The corn borer is a world-wide agricultural pest.  In this study, a high-efficiency RNAi method was explored to knock down the neuropeptide F (NPF) to determine if NPF regulates larval feeding in the Asian corn borer, Ostrinia furnacalis.  Results showed that the expression peaks of npf mRNA in both midgut and fat body are at 28 h of early 5th instar larvae.  When NPF was knocked down either by feeding dsNPF-containing artificial diet or direct dsNPF injection into the 5th instar larvae, npf expression was effectively inhibited in the midgut.  Larval feeding, body weight and development time were significantly impacted.  In contrast, the expression of the npf receptors npfr1 and npfr2 in fat body of 5th instar larvae was significantly increased by dsNPF injection.  These results indicate that NPF can be effectively knocked down in O. furnacalis, and dsNPF by injection is an effective and fast way to silence npf expression.  This study provides a critical basis for further exploration in mechanism of feeding regulation in O. furnacalis.

 

Insect neuropeptides are a group of brain neuro-regulatory factors, which plays very important roles in growth and development, molting and metamorphosis, as well as mating and reproduction.  The neuropeptide F (NPF), a multi-functional neuropeptide, is one of neuropeptides identified in numerous insect species, which plays important roles in feeding, metabolism, courtship, reproduction, aggression, ethanol sensitivity, locomotor circadian rhythms, learning and stress responses.  These roles of NPF are implemented through NPF receptors (NPFR).  The NPFR1, a G protein-coupled receptor with 7 transmembrane domains, is one of these receptors and is found to be important for NPF regulation.  The NPF usually is consisted of around 36–40 amino acid residues, but the short neuropeptide F (sNPF) consisted of 7–16 amino acid residues have also been found in some insects.  In this review, the structure and function of both NPF and sNPF in insects are discussed.