Effect of Substrate Composition on Bioconversion and Nutritional Quality of Hermetia illucens Larvae in Tropical Systems

Organic waste valorisation using black soldier fly larvae (BSFL), Hermetia illucens L., offers a biological strategy to transform biodegradable residues into biomass with potential feed applications. This study evaluated five fruit–vegetable residue mixtures under tropical conditions: 100% fruit (100F), 100% vegetables (100V), 50% fruit–50% vegetables (50F–50V), 70% fruit–30% vegetables (70F–30V) and 30% fruit–70% vegetables (30F–70V), using three independent rearing units per diet. The analysis included initial egg mass, estimated viable larvae, coffee husk input as structural bulking material, tray-level process conditions, larval biomass, dry feed offered and estimated bioconversion indicators. The 100F treatment produced the greatest dry biomass (0.1311 ± 0.0132 kg), while 100V and 50F–50V showed favourable input-normalised responses. Biomass was also expressed relative to estimated viable larvae and dry feed offered to support treatment interpretation under the operational conditions evaluated. Coffee husk improved substrate handling and was incorporated into the dry-matter balance; therefore, adjusted BCR was interpreted as a process balance indicator and complemented with biomass yield per dry feed offered. Estimated protein values ranged from 35.4% to 38.1% in selected composite samples. Salmonella spp. were absent in pooled microbiological samples, Escherichia coli was <10 CFU/g, and screened heavy metals were below the laboratory detection limit in selected composite samples. Overall, the results support the potential of BSFL systems for valorising local fruit and vegetable residues under tropical conditions.