Feeding Fusarium-infected wheat to yellow mealworm larvae (Tenebrio Molitor) to produce a safe, replacement protein source for animal feed

Abstract

Various insect species including the yellow mealworm (Tenebrio molitor) could be an alternative and sustainable source of protein for animal feed. There is evidence that yellow mealworm larvae can utilize deoxynivalenol (DON)-contaminated wheat as a food source without sequestering it, producing a safe protein ingredient. This study aimed to determine the potential accumulation of DON in T. molitor larvae reared on Fusarium-infected wheat containing high levels of DON and investigate the effects of DON exposure on production, survival and nutritional traits of the larvae. Wheat containing 200 μg/kg DON was used as the control diet. A different source of wheat was sorted into six fractions and mixed to obtain three levels of DON for low (2,000 μg/kg), medium (10,000 μg/kg) and high (12,000 μg/kg) treatments. Each treatment was replicated five times with 300 or 200 mealworms per replicate for the feeding and breeding trials, respectively. Trial termination was determined when the first two pupae were observed (32-34 days). There was no difference in the levels of DON detected in the larvae between treatments and ranged from 121.8±19.3 to 136.4±40.5 μg/kg (P=0.883). Excretion of DON in pooled frass samples was 131.0, 324.0, 230.4 and 742.1 μg/kg for control, low, medium and high, respectively. The concentrations of 3-acetyldeoxynivalenol (3-ADON) detected in frass ranged from 279.5 to 326.4 μg/kg, whereas levels in larvae ranged from 65.3 to 66.2 μg/kg and were from undetectable to 204.9 μg/kg in wheat. Nutritional analysis on pooled samples from both trials showed maximum levels of crude protein (CP) of 52% and crude fat (CF) of 36%. Ash, fiber, chitin, fatty-acids and amino-acids content were consistent across treatments. Survival was greater than 96% for all life stages in both trials. In the feeding trial, average daily gain (ADG) ranged from 1.9±0.1 to 2.1±0.1 mg/day per mealworm. Less than 1.2% of the ingested DON was accumulated by larvae when they consumed Fusarium-infected wheat containing levels up to 12,000 μg/kg. These results along with the lack of effect on the nutritional profile, survival, or production traits, supports using DON-contaminated wheat in large-scale production of mealworms to produce a sustainable, safe protein source.