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Activity of Cupressus funebris, Juniperus communis, and J. chinensis (Cupressaceae) Essential Oils as Repellents against Ticks (Acari: Ixodidae) and as Repellents and Toxicants against Mosquitoes (Diptera: Culicidae)
Juniperus communis leaf oil, J. chinensis wood oil and Cupressus funebris wood oil (Cupressaceae) from China were analyzed by GC-FID and GC-MS. The major components for each species were: J. communis contained α-pinene (27.0%), α-terpinene (14.0%), and linalool (10.9%); J. chinensis contained cuparene (11.3%) and δ-cadinene (7.8%); C. funebris contained α-cedrene (16.9%), cedrol (7.6%), and β-cedrene (5.7%). The essential oils of C. funebris, J. chinensis, and J. communis were evaluated for repellency against Aedes aegypti (L.), host-seeking nymphs of the lone star tick, Amblyomma americanum (L.) and the blacklegged tick, Ixodes scapularis Say, and for toxicity against Ae. aegypti larvae and adults, all in laboratory bioassays. All the oils were repellent to both species of ticks. The EC95 values of C. funebris and J. communis against A. americanum were 0.426, 0.508, and 0.917mg oil/cm2 filter paper, respectively, compared to 0.683mg deet/cm2 filter paper. All I. scapularis nymphs were repelled by 0.103mg oil/cm2 filter paper of C. funebris oil. At 4h after application, 0.823mg oil/cm2 filter paper, C. funebris and J. chinensis oils repelled=80% of A. americanum nymphs. The oil of J. communis had a Minimum Effective Dosage (estimate of ED99) for repellency of 0.029±0.018mg/cm2; this oil was nearly as potent as deet. The oil of J. chinensis showed mild ability to kill Ae. aegypti larvae, at 80 and 100% at 125 and 250ppm, respectively.