Synergistic effect of β-ocimene on Hyphantria cunea sex pheromone and its potential attraction mechanism related to Ca2+ stimulation

Hyphantria cunea , a globally significant quarantine pest, causes severe ecological and economic impacts in invaded regions. Attractants are environment-friendly and valuable pest management tools for H. cunea control. In this study, we identified that the combination of β-ocimene with sex pheromone components was strongly attractive to H. cunea males. This attractant combination activates the Ras signaling pathway and stimulates Ca 2+ in male adults following exposure. Feeding and oviposition behavior results demonstrated that H. cunea prefers Morus alba over Platanus × acerifolia , Metasequoia glyptostroboides , and Taxodium distichum . In the fresh branches of M. alba with leaves, the relative abundance of β-ocimene (36.33 ± 0.41 %) was significantly higher than the other hosts. Electroantennography recordings, behavioral choice assays, and field trapping trials showed that the combination of β-ocimene with sex pheromone components significantly enhanced male response and attraction. The number of trapped males using β-ocimene/ sex pheromone blend was 3.7-fold higher than that of sex pheromone or β-ocimene alone in the field, indicating a synergistic effect of adding β-ocimene to sex pheromone. The molecular mechanism of β-ocimene/sex pheromone synergism was further analyzed. After exposure to the attractant, the Ras signaling pathway in the heads of males are activated ( HcILP and HcPLCε1 are upregulated, while HcRasGAP and HcPLD are downregulated), which further stimulates the expression of IP3 and Ca 2+ . The activation of Ca 2+ may be the key reason for its higher attraction to males. These findings provide a theoretical basis for the selection and mechanistic understanding of attractants for H. cunea , offering insights for attractant-based pest control strategies.