Artificial diets for Hermetia illucens (Diptera: Stratiomyidae): Investigating nutritional and environmental limitations

In recent decades, interest has grown in utilising black soldier fly ( Hermetia illucens ) larvae (BSFL) to bioconvert organic waste streams into valuable products such as animal feed and fertilisers. However, there are still gaps in knowledge regarding the nutritional components and environmental conditions required to effectively harness BSFL for processing diverse, often non-optimal, organic waste streams. The objective of our study was to characterise key nutritional and environmental limitations affecting BSFL cultivation, with relevance to future use under low-input or challenging conditions. We formulated iso-caloric artificial diets, systematically varying one component at a time (i.e. protein, carbohydrates, fats, fibres, and calories) to establish their impact on BSFL growth, development rate, and biomass yield. Additionally, environmental parameters, including temperature, substrate moisture, pH, concentration of bulking agents, and presence of common agricultural waste chemicals (NaCl, NaOCl, NH 4 + ) were evaluated for their effects on larval performance. Our findings indicate that optimal BSFL development occurs within defined nutritional and environmental ranges: dietary protein levels of ≥10%, digestible energy ranging from 239–340 calories per 100 g, substrate moisture above 60% and below a well-drained, saturated state (without free water), and temperatures between 26–40 °C. Growth rates declined under suboptimal nutrient conditions, temperature extremes, drought or water saturation, and high concentrations of agricultural chemicals; NaCl (>5.5%) and NH 4 + (>1.25%) were particularly fatal. This research underscores the potential of BSFL for effectively valorising low-quality agricultural waste, offering clear guidelines for dietary optimisation and improved waste management practices.