Copyright © 2006 John Wiley & Sons, Ltd. Phytother. Res. 20, 1088–1090 (2006) DOI: 10.1002/ptr 1088 H. CETIN ET AL. Copyright © 2006 John Wiley & Sons, Ltd. PHYTOTHERAPY RESEARCH Phytother. Res. 20, 1088–1090 (2006) Published online 28 September 2006 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/ptr.2004 Larvicidal Activity of some Labiatae (Lamiaceae) Plant Extracts from Turkey Huseyin Cetin*, Ilker Cinbilgel, Atila Yanikoglu and Mustafa Gokceoglu Akdeniz University, Faculty of Arts and Science, Biology Department, 07058 Antalya, Turkey Ethanol extracts of the aerial parts from five Labiatae (Lamiaceae) species, obtained from Antalya, Turkey, were tested for larvicidal activity against the house mosquito Culex pipiens L. (Diptera: Culicidae) under laboratory conditions. Third and fourth instar mortality from six concentrations (5, 10, 25, 50, 100 and 200 ppm) of each plant extract were compared against the organophosphorus insecticide, temephos which is currently used for larval control. All plant extracts showed high larvicidal activity in 24 h exposure tests. Teucrium divaricatum Sieber was the most toxic, followed by Mentha longifolia (L.) Huds., Melissa officinalis L., Salvia sclarea L. and Mentha pulegium L. with LC 50 values of 18.6, 26.8, 39.1, 62.7 and 81.0 ppm, respectively. This study is the first to report on the larvicidal activity of ethanol extracts of these five plant species against C. pipiens. Copyright © 2006 John Wiley & Sons, Ltd. Keywords: aromatic plants; Culex pipiens; extract; Labiatae; larvicidal activity; phytopesticides. Received 12 February 2006 Revised 7 July 2006 Accepted 13 August 2006 * Correspondence to: Huseyin Cetin, Akdeniz University, Faculty of Arts and Science, Biology Department, 07058 Antalya, Turkey. E-mail: hcetin@akdeniz.edu.tr; hcetin4477@yahoo.com INTRODUCTION The flora of Turkey contains >12 000 generic taxa and >9150 species. It is estimated that a third of the flora from this country consists of aromatic and medicinal plants (Davis et al., 1988; Guner et al., 2001; Baser, 2002). Many of these plant species are common sources of drugs and insecticides used in traditional medicine. In addition, essential oils and extracts from roots, leaves, twigs and flowers are widely used in the food, tea, cos- metic, pharmaceutical and perfumery industries. More- over, Turkey is regarded as an important gene depository center for the Labiatae plant family where a wide diversity of active compounds has been found to be effective against a variety of pest insects (Soliman and El-Sherif, 1995; Isman et al., 2001; Traboulsi et al., 2002; Singh et al., 2003; Kocabas and Karaman, 2001). Globally, Culex pipiens L. (Diptera: Culicidae) is one of the most medically important mosquito species because it is the primary vector of many viruses from animals to humans (Campell et al., 2002; Fonseca et al., 2004). C. pipiens is the most widely distributed mosquito in the world except Antarctica, mainly found in urban and suburban areas. The most efficient approach to the control of C. pipiens is to target the immature stages of the life cycle. Synthetic chemical larvicides continue to be applied for controlling mos- quitoes in most parts of the world. But many of these chemicals are toxic to human, plant and animal life, and resistance can be problematic in maintaining con- trol, especially with organophosphate and pyrethroid larvicides. As a result, researchers are currently inves- tigating natural subtances to use as insecticides for con- trolling larval mosquitoes. Phytochemical insecticides have received much attention, in this regard, as they are considered to be more environmentally biodegrad- able and considered safer than synthetic insecticides (Moretti et al., 2002; Cetin et al., 2004). The purpose of the present study was to explore the larvicidal activity of ethanol extracts from aerial parts of five Labiatae species [Mentha longifolia (L.) Huds., Melissa officinalis L., Mentha pulegium L., Salvia sclarea L. and Teucrium divaricatum Sieber] against the house mosquito C. pipiens. MATERIAL AND METHODS Plant materials. All plant materials, in the flowering stage, were collected from various natural habitats in Antalya, Turkey, between May and September 2005 and are listed in Table 1. Plant taxonomists in the Department of Biology at Akdeniz University, Antalya, confirmed the taxonomic identification of the plant spe- cies. Voucher specimens have been deposited at the herbarium of the Pesticide Test Laboratory, Depart- ment of Biology, Antalya, Turkey. Extraction method. Aerial plant parts were air-dried and powdered in an electrical blender. One hundred grams of material from each species was extracted with 750 mL ethanol (96%) (Merck, Darmstadt) for 48 h using Soxhlet equipment (Vogel, 1978). After extrac- tion each sample was filtered through a Whatman filter paper no.1 and filtrates further evaporated under re- duced pressure and dried using a rotary evaporator at 40 °C. Dried extracts were stored in labeled sterile screw capped bottles at 4 °C. Larvicidal bioassays. Prior to bioassays, 1 g of plant extract was dissolved in 100 mL of ethanol (stock solu- tion). From the stock solution six concentrations, 5, 10, 25, 50, 100 and 200 ppm, were prepared in distilled water. In addition, one drop of emulsifier (Tween 80)