Characterization of the Dermanyssus gallinae octopamine receptor DgOctβ2R as the molecular target for synthetic and natural acaricides.

BACKGROUND: The poultry red mite (Dermanyssus gallinae) seriously threatens the global poultry industry. Reliance on chemical acaricides has led to resistance, and plant essential oils represent an eco-friendly alternative, but their mode of action remains unclear. Amitraz targets the β2-adrenergic-like octopamine receptor (Octβ2R). This study aimed to clone and characterize Octβ2R from D. gallinae, elucidate the mechanism of amitraz and essential oils, and support resistance monitoring. RESULTS: We cloned DgOctβ2R. Evolutionary analysis revealed that DgOctβ2R clusters with other mite Octβ2Rs, distinct from insect orthologs. Functional assays in HEK293T cells demonstrated that amitraz and its metabolite N'-(2,4-dimethylphenyl)-N-methylformamidine(DPMF) potently activated DgOctβ2R, with DPMF acting as a full agonist. The plant essential oil component thymol also exhibited agonist activity at micromolar concentrations. Molecular docking revealed that DPMF and thymol bind the orthosteric pocket via a hydrogen bond with D3.32, whereas octopamine additionally engages S5.46. CONCLUSION: This study successfully identified and functionally characterized DgOctβ2R from D. gallinae, providing molecular evidence that amitraz and DPMF target this receptor. The differential potency between synthetic and natural compounds reveals distinct agonistic profiles. These findings establish a molecular basis for rational use of amitraz, resistance surveillance, and structure-based design of novel and environmentally friendly acaricides targeting DgOctβ2R. © 2026 Society of Chemical Industry.