Insecticidal and genotoxic activity of Psoralea corylifolia Linn. (Fabaceae) against Culex quinquefasciatus Say, 1823

Background: Indiscriminate use of synthetic insecticides to eradicate mosquitoes has caused physiological resistance. Plants provide a reservoir of biochemical compounds; among these compounds some have inhibitory effect on mosquitoes. In the present study the larvicidal, adulticidal and genotoxic activity of essential oil of Psoralea corylifolia Linn. against Culex quinquefasciatus Say was explored. Methods: Essential oil was isolated from the seeds of P. corylifolia Linn. Larvicidal and adulticidal bioassay of Cx. quinquefasciatus was carried out by WHO method. Genotoxic activity of samples was determined by comet assay. Identification of different compounds was carried out by gas chromatography-mass spectrometry analysis. Results: LC50 and LC90 values of essential oil were 63.38 +/- 6.30 and 99.02 +/- 16.63 ppm, respectively against Cx. quinquefasciatus larvae. The LD50 and LD90 values were 0.057 +/- 0.007 and 0.109 +/- 0.014 mg/cm(2) respectively against adult Cx. quinquefasciatus,. Genotoxicity of adults was determined at 0.034 and 0.069 mg/cm(2). The mean comet tail length was 6.2548 +/- 0.754 mu m and 8.47 +/- 0.931 mu m and the respective DNA damage was significant i.e. 6.713% and 8.864% in comparison to controls. GCMS analysis of essential oil revealed 20 compounds. The major eight compounds were caryophyllene oxide (40.79%), phenol, 4-(3,7-dimethyl-3-ethenylocta-1,6-dienyl) (20.78%), caryophyllene (17.84%), alpha-humulene (2.15%), (+)-aromadendrene (1.57%), naphthalene, 1,2,3,4-tetra hydro-1,6-dimethyle- 4-(1-methyl)-, (1S-cis) (1.53%), trans-caryophyllene (0.75%), and methyl hexadecanoate (0.67%). Conclusion: Essential oil obtained from the seeds of P. corylifolia showed potent toxicity against larvae and adult Cx. quinquefasciatus. The present work revealed that the essential oil of P. corylifolia could be used as environmentally sound larvicidal and adulticidal agent for mosquito control.