Degradation and excretion of the Fusarium toxin deoxynivalenol by an edible insect, the Yellow mealworm (Tenebrio molitor L.)

Insects could provide an alternative and more sustainable source of animal protein compared to conventional livestock. Yellow mealworms (Tenebrio molitor L.) can be grown on diets composed of organic by-products. However, these diets could be contaminated with mycotoxins. Thus far, little is known about possible retention, sequestration, excretion or detoxification of mycotoxins by edible insects. T. molitor larvae were grown on wheat flour naturally contaminated with mycotoxins among which deoxynivalenol (DON) was predominant (4.9 mg/kg), wheat flour spiked with 8 mg/kg pure DON, and uncontaminated wheat flour. Larval survival and weight gain on the three diets were compared. Survival was high for larvae on all dietary treatments (>98%) and no difference in weight gain was observed when comparing larvae grown on uncontaminated control diet with larvae grown on contaminated diets (P=0.091). Presence of mycotoxins in larvae and larval faeces was analysed using LC-MS/MS. No DON or DON-derivatives were detected in T. molitor after harvest of the larvae, pointing to degradation by the larvae. Excretion of DON in larval faeces was ca. 14% of the amount of DON ingested for larvae grown on naturally contaminated diet and ca. 41% for larvae grown on DON-spiked diet. These are promising results with respect to food safety of mealworms or derived products grown on mycotoxin-contaminated feed. However, enzymatic degradation of DON in T. molitor, as well as possible toxicity of the resulting metabolites, remain to be further investigated.