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 breed. Both T16 and T40 breeds exhibited higher body weight, survival rate, and substrate reduction efficiency compared to control groups (C16 and C40). Transcriptome analysis showed significant gene expression changes in both T16 and T40 groups at various time points compared to control groups. Specifically, T16 had 84 upregulated and 64 downregulated genes, while T40 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 T16, and 128 upregulated and 68 downregulated in T40. 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 to adapt to cold and heat stress.