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Terpenes on Rhipicephalus (Boophilus) microplus: Acaricidal activity and acetylcholinesterase inhibition

2020; Elsevier BV; Volume: 280; Linguagem: Inglês

10.1016/j.vetpar.2020.109090

1873-2550

Alana dos Santos Cardoso, Everton Gomes Guimarães dos Santos, Aldilene da Silva Lima, Kevin B. Temeyer, Adalberto Á. Pérez de León, Lívio Martins Costa, Alexandra Martins dos Santos Soares,

Vector-borne infectious diseases

The Rhipicephalus (Boophilus) microplus tick is the main ectoparasite of cattle in tropical and subtropical regions worldwide. Resistance to chemical acaricides has become widespread affirming the need for new drugs to tick control. Terpenes have become a promising alternative for cattle tick control, however the mechanism of action of these compounds is still controversial. Inhibition of acetylcholinesterase (AChE) is a well established mechanism of action of organophosphate and carbamate acaricides, but the possible action of terpenes on tick AChEs has seldom been studied in resistant and sensitive strains of R. (B.) microplus. The aim of the present study was to evaluate terpene inhibition of AChE from resistant and sensitive strains of R. (B.) microplus in correlation with their acaricidal activity. Among the terpenes used in the present study, p-cymene, thymol, carvacrol, and citral displayed acaricidal activity with LC50 of 1.75, 1.54, 1.41, and 0.38 mg.mL-1 for the susceptible strain, and LC50 of 1.40, 1.81, 1.10, and 1.13 mg.mL-1 for the resistant strain. Thymol and carvacrol inhibited the AChE of the susceptible strain larvae with IC50 of 0.93 and 0.04 mg.mL-1, respectively. The IC50 exhibited by eucalyptol, carvacrol and thymol for AChE of the resistant strain larvae were 0.36, 0.28, and 0.13 mg.mL-1, respectively. This was the first study to investigate the action of terpenes on AChE from susceptible and resistant R. (B.) microplus. As not all terpenes with acaridical activity showed AChE inhibition, the participation of AChE in the acaricidal activity of terpenes needs further investigation.