Evaluation of Activity of the Crude Ethanolic Extract of Magonia pubescens St. Hil (Sapindaceae) Against Larvae of the Cattle Tick Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae).

The acaricidal potential, of the crude ethanolic extract (c.e.e.) of the stem peel of Magonia pubescens was evaluated against larvae of Rhipicephalus (Boophilus) microplus. The larvae were placed in filter paper envelopes impregnated with different concentrations of c.e.e., dissolved in dimethylsulfoxide (DMSO) and distilled water for determination of lethal concentrations (LC). The following treatments were used: 1. Envelopes of dry filter paper; 2. Envelopes of filter paper moistened with distilled water; 3. Envelopes of filter paper moistened with a solution of DMSO in distilled water; - and 4. Envelopes moistened with 2 mL of each concentration of the c.e.e. to be tested. The bioassays were carried out in quadruplicate at 27 degrees +/- 1 degrees C and RH >= 80% and 12h light. Mortality was observed after 48 h, LC50 and LC99 values of 365 and 4,000 ppm being obtained. There was no significant mortality in larvae exposed to the first three treatments (p < 0.05).