Proteomic and transcriptomic analysis of cold- and heat-tolerant black soldier fly (Hermetia illucens) larvae

The larvae of black soldier fly (BSFL) can convert organic waste into insect proteins. Their bioconversion performance is considerably reduced under hot and cold conditions. To address this problem, we performed selective breeding of BSFL at 16 °C (T16) and 40 °C (T40), and evaluated differentially expressed genes and proteins in the heat- and cold-tolerant breeds. Both the T16 and T40 breeds exhibited higher body weight, survival rate, and substrate reduction efficiency compared to the control groups (C16 and C40). Transcriptome analysis showed significant gene expression changes in both the T16 and T40 groups at various time points compared to the control groups. Specifically, the T16 group had 84 upregulated and 64 downregulated genes, while the T40 group had 117 upregulated and 483 downregulated genes. Full-length transcriptome analyses revealed 27,414 new transcripts in the T16 group. Proteomic analysis revealed 57 upregulated and 114 downregulated proteins in the T16 group, and 128 upregulated and 68 downregulated in the T40 group. The upregulated genes, proteins, and novel transcripts in the bred strains mainly participated in Toll and Imd signalling, carbon metabolism, carbohydrate metabolism, fatty acid biosynthesis and metabolism, and amino acid metabolism. These findings provide insights into the molecular mechanisms that help BSFL adapt to cold and heat stress.