Beyond the Black Box: Reproductive Strategies of the Black Soldier Fly as a Model for Bridging Evolutionary Biology and Applied Entomology

The black soldier fly (BSF; Hermetia illucens) is rapidly emerging as a model for evolutionary biology and insect biotechnology. While larval biology has been extensively characterised, the reproductive biology of adults remains largely underexplored. Here, we present a timely review synthesizing recent empirical findings in physiology, behavioural and chemical ecology to open the “black box” of BSF reproduction, focusing on processes that span eclosion to senescence. We highlight pre- and post-mating mechanisms that underlie overall reproductive fitness: From mating latency, lekking dynamics, courtship and copulation, to sperm transfer, storage and oviposition. We discuss these elements in the context of sexual selection theory and identity notable characteristics of BSF reproduction that differ from traditional insect reproductive models. These include the unique capital breeding life history (non-feeding adults dependent on larval reserves), protandry (early male emergence) that couples with nutritionally influenced sexual maturation and a lek-like mating system. The sex-specific longevity that varies with mating status and morphologically complex reproductive tracts also suggest opportunity for strong postcopulatory sexual selection. Increasingly, environmental factors such as light, substrate volatiles, and rearing design are reported to significantly modulate BSF reproduction in an industrial environment, highlighting the potential for bridging fundamental and applied biology. We propose a novel conceptual framework that interconnects these elements and we outline critical questions that are still unresolved (e.g., mechanisms of sperm precedence, female control of fertilization). This interdisciplinary model supports both fundamental insights into reproductive evolution and provides practical improvements for optimizing industrial mass-rearing.