Ixodicide activity of methanolic extracts of Acacia farnesiana and Acacia cornigera (Fabaceae) against Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae) larvae

Abstract

The in vitro activity of methanolic extracts of plant organs of Acacia farnesiana and Acacia cornigera (Fabaceae) on the mortality of Rhipicephalus microplus larvae was conducted by the larval inmersion technique. In addition, the fractionation of the methanolic root extract of A. cornigera was performed and the chromatographic profile of the most active fraction was determined. The experiment was established under a completely randomized design with five replicates, each replicate consisted of a group of 20 larvae. Extracts that produced > 90 % mortality of lavae were considered highly effective. Ethanolic extracts of A. farnesiana (stem) and A. cornigera (stem and root) had high effectiveness. The analysis of dose-response for the most effective extracts showed that A. cornigera (root) had the lowest values of CL50 (2.12 mg/mL). From this methanolic extract, five fractions were generated. Fraction M2b1 (1 mg/mL) was the most active and caused 88 % mortality of larvae. The chromatographic profile of this fraction showed that the most abundant components were sacarose, quercitrine and two unindentified compounds. These results highlight the potencial of the ethanolic extract of A. cornigera (root) as a promising source of natural product against Riphicephalus microplus larvae.