Integrated multi-omics analysis and RNAi reveal Toll signaling pathway and melanization as key defenses in Ostrinia furnacalis against Meteorus pulchricornis parasitism

Ostrinia furnacalis, a worldwide agricultural pest, can be effectively controlled using the endoparasitic wasp Meteorus pulchricornis. However, the molecular mechanisms underlying the host immune response to parasitism remain poorly understood. This study aimed to explore the possible immune molecular mechanisms of O. furnacalis under parasitism by M. pulchricornis for 24 and 48 h (P24 and P48). Overall, 97 differentially expressed genes (DEGs) and 18 differentially expressed proteins (DEPs) associated with immunity were identified, including pattern-recognition receptors (PRRs), antimicrobial peptides (AMPs), antioxidant enzymes, Toll signaling pathway and melanization components. Three Toll signaling pathway downstream genes OfMyD88, OfGlov, and OfLys were chosen for functional analysis by RNA interference (RNAi). The results showed a notable increase in parasitism rate (7–9 %) in immunocompromised hosts and a significant decrease in survival rates (23–27 %), demonstrating that OfMyD88, OfGlov, and OfLys play crucial roles in the parasitic stress response and larvae survival. Our findings reveal novel insights into the immune molecular mechanisms of O. furnacalis and highlight potential targets for enhancing parasitic wasp-based biocontrol strategies.