LARVAE: PRELIMINARY RESULTS Adele Muscolo, Orlando Campolo, Francesca Laudani, Vincenzo Palmeri, Agostino Sorgonà

Composting of agro-industrial wastes by black soldier fly (Hermetia illucens) larvae: preliminary results

Adele Muscolo 1 , Orlando Campolo 1 , Francesca Laudani 1 , Vincenzo Palmeri 1 , Agostino Sorgonà 1

1 Dipartimento Agraria, Università “Mediterranea” di Reggio Calabria, Italia

The insect-assisted composting by black soldier fly (Hermetia illucens L.) (BSF) larvae was commonly used for the management of organic wastes from different sources. However, no experiments focused on solid biowaste constituted by dry olive cake (DOC) mixed with chicken manure (CM) and olive leaves (OL). The insect-assisted composting process of these agro-industrial wastes was the objectives of the research projects, “Biocompostaggio degli scarti dell’industria agroalimentare mediata da insetti: sviluppo di un processo innovativo di bioconversione e valorizzazione” - POR CALABRIA FESR-FSE 2014-2020 Azione 1.2.2 funded by Regione Calabria. In particular, this study reported the preliminary results related to the specific physico-chemical parameters of a continuous BSF composting system used for the bioconversion of different mixture ratios of DOC+CM+OL wastes and the phytotoxicity of the best performant mixtures. For the composting process, we used a glass container (5 L) filled with the agro-industrial wastes (1.5 Kg) inoculated with larvae (7 days old) of H. illucens (20 g larvae/ 1 Kg wastes) and placed in a climatic chamber (27°C, 60% RH). In particular, the mixture ratios were the followings: M (100% fresh chicken manure), OC (100% dry olive cake), MIX0 (CM:DOC:OL, 45:45:45, w/w), MIX1 (CM:DOC:OL, 75:25:0, w/w), MIX2 (CM:DOC:OL, 70:20:10, w/w), MIX3 (CM:DOC:OL, 20:70:10, w/w), MIX4 (CM:DOC:OL, 30:30:40), MIX5 (CM:DOC:OL, 50:50:0, w/w), MIX6 (CM:DOC:OL, 25:75:0, w/w) and the control (feeding media standard for larvae). Three replicates for each treatment were considered. At 15 days of composting, the humidity, pH, electrical conductivity, organic matter, organic C and total N were measured and the three best performant compost (MIX0, MIX3 and MIX6) were used for the phytotoxicity assays as indicated by the UNICHIM N. 1651/2003 method. The results pointed out that 1) only the MIX0, MIX3 and MIX6 showed all the physico-chemical values within the mandatory limits as indicated by the Italian legislation (dlgs. no. 75/2010 and followings) and 2) only the MIX0 produced a lower phytotoxicity in terms of both germination index and root elongation, while the absence of phytotoxic substances of MIX3 and MIX6 was only observed in root elongation assay.

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Figure 1 –A) Adult of H. illucens, B) larvae of H. illucens in action on biowaste solids, and C) biowastes residues after the composting process.