Aphids vs. wasps
Nature is a system of checks and balances, as is the case between aphids and wasps. Aphids feed on plants; wasps lay eggs inside aphids, killing them and increasing plant production. Some aphids harbor bacterial symbionts, or smaller organisms that live in close association with a host, that provide protection by killing the internally developing wasps. Wasps are able to decipher which aphids are infected and use superparasitism to override the poison.