Crude Protein, Amino Acid, and Iron Content of Tenebrio molitor (Coleoptera, Tenebrionidae) Reared on an Agricultural Byproduct from Maize Production: An Exploratory Study

Abstract

Abstract Edible insects offer environmental and nutritional benefits, as they are characteristically nutrient-dense, are efficient biotransformers of organic material, and emit fewer greenhouse gasses than traditional livestock. Cultivating Tenebrio molitor (yellow mealworm) as ‘minilivestock’ is one possible means of increasing access to insect protein for food insecure populations. Tenebrio molitor growth and nutrient content varies with diet and rearing conditions, but little is known about the precise impact of poor quality feedstocks, such as maize crop residue (stover). Stover is widely available across sub-Saharan Africa where maize is a common dietary staple. Early instar larvae were reared under controlled conditions on three feed substrates: a standard control; a mixed soy, maize grain, and stover diet; and a 100% stover diet. Larvae reared for 32 d were analyzed for total amino acid profile, crude protein, and iron content. Larvae fed the three diets contained all essential amino acids for human nutrition and compared favorably to other traditional protein sources. The mixed diet contained 40% stover by weight and yielded amino acid values similar to the control diet, suggesting that some grain feedstock could be replaced with stover without hampering nutrient content. A second experiment demonstrated that T. molitor were able to complete metamorphosis and survive on a 100% stover diet for multiple generations. These results suggest that stover could be a suitable dietary component for T. molitor, which could facilitate the development of low-cost insect farming systems in low-resource settings that stand to benefit from increased access nutrient-dense edible insects.