The Use of increasing false Flax [Camelina sativa (L.) Crantz] Cake Levels as rearing Substrate of Black Soldier Fly (Hermetia illucens) Larvae

False flax (Camelina sativa, CS) is an oilseed crop used for the production of biofuels. Compared with other conventional oilseeds (such as canola and sunflower) CS has several agrotechnical benefits: cultivation of the crop is simple and environmentally friendly; application of pesticides/herbicides is not needed;1 the plant is adaptable to marginal soils, showing good productivity,2-4 and may be a suitable candidate for biofuel production in marginal environments. The by-product (cake) obtained after the seed oil extraction is high in protein (350-400 g kg-1) and contains a residual of oil of 100-130 g kg-1. The energetic value of CS cake (MJ kg-1 DM) is higher for ruminants (15.0) than for pigs (14.0) and poultry (8.00).6 A potential disadvantage of using CS cake in livestock diets is the presence of the glucosinolates (GSL).7 However, to overcome this disadvantage the cake of a CS line with a reduced GSL content has been used in this trial. The residual oil, present in the seedcake, is characterized by approximatively 90% of unsaturated fatty acids (FA) and the n-3 accounts for about 37.0% of the total FA content. The lipid content of insects is largely dependent on their diets and stage of development, therefore, we hypothesize that the composition of FA in black soldier fly (BSF) larvae, one of the most promising authorized insect species for animal feed purposes, is influenced by the composition of FA in their diet. We therefore consider that the larvae of BSF could similarly accumulate PUFA, thereby improving their dietary value. Accordingly, the aim of the present work was to determine the impact of CS cake on the development of BSF larvae and if it is possible to dietary enrich BSF larvae with n-3 FA with a rearing substrate containing PUFA and to determine the time required to modify their FA profile. A trial was carried out at the Experimental Facility of the Department of Agricultural, Forest and Food Sciences (DISAFA; University of Torino, Torino, Italy). A standard crop diet (Gainesville diet) was used as control diet. Four diets were formulated with a substitution of 25% (CS25), 50% (CS50), 75% (CS75) and 100% (CS100) of control diet with a CS low GSL cake content. Six replicates per treatment were performed and the replicates were fed daily with 40 g on a wet basis (70% moisture) in a climatic chamber with 28 °C T and 70% RH.