The Effects of Density on the Growth and Temperature Production of Tenebrio molitor Larvae

Tenebrio molitor larvae live, at least partially, inside their feed. Hence, they do not live on a 2D plane but in a 3D environment. However, previous studies mainly focused on the optimal number of larvae for a given surface area, not the available volume. The goal of this study was to assess the growth and survival of mealworms in a standardized semi-industrial setting with a varying density (cm 3 ) and substrate height. A full factorial experimental design was used with five larval densities (0.5–8 larvae/cm 3 ) and four feed heights (1–8 cm) in 60 × 40 cm crates. Furthermore, the in-crate temperature was monitored and linked to the density. The results of this study clearly indicate that mealworm larvae prefer a low density (cm 3 ). At low larvae densities, the substrate height was less important, with a slight preference for a thicker layer. In contrast, at high(er) larval densities, a lower layer thickness resulted in better growth. The in-crate week temperature varied up to 14 °C (25–39 °C) between treatments and could be predicted well based on the number and size of the larvae. These results may help the industry to improve their production efficiency in terms of larvae density, substrate height and room temperature.