Vegetable by-products bioconversion for protein meals production through black soldier fly larvae

The aims of this trial were to evaluate the effect of four different substrates on growth performance and chemical composition of black soldier fly (Hermetia illucens) larvae. Two trial were performed: in the first, vegetable and fruit waste (VEG) or only fruit waste (FRU) were used as rearing substrates, while the second trial used winery by-products (WIN) and brewery by-products (BRE). Two thousand four hundred larvae were counted, weighed in batch of one hundred and homogenously divided in plastic containers. Six replicate per substrate were performed to evaluate growth performance. The containers were placed in a climatic chamber with a temperature (27±0.5 °C) and relative humidity (70±0.5%). Larvae were fed with an initial amount of one hundred grams of substrate/container, the containers were monitored everyday and 50 g of feed was added as needed. For each trial, to obtain the needed larvae amount for proximate composition analyses, a second set of six replicates (500 larvae per replicate) per rearing substrate was concurrently prepared. Larvae weights and lengths were monitored and data subjected to a two-way Mixed ANOVA, differences of means by Shapiro-Wilk test (P<0.05). Final larvae weights, lengths and chemical composition were further subjected to independent samples Student's t-tests to assess differences. Growing time showed significant differences in the two trials. VEG reached 30% of prepupae faster than FRU. In the second trial, the fastest growth rate was reported by BRE. As far as weight is concerned, at the end no statistical differences were highlighted between treatments in both trials. Final larvae chemical composition was dramatically influenced by the rearing substrates.