Pereira Filho_2024_Int.J.Mol.Sci_25_

Amblyomma sculptum is a species of tick in the family Ixodidae, with equids and capybaras among its preferred hosts. In this study, the acaricidal activity of the essential oil (EO) from Piper aduncum and its main component, Dillapiole, were evaluated against larvae of A. sculptum to establish lethal concentration values and assess the effects of these compounds on tick enzymes. Dillapiole exhibited slightly greater activity (LC(50) = 3.38 mg/mL; 95% CI = 3.24 to 3.54) than P. aduncum EO (LC(50) = 3.49 mg/mL; 95% CI = 3.36 to 3.62) against ticks. The activities of alpha-esterase (alpha-EST), beta-esterase (beta-EST), and glutathione-S-transferase (GST) enzymes in A. sculptum larvae treated with Dillapiole showed a significant increase compared to the control at all concentrations (LC(5), LC(25), LC(50) and LC(75)), similar results were obtained with P. aduncum EO, except for alpha-EST, which did not differ from the control at the highest concentration (LC(75)). The results of the acetylcholinesterase (AChE) activity show an increase in enzyme activity at the two lower concentrations (LC(5) and LC(25)) and a reduction in activity at the two higher, lethal concentrations (LC(50) and LC(75)) compared to the control. These results suggest potential mechanisms of action for these natural acaricides and can provide guidance for the future development of potential plant-derived formulations.