英语听力文摘 求偶的蚊蚋
How to Meet an Eligible Gnat
夏夜，蚊子的嗡嗡声常令人抓狂，但对异性蚊子来说这或许是甜蜜的“情歌”。美国康奈尔大学研究人员的最新研究发现，埃及伊蚊就是通过这些嗡嗡声上演着求偶二重奏。
蚊子的嗡嗡声并非从蚊子口中发出，而是其飞行时翅膀快速振动产生的。雄性埃及伊蚊的振翅频率是600赫兹，雌性为400赫兹。研究人员发现，在求偶过程中，雄性和雌性伊蚊都会将振翅频率调整到1200赫兹。
此外，研究人员还将微电极植入埃及伊蚊的听觉器官中，结果发现这种伊蚊的听觉器官对频率高达200赫兹的声音都很敏感，而此前的研究认为，雄性蚊子听不到频率超过800的声音。
研究人员表示，埃及伊蚊能传播黄热病、登革热等疾病，对其求偶过程进行声学干预，或许可以在一些黄热病和登革热肆虐的地区控制埃及伊蚊的数量。
'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.
