Salivary proteins NlSP5 and NlSP7 are required for optimal feeding and fitness of the brown planthopper, Nilaparvata lugens

Abstract BACKGROUND Saliva has a crucial role in determining the compatibility between piercing–sucking insects and their hosts. The brown planthopper (BPH) Nilaparvata lugens , a notorious pest of rice in East and Southeast Asia, secretes gelling and watery saliva when feeding on rice sap. Nlsalivap‐5 (NlSP5) and Nlsalivap‐7 (NlSP7) were identified as potential planthopper‐specific gelling saliva components, but their biological functions remain unknown. RESULTS Here, we showed by transcriptomic analyses that NlSP5 and NlSP7 were biasedly expressed in the salivary glands of BPHs. Using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9‐mediated genome‐editing system, we constructed NlSP5 and NlSP7 homozygous mutants ( NlSP5 −/− and NlSP7 −/− ). Electrical penetration graph assay showed that NlSP5 −/− and NlSP7 −/− mutants exhibited abnormal probing and feeding behaviors. Bioassays revealed that the loss‐of‐function of NlSP5 and NlSP7 significantly reduced the fitness of BPHs, with extended developmental duration, shortened lifespan, reduced weight, and impaired fecundity and hatching rates. CONCLUSION These findings deepen our understanding of the BPH–host interaction and may provide potential targets for the management of rice planthoppers. © 2024 Society of Chemical Industry.