Rhipicephalus microplus is the ectoparasite responsible for large economic losses in cattle herds. The aim of this study was to investigate the in vitro action of leaf extracts of Protium spruceanum on resistant strains of this tick. Ethanolic extracts (EE) and ethyl acetate extracts (EAE) of P. spruceanum leaves were used against engorged females and larvae by biocarrapaticidogram and larval package (TPL) tests. Chromatographic analyses were performed using a gas chromatograph and showed the presence of the flavonoid catechin in both extracts and the terpenoid β-amirine only in EAE. EE and EAE were not effective in altering the mortality of engorged females; however, 92% of females treated with the extracts reduced the postures and > 90% of larval hatching was inhibited at 100 mg/ml of extracts. Acaricidal efficacies were > 80% for 100 mg/ml EE and > 90% for EAE at 50 mg/ml. In TPL tests, EE and EAE promoted larval mortality > 88% at 100 mg/ml. In this study, EAE was more effective against adult females and larvae than EE, representing an alternative agent for the integrated control of R. microplus.
Keywords: Bovine tick; Burseraceae; Flavonoids; Phytotherapy; Terpenoids.