in-vitro assessment of the acaricidal properties of artemisia annua and zataria multiflora essential oils to control cattle ticks

background : the aim of this study was to investigate the ‘acaricidal effect' of zataria multiflora and ar­temisia annua essential oils on rhipicephalus (boophilus) annulatus . methods: this study was carried out in 2009 in the laboratory of parasitology of the faculty of veteri­nary medicine of shahrekord  university, west central iran. six dilutions (5, 10, 20, 40, 60 and 80 µl/cm 3 ) of both essential oils were used against engorged female r. (boophilus) annula­tus ticks using an in vitro immersion method. the mortality rates for each treatment were re­corded 6, 15 and 24 hours post inoculation (hpi). mortality rate was analyzed using repeated meas­ures analysis of variance, and compari­son of means was carried out using general linear models procedure. results: the mortality rate caused by different dilutions of z. multiflora essential oil ranged from 26.6% (using 10 µl/cm 3 ) to 100% (using 40 µl/cm 3 ) and for a. annua essential oil it was 33.2 to 100% (using 20 and 80 µl/cm 3 , respectively) by the end of the experiment (36 hpi). no mortality was recorded for the non-treated control group or for dilutions less than 5 and 10 µl/cm 3 using zataria and artemisia essential oils, respectively. for z. multiflora mortality peaked at 15 hpi for all concentrations other than 20 µl/cm 3 and took 24 h to achieve its maximum effect while for a. an­nua the two highest concentrations needed 24 hpi to reach their full effect. in addition, essen­tial oils applied at more than 20 and 60 µl/cm 3 caused 100% egg-laying failure in engorged fe­male ticks by zataria and artemisia , respectively while no failure was observed for the non-treated control group. the mortality rate in both botanical acaricides was dose-dependent. conclusion: both these medicinal plants have high potential acaricidal effects on the engorged stage of r. (boophilus) annulatus in vitro.