In silico and in vitro assessment of the eucalyptus wood vinegar impact on reproduction of ticks Rhipicephalus microplus (Acari: Ixodidae).

Responsible for significant livestock losses, especially in tropical and subtropical regions, the tick Rhipicephalus microplus represents one of the main challenges for cattle farming and requires control in herds. However, the inappropriate use of synthetic acaricides has led to the development of chemical resistance in parasites, potential environmental contamination, and residues in animal products intended for human consumption. The objective of this research was to integrate in silico approaches and in vitro studies of eucalyptus wood vinegar (WV) on the reproduction of the tick R. microplus. For the experiment, cattle herds not receiving antiparasitic treatment were used, from which ingurgitated females were collected, identified, cleaned, weighed, and distributed into groups of ten for each WV concentration, with four replicates per treatment, totaling 280 specimens. In all tests, ticks were immersed in the WV at 6.25, 12.50, 25, 50, and 100% (mg mL-1). Two control treatments were conducted, one negative (distilled water) and one positive with Amitraz (20 mg mL-1). Regarding the reproductive parameters tested at the concentrations, they showed product efficiency values greater than 95%, indicating significant biological activity. Molecular docking revealed an interaction between the molecules 2-cyclopenten-1-one, furfural, and phenol-2-methoxy and the transmembrane protein GABA-gated chloride channel of the tick. This interaction was stable, as evidenced by the low binding energies and the molecular interactions formed, which most likely can explain the deadly effect of WV on the parasites. In conclusion, eucalyptus WV appears to be a viable natural alternative for controlling R. microplus.