Combination of thymol and eugenol for the control of Rhipicephalus sanguineus sensu lato: Evaluation of synergism on immature stages and formulation development

Publication date: Available online 16 November 2019Source: Veterinary ParasitologyAuthor(s): Letícia Coelho, Luiza Gabriella Ferreira de Paula, Susy das Graças Alecrim Alves, Aparecida Lorrany Nunes Sampaio, Giovana Pereira Bezerra, Fernanda Maria Pinto Vilela, Renata da Silva Matos, Viviane Zeringóta, Lígia Miranda Ferreira Borges, Caio MonteiroAbstractThe aim of this study was to investigate whether the combination of thymol with eugenol has a synergistic effect on the immature life stages of Rhipicephalus sanguineus sensu lato (s.l.), to evaluate the cost-benefit ratio of using these compounds in combination, and to develop a formulation combining thymol with eugenol with activity on immature stages of R. sanguineus s.l. To evaluate synergism, thymol and eugenol, combined (ratio 1:1) or not, were tested at concentrations of 2.5, 5.0, 10.0, 15.0 and 20.0 mg/mL on unfed larvae and nymphs using a larval packet test, and 0.625, 1.25, 2.5, 5.0 and 10 mg/mL on engorged larvae and nymphs using an immersion test. A cost estimate was calculated to produce 1 L of a solution containing a concentration of thymol and eugenol, combined or not, that could cause a tick mortality rate greater than 95%. Finally, a formulation was developed, consisting of a micellar dispersion containing polymers (MDP), with thymol + eugenol (1:1), at concentrations of 2.5, 5.0, 10.0, 15.0 and 20.0 mg/mL, and the activity was evaluated on unfed and engorged larvae and nymphs. For unfed larvae...
Source: Veterinary Parasitology - Category: Veterinary Research Source Type: research