Organic side streams (bioproducts) as substrate for black soldier fly (Hermetia illucens) intended as animal feed: chemical safety issues

The growing world population accompanied by urbanisation and improved economies has resulted in an increased demand for diets rich in animal proteins. The rearing of livestock by existing practices is also becoming increasingly difficult due to changing environmental conditions. The use of black soldier fly larvae (BSFL) grown on organic side streams (bioproducts) as feed for animals presents a sustainable alternative to conventional feed ingredients. The nutritional and compositional profile of BSFL reared on organic side streams and their potential to be used as animal feed has been extensively explored. However, little information is available on the chemical safety of BSFL reared on organic side streams. This review addresses the chemical safety hazards of BSFL reared on substrates spiked with different chemical contaminants, including heavy metals, mycotoxins, pesticides, and pharmaceuticals. BSFL were observed to excrete mycotoxins and were able to reduce the concentration of pesticides and pharmaceutical compounds in the substrate. Certain heavy metals were found to be accumulated in BSFL when grown on spiked substrate. Initial studies have also indicated that the growth parameters and composition of BSFL are not altered by the presence of microplastics and organic pollutants in the substrate. Information about these feed-safety issues will assist in developing regulatory frameworks and appropriate processing methods to mitigate these hazards, thereby providing a framework of risks for the commercialisation of BSFL destined for animal feed.