Immune responses of the black soldier fly Hermetia illucens (L.) (Diptera: Stratiomyidae) bred on catering waste

Partner: Valentina Candian¹, Marco Meneguz² and Rosemarie Tedeschi¹

¹Università di Torino

²BEF Biosystems

Published in Life

Link:https://doi.org/10.3390/life13010213

Person of interest:Valentina Candian, young researcher

https://www.disafa.unito.it/do/docenti.pl/Show?_id=vcandian#tab-profilo

Summary

The black soldier fly (BSF), Hermetia illucens L. (Diptera: Stratiomyidae), has great potential for bio-conversion and the ability to grow on different substrates. Although the use of catering waste and food by-products containing meat and fish would reduce the footprint of the insect industry, to date, insects as food and feed still face legal barriers to their use in Europe.
As one of the main demands of the EU insect industry is to diversify the spectrum of allowed substrates and considering that variations in diet composition could affect insect immune responses, we evaluated the impact of different catering wastes on the immunity of BSF prepupae.

The insects were raised on five diets: one based on laying hen feed and four based on kitchen waste containing (i) fruits and vegetables; (ii) fruits, vegetables and bread; (iii) fruits, vegetables, bread and dairy products; and (iv) fruits, vegetables, bread, meat and fish.
Gene expression of two antimicrobial peptides (AMPs), a defensin and a cecropin, was evaluated. In addition, the inhibitory activity of hemolymph against Escherichia coli DH5α and Micrococcus yunnanensis HI55 was evaluated by diffusion assays in solid media. Up-regulation of both genes encoding AMPs was observed in insects fed a diet of bread and dairy products.
All hemolymph samples showed inhibitory activity against both bacteria, affecting colony size and number. The results obtained show how catering waste positively influences the immune system of H. illucens. The possibility of modulating the expression levels of AMPs through diet opens up new perspectives in managing insect health in mass farming.