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

Abstract

Goals number 2, 11 and 12 of the 17 sustainable development goals, enacted by the United Nations as part of the 2030 Agenda for sustainable development, aim to end hunger as a priority, create sustainable cities and above all encourage responsible consumption and production. With increasing world population and higher demand for food, we need to find ways of producing cheap sources of protein and lipid that may in turn be used as animal or aquaculture feed. A multitrophic system involving mealworm larvae (MWL, Tenebrio molitor) and black soldier fly larvae (BSFL, Hermetia illucens) was developed to transform fruit and vegetable kitchen waste into usable biomass. MWL, fed mainly on kitchen waste, reached an average prepupal length of 2.4 cm, fresh weight of 0.12 g and dry matter protein and lipid contents 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. Conversely, BSFL fed on a variety of feeds, including MWL frass, kitchen waste and oats, had an average prepupal length of 1.3 cm, fresh weight of 0.16 g and dry matter protein and lipid contents of 41.4% and 26.3% respectively, with an average SGR and FCR of 4.3%/day and 8.9 respectively. The BSFL fed MWL frass obtained some of highest SGR and lowest FCR values, with one group achieving 7.5%/day and 2.9 respectively. This investigation has demonstrated the feasibility of a multi-trophic production system using kitchen waste to feed MWL whose frass was in turn used to feed BSFL thereby producing protein- and lipid-rich biomass that can serve as animal or aquaculture feed.