Organisms in nature often reach a "dynamic equilibrium" in which they do not destroy each other. In North America, native pine trees have developed resistance to nematodes, and so are only sporadically affected by pine wilt disease--it does not strike whole swathes of forest at one time.
自然萬物往往相生相剋，彼此達成「動態平衡」，不致兩敗俱傷，在北美，松樹就對線蟲具有抗病性，並未出現全軍覆沒的慘況。