Tick-killing effects of essential oils and main ingredients from different types of Lippia alba plants

Citral chemotypes showed greater larvicidal activity against Rhipicephalus microplus with an LC50 of 7.0 mg/mL.

• Purified citral demonstrated adulticidal activity with an LC50 of 29.8 mg/mL.
• Purified enantiomers of carvone had higher larvicidal activity compared to limonene.
• R-(+) limonene exhibited significantly higher efficacy (LC50 of 31.2 mg/mL) than S-(-) limonene (LC50 of 54.5 mg/mL).
• The essential oils and purified compounds were generally less toxic to engorged adult females, except for citral.
• Limited cuticular penetration may explain the reduced toxicity observed in the adult females.

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