Selected commercial <scp> <i>Bacillus</i> </scp> probiotic strains improve the performance of black soldier fly larvae, <scp> <i>Hermetia illucens</i> </scp> L. (Diptera: Stratiomyidae)

Abstract The inability of black soldier fly larvae to efficiently extract and assimilate nutrients from diverse organic substrates leads to the production of small‐sized and poor‐quality larvae. Suboptimal nutrient digestion reduces overall biomass yield, survival and overall larval quality. Incorporating exogenous probiotics into black soldier fly larvae feeding systems is important in improving overall black soldier fly production. The study focused on the use of an exogenous Bacillus probiotic strain mixture to improve larval survival, growth and nutrient accumulation. A total of 1500 four‐day‐old black soldier larvae were manually counted in triplicate for each treatment and subjected to exogenous Bacillus probiotic strain mixture inoculation levels using a poultry feed. Four inoculation levels were used: P0 (0 colony‐forming unit [CFU]/kg) as a control, P1 (4 × 10 10 CFU/kg) as treatment 1, P2 (8 × 10 10 CFU/kg) as treatment 2 and P3 (12 × 10 10 CFU/kg) as treatment 3. The experiment was carried out in the laboratory under a completely randomised design. Larvae were reared under ambient conditions, with an average temperature of 28 ± 1.09°C and relative humidity of 70 ± 8.1%, using a poultry feed with a pH of 8.2 ± 1.0. Significant differences among inoculation levels for length, weight, survival and proximate composition were recorded ( p &lt; 0.001). Significantly higher growth, survival rates and protein content were observed in larvae fed on P2‐inoculated feed ( p &lt; 0.001). Findings of the present study demonstrate that exogenous Bacillus probiotic strain mixtures not only enhance larval growth but also survival rates and nutrient accumulation, thereby increasing overall production.