英語聽力文摘 求偶的蚊蚋

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How to Meet an Eligible Gnat

夏夜，蚊子的嗡嗡聲常令人抓狂，但對異性蚊子來說這或許是甜蜜的“情歌”。美國康奈爾大學研究人員的最新研究發(fā)現，埃及伊蚊就是通過這些嗡嗡聲上演著求偶二重奏。

蚊子的嗡嗡聲并非從蚊子口中發(fā)出，而是其飛行時翅膀快速振動產生的。雄性埃及伊蚊的振翅頻率是600赫茲，雌性為400赫茲。研究人員發(fā)現，在求偶過程中，雄性和雌性伊蚊都會將振翅頻率調整到1200赫茲。

此外，研究人員還將微電極植入埃及伊蚊的聽覺器官中，結果發(fā)現這種伊蚊的聽覺器官對頻率高達200赫茲的聲音都很敏感，而此前的研究認為，雄性蚊子聽不到頻率超過800的聲音。

研究人員表示，埃及伊蚊能傳播黃熱病、登革熱等疾病，對其求偶過程進行聲學干預，或許可以在一些黃熱病和登革熱肆虐的地區(qū)控制埃及伊蚊的數量。

'How to Meet an Eligible Gnat' on this Moment Of Science.

Have you ever walked into a swarm of insects–gnats, mosquitoes, or one of their many cousins–and then found yourself unable to shake the swarm? You fake left, go right, but the little buggers still hover above. As if it that weren’t bad enough, did you know your head had just become the happening scene, where every hip gnat wants to be–in other words, the insect world’s equivalent of a singles bar?

That’s right, swarms are places for the sexes to meet and greet. The first time an entomologist reported the purpose of swarms was in 1906. Frederick Knab wrote that he’d netted 901 mosquitoes from a swarm, but only 4 were females!

Here’s how Knab explained it: males gather around some landmark–a cornstalk, perhaps the head of an unsuspecting human–and wait for eligible females. When a female enters the swarm, the males immediately pick up her flight tone, which is different from theirs. Coupled with one lucky guy, she flies to some protected place to mate.

After their interlude, the female goes to lay her eggs, but the male returns to the swarm, on the outside chance that he’ll get lucky once more. That’s why Knab netted so many more males than females.

Sometimes, these gatherings get quite large. In Germany, in 1807, people saw a huge cloud of smoke billowing over a church. So they called in the fire brigade, only to realize that the dark cloud was actually a swarm of gnats who’d picked the church steeple as their rendezvous.