Abstract
The aim of the present study was to evaluate in vitro and in vivo the acaricidal activity of two forms of geranium (
Pelargonium graveolens
) (PG). These two forms were the
P. graveolens
essential oil nanoemulsion (PGN), and the PG in combination with the sesame oil (SO), PGSO). These forms were first evaluated in vitro for their adulticidal, ovicidal, and larvicidal activities against the different stages of acaricide-resistant
Rhipicephalus annulatus
(Say). Geranium nanoemulsion was prepared and then characterized by UV–Vis spectrophotometer, and zeta droplet size measurement. The results revealed that LC
50
of the PG against the adult ticks was attained at concentration of 7.53% while it was decreased to 1.91% and 5.60% for PGSO and PGN, respectively. Also, the LC
50
of PGN and PGSO were reached at concentrations of 1.688 and 0.944%, respectively against the larvae while the LC
50
of the PG was reached at concentration of 3.435% for. The combination of PGN with PG exhibited non-significant ovicidal effect meanwhile PGSO showed significant ovicidal effect even at the low concentration (2.5%). The PGSO and PGN formulations were applied in a field trial to control the ticks of the naturally infested cattle. PGSO and PGN significantly reduced the tick burden to 74.83% and 87.97%, respectively at 3 weeks post-application with performance better than the deltamethrin (29.88%). In conclusion, the two PG forms can be used as suitable alternatives to control
R. annulatus
tick and they need further modifications for effective field application.