Identification of Neuropeptide F (NPF) Signaling and Associated Regulation of Food Intake in the Dark Black Chafer Beetle Holotrichia parallela

Holotrichia parallela is a globally distributed soil-dwelling pest that poses a major threat to peanut cultivation in China. Neuropeptides, as critical signaling molecules, regulate multiple physiological and behavioral processes in insects and represent highly promising targets for pest management. To date, the functional characteristics of neuropeptides in H. parallela remain unreported. In this study, we isolated and cloned one NPF and one NPFR gene, respectively. Bioinformatics analysis revealed that alternative splicing of the NPF gene produces two transcript variants, NPFa (255 bp) and NPFb (369 bp). The NPFR gene spans a length of 1188 bp, encoding 395 amino acids that contain seven α-helical transmembrane domains, indicating that it belongs to the family A G protein-coupled receptor (GPCR) family. Spatiotemporal expression profiles demonstrated that NPF was most abundant in the adult brain, whereas NPFR was highly enriched in the brain and antennae. NPF expression peaked in second-to-third-instar larvae, while NPFR was highly expressed in eggs. Starvation stress significantly upregulated the expression of both genes. RNA interference (RNAi)-mediated silencing of NPF and NPFR significantly reduced food intake, female fecundity, and glycogen content in adults. These findings enhance our understanding of insect neuropeptides signaling networks and support the development of behavior-based pest control strategies.