Larvicidal efficacy of Sphaeranthus indicus, Cleistanthus collinus and Murraya koenigii leaf extracts against filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae).

Sphaeranthus indicus, Cleistanthus collinus and Murraya koenigii leaf extracts were tested against the third instar larvae of Culex quinquefasciatus. The plant material was shade dried at room temperature and powdered coarsely. From each plant, 500 g powder was macerated with 1.5 L of hexane, chloroform and ethyl acetate sequentially for a period of 72 h each and filtered. The yield of the S. indicus, C. collinus and M. koenigii crude extracts by hexane, chloroform and ethyl acetate was 9.16, 11.71 and 10.83 g for S. indicus; 8.17, 10.69 and 9.85 g for C. collinus; and 10.11, 11.92 and 9.87 g for M. koenigii, respectively. The extracts were concentrated at reduced temperature on a rotary vacuum evaporator and stored at a temperature of 4°C. The S. indicus, C. collinus and M. koenigii leaf extracts at 250, 500, 750 and 1,000 ppm caused a significant mortality of C. quinquefasciatus. The LC(50) and LC(90) values of S. indicus, C. collinus and M. koenigii against third instar larvae at 24, 48 and 72 h (hexane, chloroform and ethyl acetate) were the following: S. indicus LC(50) values were 544.93, 377.86 and 274.79 ppm and LC(90) values were 1,325.32, 1,572.55 and 1,081.29 ppm at 24 h; C. collinus LC(50) values were 375.34, 318.29 and 226.10 ppm and LC(90) values were 699.65, 1,577.62 and 1,024.92 ppm at 24 h; and M. koenigii LC(50) values were 963.53, 924.85 and 857.62 ppm and LC(90) values were 1,665.12, 1,624.68 and 1,564.37 ppm at 24 h, respectively. However, the highest larval mortality was observed in C. collinus followed by S. indicus and M. koenigii of various concentrations at 24, 48 and 72 h. The study proved that S. indicus, C. collinus and M. koenigii leaf extracts had larvicidal property against species of C. quinquefasciatus. This is an ideal ecofriendly approach for the control of vector control programmes.