Effect of rearing diet on gene expression of antimicrobial peptides in Hermetia illucens (Diptera: Stratiomyidae)

Partner: Valentina Candian², Carlotta Savio², Marco Meneguz¹, Laura Gasco², Rosemarie Tedeschi²

¹BEF Biosystems

²University of Turin

Person of interest: Rosemarie Tedeschi associate professor

https://www.disafa.unito.it/do/docenti.pl/Alias?rosemarie.tedeschi#tab-profilo

Published in Insect Science

Link to article https://doi.org/10.1111/1744-7917.13165

Summary

Insect proteins have been proposed for human and animal food production. Preserving the health status of insects in mass breeding allows obtaining high-quality products and avoiding serious economic losses due to entomopathogens. Therefore, it is necessary to implement new strategies to preserve insect health. Modulation of the insects' immune system through diet is one such strategy.

We evaluated the gene expression of two antimicrobial peptides (a defensin and a cecropin) in Hermetia illucens (L.) (Diptera: Stratiomyidae) bred on different diets. Analyses were performed on 10-day-old prepupae and larvae bred on cereal-based diets and municipal organic waste and only on prepupae bred on a cereal-based diet supplemented with sunflower oil, corn or soybean. The inclusion of sunflower oil at different points in the grain-based diet was also evaluated. In addition, differences in diet-determined hemolymph inhibitory activity against Escherichia coli DH5α and Micrococcus yunnanensis HI55 were tested using diffusion assays in solid media.

Results showed that a diet of urban organic waste produced significant overexpression of antimicrobial peptides in prepupae only. Inclusion of vegetable oils caused overexpression of at least one peptide, except for corn oil. Increased expression of both genes was observed with the addition of sunflower oil 5 days before pupation. All hemolymph samples showed inhibitory activity against bacterial colonies.
Our results suggest that urban organic waste diet and diet with added vegetable oil may have a positive impact on the immune system of H. illucens. Such alternatives may also exist for other species of economic interest.