【经济学人】植物王国里的“欺骗”丨2016.10.08丨总第715期

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翻译 | 栏目二第四组

审核 | 阳光下的冰叶

小编 | 璃儿

Botany

植物学

Summoned by screams

“求救”的陷阱

The ways plants attract pollinators can be strange indeed

一种奇特的传粉方式

Oct 8th 2016 | From the print edition 

2016年10月8日 | 来自印刷版

Come into my parlour 

“请君入瓮”

THE botanical kingdom is rife with deceivers. Carrion flowers mimic the smell of rotten meat in order to attract scavenging beetles and flies and then cover them in pollen. Passion vines, beloved by some butterflies as food for their caterpillars, have yellow spots on their leaves that make them look as if they have already had an egg-laying visit from a gravid female. And numerous carnivorous plants lure insects with sweet odours, only to devour them. Now Stefan Dötterl and Annemarie Heiduk, of the Universities of Salzburg and Bayreuth respectively, think they have uncovered yet another form of deception. As they describe in Current Biology, a vegetable called the parachute plant uses chemical signals to trick carnivorous flies into believing the insects those flies prey on are lying wounded inside it.

植物王国里充斥着“欺骗”。腐肉花散发腐肉的气味吸引嗜腐甲虫和苍蝇，使它们沾上花粉。西番莲是一些蝴蝶幼虫非常喜爱的食物，它的叶子上带有黄色的斑点，看起来就像是雌虫产下的卵。此外，还有大量的食虫植物散发出香甜的气味引诱昆虫，只为了吞噬它们。萨尔茨堡大学和拜罗伊特大学的StefanDötterl和Annemarie Heiduk认为他们发现了另一种形式的“欺骗”。近日，他们在发布在《当代生物学》上的文章中称，一种名为醉龙的伞状植物，可通过释放化学信号引诱食肉苍蝇，让它们“心甘情愿”上钩。

At first sight parachute plants, which have cone-shaped flowers (see picture) decorated inside with needlelike inward-pointing hairs, look as though they might be carnivorous themselves. They are not, though they come close to it. Insects that enter a parachute-plant flower fall into a pit of pollen and cannot escape past the needle-hairs until the flower begins to wilt—by which time they are thoroughly covered in the stuff.

醉龙锥形的花上长有像针一样指向内部的纤毛（如图所示）。虽然醉龙长得很像食肉植物，但并非如此。被吸引进入到花朵内的昆虫会落入花粉坑，直到花开至荼靡才能越过纤毛逃出去，而那时它们已经浑身裹满醉龙的花粉了。

That raises the question of why those insects go inside in the first place, for parachute-plant flowers do not smell of any of the conventional odours, sweet or rank, that plants employ to attract attention. To answer that, the two researchers asked themselves two other questions: exactly which insects do parachute flowers attract and what volatile chemicals, if any, do those flowers produce?

这令人不由感到好奇：醉龙的花伞并没有像其他花朵一样散发香甜或恶臭的气味去吸引昆虫的注意，那这些昆虫为什么会被吸引入花内呢？为了搞清这个问题，StefanDötterl和Annemarie Heiduk进一步提出了两个问题：究竟是哪些昆虫会受到醉龙的吸引？如果醉龙只吸引特定昆虫，那么散发的又是哪种化学物质呢？

By collecting the victims of many wild parachute plants Dr Dötterl and Ms Heiduk discovered that most of the trapped insects were flies of the genus Desmometopa, a group with a predilection for sucking up vital fluids that leak out of honey bees as their bodies are pierced by the fangs of spiders. Meanwhile, collecting chemicals given off by the flowers and running them through a gas chromatograph showed a combination of four molecules—2-heptanone, geraniol, 2-nonanol and (E)-2-octenyl acetate—previously unknown in plants. When Dr Dötterl and Ms Heiduk caught some foraging bees, stuck them in test tubes and poked them with the tip of a glass pipette to mimic a spider attack, the bees produced exactly these four compounds. And when the two researchers set traps containing the four chemicals out in the wild, they instantly attracted a goodly haul of Desmometopa.

通过收集许多野生醉龙的猎物后， Dötterl博士和Ms Heiduk 博士发现大多数被困的昆虫都是塞氏纹额叶蝇属的，它们以吸食被蜘蛛的毒牙刺穿的蜜蜂所渗出的蜂蜜为生。同时，两位博士通过收集花朵上的化学物质并利用气相色谱仪分析，发现它由四种分子所组成： 2-庚酮，香叶醇，2 -壬醇以及（E）-2辛烯基-醋酸，而这四种物质之前从未出现在植物中。Dötterl博士和Ms Heiduk 博士捕捉了一些正在捕食的蜜蜂，将它们放入试管并用玻璃吸管的尖端触碰它们来模仿蜘蛛的攻击，然后这些蜜蜂就会产生这四种化合物。当两位研究员在野外利用这四种化学物质设计了一个陷阱，立刻就吸引了一大批的塞氏纹额叶蝇。

An examination of past apiological research showed that the compounds in question are already known to students of bees. The insects’ mandible glands produce 2-heptanone when they are attempting to bite predators, and this chemical has a debilitating effect on such threats to the hive as predatory moth larvae and mites. The other three compounds, meanwhile, are signal molecules released by bees fighting for their lives, to notify colony members of the danger. Together, then, these four substances are a good indication of a honey bee in the sort of trouble that is a dinner gong to Desmometopa. That parachute plants have evolved to mimic this gong is yet another example of the deceptive power of plants.

这四种化合物早在过去的蜂科研究中就已经被大家所熟知。期待您的翻译。此外另外三种化合物是当蜜蜂遇到危险时，通知同伴而释放的信号分子。当这四种化学物质同时释放就表明蜜蜂遇到了麻烦，比如即将成为一只塞氏纹额叶蝇的晚餐。醉龙释放这些化合物来吸引塞氏纹额叶蝇，成为了植物具有欺骗力的另一证据。

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