Larval and pupal development in Hermetia illucens: developmental checkpoints and starvation-induced dormancy.

The black soldier fly (BSF) Hermetia illucens is a cosmopolitan insect species distributed across five continents. This broad distribution suggests a high capacity to adapt its life history to diverse ecological niches. However, the developmental checkpoints that determine the transition to metamorphosis, as well as whether starvation induces a dormancy-like state and its underlying structural basis, remain unclear. In this study, we characterized the anatomical features, developmental timeline, starvation resistance, and developmental checkpoints of BSF. We identified a critical weight (CW) of 83 mg, above which larvae irreversibly committed to metamorphosis. Notably, larvae below the CW survived starvation for several months and immediately resumed growth and development upon re-feeding, indicating that they enter a starvation-induced quiescent state. Starvation caused severe atrophy of the fat body, whereas five days of re-feeding fully restored fat body morphology, suggesting that stored energy reserves are mobilized during starvation to support survival. These findings reveal a previously unrecognized dormancy-like strategy in BSF and suggest that this developmental plasticity facilitates colonization of environments with intermittent or seasonal food availability.