Plasmids can be transferred to E. coli. These transformed E. coli can be fed to C. elegans to silence its gene expression by RNAi.
How can E.coli release RNAi to C. elegans? Even if we assume E. coli could enter cells of C. elegans for being intracellular Bacteria, it is hard to imagine that RNAi will exit E.coli directly and enter C.elegan's cells? Normally, no cells or bacteria will release RNA or genomic material outside of their cells?