Nutritional immunology: Diversification and diet-dependent expression of antimicrobial peptides in the Black soldier fly Hermetia illucens

The black soldier fly Hermetia illucens is globally the economically most important farmed insect used for the bioconversion of organic waste into feed for livestock and aquaculture. The larvae can be fed with agricultural waste and even with liquid manure, resulting in highly unpredictable pathogen levels as well as dietary conditions. Here we show that H. illucens larvae express high numbers of antimicrobial peptides (AMPs), many of which are inducible through simple feeding on diet with high bacterial loads. Strikingly, addition of sulfonated lignin, cellulose, chitin, brewer’s grains or sunflower oil to the diet elucidated a diet-dependent expression pattern of AMPs in larvae. Particularly, sun flower oil exhibited a strong immune-stimulatory activity, resulting in high gene expression levels of the majority of identified AMPs. Obtained data provide intriguing insights for the emerging field of nutritional immunology and could also have implications for more applied aspects of H. illucens bioconversion of organic waste.