Target identification and acaricidal activity difference of amitraz and its metabolite DPMF in Tetranychus cinnabarinus (Boisduval)

Abstract BACKGROUND Amitraz is a broad‐spectrum formamidine acaricide proven to be effective against mites in all development stages. Under acidic conditions, amitraz is hydrolyzed to N 2 ‐(2,4‐dimethylphenyl)‐ N 1 ‐methyformamidine (DPMF), an active metabolite for mite control. Octopamine and tyramine receptors are well known targets of amitraz. Until now, no research has been conducted about the amitraz target in Tetranychus cinnabarinus . This study aimed to identify the target genes of amitraz in T. cinnabarinus and reveal the mechanisms behind the differential acaricidal activities of amitraz and DPMF. RESULTS Analysis of the toxicity, stress expression, target sensitivity and binding site of amitraz against T. cinnabarinus showed that TcOctβ2R was the main target gene of amitraz. DPMF had more potent acaricidal activity against T. cinnabarinus and was more effective at activating TcOctβ2R than amitraz. Furthermore, the three synergists had no significant effect on amitraz and DPMF, indicating that the detoxification metabolism was not related to the difference in acaricidal activity. CONCLUSION In this study, TcOctβ2R was identified as the main target gene of amitraz against T. cinnabarinus . The divergence of target binding was responsible for the difference in acaricidal activity between amitraz and DPMF. The results also revealed the physiological and pharmacological functions of octopamine receptors (OARs) in T. cinnabarinus and could provide a basis for the design of new acaricides, with OARs as a special target. © 2023 Society of Chemical Industry.