In vitro evaluation of acaricidal activity of eugenol and benzaldehyde against Rhipicephalus annulatus

Economic importance of ticks for both humans and animals is significant primarily because of their involvement in disease transmission. The continuous use of synthetic chemical acaricides on animals and/or in the environment has resulted in the emergence of resistant tick populations. Consequently, there is a compelling need to explore newer natural alternatives that can address their adverse effects effectively. Since, there are no earlier reported studies on the acaricidal activity of eugenol and benzaldehyde against Rhipicephalus annulatus, the present study compared the in vitro adulticidal and larvicidal activities of these phytochemicals against R. annulatus. Concentration-dependent mortality and inhibition of fecundity were observed in the adult female ticks treated with both eugenol and benzaldehyde. The LC₅₀ and LC₉₀ values of eugenol against R. annulatus were 162.33 and 467.74 mg/mL for adult female, while it was 1.26 and 1.73 mg/mL for larvae respectively. The LC₅₀ and LC₉₀ values of benzaldehyde against R. annulatus were 178 and 395 mg/mL for adult female and 0.69 and 4.32 mg/mL for larvae respectively.