Antibacterial and antioxidant potentials of larval extract of black soldier fly, Hermetia illucens and blow fly, Lucilia sericata, for biomedical applications

Background This study was conducted to assess the antibacterial and antioxidant activities of the larval extracts of whole black soldier fly, Hermetia illucens, and green bottle blow fly, Lucilia sericata. Material and methods The disk diffusion method was used to determine the antibacterial activities of larval extracts of black soldier fly and blow fly. Five concentrations of the methanol extracts of larvae of these fly species (0, 40, 80, 160, and 325 mg/ml) were prepared in dimethyl sulfoxide and tested against Gram-positive and Gram-negative bacteria. The antioxidant activity was determined by DPPH free radical scavenging assay using four different concentrations, with ascorbic acid as the standard. Results The disc diffusion assay showed that the larval extracts of both fly species possess strong antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Salmonella enterica. The highest antibacterial activity was observed at 80 mg/ml concentration. However, an increase in concentration beyond 80 mg/ml did not increase the antibacterial activity. Significant diffe­rences were observed between the effects of the two larval extracts, concentrations, and tested bacterial species (p < 0.05). The DPPH free radical scavenging assay of the larval extracts of both flies showed moderate antioxidant activities. Conclusions The methanol extracts of larvae of two insect species exhibited strong antibacterial activities against both Gram-negative and Gram-positive bacteria and moderate antioxidant activities, indicating their pharmacological potential for use as a natural antibacterial and antioxidant source for health benefits.