Acaricidal activity of petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston against Rhipicephalus (Boophilus) annulatus.

The acaricidal activity of the petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston (family: Vitaceae) against Rhipicephalus (Boophilus) annulatus was assessed using adult immersion test (AIT). The per cent of adult mortality, inhibition of fecundity, and blocking of hatching of eggs were studied at different concentrations. The extract at 10% concentration showed 88.96% inhibition of fecundity, 58.32% of adult tick mortality, and 50% inhibition of hatching. Peak mortality rate was observed after day 5 of treatment. Mortality of engorged female ticks, inhibition of fecundity, and hatching of eggs were concentration dependent. The LC50 value of the extract against R. (B.) annulatus was 10.46%. The HPTLC profiling of the petroleum ether extract revealed the presence of at least seven polyvalent components. In the petroleum ether extract, nicotine was identified as one of the components up to a concentration of 5.4%. However, nicotine did not reveal any acaricidal activity up to 20000 ppm (2%). Coconut oil, used as diluent for dissolving the extract, did not reveal any acaricidal effects. The results are indicative of the involvement of synergistic or additive action of the bioactive components in the tick mortality and inhibition of the oviposition.

Acaricidal effects of fenvalerate and cypermethrin against Rhipicephalus (Boophilus) annulatus.

The acaricidal effects of two most commonly used acaricides viz., fenvalerate and cypermethrin against Rhipicephalus (Boophilus) annulatus were studied using Adult Immersion Test (AIT). The LC50 values observed for fenvalerate and cypermethrin were 1570 ppm and 184 ppm respectively. The death of ticks was not an immediate process. Fenvalerate caused death only after 7 days while cypermethrin after 5 days of treatment. The eggs laid by treated ticks did not hatch at all concentrations tested.