Mankind has been battling aphids since the beginning of the prehistoric agricultural revolution. These small sap-sucking insects that are to most people nothing but tiny dots that kill off their plants, cripple crops and vector plant viruses all over the world. How then, with all our technology and sophistication, do we still suffer billions of dollars in damage to our food crops every year?
一个简单的答案是，今天活着的约5,000种蚜虫已经超过2亿年来改进了他们的军械库。在每一代蚜虫中，自然选择都偏爱较硬的蚜虫，而这一漫长过程的结果是具有许多显着生存机制的超级测试。
For example, aphids have an unprecedented rate of reproduction: in some species, females can give birth every two hours and to make things worse, they are actually born pregnant. They do this by making only self-reproducing females throughout spring and summer. By giving up on all the he-she business and not having to postpone pregnancy until they are sexually mature, aphids have become rapid assembly lines for more aphids.
许多蚜虫物种也具有令人印象深刻的检测敌人并在时间上逃脱的能力。这些敌人包括捕食者和寄生虫，但是由于蚜虫生活在其他较大的植物食物的食物上，因此它们不断地通过放牧哺乳动物而易于无意间捕食。一些蚜虫实际上可以温暖和潮湿的气息of a foraging mammal and drop to the ground right before their host plant is eaten. Most often, this leads to numerous aphids of different ages walking on the ground, hurrying to get to a new host plant before they starve to death or fall prey to patrolling predators such as ants.
While studying the emergency escape behavior of pea aphids we noticed that after dropping to the surface, some of the very young aphids manage to quickly climb on the backs of adults and then “piggyback” on them, while the latter start walking in search of a new host plant.
Adult pea aphids are quite agile, capable of passing over cracks, clumps of soil, stones, twigs and fallen leaves that normally cover the ground. However, for newborn aphids, walking on the ground is a whole different ball game; to them, every stone is a hill and every crack in the soil a chasm. Therefore, young aphids should benefit from riding on adults, even if the riding lasts only part of the way to a suitable host plant. But how exactly would the young benefit from riding on adults?
In a set of laboratory experiments using simplified, paper-covered arenas, we found that young aphids riding on adults reached a host plant over 4 times faster than those walking on their own. On natural soil covered with stones and plant debris, these differences may be even greater. After reaching a host plant on the back of an adult, the young aphids always disembarked on the stem and resumed feeding.
But could the young also benefit from a potential better ability of the adults to detect host plants from a distance? We found no evidence to support this. Does this mean that out in the field adult aphids do not have a better ability to detect host plants than their young? Not necessarily. One must take caution when extrapolating laboratory experiments to the real world and in this case, further research is needed for answering this question.
将实验室实验推向现实世界时，必须谨慎行事。
Interestingly, the adults did not seem to like being climbed on. Often they were observed trying to shake off the young, especially when being mounted by several newborn aphids. This slowed down the adults, which usually did not start walking until only one young remained on their back.
In addition, we tested whether relatedness between adults and young affected the frequency of this interaction, and found no relation between riding behavior and kinship. Therefore, this behavior does not seem to be a form of maternal care.
因此，我们得出的结论是，当一个蚜虫菌落在发现接近植物的哺乳动物后，年轻的蚜虫急于爬上成年人时。反过来，成年人竭尽所能将大多数年轻人从身体中移走。那些能够留在成年人的年轻人将受益于其在自然地形上的卓越步行能力。
关于蚜虫生态学的新发现，即使它们没有直接导致新颖的根除方法，也可以帮助我们了解这些小生物的成熟程度。因此，当我们努力杀死它们时，即使它们成为滋扰，我们也应该不时地停下来欣赏进化的奇观。
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