Acaricidal properties of the essential oil from Hesperozygis ringens (Lamiaceae) on the cattle tick Riphicephalus (Boophilus) microplus.

Abstract Hesperozygis ringens (Benth.) Epling (Lamiaceae) is a strongly aromatic plant employed popularly for its antiparasitic properties. The leaves afforded 4% of essential oil constituted mainly by pulegone (86%). Laboratory tests were carried out to determine the toxicity of the essential oil species on engorged females and larvae of the cattle tick Riphicephalus ( Boophilus ) microplus using the adult immersion test (AIT) and the larval immersion test (LIT). It was observed that the essential oil at the concentration of 50 μL/mL and 25 μL/mL inhibited the egg laying significatively in relation to the controls and the eggs from these treated females were affected by the oil; the hatching was inhibited in 95% and 30%, respectively. In the LIT it was verified that the LC 99.9 , LC 50 and LC 1 was 0.541 μL/mL, 0.260 μL/mL and 0.015 μL/mL, respectively. Pulegone, isolated from the oil, showed similar effect on the females and on the larvae, indicating that it is responsible for the oil activity.