Exactly my point. A (properly designed) dsRNA only targets a single organism. It's not like an insecticide that kills everything, so is sprayed all the time. Other insects don't build up resistance, as it has no impact on them. If resistance builds up in the target insect, well, we're back where we started using toxic insecticides. Given the sequence is easy to change, resistance on a sequence basis at least is unlikely in the target itself.