Journal of Scientific & Industrial Research Vol. 64, February 2005, pp 129-133 Evaluation of anti-mosquito properties of essential oils Mohini Makhaik 1 , Satya Narayan Naik 1, * and Dhananjay Kumar Tewary 2 1 Centre for Rural Development and Technology, Indian Institute of Technology, Hauz Khas, Delhi 110 016 2 Institute of Himalayan Bioresource Technology, CSIR, Palampur 176 061 Received 24 September 2004; accepted 26 December 2004 Essential oils from Cedrus deodara, Eucalyptus citriodora, Cymbopogon flexuous, C. winterianus, Pinus roxburghii, Syzygium aromaticum and Tagetes minuta were evaluated for bioactivity against the adults of Culex quinquefasciatus and Aedes aegypti. Serial dilutions of the oils were made in deodorized kerosene to obtain a range of concentrations (0.5-10%) and the adults were exposed to the vapour of the different oils for 1h in WHO kits for sensitivity testing. C. winterianus and S. aromaticum oils were equi effective and found most effective with LC 50 and LC 95 values respectively at 0.5 and 0.9 % for C. quinquefasciatus and 1.0 and 2.0 % for A. aegypti. Activity was found in the order: S. aromaticum > C. flexuous > E. citriodora > C. winterianus > C. deodara > T. minuta. Keywords: Culex quinquefasciatus, Aedes aegypti, Essential oils, Mosquito repellents Introduction Mosquitoes are the major vectors for dengue fever, yellow fever, malaria, filariasis, Japanese encephalitis and other fevers 1 . Synthetic organic insecticides used to control mosquitoes have produced a feedback of environmental ill effect, non-targets organisms being affected and most mosquito species have becoming physiologically resistant to synthetic insecticides 2 . Several phytochemicals have detrimental effects on mosquitoes 3,4 . Essential oils and terpenoids are reported to show repellency to adult mosquitoes 5,6 . Strong repellent action of Azadirachta indica, Cymbopogon martini var sofia, C. citratus, C. nardus and Oscimum sp. have been reported against some species of mosquitoes 7 . These findings have reemphasized the possibility of developing an effective and safe insecticide from plant derived products. India represents a vast repository of diverse flora of considerable medicinal importance. Many researchers have reported the bioactivity of Eucalyptus sp. 8-10 , Cedrus deodara 7,8,11 Cymbopogon sp. 8,12-15 and Tagetes minuta 16 against mosquitoes. In all these studies, bioactivity of the plant/parts has been evaluated either as repellent or as larvicide. Some of the studies pertain to the evaluation of adult mortality activity is generally tested using laboratory bioassay 16 . However, scanty research work is available to determine the bioactivity of essential oils directly on the adult mortality. The present paper evaluates bioactivity of the oils from seven plants, Cedrus deodara (Roxb.) Loud (Pinaceae), Eucalyptus citriodora (Myrtaceae), Cymbopogon flexuous (DC.) Sapf (Graminae), Cymbopogon winterianus(Linn.) Randle (Graminae), Pinus roxburghii (Sarg.) (Pinaceae), Syzygium aromaticum (Linn.) Merr & Perry (Myrtacae) and Tagetes minuta L. (Compositae) on the adults of two mosquito species, Culex quinquefasciatus and Aedes aegypti. Materials and Methods Extraction and Preparation of Test Solution Plant materials were collected from naturally growing regions of North India. Clevenger’s type apparatus 17 was used to obtain essential oils from freshly collected leaves of C. winterianus, C. flexuous, E. citriodora and T. minuta, crushed wood chips of C. deodara and crushed clove buds of clove oil. The oils were refrigerated and used as a test sample. The pine oil was obtained from resins. GC Analysis of Chemical Constituents Chemical constituents of oils were identified by Gas Chromatography using SE-30 column and the GC parameters as follows: Oven temperature, 80-200°C _____________ * Author for correspondence Tel: 91-11-26591162, 91-11-2659 6229; Fax: 91-11-6591121 E-mail: sn_naik@hotmail.com