Mealworm larvae promote Artemia franciscana metanauplii nutritional status and survival against marine aquaculture pathogens

Abstract

Mass culture of Artemia sp. requires suitable feed, commonly microalgae, the production of which is a high-cost process. Moreover, in marine aquaculture Artemia sp. enrichment protocols are imperative to increase the content in the essential n-3 highly unsaturated fatty acids (HUFA), required for marine fish. The insect Tenebrio molitor appears as a sustainable alternative protein source for aquaculture feeds. In this study, the capacity of insect-based diets to enhance survival, growth, and nutritional composition of Artemia franciscana was assessed by preparing five different T. molitor emulsions with increasing amounts of insect powder of 5, 10, 15, 20, or 25% (w/w) corresponding to TM5, TM10, TM15, TM20, and TM25 feeds, in comparison with a yeast diet. Our results showed that all T. molitor-based diets except TM25 supported survival. The TM20 feed provided the best results in terms of metanauplii nutritional value, growth rate, and feed conversion efficiency. The TM20 group metanauplii presented significantly higher fatty acids content, mainly regarding palmitic, palmitoleic, oleic, linoleic, eicosapentaenoic, and docosahexaenoic acids, and a lower n-3 to n-6 ratio, compared to control fed on yeast. Moreover, an experimental infection of the TM20 A. franciscana group with Photobacterium damselae ssp. piscicida or Vibrio (Listonella) anguillarum, resulted in significantly increased metanauplii survival, nutritional content, and fatty acids content compared to the infection group. Our findings confirm the potential use of T. molitor as a suitable, low-cost, and environmentally friendly alternative feed to be used in the mass culture of Artemia sp.