Use of black soldier fly (Hermetia illucens (L.), Diptera: Stratiomyidae) larvae processing residue in peat-based growing media

The Black Soldier Fly (Hermetia illucens(L.), Diptera: Stratiomyidae) is an insect whose larvae thrive onagro-industrial by-products. This study reports the first use of black soldier fly larvae processing residue(BSPR) as an innovative ingredient for growing media. BSPR was characterized and evaluated to partiallyreplace commercial peat (CP) in the production of potted plants. Chemical and microbiological analysisshowed the suitability of BSPR for soilless production. Hence, six growing media mixtures (CP 100%+ slow acting synthetic solid fertilizer, CP 90% + BSPR 10%, CP 80% + BSPR 20%, CP 70% + BSPR 30%, CP60% + BSPR 40% and CP 100% without fertilizer) were assessed for the production of baby leaf lettuce,basil and tomato potted plants. Using BSPR in a proportion up to 20%, all investigated crops showed val-ues significantly greater than or comparable to those obtained using CP 100% + slow acting synthetic solidfertilizer. In general, BSPR used in a proportion up to 20% increased the crop growth of baby leaf lettuce,basil and tomato, recording a high total dry weight (+31%, compared to the total average) and the mea-sured leaf parameters (+39% of leaf area, +14% of leaf number), without showing abiotic stresses. Thisstudy indicates that BSPR used in a proportion up to 20% might be a valid approach for soilless productionof potted baby leaf lettuce, basil and tomato plants.