Abstract:
In this study we examined the anti-tick properties of the essential oil of Tagetes minuta L.
(Asteraceae: Asterales) against Hyalomma rufipes ticks. We obtained the essential oil of T. minuta
by hydro-distillation of a combination of fresh flowers, leaves and soft stems, and analysed
these by using gas chromatography (GC) and gas chromatography-linked mass spectrometry
(GC-MS). The oil had a high percentage of monoterpenes and the major compounds identified
were cis-ocimene (28.5%), beta-ocimene (16.83%) and 3-methyl-2-(2-methyl-2-butenyl)-furan
(11.94%). Hyalomma rufipes adults displayed a significant (P < 0.05) dose repellent response to
the essential oil of T. minuta. Probit analysis indicated a repellent EC50 of T. minuta essential
oil for male ticks to be 0.072 mL/mL (CI 0.053 mL/mL to 0.086 mL/mL) and 0.070 mL/mL
(CI 0.052 mL/mL to 0.084 mL/mL) for female ticks. There were no significant differences in
repellent responses between male and female ticks. The oil also significantly (P < 0.05) delayed
moulting of 60% of H. rufipes engorged nymphs. These results suggest that T. minuta may be a
potential source of anti-tick agents.
