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Aphids and Brussels Sprouts

We're all familiar with how a food chain works-big insects eat little insects, birds eat the big insects, larger prey eat the birds, and so on.

You may not know, however, that changing just one element, at the very bottom of a food chain, can have far-reaching consequences.

To demonstrate this point, researchers in the Netherlands and England studied aphids, tiny insects that are eaten by many larger insects. In a field experiment, the scientists compared a group of aphids that lived on Brussels sprouts, to a group that lived on cabbage.

As sprouts aren't as nutritious for aphids as cabbage, the sprout-eating aphids tended to be smaller and less prevalent, attracting fewer predators than the larger, more appetizing, cabbage-eating aphids.

If aphids are eating cabbage and thriving, wasps and other insects will also be thriving, which in turn means that there will be a greater diversity of animals filling out the food web. To put it simply, the study shows that even a minute altering of the food supply can effect all members of the chain from the very bottom, all the way to the very top, including humans.

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