Effect of rearing substrate on growth performance, waste reduction efficiency and chemical composition of black soldier fly (Hermetia illucens) larvae

BACKGROUND: Wastes can be used as rearing substrate by black soldier fly (BSF)
larvae, the latter being exploitable as protein source in animal feed. This research
aimed to assess the influence of four rearing substrates [Trial 1 (organic wastes): a
mixture of vegetable and fruit (VEGFRU) vs a mixture of fruits only (FRU); Trial 2(agro-industrial by-products): brewery (BRE) vs winery (WIN) by-products] on BSF
larvae development, waste reduction efficiency, and nutritional composition.
RESULTS: If respectively compared to FRU and WIN, VEGFRU and BRE larvae
needed less time to reach the prepupae stage (22.0, 22.2, 20.2 and 8.0 days of
trial, respectively) and had higher protein content (229.7, 257.3, 312.9 and 395.7
g kg-1 DM). The waste reduction index ranged from 2.4 (WIN) to 5.3 g d-1 (BRE).
BRE larvae showed the lowest saturated and the highest polyunsaturated fatty
acids proportions (612.4 and 260.1 g kg-1 total fatty acids, respectively).
CONCLUSION: Vegetable and fruit wastes and winery by-products can be used as
rearing substrates for BSF larvae mass production. Brewery by-products led to very
promising larvae performances and nutritional composition. However, given BRE
limited availability, low BRE dietary inclusion levels could be used with the purpose
of increasing larvae performances.