The nutritional profile of the yellow mealworm larvae (Tenebrio molitor) reared on four different substrates

The utilisation of Tenebrio molitor L. (the yellow mealworm) as a cheaper, alternative and readily available ingredient for food and feed is gaining interest globally. However, there has been limited research on locally and readily available substrates for mealworm mass rearing in South Africa. This study evaluated the impact of four substrates; wheat bran (control diet), wheat flour, maize flour, and Lucerne (pellets) on the rearing of mealworm larvae under controlled conditions over two generations and analysed the nutrient composition using standard nutritional analysis techniques. The results revealed that the crude protein contents of T. molitor larvae ranged between 28 – 36 % when raised on different substrates and varied significantly in the order Lucerne > wheat bran > wheat flour > maize flour. The major minerals found in the larvae included sodium, magnesium, phosphorus, potassium, copper, and zinc. The larvae were also rich in saturated, mono and polyunsaturated Fatty Acids (FAs) with oleic, linoleic, and palmitic as the main FAs. The nutritional profiles of first- and second-generation larvae raised on the same substrates remained the same. Wheat flour was found to be the best alternative to wheat bran. The finding demonstrates the suitability of local, inexpensive substrates for commercial production of yellow mealworm without compromising their nutritional quality and utilisation for food and feed.