Effects of olive pomace, date palm residues, and banana leaves on growth, bioconversion, and biomass composition of black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), larvae.

Larvae of the black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), are increasingly used to convert organic residues into insect biomass. This study evaluated whether locally available olive pomace, date palm residues, and banana leaves, used alone or in equal combinations with olive pomace, could support larval growth, substrate reduction, and production of biomass with different proximate composition. Larvae were reared for 15 days in a completely randomized laboratory trial using five substrate treatments: olive pomace, date palm residue, banana leaves, olive pomace mixed with date palm residue, and olive pomace mixed with banana leaves. Larval size, survival, substrate reduction, bioconversion efficiency, and larval proximate composition were compared among treatments. Mixed substrates generally supported greater larval growth than single-residue diets, with OP + BL producing the strongest overall growth and bioconversion-efficiency performance. BL achieved the greatest substrate reduction, whereas DP produced larvae with the highest measured crude protein concentration but showed comparatively weak growth and conversion performance. OP produced the highest measured crude fat concentration. These findings indicate that substrate selection involves a trade-off between larval growth, waste-conversion performance, and biomass composition, and that no single treatment maximized all outcomes.