Artificial feeding-based oral secretion collection system and multi-omics analysis reveal insecticidal saliva and salivary proteome in Orius nagaii.

Orius nagaii is an important predatory natural enemy in agricultural pest management. In this study, we established an artificial feeding system to collect oral secretions (OS) from O. nagaii and demonstrate that microinjection of either oral secretions (OS) or salivary reservoir extracts (SRE) into Ostrinia furnacalis larvae significantly increases larval mortality, indicating that the saliva of this natural enemy insect contains bioactive factors with insecticidal activity. Comparative proteomic analysis of OS and SRE identified 328 overlapping proteins as candidate salivary proteins. Integration of this candidate dataset with the salivary gland transcriptome enabled the systematic identification of 311 salivary proteins, covering the complete trajectory from synthesis in the salivary gland (SG) and storage in the salivary reservoir to release during feeding. Of these, 112 proteins are unique to O. nagaii, including several venom-associated candidates potentially involved in prey subjugation. This study provides a foundational resource for functional studies of salivary proteins in predatory natural enemies and offers potential molecular targets for developing novel biopesticides and genetic improvement of biological control agents.