Concerning agricultural by-products, a huge number of sources remains unexplored for insect feeding. One example are those derived from the olive oil industry, such as the problematic olive leaves, olive mill waste, “alperujo” or olive pomace. Therefore, due to the extraordinary bioconversion ability of Hermetia illucens (black soldier fly, BSFL), the main aim of this study was to explore the potential of valorization of olive oil by-products by using them in the feeding BSFL. BSFL diets were based on laying hen feed (control diet) or partial replacement with the different by-products: dry olive leaves at 15%, 30% or 50% (OL15, OL30, OL50) and dry olive pomace at 30%, 50%, 70%, 90% (OP30, OP50, OP70, OP90). Each diet (15 kg, 1:2 ratio of dry feed to water) was produced in triplicate. A total number of 13.000 larvae (91 g) were reared per replicate for 12 days. Total larvae biomass gained (WG), growth rate (GR), bioconversion efficiency (BE), mass reduction (MR) and mass reduction index (MRI) were estimated at fresh basis. The proximal composition of the diets and the fresh larvae was analyzed. Control larvae reached a WG of 157 ± 16 mg per larvae, at rate of 13 mg/d. Only in case of OL15, a significant same WG of 141 ± 25 mg than control was obtained, at rate of 12 mg/d. The rest of treatments caused significant lower WG and GR, being worse as the replacement level increased. Thus, OL50 reached 43 ± 7 mg per larvae and OP90, 51 ± 9 mg per larvae. Most diets did not differ on the BE, with a mean value closer to 13%, but being significantly lower for OP70 (9%) and OP90 (7%). MR was close to 80% for control diet, OL15 and OP30, with a MRI of 7%/day. The protein and lipid content of the larvae from control, OL15 and OP30 diets did not differ; but being lower the protein content of the larvae for the rest of diets. Therefore, considering all the productive parameters together, dry olive leaves at 15% and dry olive pomace up to 30% can be used for BSFL feeding, reaching an excellent bioconversion of these by-products into nutritive BSFL meal.

The INSECTA Conference 2024 was held from May 14 to May 16 in Potsdam, Germany.

No