Acaricidal activity of the essential oil from Tetradenia riparia (Lamiaceae) on the cattle tick Riphicephalus (Boophilus) microplus (Acari; Ixodidae)

This experiment was carried out to study the bioacaricidal activity of Tetradenia riparia (Hochst.) Codd essential oil against engorged females of Rhipicephalus (Boophilus) microplus (Acari; Ixodidae). For this purpose, nine serial concentrations (12.50, 6.25, 3.75, 1.80, 0.90, 0.45, 0.22, 0.11, and 0.056% w/v) of T. riparia were used for the adult immersion test (AIT). For the larval packet test (LPT), we used 14 serial concentrations (100.00, 50.00, 25.00, 12.50, 6.25, 3.65, 1.82, 0.91, 0.45, 0.228, 0.114, 0.057, 0.028, and 0.014% w/v). The results for AIT showed that the LC50 and LC99.9, calculated using the Probit test, were for mortality (%) 0.534g/mL (0.436–0.632) and 1.552g/mL (1.183–1.92); for total number of ovipositions were 0.449g/mL (0.339–0.558) and 1.76g/mL (1.27–2.248); and for hatchability inhibition were 0.114g/mL (0.0–0.31) and 2.462g/mL (1.501–3.422), respectively. The LPT showed that the LC₅₀ and LC99.9 were 1.222g/mL (0.655–1.788) and 11.382g/mL (7.84–14.91), respectively. A positive correlation between T. riparia EO concentration and tick control, was observed by the strong acaricidal effects against R. (B.) microplus, and the mortality rate of ticks was dose-dependent. Our results showed that T. riparia is a promising candidate as an acaricide against resistant strains of R. (B.) microplus.

Keywords: Tetradenia riparia, acaricide, Ixodidae, Tick; Rhipicephalus (Boophilus) microplus

Acknowledgement: The authors are grateful to CNPq for providing a research grant and fellowships

References: 1. Gazim ZC et al. (2010) Molecules 15: 5509–5524.