Chemical contamination of black soldier fly larvae raised on EU-authorized or unauthorized substrate

Abstract

Black soldier fly larvae (BSFL), Hermetia illucens, can efficiently convert biowaste into high-quality protein for the feed industry. However, biowaste can contain several chemical hazards and their fate in BSFL remain largely unexplored, even though they can pose a threat for both the insect sector and the higher levels of the trophic chain. The purpose of this study was to evaluate the chemical contamination of BSFL reared on authorized biowaste (wheat bran, carrots, apricots, salad) or unauthorized biowaste in the EU (school canteen and supermarket biowaste). PFAS were not quantifiable in the substrates in contrast with persistent organic pollutants, pesticides and trace metal elements. The chlormequat pesticide was the only pesticide quantified in BSFL (15 µg/kg), slightly above the maximum residue limit in the EU for feed (10 µg/kg). Concentrations of PCBs and PCDD/Fs in BSFL were below the maximum limit (ML) but bioaccumulation factors up to 5 were obtained. As and Cd were highly bioaccumulated with concentrations approaching the ML for Cd (0.5 mg/kg) or 8 times below for As (ML = 2 mg/kg). The unauthorized substrate samples tested led to higher chemical safety risks in BSFL, with 10 times higher concentrations of As than in BSFL reared on authorized substrates and the presence of PCDD/Fs and PCBs. The concentrations of chemical contaminants in animal products consumed by humans such as eggs were estimated using transfer models when animals were fed with BSFL reared on unauthorized substrates. The concentrations were below the maximum limits in all cases.

Keywords: By-product; Hermetia illucens; Persistent organic pollutants; Pesticides; School canteen and supermarket biowaste; Trace metal elements.