Optimizing substrate moisture content for enhanced larval survival and growth performance in Hermetia illucens: exploring novel approaches

Abstract

Insects are receiving a lot of attention as an alternative protein source, especially the black soldier fly, Hermetia illucens . This insect is of particular interest due to its potential as a waste converter as it can be grown on low-value organic substrates, such as agricultural side-streams, manure and decomposing materials. It’s capacity to turn low-value biomass into high-quality protein provide new opportunities in organic waste management. Unfortunately, rearing of black soldier fly larvae (BSFL) does not run efficiently on most substrates. Several parameters influence the rearing efficiency of BSFL. One of the parameters that is often overlooked is the moisture content of the substrate and the physical properties, such as water release/holding, associated with it. In this study the water release properties of 3 BSFL feeds, each at a dry matter content ranging from 10 to 90%, were investigated using 4 different methods, being water release by (1) filtration, (2) sedimentation, (3) syneresis and (4) centrifugation. Rearing of BSFL on the substrates with different dry matter content showed that water release influences larval performance and survival. Moreover, correlating survival to water release indicated that when substrates are hydrated to the minimum dry matter content, at which no water release is measured by the sedimentation method, the highest BSFL survival can be achieved for that substrate. In addition, a standardised method for determining the most optimal dry matter content of substrates based on substrate water holding capacity was developed.