infectious diseases to humans.

世界上大約有3500種蚊子，但只有少數(shù)幾種會向人類傳播傳染病。

Among those mosquitoes that are thirsty for human blood is the Aedes aegypti, which is the primary spreader of yellow fever, Zika virus, dengue and Chikungunya virus.

在那些嗜血的蚊子中有埃及伊蚊，它是黃熱病、寨卡病毒、登革熱和基孔肯雅病毒的主要傳播者。

But how did Aedes aegypti mosquitoes evolve to specialize in biting people? New research published today in the journal Current Biology has revealed that two factors play a major role: dry climate and city life.

但是埃及伊蚊是如何進化成專門叮咬人類的呢?今天發(fā)表在《當(dāng)代生物學(xué)》雜志上的一項新研究顯示，有兩個因素在其中發(fā)揮了重要作用:干燥的氣候和城市生活。

Scientists studied mosquitoes across sub-Saharan Africa and found that mosquitoes actually have wide-ranging palates.

科學(xué)家研究了撒哈拉以南非洲地區(qū)的蚊子，發(fā)現(xiàn)蚊子的味覺其實很廣泛。

"There's a huge diversity in mosquito preferences. Some like to bite humans and others don't like to bite humans at all," said the paper's co-author Noah Rose, a postdoctoral researcher at Princeton University in New Jersey.

“蚊子的偏好有很大的差異。有些喜歡咬人，有些則根本不喜歡咬人，”論文的合著者、新澤西州普林斯頓大學(xué)的博士后研究員諾亞·羅斯說。

"At first we thought that mosquitoes who lived around people would simply like to bite people and that those who lived in the forests wouldn't like to bite humans," Rose said. "We were really surprised that that wasn't the case."

羅斯說:“一開始，我們認為生活在人類周圍的蚊子只會叮咬人類，而生活在森林里的蚊子不會叮咬人類。”“我們真的很驚訝事實并非如此。”

While mosquitoes living near dense cities such as Kumasi, Ghana, or Ouagadougou, Burkina Faso, showed increased willingness to bite humans, researchers found that city life alone didn't explain the mosquitoes' evolution. In fact, any mosquitoes living in large cities still preferred to bite animals rather than human hosts.

盡管蚊子生活在加納的庫馬西或布基納法索的瓦加杜古等人口密集城市附近，但它們更愿意叮咬人類，研究人員發(fā)現(xiàn)，城市生活本身并不能解釋蚊子的進化。事實上，任何生活在大城市的蚊子仍然更喜歡叮咬動物而不是人類。

That's where the second factor -- dry climate -- comes in. In areas with harsh dry seasons, such as Africa's Sahel region, extending from Senegal to Sudan and Eritrea, mosquitoes evolved to have a strong preference for humans.

這就是第二個因素出現(xiàn)的原因——干燥的氣候。在干旱季節(jié)惡劣的地區(qū)，比如非洲的薩赫勒地區(qū)(從塞內(nèi)加爾延伸到蘇丹和厄立特里亞)，蚊子進化得對人類有強烈的偏好。

"Mosquitoes are dependent on containers of water for their larvae," Rose told CNN. "So in places with an intense long dry season, mosquitoes become very dependent on humans who store water."

“蚊子依賴裝有水的容器來喂養(yǎng)它們的幼蟲，”羅斯告訴CNN。“所以在干旱季節(jié)非常漫長的地方，蚊子變得非常依賴儲存水的人類。”

The mosquitoes' evolution to bite humans is a by-product of their dependency on breeding in areas close to human city life. That means urbanization in the coming decades could lead to even more human-biting mosquitoes in the future.

蚊子進化成叮咬人類，是它們依賴于在靠近人類城市生活的地區(qū)繁殖的副產(chǎn)品。這意味著未來幾十年的城市化可能會導(dǎo)致更多叮咬人類的蚊子。

Urbanization to spark further change in mosquitoes

城市化將進一步引發(fā)蚊子的變化

Sub-Saharan Africa is expected to see an increase in the total number of births over the next several decades, as well as increasing life expectancy, according to population projection datafrom the United Nations. That means a projected population increase of 1.05 billion in sub-Saharan African countries in the next three decades, for an estimated total population of more than 2.1 billion people.

根據(jù)聯(lián)合國的人口預(yù)測數(shù)據(jù)，在未來幾十年，撒哈拉以南非洲地區(qū)的出生人數(shù)將會增加，預(yù)期壽命也會延長。這意味著，預(yù)計撒哈拉以南非洲國家的人口在未來30年將增加10.5億，估計總?cè)丝趯⒊^21億。

The new research predicts this rapid urbanization will drive further mosquito evolution, causing a shift toward biting humans in many large cities by 2050.

這項新的研究預(yù)測，這種快速的城市化將進一步推動蚊子的進化，導(dǎo)致到2050年許多大城市的蚊子轉(zhuǎn)向叮咬人類。

"We should be watching these mosquitoes," said Rose, noting that the future of mosquito adaptations is still uncertain.

“我們應(yīng)該觀察這些蚊子，”羅斯說，并指出蚊子適應(yīng)的未來仍然不確定。

"We don't really know what will happen when the urbanization of sub-Saharan Africa moves beyond what we see in the present day. But we know something will happen and we think that it will be a shift to biting more human hosts."

他說:“我們真的不知道當(dāng)撒哈拉以南非洲地區(qū)的城市化超越我們目前所看到的水平時，會發(fā)生什么。但我們知道會發(fā)生一些事情，我們認為這將是一個轉(zhuǎn)變，(蚊子會)咬更多的人類宿主。”

That means the way mosquitoes spread disease could also change.

這意味著蚊子傳播疾病的方式也可能改變。