Short communciation Acaricidal effect of Pelargonium roseum and Eucalyptus globulus essential oils against adult stage of Rhipicephalus (Boophilus) annulatus in vitro Khodadad Pirali-Kheirabadi a, *, Mehdi Razzaghi-Abyaneh b , Ali Halajian c a Department of Pathobiology, Faculty of Veterinary Medicine, University of Shahrekord, Shahrekord 115, Iran b Department of Mycology, Pasteur Institute of Iran, Tehran 13164, Iran c Islamic Azad University, Tehran Science and Research branch, Tehran, Iran 1. Introduction Ticks, obligatory blood-sucking arthropods are among the most harmful ectoparasites of domestic and wild animals as well as important vectors of human and animal pathogens (Samish and Rehacek, 1999). The genus Boophilus recently reclassified by Horak et al. (2002) as the genus Rhipicephalus is one of the most important bovine tick species in the North of Iran. It causes economic loss by sucking blood from host animals, in addition to this, it is an important vector of babesiosis, a protozoan disease of cattle. Rhipicephalus (Boophilus) annulatus has been controlled by chemical acaracides, resistance has devel- oped to these acaracides and in addition to this they also have a deleterious effect on the environment. Alternative control strategies such as habitat modification, use of pheremones and hormones, improvement of host resis- tance and biological control have also been considered in recent years by different researchers (Samish and Rehacek, 1999). A wide range of microorganisms have also been tested as pathogens or tick predators (Hassanain et al., 1997; Zhioua et al., 1999; Onofre et al., 2001; Pirali- Kheirabadi et al., 2007a,b). But little has been documented Veterinary Parasitology 162 (2009) 346–349 ARTICLE INFO Article history: Received 7 October 2008 Received in revised form 28 February 2009 Accepted 3 March 2009 Keywords: Rhipicephalus (Boophilus) annulatus Pelargonium roseum Eucalyptus globulus Biological control Cattle Essential oil ABSTRACT In a laboratory trial, in west-central Iran, the acaricidal effects of the essential oils (EOs) prepared from two medicinal plants, i.e. Pelargonium roseum and Eucalyptus globulus on the adult stage of Rhipicephalus (Boophilus) annulatus were evaluated. For this purpose, the engorged females of R. (B) annulatus were exposed to two-fold serial dilutions of oils (0.31– 5.0%) using a ‘‘dipping method’’ in vitro. The engorged ticks were immersed in different plant dilutions (eight per dilution) for 1 min then each replicate was incubated in separate petri dishes at 26 8C and 80% relative humidity. The mortality rate for adult ticks exposed to different dilutions of P. roseum and E. globulus EO’s showed a dose-dependent decrease. It was however significant only for the 2.5% and 5.0% dilutions of P. roseum EO, when compared to the non-treated control (P < 0.05). The mass of produced eggs in adult female ticks exposed to both P. roseum and E. globulus EOs had decreased dose-dependently. It was significant for only 2.5% and 5.0% dilutions of P. roseum EO, comparing the non-treated control (P < 0.05). The highest decrease in egg laying was reported for ticks treated with 5% dilutions of P. roseum (87.5%) and E. globosus (25%) (P < 0.05). This is the first report that details the acaricidal activity of EO’s obtained from P. roseum and E. globosus against R. (B) annulatus. The results show that both plants, particularly P. Roseum can be considered as potential candidates for biocontrol of R. (B) annulatus in the field. ß 2009 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +98 3814424427; fax: +98 3814424427. E-mail addresses: Pirali-k@vet.sku.ac.ir, khpirali@yahoo.com (K. Pirali-Kheirabadi). Contents lists available at ScienceDirect Veterinary Parasitology journal homepage: www.elsevier.com/locate/vetpar 0304-4017/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2009.03.015