Plastivorous activity of Hermetia illucens larvae (Diptera Stratiomyidae)

The world's production of plastics has increased dramatically in recent years, going from 234 million tons in 2000 to 460 million tons today. The same phenomenon is evident in the production of plastic waste which has currently reached 353 million tons. Globally, the mismanagement of plastic waste has led to its accumulation in freshwaters, oceans and land in any form, including microplastics. Reducing plastic pollution has become one of the most pressing environmental challenges that require effective and integrated strategies. Recently scientific research is focusing on the identification of insect species which, thanks to their intestinal microbiota, have the ability to effectively degrade synthetic polymers. Although the larvae of some coleopterans and lepidopterans are the most studied organisms for the biodegradation of plastics, other species could offer similar capabilities. Therefore, the present research has had the aim of evaluating the "plastivorous" activity of Hermetia illucens (Diptera Stratiomyidae), reared on a diet contaminated by fluorescent polystyrene (PS) microparticles (latex beads, carboxylate-modified polystyrene, fluorescent yellow-green, 2 µm, aqueous suspension 2.5%). Evaluation of larval performance did not reveal significant differences in development and mortality between the larval population reared on the PS-contaminated diet compared to that reared on the control diet. The examination of the larval intestinal tissues through the laser scanning confocal microscope, in a bright field and with fluorescence, allowed us to observe the abundant presence of the fluorescent particles of PS in the foregut and midgut and minimally in the hindgut, with translocation of the fluorescent particles of PS within the cells of the midgut epithelium. Moreover, the formation of low molecular weight products from the biodegradation of PS was investigated by GC-MS. This research, which should be completed with the analysis of the intestinal microbiota and proteomic analysis to identify the microorganisms and enzymes involved in the degradation of PS, provides interesting results on the potential "plastivorous" capacity of H. illucens.