科學家教你如何打蒼蠅

The brains of flies are wired to avoid the swatter, US researchers said on Thursday.

At the mere hint of a threat, the insects adjust their preflight stance to flee in the opposite direction, ensuring a clean getaway, they said in a finding that helps explain why flies so easily evade swipes from their human foes.

"These movements are made very rapidly, within about 200 milliseconds, but within that time the animal determines where the threat is coming from and activates an appropriate set of movements to position its legs and wings," Michael Dickinson of the California Institute of Technology said in a statement.

"This illustrates how rapidly the fly's brain can process sensory information into an appropriate motor response," said Dickinson, whose research appears in the journal Current Biology.

Dickinson's team studied this process in fruit flies using high-speed digital imaging equipment and a fancy fly swatter.

In response to a threat from the front, the fly moves its middle legs forward, leans back and raises its back legs for a backward takeoff. If the threat is from the side, the fly leans the other way before takeoff.

The findings offer new insight into the fly nervous system, and lends a few clues on how to outsmart a fly.

"It is best not to swat at the fly's starting position," Dickinson said. Instead, aim for the escape route.

Dickinson, a bioengineer, has devoted his life's work to the study of insect flight. He has built a tiny robotic fly called Robofly and a 3-D visual flight simulator called Fly-O-Vision.

蒼蠅爲何如此難打？美國研究人員於上週四稱，這主要和蒼蠅的大腦反應有關。

研究人員稱，即使是很微小的危險信號，蒼蠅在察覺後都能迅速調整好它的起飛姿勢，然後向相反方向飛離，逃之夭夭。這一發現有助於解釋爲什麼蒼蠅如此難打。

加利福尼亞科技學院的邁克爾•迪金森在一份聲明中說：“整個飛離過程十分迅速，只需約200毫秒。但就是在這麼短的時間內，蒼蠅就能確定威脅來自何方，然後啓動一套動作，調整好腿和翅膀的姿勢。”

迪金森說：“這就說明蒼蠅的大腦能夠非常迅速地將感官信息轉化爲相應的動作反應指令。”該研究報告在《當代生物學》期刊上發表。

迪金森的研究小組採用高速數碼成像設備以及一個奇特的蒼蠅拍對果蠅的逃命過程進行了研究。

當察覺到威脅來自前方，蒼蠅就會向前微移中足，身體後傾，然後擡起後足向後飛離；如果威脅來自側面，那麼蒼蠅則會將身體傾向另一側，然後逃離。

這一發現讓人類對蒼蠅的神經系統有了更新的認識，而且幫助人們找到了打蒼蠅的方法。

迪金森說：“打蒼蠅時不能對準蒼蠅。”正確的方法應該是對準它的飛離方向。

迪金森是一名生物工程學家，他一直從事昆蟲飛行方面的研究。他研發了一款名叫Robofly的微型機器人蒼蠅，以及一種名叫Fly-O-Vision的三維可視飛行模擬器。

fly swatter: 蒼蠅拍