If I am going to transform a plasmid into a bacterium, which will then be fed to a C. elegans, the expression vector needs to be bacterial correct? The other option is to have a worm expression vector, but I just wanted to make sure that I was correct in my thinking. Thank you.
You are trying to express the plasmid in C. elegans, so it should be a worm expression vector and promoter. Otherwise, it will be expressed in the host bacteria, but not in the worm, so you won't get the phenotype you're looking for.
One thing you can do is add a bacterial origin of replication to the vector (if one isn't already present) so the bacteria produce multiple copies of the plasmid after transformation. Otherwise, the amount of plasmid consumed by the worms will be rather low.