Assessment of Hermetia illucens larvae performance reared on raw or contaminated peanut by-products with Aspergillus flavus and Fusarium graminearum

The peanut supply chain is characterised by a high production of by-products, mainly shells and small pods,\r\noften discarded by processing companies. However, the richness of nutritive substances makes these products\r\nvaluable as feed substrates for Hermetia illucens larvae rearing. Therefore, the aims of this work were to (1) evaluate\r\nthe performance of H. illucens larvae reared on peanut by-products and (2) study the effect of various levels of\r\nfungal contamination in by-products on H. illucens larvae performance, focusing on growth and mortality. Two\r\nagro-industrial peanut by-products (rich by-product, R; poor by-product, P) were ground and mixed in different\r\npercentages (0-100%, step 10%) to obtain 11 different feeding substrates, then rehydrated to 70% moisture. Three\r\ndifferent trials were conducted using these substrates, with three-day-old H. illucens larvae reared for 10 days.\r\nWhereas, the effect of fungal contamination was investigated by inoculating chicken feed (standard, S) and substrate\r\nP5R5 (50% P and 50% R) with two spore suspensions (Aspergillus flavus and Fusarium graminearum, 105 spore/mL),\r\nat three different inoculation times (5, 3 and 0 days before the addition of larvae). The substrate composition\r\nconsiderably impacted larval growth, with the highest larval weight increase obtained when R reached 50% in the\r\nsubstrate. Fungal contamination in by-products significantly reduced larvae performance, with a stronger negative\r\neffect from A. flavus. These findings suggest the potential for enhancing peanut by-products as a rearing substrate\r\nfor H. illucens larvae, although the composition and the possible fungal contamination may reduce the effectiveness\r\nof the process.