Title : Feeding study for the mycotoxin zearalenone in yellow mealworm Tenebrio molitor larvae investigation of biological impact and metabolic conversion
I nsects could be used as an additional source of animal protein incorporated in food and/or feed. The processed proteins of yellow mealworm larvae (Tenebrio molitor) are, together with six other insect species, legally allowed in animal feed. Before considering T. molitor larvae as suitable for consumption, the possible presence of contaminants must be identified. One of the contaminants of most concern are mycotoxins. This report focusses on the effect of the presence zearalenone (ZEN) and its metabolites on T. molitor larvae. Seven different diets were prepared, namely the; control, spiked (S1: 558.5 µg/kg ZEN; S2: 2254 µg/kg ZEN), artificially contaminated (A1: 427.0 µg/kg ZEN; A2: 2283 µg/kg ZEN) and naturally contaminated (N1: 602.3 µg/kg ZEN; N2: 919.3 µg/kg ZEN). The amount of ZEN and its metabolites in the feed, larvae and the residue (combination of left over feed and faeces) were measured by HPLC-MS/MS. A significant difference in individual larval weight gain was found between the diets containing naturally contaminated wheat (N1: 7.80 mg; N2: 9.25 mg) and the other diets after eight weeks of exposure. No ZEN or ZEN metabolites were detected in the T. molitor larvae after harvest. However, ZEN, α- and β-ZEL were found in the residue samples. Lastly, ZENand ZEL-sulphates were only detected in the control and the naturally contaminated samples. Thus, suggesting that mainly transformation to of either ZEN to ZEL or ZENS to ZELS takes place during larval metabolism.