Exploring the plastivorous activity of Hermetia illucens (Diptera Stratiomyidae) larvae

Hermetia illucens (Diptera Stratiomyidae), also known as Black Soldier Fly (BSF), is one of the insect species most investigated for biodegradation ability in its larvae. H. illucens larvae can biodegrade organic waste but also contaminants like pesticides, antibiotics, and mycotoxins. This study wants to investigate the ability of these larvae to degrade polystyrene (PS). Experiments evaluated the growth performance, survival rates, intestinal and intracellular morphological alterations, degradation by-product formation and intestinal microbiota alterations of larvae fed a PS-enriched diet. Despite the addition of PS microparticles, no significant differences in growth or survival were observed compared to the standard diet (p > 0.05). Confocal Laser Scanning Microscopy and Transmission Electron Microscopy confirmed the presence of PS microparticles in the larval gut, with potential signs of biodegradation. Metabolomic analyses identified styrene in the gut after 1 and 3 days of PS feeding, but its occurrence was likely due to thermal depolymerisation of the PS microparticles under GC-MS conditions. Metagenomic analysis revealed significant shifts in the intestinal microbiota. Notably, an enrichment of Corynebacterium, known for its role in aerobic PS degradation, and the abundance increase of other genera (Enterococcus, Enterobacteriaceae, Enterobacter, and Escherichia-Shigella) associated with synthetic polymer metabolism was observed. These results confirm the potential of BSF larvae to manage plastic waste through the interaction between their gut microbiota and synthetic materials. This study provides a foundation for future research focusing on isolating bacterial communities and enzymatic processes involved in polymer degradation, aiming to develop sustainable strategies for plastic waste management.