Peripheral Enhancement of Sex Pheromone Detection by Plant Volatiles in Helicoverpa armigera (Hübner)

Efficient mate location is critical for reproductive success in male moth. While plant volatiles can synergize attraction to sex pheromones in many insects, the underlying mechanisms remain poorly understood. We examined this interaction using the cotton bollworm Helicoverpa armigera, a major pest that serves as a model due to its well-defined pheromone system. We found that the plant volatiles (Z)-3-hexenyl acetate and linalool were not attractive alone, yet each significantly enhanced male attraction when combined with the sex pheromone in wind tunnel assays. Single sensillum recording revealed that this synergy occurs peripherally within the pheromone-sensitive type A sensilla. Furthermore, transgenic Drosophila OR expression, and CRISPR-Cas9-mediated HarmPBP1 knockout, demonstrated that the pheromone-binding protein HarmPBP1, but not the odorant receptor HarmOR13, is critical for the synergistic effect of (Z)-3-hexenyl acetate. Our study elucidates a peripheral mechanism for olfactory signal integration, providing insights for developing sustainable behavioral control strategies.