Behavioral Suppression and Rapid Lethality: Beauveria bassiana B4 Targets Adult Monochamus alternatus for Sustainable Management of Pine Wilt Disease

Pine wilt disease, transmitted primarily by <i>Monochamus alternatus</i> (Hope, 1842) adults, causes severe ecological and economic losses globally. Conventional chemical controls face challenges of resistance and non-target toxicity. This study identified <i>Beauveria bassiana</i> (Bals.-Criv.) Vuill. strain B4 as a high-virulence biocontrol agent against adult <i>M. alternatus</i>. Laboratory bioassays compared four strains (B1-B4), with B4 exhibiting rapid lethality (LT₅₀ = 6.61 days at 1 × 10⁸ spores/mL) and low median lethal concentration (LC₅₀ = 9.63 × 10⁵ spores/mL). Critically, B4 infection induced significant behavioral suppression, including reduced appetite and mobility prior to death. In forest trials, pheromone-enhanced nonwoven fabric bags impregnated with B4 spores reduced trap catches by 66.4% within one month, with effects persisting for over a year without reapplication. The slow-release carrier system enabled continuous spore dissemination and sustained population suppression. These results demonstrate that B4's dual action-rapid lethality and behavioral disruption-provides an effective, eco-friendly strategy for sustainable pine wilt disease management.