Uptake of heavy metals and arsenic in black soldier fly (Hermetia illucens) larvae grown on seaweed‐enriched media

BACKGROUND The black soldier fly (Hermetia illucens) is one of the most promising insect species for the use in animal feed. However, studies that investigate feed and food safety aspects of using black soldier fly as feed are scarce. In this study, we fed black soldier fly larvae feeding media enriched with seaweed, which contains naturally high concentrations of heavy metals and arsenic. The aim of this study was to investigate the potential transfer of such undesirable substances from the feeding media to the larvae. RESULTS The larvae accumulated cadmium, lead, mercury and arsenic. Concentrations of these elements in the larvae increased when more seaweed was added to the feeding media. The highest retention was seen for cadmium (up to 93 %) and the lowest for total arsenic (up to 22 %). When seaweed inclusion exceeded 20 % in the media, this resulted in larval concentrations of cadmium and total arsenic above the current European Union maximum levels for these elements in complete feed. CONCLUSION Our results confirm that insect larvae can accumulate heavy metals and arsenic when present in the feeding media. A broader understanding of the occurrence of these undesirable substances in processed larvae products is needed to assess feed and food safety.