The world production of quinoa has tripled in the last 20 years. Expanding at a rate of 11%, the global quinoa market is projected to increase up to 1.4 billion by 2032. However, its expansion and intensification entail a large volume of husk, an emerging waste of poor value from the scarification of the grain performed to reduce its bitterness due to saponins. Some scarce studies have explored the use of husk for animal feeding, but with limited or unclear results. Therefore, due to the remarkable bioconversion capability of edible insects, the aim of this study was to explore the potential bioconversion of quinoa husk by T. molitor or H. illucens. Diets were formulated based on wheat bran (control diet) or partial replacement with quinoa husk at 15%, 30% or 50% (Q15, Q30, Q50). Each diet (6 kg for T. molitor or 15 kg for H. illucens) was produced in triplicate. A mean number of 15.000 larvae (4 weeks old and >1 cm of length for T. molitor) or 13.000 larvae (H. illucens) were reared for each replicate of substrate until 11 weeks old (T. molitor) or 12 days old (H. illucens). Total larvae biomass gained (WG), growth rate (GR), bioconversion efficiency (BE), mass reduction (MR) and mass reduction index (MRI) were assessed on a fresh basis. The proximal composition of the diets and the fresh larvae was analyzed. Control larvae attained a WG of 45 ± 5 mg per larvae, at rate of 6 mg/week for T. molitor and 157 ± 16 mg per larvae, at rate of 13 mg/d for H. illucens. Q15 and Q30 reached a significant same WG respect to the control for both insect species, while Q50 caused significant lower WG and GR. All quinoa levels for H. illucens did not differ on the BE, MR and MRI respect to control diet, while such similarity to control was only evident for Q15 in case of T. molitor. Therefore, considering all the productive parameters together, quinoa husk up to 15% for T. molitor and 30% for H. illucens can be used for insect feeding, reaching an excel-lent bioconversion of these by-products into nutritive insect meals.

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

Peer reviewed