title: Acaricidal effects of Corymbia citriodora oil containing para-menthane-3,8-diol against nymphs of Ixodes ricinus (Acari: Ixodidae).
abstract: The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A-E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results obtained by methods A, C and E, the LC(50) range was 0.035-0.037 mg PMD/cm(2) and the LC(95) range was 0.095-0.097 mg PMD/cm(2) at 4 h of exposure; the LT(50) range was 2.1-2.8 h and the LT(95) range was 3.9-4.2 h at 0.1 mg PMD/cm(2). To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm(2)) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic to nymphs of I. ricinus and may be useful for tick control.
authors.affiliation: Medical Entomology Unit, Department of Systematic Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18d, 752 36, Uppsala, Sweden.
authors.forename: Fawzeia H
authors.initials: FH
authors.lastname: Elmhalli
authors.forename: Katinka
authors.initials: K
authors.lastname: Pålsson
authors.forename: Jan
authors.initials: J
authors.lastname: Orberg
authors.forename: Thomas G T
authors.initials: TG
authors.lastname: Jaenson
mesh_terms: D000818:Animals; D000081005:Cyclohexane Monoterpenes; D007306:Insecticides / Q000737:chemistry*; D018884:Ixodes / Q000254:growth & development*; D008610:Menthol / Q000031:analogs & derivatives*; D009026:Mortality; D009758:Nymph; D013983:Tick Control; D013997:Time Factors
chemical_list: D000081005:Cyclohexane Monoterpenes; D007306:Insecticides; D008610:Menthol; C005804:terpin