Reduced 20-Hydroxyecdysone Signaling Modulates Antifungal Immune Responses and Growth in Lymantria dispar Against Beauveria bassiana
Simple Summary Lymantria dispar is one of the most destructive defoliating pests worldwide, feeding on over 300 species of coniferous and deciduous trees and posing a serious threat to forest productivity and ecological health. Biological control with entomopathogenic fungi, such as Beauveria bassiana, has attracted considerable interest and wide application in agricultural and forestry pest management. However, the robust innate immune system of L. dispar greatly limits the insecticidal efficacy of B. bassiana. 20-Hydroxyecdysone (20E) is an endogenous insect hormone, and previous studies have primarily focused on its regulatory roles in development, molting, and metamorphosis. In our preliminary experiments, we observed that B. bassiana infection significantly reduced the 20E titer, decreased larval weight, and simultaneously triggered innate immune responses in L. dispar. Accordingly, the present study aims to investigate the role of 20E in regulating innate immunity and to elucidate its modulatory effects on both growth and immune defense during B. bassiana infection.