Research Article Evaluation of In Vivo Acaricidal Effect of Soap Containing Essential Oil of Chenopodium ambrosioides Leaves on Rhipicephalus lunulatus in the Western Highland of Cameroon Marc K. Kouam, 1,2 Vincent K. Payne, 3 Emile Miégoué, 1 Fernand Tendonkeng, 1 Jules Lemoufouet, 1 Jean R. Kana, 1 Benoit Boukila, 4 E. Tedonkeng Pamo, 1 and Bertine MNM 1 1 Department of Animal Production, Faculty of Agronomy and Agricultural Sciences, University of Dschang, P.O. Box 222, Dschang, Cameroon 2 Center for Research on Filariasis and Other Tropical Diseases (CRFilMT), P.O. Box 5797, Yaound´ e, Cameroon 3 Department of Animal Sciences, Faculty of Sciences, University of Dschang, P.O. Box 67, Dschang, Cameroon 4 Higher National Institute of Agronomy and Biotechnology (INSAB), University of Sciences and Techniques of Masuku, P.O. Box 941, Franceville, Gabon Correspondence should be addressed to Marc K. Kouam; mkouam2003@yahoo.fr Received 26 May 2015; Revised 16 September 2015; Accepted 7 October 2015 Academic Editor: Alexander Idnurm Copyright © 2015 Marc K. Kouam et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A study on the acaricidal properties of foam soap containing the essential oil of Chenopodium ambrosioides leaves was carried out on Rhipicephalus lunulatus. Four doses (0.03, 0.06, 0.09, and 0.12 L of essential oil per gram of soap) and a control (soap without essential oil) with four replications for each treatment were used for in vitro trial. Each replication consisted of 10 ticks in a Petri dish with filter paper impregnated with the foam soap on the bottom. Following in vitro trials, three doses (0.06, 0.09, and 0.12 L/g) and the control in two replications were selected for in vivo test based on mortality rate recorded from the in vitro trial. Each replication was made up of 10 goats naturally infested with ticks. Results show that soap containing essential oil is toxic to R. lunulatus. e in vivo mortality rate in the control on day 8 was 22.69% whereas the highest dose (0.12 L/g) killed 96.29% of the ticks on day 8. e LD 50 of the foam soap containing essential oil was 0.037 and 0.059 L/g on day 2 in the laboratory and on the farm, respectively. is indicates the potentially high efficiency of this medicated soap on this parasite. 1. Introduction Ruminant breeding constitutes one of the main production activities in many sub-Saharan African countries in general and Cameroon in particular [1]. Although small ruminants in Cameroon have attracted interest as an alternative and cheap source of income and protein, they are also exaggeratedly used during festivities and traditional rites. Based on these considerations, goats in particular represent for breeders an easily mobilizable investment due to their short develop- mental cycle [2]. Data on the importance of goat industry in the country is very scarce, but globally goats represent 20% of ruminant production in developing countries [3]. Because goats’ breeding especially depends on natural pasture for their diet, normally they are exposed to a wide variety of constraints, some of which affect growth and quality of mutton. eir constant exposure to natural pastures persistently exposes them to arthropods most especially ticks which in the course of feeding on blood could also transmit disease. Indeed ticks do not only transmit diseases such as piroplasmosis, cowdriosis, or rickettsiosis [4] but also cause skin lesions, asthenia, and anorexia leading to anemia [5]. Ticks in general and Rhipicephalus lunulatus in particular constitute one of the main causes of morbidity and mortality in animals [6] and are also responsible for secondary pathogen infections [7]. R. lunulatus is a two-host tick; larva and nymph feed on the same host, and adult feeds on a second host on which it remains for five to nine days. Losses incurred worldwide due to ticks’ infestation are enormous and even incalculable [8]. According to some Hindawi Publishing Corporation Journal of Pathogens Volume 2015, Article ID 516869, 5 pages http://dx.doi.org/10.1155/2015/516869