NPF-OBP5 regulate sugar sensitivity and feeding behavior of rice planthoppers

Neuropeptide F (NPF) is considered to be related to the feeding behavior and odorant binding protein (OBP) is very important for the chemical perception of herbivorous insects to host plants, while, food sugar is a strong inducer for insect feeding. However, it is unknown whether NPF and OBP can regulate the sugar perception, thus affecting the feeding behavior and sugar metabolism in brown planthopper (BPH) Nilaparvata lugens. The results showed that NlOBP1, NlOBP5-8 and NlOBP10 were highly expressed in N. lugens heads. Fluorescence competitive binding assays demonstrated that only NlOBP5 exhibited strong combination to soluble sugars (including glucose, fructose, and sucrose). Additionally, NlNPF was predominantly expressed in N. lugens brain. NlNPF knockdown resulted in upregulated NlOBP5 expression and enhanced the sensitivity of N. lugens to soluble sugars. Conversely, NlOBP5 knockdown reduced the sugar sensitivity of N. lugens, while simultaneous knockdown of both NlNPF and NlOBP5 partially rescued the sugar sensitivity impairment caused by NlOBP5 knockdown individually. Furthermore, NlNPF knockdown promoted feeding and led to trehalose accumulation in N. lugens. In contrast, NlOBP5 knockdown inhibited feeding and decreased trehalose levels in N. lugens, while simultaneous knockdown of NlNPF and NlOBP5 partially reversed the negative effects on feeding and trehalose metabolism observed with NlOBP5 knockdown individually. NlNPF knockdown decreased the survival of N. lugens more than NlOBP5 knockdown. These findings confirm the regulation of NlNPF-NlOBP5 on sugar sensitivity, feeding behavior and trehalose metabolism of N. lugens, providing potential targets for the control strategies on rice planthoppers.