Interactions between species and even kingdoms in nature can be complex and multilayered. This means that when we want to intervene to cause a particular outcome, there may be multiple points at which we can act, but the consequences may be hard to predict.
In this study, action was taken to counteract the damage the Western corn rootworm causes to corn crops, using a tiny roundworm that attacks the insect pest with deadly bacteria. The rootworm defends itself by accumulating plant-produced toxins that inhibit the bacteria. Directed evolution was used to make the bacteria more resistant, and this led to more effective killing of the pest.