The Function of C-Terminal Pentapeptide in Allatostatin Type-C: Regulating Growth and Development by Affecting Juvenile Hormone Biosynthesis in Ostrinia furnacalis.

Allatostatin Type-C (AstC) is an insect neuropeptide involved in developmental regulation, but whether its conserved C-terminal pentapeptide, PISCF, remains bioactive as an isolated fragment is unclear. Herein, the synthetic PISCF was evaluated on the Asian corn borer, Ostrinia furnacalis, with AstC as a reference. Under sublethal exposure, PISCF suppressed larval growth, reduced relative consumption rate by 47.8-62.5%, impaired nutrient utilization, and modestly advanced molting. It also induced a time-dependent juvenile hormone (JH)-associated response: JH III decreased at 24 h, reached its lowest level at 48 h, and partially recovered by 72 h, and was again lower than the control at 96-120 h. These changes were accompanied by altered JH-related gene expression and biochemical indices. Molecular docking indicated structural compatibility between PISCF and the O. furnacalis AstC receptor. These findings suggest that PISCF is a bioactive AstC-derived core motif and a potential scaffold for peptide-based insect growth regulator discovery.