The technique, called RNA interference or RNAi, works by creating snippets of RNA that correspond to genes in the target species, say corn rootworm. When these chunks of genetic material enter the rootworm, perhaps after being sprayed onto the crop, the animal reacts to this RNA snippet as it would an invading virus. This prompts a response that attacks and silences the corresponding gene in the host's own DNA. If this gene is necessary for the organism's survival, the theory goes, it dies. The idea behind RNAi was awarded the 2006 Nobel Prize in physiology/medicine, but applying it to fight pests is a recent development.