Acaricidal Activity of Crude Ethanolic Extract of Sphaeranthus indicus, its Fractions and Subfractions against Rhipicephalus (Boophilus) annulatus (Acari: Ixodidae)

Plants constitute a rich source of bioactive compounds and its acaricidal effect is increasingly been investigated as a potential solution against acaricide resistance. In the present study, the in vitro efficacy of crude ethanolic extract of leaves of Sphaeranthus indicus, its fractions (hexane, chloroform, butanol and water) and subfractions of the active acaricidal fraction were evaluated against Rhipicephalus (Boophilus) annulatus using the adult immersion technique (AIT). The percentage of adult mortality, inhibition of fecundity and hatching rate were assessed. The crude ethanolic extract of leaves of Sphaeranthus indicus revealed hundred per cent adult mortality and inhibition of fecundity at a concentration of 250 mg/mL. Among the four fractions of this extract tested, hexane fraction showed concentration dependent delayed adult tick mortality. At 10 per cent concentration of hexane fraction, 87.41 per cent mortality and 77.78 per cent inhibition of fecundity were observed. Among the 14 subfractions of the active hexane fraction, the subfraction 4 (at 2000 ppm) produced 45.83 per cent mortality and 41.06 per cent inhibition of fecundity. It may be concluded that the hexane fraction of the leaves of ethanolic extract of S. indicus and its subfraction 4 revealed significant acaricidal effects.