Identification of the neuropeptide gene family and feeding regulation by neuropeptide Y in Mythimna separata (Lepidoptera: Noctuidae)

Mythimna separata is a crucial agricultural pest with polyphagous characteristic. Neuropeptide signaling, especially neuropeptide Y (NPY) involved in feeding regulation, is considered as a potential pest control target. In this study, we identified 50 neuropeptides including NPY of M. separata using transcriptome sequencing. Bioinformatics analysis showed that NPY had a conserved carboxyterminal motif of RGRYamide and shared very high homology across lepidopteran insects. Spatio-temporal expression profile articulated that NPY was mainly expressed in the larval stage, and with the highest expression in larval midgut and adult alimentary canal. RNAi knockdown by the injection of dsNPY into larvae significantly inhibited food uptake and body weight, delayed developmental duration, and also caused increase of trehalose and decrease of glycogen and total lipid compared to dsGFP. This study identified nearly the entire neuropeptide gene family of M. separata and further indicated that NPY signaling pathway might played a vital role in the feeding regulation and related to energy metabolism. Our results not only laid a preliminary foundation for functional studies on neuropeptide of M. separata, but also provided a potential molecular target for future pesticide development.