One major advantage of RNAi by feeding over injection is that it is considerably less labor-intensive. In practice, this means that RNAi can be performed on thousands of worms for little more effort than feeding a single worm. Thus, feeding affords the possibility of using RNAi in ways not practically possible by injection, such as doing large-scale biochemistry on worms with a mutant RNAi phenotype. A second advantage of RNAi by feeding is that once a bacterial strain expressing a specific dsRNA is created, it can be reused indefinitely to repeatedly perform RNAi on a given gene. Thus, feeding is extremely useful for large-scale experiments in which either many worms will be subjected to RNAi, many genes will be used for RNAi, or a few genes will be used for RNAi many times. Indeed, this method has been used by Fraser et al. [21] to efficiently screen roughly 90% (2,500 predicted genes) of C. elegans chromosome I by RNAi.
