Short Communication Evaluation of the toxicity of different phytoextracts of Ocimum basilicum against Anopheles stephensi and Culex quinquefasciatus Prejwltta Maurya, Preeti Sharma, Lalit Mohan, Lata Batabyal, C.N. Srivastava ⁎ Applied Entomology and Vector Control Laboratory, Department of Zoology, Faculty of Science, Dayalbagh Educational Institute (Deemed University), Dayalbagh, Agra-282005, India abstract article info Article history: Received 29 December 2008 Revised 7 February 2009 Accepted 10 February 2009 Keywords: Anopheles stephensi Culex quinquefasciatus Larvicide Ocimum basilicum Phytoextract The larvicidal effect of the crude carbon tetrachloride, methanol and petroleum ether leaf extracts of a widely grown medicinal plant, Ocimum basilicum, against Anopheles stephensi and Culex quinquefasciatus was evaluated. Petroleum ether extract was found to be the most effective against the larvae of both mosquitoes, with LC 50 values of 8.29, 4.57; 87.68, 47.25 ppm and LC 90 values of 10.06, 6.06; 129.32, 65.58 ppm against A. stephensi and C. quinquefasciatus being observed after 24 and 48 h of treatment, respectively. The efficacy of petroleum ether was followed by that of the carbon tetrachloride and methanol extracts, which had LC 50 values of 268.61,143.85; 446.61, 384.84 ppm and LC 90 values of 641.23, 507.80; 923.60, 887.00 ppm against A. stephensi after 24 and 48 h, respectively, and LC 50 values of 24.14,17.02; 63.48, 53.77 ppm and LC 90 values of 295.38, 204.23; 689.71, 388.87 ppm against C. quinquefasciatus after 24 and 48 h of treatment, respectively. These extracts are highly toxic against mosquito larvae from a range of species; therefore, they may be useful for the management of mosquito larvae to control vector borne diseases. © Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2009 Published by Elsevier B.V. All rights reserved. Introduction Anopheles stephensi and Culex quinquefasciatus are the potential vectors of malaria and filariasis, respectively. Worldwide, these vectors are responsible for the transmission of 500 and 100 million clinical cases of malaria and filariasis diseases per annum, respectively; therefore, they can be referred to as global vectors (Das, 2007). In addition, the cost of mosquito borne diseases is not restricted to the loss of human, but also includes the lost of labour and productivity which impacts the overall social and economic progress of a country. Conventional synthetic pesticides such as, DDT, malathion and pyrethroides are used for mosquito management to protect humans from the adverse effects of mosquito borne diseases. However, unsystematic prolonged application of these pesticides can have adverse effects on the environment, as well as cause residual effects and induce the development of resistance to the pesticide by the vector (Mohan and Ramaswamy, 2007). Therefore, it is necessary to develop environmentally safe, biodegradable, economical and indigenous methods for the control of vectors that can be used with minimum care by individuals and communities (Mittal and Subbarao, 2003). A review indicated that assessment of the efficacy of different phyto- chemicals obtained from various plants is the best way to develop novel synthetic insecticides (Sukumar et al., 1991; Sharma et al., 2006; Mohan and Ramaswamy, 2007). Therefore, in this study, the larvicidal effects of different (petroleum ether, carbon tetrachloride and methanol) leaf extracts of a widespread aromatic medicinal plant, Ocimum basilicum (Linnaeus) on the malaria and filarial vectors, A. stephensi and C. quinquefasciatus, were evaluated. Materials and methods Collection of plant and preparation of extract Freshly harvested leaves of O. basilicum Linnaeus (Family: Lamia- ceae) were collected from the botanical garden of Dayalbagh Educa- tional Institute (Deemed University), Dayalbagh, Agra. The leaves were washed and dried in the shade at room temperature (37–39 °C) till they become brittle. The completely dried leaves (250 g) were then pow- dered manually and extracted using a soxhlet apparatus. Extraction was conducted using the three different solvents according to their polarity range (petroleum ether successively followed by carbon tetrachloride and then methanol) for 72 h. The extracts were then concentrated by evaporation of the solvents in a rotary vacuum evaporator (Biocraft Scientific Industries, India) to obtain 44.40 g/kg (petroleum ether), 20.0 g/kg (carbon tetrachloride) and 54.0 g/kg (methanol) of a semi solid crude extract, which was stored in the refrigerator for later use. Preparation of stock and test concentrations The residue (10 g) obtained from each fraction was dissolved in 100 ml of ethanol independently to obtain stock solutions of Journal of Asia-Pacific Entomology 12 (2009) 113–115 ⁎ Corresponding author. Fax: +91 562 2801226. E-mail address: chandnarayan_dei@rediffmail.com (C.N. Srivastava). 1226-8615/$ – see front matter © Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2009 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.aspen.2009.02.004 Contents lists available at ScienceDirect Journal of Asia-Pacific Entomology journal homepage: www.elsevier.com/locate/jape