Transcriptome Analysis of the Brain and Gnathal Ganglion Reveals Feeding-Mediated Genes in Helicoverpa armigera Larvae

Despite the central role of the gustatory nervous system in regulating feeding behavior in the larvae of the major agricultural pest Helicoverpa armigera, the systemic molecular basis of this process is largely unknown. To investigate the molecular basis, we performed RNA-seq on dissected brains and gnathal ganglion (GNG) from fifth-instar larvae, revealing 944 differentially expressed genes (DEGs) that are potentially involved in feeding behaviors. Bioinformatic analyses revealed significant enrichment of these DEGs in pathways including “taste transduction”, “neuroactive ligand–receptor interaction”, and “feeding behavior”. Furthermore, 41 candidate genes closely associated with feeding behaviors were screened, including neuropeptides, neuropeptide receptors, gustatory receptors, and feeding-mediated proteins. Phylogenetic analyses demonstrated that these key genes are evolutionarily conserved. Quantitative real-time PCR (qPCR) results confirmed that most of these candidate genes were significantly upregulated during the fifth instar stage, and their expression was further enhanced under starvation conditions (p < 0.05). Our study presents the first systemic feeding-mediated transcriptomic profile in the insect central nervous system and identifies key feeding-mediated genes in H. armigera larvae. These findings advance our understanding of the molecular basis of feeding in Lepidopteran pests and offer potential target genes for developing gustatory-based pest control strategies.