Methods for inducing systemic, non-specific and/or sequence specific immune responses in invertebrates, e.g., marine invertebrates such as mollusks, porifera, ctenophora, echinodermas, marine worms, cnideria and preferably crustaceans, by the administration of at least one dsRNA, that confers immunity against a pathogen, or modulates expression of gene that affects growth, reproduction, and general health or "robustness" are provided. Also provided are methods of identifying invertebrate genes, e.g., crustacean genes, the expression of which is involved in the induction of non-specific (systemic) immune responses against pathogens. Also disclosed are preferred delivery systems and methods for stably administering at least one dsRNA to a crustacean whereby the dsRNA is administered via injection, immersion, in a feed or nutrient medium or comprised in a microorganism, e.g., yeast or microalgae, that expresses said dsRNA and is ingestible by said crustacean, e.g., a shrimp.
