Impact of waste-derived ethanol on growth and metabolic allocation in black soldier fly larvae: Implications for organic waste treatment.

Insects possess chemosensory signalling systems that elicit coordinated behavioural and physiological responses to chemical stimuli. This study investigates the effects of ethanol (EtOH) exposure on black soldier fly larvae (BSFL) and evaluates its relevance to organic waste valorisation. Behavioural assays show that BSFL are attracted to EtOH and exhibit a stronger preference for direct contact over volatilised EtOH. Dietary EtOH supplementation enhances BSFL growth at concentrations of 1-5%, with larval dry weight increasing by up to 12% relative to the control. Further, EtOH supplementation alters lipid metabolism, leading to concentration-dependent increases in lipid accumulation. BSFL reared on feed containing 10% EtOH reached a lipid content of 11.25 wt%, which was 28% higher than that of the control. In contrast, the protein content and amino acid composition remained unchanged across all treatments. These results confirm that dietary EtOH contributes to the central carbon metabolism in BSFL and preferentially supporting growth and lipid biosynthesis rather than protein production. This study demonstrates that fermentation-derived EtOH functions as both a chemosensory signal and metabolic substrate in BSFL. These findings provide a basis to exploiting insect chemosensory responses in organic waste treatment and resource recovery systems.