Toxicity of essential oils obtained from Juniperus thurifera var. africana and Mentha suaveolens subsp. timija chemotypes against pre-adult stages of Hyalomma aegyptium tick (Acari: Ixodidae)

Abstract

This experiment was undertaken to compare the acaricidal activity of two essential oil chemotypes obtained from Mint Timija (Mentha suaveolens subsp. timija (Briq.) Harley) and Incense Juniper (Juniperus thurifera var. africana Maire) against immature stages of Hyalomma aegyptium ticks. The results showed that both chemotypes obtained from the two species presented interesting acaricidal activity. The pulegone and menthone-rich chemotype of Mint Timija (CM1) presented the highest toxic activity, particularly against eggs (LD₅₀ = 17.931 and LD₉₀ = 36.547 ppm) and larvae (LD₅₀ = 0.03 and LD₉₀ = 2.29 ppm). While the piperitone-rich Mint Timija EO (CM2) presented the weakest activity (LD₅₀ = 51.134 and LD₉₀ = 83.663 ppm for eggs, LD₅₀ = 7.84 and LD₉₀ = 21.03 ppm for larvae). Regarding Incense Juniper, the two chemotypes presented relatively moderate activity, with that of sabinene-rich oil (CJ2) being the most effective against eggs (LD₅₀ = 22.293 and LD₉₀ = 53.112 ppm).

Keywords: Juniperus thurifera; Mentha suaveolens; acaricide activity; essential oils; ticks.