Evaluating the impact of pupation substrates on life cycle transition and reproductive output of black soldier fly (Hermetia illucens)

Abstract

Abstract The black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), is a key species in sustainable protein production and organic waste bioconversion. While larval nutrition has been extensively investigated, the role of pupation substrate particularly its physical properties in shaping adult emergence and reproductive performance remains poorly resolved. This study evaluated four pupation substrates (sand, coconut coir, sawdust, and corrugated cardboard) differing in particle structure, porosity, and moisture retention capacity. Late-instar larvae (n = 200 per replicate; five replicates per treatment) were reared under controlled conditions (27 ± 1 °C; 70 ± 5% RH; 12:12 h L:D). Substrate type significantly affected pupation rate, pupal duration, adult emergence, fecundity, and egg hatchability ( ). Coconut coir, characterised by high porosity and moisture buffering capacity, yielded the highest pupation rate (95.1 ± 1.7%), shortest pupal duration (12.1 ± 0.4 days), and greatest emergence (92.3 ± 2.1%). In contrast, sand, with higher compactability and lower moisture retention, resulted in reduced pupation success (81.2 ± 3.5%) and prolonged development (14.8 ± 0.6 days). Fecundity followed similar trends, with coir producing 512 ± 36 eggs per female compared to 389 ± 27 in sand. Egg hatchability varied among treatments; however, differences are more likely attributable to incubation microconditions rather than maternal physiological effects. These findings demonstrate that substrate physical structure rather than composition alone plays a dominant role in pupal success and downstream reproductive performance. Optimising pupation substrates with appropriate aeration, particle size distribution, and moisture stability can substantially improve productivity in industrial mass-rearing systems.