Acetylation of carvacrol raises its efficacy against engorged cattle ticks Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Abstract

The effects of acetylcarvacrol on the reproductive performance of engorged female R. microplus were evaluated. Carvacrol was acetylated by a reaction with acetic anhydride, confirmed by the identification of its melting point and by infrared spectroscopy. Based on the median lethal concentration, females were exposed to sublethal concentrations (3.7, 4.6 and 5.0 μL/mL) of acetylcarvacrol by means of the adult immersion test. The following parameters were evaluated: female weight before oviposition, pre-oviposition period, egg mass weight, egg production index, incubation period, hatching rate, fecundity rate, percentage of reduction in oviposition, percentage of reduction in hatching and product efficacy. The greatest efficacy was observed in the group treated with the highest concentration (91.69%) due to the greater weight reduction in egg mass (34.91 ± 0.02 mg) and the lower hatching rate (7.23 ± 15.50%). Therefore, this compound is a promising alternative for the control of R. microplus infestations.