英语听力文摘 English Digest 566、小虫防冻秘招！

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　　Ever seen a cricket wearing a parka? Probably not, but you might have wondered how insects make it through the winter! After all, they’re cold-blooded, so their body temperature is pretty close to the temperature around them! Why don’t bugs² turn into popsicles?

 

　　Well, some do, of course. In a lot of insect species, only one stage is adapted to live through winter cold. For example, in some species, only those in the pupa stage, wrapped in insulated cocoons³, can stay warm enough to survive. Other bugs, like mosquitoes and grasshoppers⁴, don’t survive the winter themselves, but they lay their eggs in deep water or soil that won’t freeze hard. As long as their environment doesn’t freeze, the eggs will hatch in the spring.

 

　　Some adult insects and spiders actually do live through the winter, either by burying themselves deep in the ground, where the temperature is more moderate than the air temperature, or, of course, by moving into warm buildings!

 

　　Most bugs survive the winter’s cold by undergoing diapause, or insect hibernation⁵. No one knows whether bugs in diapause actually sleep, but most are totally inactive. Like animal hibernation, diapause drastically lowers a bug’s metabolism⁶, allowing it to survive all winter on its stored-up body fat.

 

　　Many diapausing bugs can survive even if their body temperatures drop below freezing. How? By making their own antifreeze! In diapause, insects’ bodies produce different types of alcohol. The alcohol in the bug’s system lowers the freezing point of its body fluids. This natural antifreeze lets many insects survive winter’s below-freezing temperatures, and wake up to make even more bugs next spring!

 

 

　　小虫防冻秘招！

 

　　你见过蟋蟀穿皮大衣吗？应该没有吧，但你或许想知道昆虫们是怎样度过冬天的。毕竟它们都是冷血动物，那它们的体温应该和周围环境差不多。可为什么昆虫们没有冻成冰棍呢？

 

　　当然啦，有一些昆虫会冻成冰棍。对于很多昆虫来说，它们只有处于某个特定的阶段才能活过寒冷的冬天。比如说，有些昆虫只有处于蛹期，被隔热的茧包裹起来时 才能维持足够的热量以存活。而另一些昆虫，比如蚊子和草蜢，它们本身无法在冬天里存活，但它们会把卵产在深水处及泥土中，而这些地方并不会完全冻住。只要 所处的环境不结冰，这些虫卵就能在春天孵化。

 

　　一些成虫，还有蜘蛛则依靠自身便能在冬天存活。它们要么将自己深埋在地底，因为那里的温度可比空气中温和得多。要么搬到到暖和的建筑当中居住。

 

　　大多数昆虫通过滞育，即虫类冬眠，来度过寒冬。没人知道滞育中的昆虫是否真的熟睡，但大多数昆虫处于完全不动的状态。就像动物冬眠一样，滞育能大幅减缓昆虫的新陈代谢，这样一来昆虫们便能凭借自身体内储存的脂肪度过整个冬天。

 

　　许多滞育中的昆虫即使体温降至冰点以下依然能够存活。这是怎么做到的？因为这些昆虫能自己生产“防冻剂”。当处于滞育当中时，这些昆虫体内会产生多种不同 的乙醇。这些乙醇使得昆虫体液的冰点降低。这种天然的防冻剂使得许多昆虫在气温低于冰点的冬天得以存活。当它们于春天醒来时，甚至能繁殖出更多的幼虫。

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