TRANSFER OF SELECTED PERSISTENT ORGANIC POLLUTANTS IN YELLOW MEALWORM LARVAE (TENEBRIO MOLITOR)

Alemán. Introduction: The larvae of the yellow mealworm beetle (Tenebrio molitor) can be a dietary source for animals and humans. While consumed worldwide, in the EU it was authorised as feed only recently in aquaculture [1] and for feeding poultry and pigs [2]. Furthermore, dried Tenebrio molitor larvae were authorised in the EU in 2021 as novel food after the European Food Safety Authority (EFSA) assessed the larvae as safe for human consumption [3, 4]. Nevertheless, EFSA stated that only limited data are available on a transfer of chemical contaminants from contaminated substrate into larvae [4]. The aim of this study was to determine a possible transfer of different pollutants like dioxins, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) from contaminated oat-bran to yellow mealworm larvae. Materials and Methods: Yellow mealworm larvae were exposed to oat-bran ad libitum for four weeks under controlled conditions for temperature and air humidity. The contaminated oat-bran was fortified with a mixture of dioxins (final concentrations of 0.1 μg/kg), PCB (0.1 μg/kg non-ortho-PCB, 0.5 μg/kg mono-ortho-PCB, 1 μg/kg ndl-PCB) and PBDE (up to 18 μg/kg). Weekly, larvae were taken and analyzed for concentrations and results compared to control larvae reared on blank oat-bran. At the same time, larvae were weighed, counted and feces was removed. Analysis of larvae was done after automated sample preparation (Miura) using a high-resolution gas-chromatography mass spectrometry (dioxins, PCB) and gas-chromatography tandem-mass spectrometry (PBDE). Results: Yellow mealworm larvae kept on contaminated oat-bran developed similarly to control larvae reared on blank oat-bran regarding feed intake, weight and mortality. Furthermore, we observed a transfer of all compounds present in contaminated oat-bran into yellow mealworm larvae. After 3 weeks of exposure a steady-state was achieved with transfer rates of dioxins, PCBs and PBDEs ranging between 30 % and 100 %. Discussion and Conclusion: We could demonstrate a transfer of dioxins, PCBs and PBDEs from feed into Tenebrio molitor larvae. A possibility to reduce the amounts might be fasting the larvae before processing into feed and food. Therefore, further investigations on the impact of fasting for 24 h and 48 h on contamination levels are on-going.