Multigenerational effect of seaweed or selenium enriched substrates on nutritional composition of black soldier fly (Hermetia illucens)

Selenium (Se) is an essential trace element for livestock. To ensure an adequate intake is achieved, several supplementation sources have been studied targeting the different animal species. Although Se-enriched yeast remains one of the main sources of organic Se, other emerging and innovative sources, such as Se-enriched insects, could be useful for their potential use in animal nutrition. The purpose of this work was to study the effects of including algae ad/or Se in the rearing substrate of black soldier fly larvae (BSFL), where an absolute lack of information regarding nutritional compositional and multigenerational effect was identified. In this study, BSFL were reared on three different substrates: (1) a control substrate (CTR diet) of plant-ingredients (Gainesville diet), and (2) Ascophyllum nodosum diet (AN30%), with 30% substitution of the alfalfa meal with the brown algae and iii) a Se diet, where the CTR diet was fortified with 0.3 mg/kg of Se. All experiments were carried out under dark condition, at 25 °C with 70% relative humidity. The inclusion of algae seems to lengthen both larval and development time, while only minor effects were observed with the inclusion of Se in the diet. The multigenerational trial, however, showed that the substrates hereby studied (AN30% and Se diet) both affect the future generation of BSF, with considerably lower both egg-laying performance and hatching performance than in the CTR group. However, more studies are necessary to determine the effect of algae and Se on reproductive performance of BSF as well as the proximate composition of BSFL.