Yellow Mealworm (Tenebrio Molitor) Production from Agricultural and Agri-Food Side-Streams: A Narrative Review of Food, Feed, Frass, Soil Health and Circular Agricultural Applications

Abstract:

Agricultural and agri-food systems generate substantial side-streams containing carbohydrates, proteins, lipids, minerals, fibre, and other valuable components that often remain underutilised or discarded. The yellow mealworm, Tenebrio molitor, offers an opportunity to convert selected side-streams into insect biomass and nutrient-rich frass, thereby linking resource recovery with food, feed, and crop production. This narrative review synthesises a practical circular sequence in which side-streams are characterised and screened for safety, formulated as mealworm substrates, converted into insect biomass and frass, processed into food or feed products, and returned to agriculture through frass-based soil and crop applications. The review examines how nutrient balance, moisture, fibre, digestibility, palatability, inclusion level, and contaminants influence larval performance, biomass quality, and product safety. It further evaluates mealworm-derived products and the effects of frass on soil nutrient availability, microbial activity, and crop performance. The central contribution is a connected side-stream-to-crop framework showing how mealworm biomass and frass can be managed as complementary outputs within one circular agricultural pathway. Evidence from Africa, including Kenya, remains limited, highlighting the need for locally validated substrates, safety standards, field evaluation of frass, whole-chain economic assessment, and enabling markets.