Black soldier fly (BSF, Hermetia illucens) larvae can valorize food waste into high-valuable products including animal feed. However, these wastes may contain microplastics originating from food packaging, potentially compromising larval growth and their safety as feed. This study investigates the impact of microplastic sizes and shapes on their ingestion and egestion by BSF larvae during waste bioconversion. BSF larvae were reared for 10 days on artificial food waste spiked with three size ranges of spherical or irregularly shaped fluorescent polyethylene microplastics. Daily, several larvae were dissected (n = 9 per treatment) to isolate their gut and to finally determine the number of particles in their alimentary canal using a fluorescence microscope. The microplastics had no impact on larval growth and no bioaccumulation of microplastics was observed in the larval gut (bioaccumulation factors < 0.3). However, there was a significant difference in the ingestion rate based on the different particle sizes. While almost no particles exceeding 100 µm were ingested by the larvae, a steady increase in microplastics was observed in the larval gut for the smaller particles. However, a three-day starvation period reduced the number of microplastics in the larval gut by over 90 %. No significant difference was observed between spherical and irregularly shaped microplastics in terms of larval bioaccumulation. We proposed a kinetic model for representing the temporal dynamics of microplastics accumulation and elimination with respect to particle distribution parameters, enabling the results obtained in this study to be extrapolated to other microplastic sizes.

Although antimicrobials are generally found in trace amounts in meat, the human health risk they bear cannot be ignored. With the ultimate aim of making a better assessment of consumer exposure, this study explored the effects of pan cooking on sulfonamides and tetracyclines in meat. Screening of these antimicrobials in cooked meat was first performed by the European Union Reference Laboratory on the basis of HPLC-MS/MS analyses. A proof of concept approach using radiolabeling was then carried out on the most cooking-sensitive antimicrobial—sulfamethoxazole—to assess if a thermal degradation could explain the observed cooking losses. Degradation products were detected thanks to separation by HPLC and monitoring by online radioactivity detection. HPLC-Orbitrap HRMS analyses completed by 1D and 2D NMR experiments allowed the structural characterization of these degradation compounds. This study revealed that cooking could induce significant antimicrobial losses of up to 45% for sulfamethoxazole. Six potential degradation products of ¹⁴C-sulfamethoxazole were detected in cooked meat, and a thermal degradation pattern was proposed. This study highlights the importance of considering the cooking step in chemical risk assessment procedures and its impact on the level of chemical contaminants in meat and on the formation of potentially toxic breakdown compounds.

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.

This study explored the ability ofTenebrio molitor, one of the most widely bred and traded insect species in Europe, to bioaccumulate polychlorobiphenyls (PCBs) from their feeding substrate.T. molitor larvae were reared for 20 days in a temperature- and humidity-controlled incubator and fed with wheat bran artificially contaminated with PCBs at a concentration of 0.67, 4.0 or 24.4 μg/kg. The larvae PCB content was then measured based on an analysis by GC-MS and GC-μECD. Whatever the level, a bran contamination by PCBs did not affect the body weight of larvae indicating a high tolerance to PCBs. The bioaccumulation factors (BAF; concentration of PCBs in larvae / concentration of PCBs in wheat bran) obtained with fresh larvae ranged between 0.4 and 1.0 and were significantly higher with the highest contamination level for PCBs 153 and 180. Although there is no bioaccumulation of PCBs inT. molitor larvae during rearing, PCBs can be transferred from the diet to the larvae. This study highlights the significant impact of the drying process which induces an increase of the PCB concentration in larvae by a factor of almost 3. This demonstrates the importance of considering the quality of the substrates used for farming insects as food and feed in terms of content in chemical contaminants including persistent organic pollutants like PCBs.

As recently shown, black soldier fly larvae (BSFL) are capable of bioaccumulating high concentrations of vitamin E and carotenoids, but the potential bioaccumulation of polyphenols remains unknown. Wheat bran (WB), a common breeding substrate for BSFL, is particularly rich in ferulic acid (FA) and also contains caffeic acid (CA). Numerous studies suggest that these polyphenols have beneficial effects on human and animal health. BSFL ability to bioaccumulate these bioactive compounds was assessed by comparing their concentration in WB and BSFL raised on WB. The three forms of FA and CA, i.e. free, soluble-bound and insoluble-bound, were extracted from WB and BSFL and quantified by HPLC-UV. No form of CA was detected in BSFL. The three forms of FA were detected but the total FA concentration in BSFL (17 ± 1 mg/kg fresh weight) represented only 2% of the total FA concentration measured in WB (810 ± 38 mg/kg fresh weight). Since the larvae were not fasted, another experiment was carried out to find out if the small amount of FA found in the larvae was the FA contained in WB present in their digestive tract. The digestive tracts of fasted and non-fasted larvae at the end of the rearing period were weighted. And it was calculated that all the FA measured in the larvae could be the FA present in their digestive tract. Moreover, the distribution of the three different forms of FA differed between WB and BSFL. Therefore, we have demonstrated that not only BSFL do not significantly bioaccumulate FA from WB but that they apparently metabolize it. Regarding CA as a precursor of FA, the same phenomenon might have happened. However, assuming an equivalent bioaccumulation factor as FA, the amounts of CA theoretically transferred in larvae were too low to be detected.