Research on population degradation of Hermetia illucens and growth performance of hybrid strain

Hermetia illucens, the black soldier fly (BSF), as a novel resource and environmentally significant insect, offers considerable ecological and economic benefits in the treatment of various organic wastes, including kitchen waste, livestock and poultry manure, and vegetable residues. However, during large-scale BSF production, long-term indoor breeding leads to inbreeding within populations, resulting in degenerative phenomena such as deterioration in growth performance.

This study aimed to identify the generation at which degradation occurs, the associated degenerative traits, and the potential advantages of hybrid BSF strains.

Continuous inbreeding of BSF was conducted over multiple generations to determine the onset of degradation and related growth traits. Exogenous populations were then crossed with the degraded populations, and comparisons were made among the hybrid strains, degraded populations, and exogenous populations.

The results indicated that by the F9 generation of inbreeding, larval weight, crude protein, and crude fat content of BSF had decreased significantly (P < 0.05). Moreover, the oviposition amount of adult BSF showed a significant decline by the F20 generation (P < 0.05). After hybridization between the degraded and exogenous populations, the growth performance of the hybrid strain was significantly improved compared to that of the degraded population (P < 0.05), and no significant difference was observed relative to the wild population (P > 0.05). Three different populations were uesd in experiments to treat chicken manure, the crude protein and crude fat contents of the hybrid strains were approximately 35.85% and 27.57%, respectively, whereas those of the degraded population were 29.78% and 23.61%, with significant differences between them (P < 0.05). Additionally, the reduction rate and bioconversion rate of chicken manure treated with the hybrid strains were 50.23% and 33.19%, respectively, which were significantly higher than those achieved by the degraded population (P < 0.05).

This study clarifies the generational onset of degradation and key growth traits in BSF, providing a theoretical basis for the large-scale breeding of this species.