Functional Analysis of MysERG1, a Novel Immune-Related Gene in Encapsulation Regulation, in the Oriental Armyworm Mythimna separata (Lepidoptera: Noctuidae)

Encapsulation is a major cellular defense reaction in lepidopterans. However, in the oriental armyworm (Mythimna separata), the molecular regulators that coordinate hemocyte adhesion and multilayer capsule assembly remain poorly defined. In this study, we identified Mythimna separata encapsulation related gene 1 (MysERG1) as a novel cellular immune regulatory gene. MysERG1 transcripts were most abundant in hemocytes and were notably upregulated in adherent hemocytes as well as in samples of capsules, indicating an association with adhesion-dependent hemocyte activation. Following separation of granulocytes and plasmatocytes, MysERG1 expression was observed to be higher in adherent plasmatocytes than in adherent granulocytes. However, recombinant MysERG1 selectively increased granulocyte adhesion but did not significantly affect plasmatocyte adhesion and was specifically localized on granulocytes. Additionally, recombinant MysERG1 enhanced hemocyte aggregation on foreign surfaces, highlighting its functional role in facilitating encapsulation. Functional knockdown using double-stranded RNA significantly reduced the size of the capsules, indicating that MysERG1 is required for robust capsule formation. This study identifies MysERG1 as a novel factor involved in hemocyte cooperation during encapsulation in M. separata and presents a conceptual framework for inter-hemocyte communication mechanisms in lepidopteran cellular immunity.