The validity of the bioaccumulation index versus the bioaccumulation factor for assessment of element accumulation in black soldier fly larvae

Mineral and heavy metal accumulation in black soldier fly (Hermetia illucens) larvae (BSFL) is of growing interest. The bioaccumulation elements BSFL usually assessed by a factor (BAF), which the ratio between concentration an element organism its feeding substrate. Recently, new index, i.e. index (BAI), represents relative increase given to initial has been proposed. BAI claimed be more valid alternative BAF, especially because it takes into account larvae. This work assesses BAF comparison with true retention rate BSFL. Using experimental setup that included turnover two different regimes (with without substrate for neonatal larvae), we show that: (1) only tiny fraction (<0.1%) total pool system, implying main source accumulated larvae; (2) each specific pattern from start end experiments. Furthermore, cases where both diets substrates are used during larval growth period, can confounded time/age diet-related effects. From agri-food perspective rearing accumulation, body remains most evaluation parameter. results input-output calculations element-unspecific correlations suggest higher agreement than BAI. Therefore, propose assess followed under laboratory conditions.