A multitrophic culture system for the production of black soldier fly larvae (Hermetia illucens)

Abstract

A multitrophic system involving mealworm larvae (MWL) and black soldier fly larvae (BSFL) was developed to transform kitchen waste into usable biomass. MWL, fed mainly on kitchen waste, reached an average prepupal length of 2.4cm, fresh weight of 0.12g and protein and lipid content (dry matter) of 44.2% and 16.5% respectively, with an average specific growth rate (SGR) of 2.2%/day and a feed conversion ratio (FCR) of 7.9. The frass generated by the MWL was collected and subsequently fed to the BSFL for an average period of 21 days. On average each MWL, weighing about 0.13g, produced 0.14g of frass over an average period of 97 days. Different batches of BSFL, fed on a variety of feeds, including the MWL frass, kitchen waste and oats, had an average prepupal length of 1.3cm, fresh weight of 0.16g and protein and lipid contents (dry matter) of 41.4% and 26.3% respectively, with an average SGR and FCR of 4.3%/day and 8.9 respectively. BSFL fed MWL frass only obtained some of highest SGR values and the best FCR, with one group achieving 7.5%/day and 2.9 respectively. The amount of frass generated by the MWL, a total of 646g, was capable of sustaining 253.0g of prepupal stage BSFL. This preliminary investigation has demonstrated that a multi-trophic production system using kitchen waste-fed MWL frass to feed BSFL is feasible. Further studies should be carried out to see if the multitrophic concept can be exploited as a production approach.