Razi University

   Introduction: The contemporary world faces three interconnected crises, namely unprecedented population growth, the detrimental environmental impacts of conventional livestock farming, and the escalating challenge of agricultural and food waste. The yellow mealworm (Tenebrio molitor), characterized by high feed conversion efficiency, low water and land requirements, and the capacity for bioconversion of organic side-streams into high-quality protein, is recognized as one of the most promising solutions. The present study was designed and conducted with the objective of optimizing T. molitor rearing systems through investigating the effects of various dietary substrates, nutritional supplements, and genetic crosses on biological performance, reproductive parameters, nutritional composition, feed conversion efficiency, and frass fertilizer quality, within the framework of circular economy and sustainable agriculture.Materials and Methods: This research was carried out in four distinct experimental phases using T. molitor larvae (yellow and black strains) under controlled conditions (temperature: 28±1°C, relative humidity: 65±5%, complete darkness). The first phase was dedicated to inter-strain crosses (6 treatments, 5 replicates), assessing biological parameters, reproductive traits, nutritional composition, chemical profile, genetic diversity (via COI gene sequencing), and demographic parameters (using a two-sex life table). The second phase involved five types of agricultural residues (barley straw, wheat straw, lentil residue, chickpea residue, and vetch residue) at four substitution levels (25%, 50%, 75%, and 100%) with 5 replicates. The third phase comprised 19 types of wet and 8 types of dry fruit and vegetable wastes at four concentration levels with 3 replicates. The fourth phase examined milk powder supplementation (4 levels: 0, 7, 15, and 25%) and probiotic supplementation (4 treatments: control, B. bifidum, L. acidophilus