Synergistic effect of β-ocimene on Hyphantria cunea sex pheromone and its potential attraction mechanism related to Ca 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 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. The activation of Ca 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.