1. A Study of Crude Extracts from Leaves of Piper samentosum Roxb. for Inhibiting Growth of Culex spp. Surakiat Leelasithorn Budsarin Muikeao Mahidol Wittayanusorn School,THAILAND

2. Method

3. Solvent Extraction Preparing the leaves of Piper Sarmentosum Roxb. Use Hexane as Solvent Use Ethyl Alcohol as Solvent Filtering the wastes Evaporating the solvents Weighing and recording the result Soaking for 5 days

4. Calculated LC 50 24 hr Preparing the larva of Culex spp. Testing for the death at different conc. Recording the results Analyzing the data Estimating LC 50 value

5. Result

8. Solvent Extraction

9. Calculated LC 50 24 hr Table3 : Percentage of dead larva in the crude extract by ethyl alcohol

10. Calculated LC 50 24 hr Data analysis by SPSS shows that The regression is R 2 =0.972 So we can estimate LC 50 value from the equation is 1 g/l

11. Calculated LC 50 24 hr Table4 : Percentage of dead larvas in the crude extract by hexane

12. Calculated LC 50 24 hr The regression is R 2 =0.988 So we can estimate LC 50 value from the equation is 0.67 g/l Data analysis by SPSS show that