In the last decade, insect larvae have attracted increasing attention as a sustainable alternative source of dietary protein, due to their high nutritional value and low environmental impact. In line with this growing interest, the European Commission approved in 2021 the use of powder derived from Tenebrio molitor larvae (TML) as a novel food safe for human consumption, facilitating its incorporation into a wide range of food products. This regulatory advancement has stimulated research aimed at optimizing insect rearing systems, particularly towards low-cost and sustainable feed substrates. The present study evaluated the feasibility of using agricultural by-products as alternative feed sources for TML rearing. Banana Peel (BP), Cocoa Bean Shell (CBS), and Brewer’s Spent Grain (BSG) were selected as experimental substrates and compared with wheat bran, which served as the control diet. All experimental diets were formulated to be isoproteic, ensuring an equivalent protein supply to the larvae. The trial was conducted using ten replicates per treatment, each consisting of 20 larvae. Larval growth performance was monitored over a 28-day period, during which parameters such as weight gain, feed consumption, and feed conversion ratio (FCR) were recorded. The experiment was subsequently extended for an additional 28 days to assess the effects of the different diets on the life cycle of Tenebrio molitor (TM), including pupation time, adult emergence, and survival rate. The results demonstrated that FCR values were comparable among all dietary treatments and did not differ significantly from the wheat bran control. Larvae fed with BP and BSG exhibited weight gain like that of the control group and significantly higher than those fed with CBS diet. Overall, these findings indicate that selected agricultural by-products can be effectively utilized as alternative feed sources for T. molitor rearing, contributing to the reduction of agricultural waste while supporting sustainable insect production. Future studies will focus on evaluating the effects of these alternative diets on the proximate composition of larval meals and on the qualitative and quantitative characteristics of larval lipid fractions. © 2026 AIDIC Servizi S.r.l.

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