Oxygen: a driver of heat generation in black soldier fly bioconversion

Abstract Black soldier fly larvae are ectothermic insects that rely on external heat for efficient bioconversion. Yet, the heat jointly produced by the larval respiration and microbial metabolism often reduces bioconversion efficiency, increases CO 2 and NH 3 emissions, and poses several operational challenges. Understanding the underlying biochemical pathways involved in heat production is crucial for shifting from a reactive approach to a proactive, heat management strategy. These pathways mirror those observed during composting and silage fermentation. Oxygen availability in the substrate is key to modulating heat production via high-energy aerobic respiration or low-energy fermentation. Recent studies demonstrate that altering physical substrate properties (e.g. bulk density, particle size, moisture content, etc.) can effectively regulate heat generation. Future strategies should integrate oxygen management with other process parameters, including nutrient formulation, ventilation rate and regime, and carbon-to-nitrogen ratios. Modulating oxygen supply to control metabolic pathways can improve overall bioconversion efficiency, reducing energy inputs and emissions.