The toxicity of materials derived from the seed of Pongamia pinnata to third instars of insecticide-susceptible Culex pipiens pallens and Aedes aegypti and wild Aedes albopictus was examined using a direct contact bioassay. Results were compared with those of the currently used insecticides fenthion and temephos. The active principles of Pongamia pinnata were identified as the karanjin (1), karanjachromene (2), pongamol (3), pongarotene (4), oleic acid (5), and palmitic acid (6) by spectroscopic analysis. Based on 24 h LC50 values, karanjin (14.61 and 16.13 mg/L) was the most toxic compound, followed by oleic acid (18.07 and 18.45 mg/L) and karanjachromene (18.74 and 20.57 mg/L). These constituents were less toxic than either fenthion (LC50, 0.0031 and 0.0048 mg/L) or temephos (0.021 and 0.050 mg/L) against Ae. aegypti and Cx. p. pallens. Low toxicity was produced by pongamol (LC50, 23.95 and 25.76 mg/L), pongarotene (25.52 and 37.61 mg/L), and palmitic acid (34.50 and 42.96 mg/L). Against A. alpopictus instars, oleic acid (LC50, 18.79 mg/L) was most toxic. Low toxicity was observed with the other five constituents (LC50, 35.26- 85.61 mg/L). P. pinnata seed-derived active principles, particularly karanjin, karanjachromene, and oleic acid, merits further study as potential mosquito larvicides for the control of mosquito populations in light of global efforts to reduce the level of highly toxic synthetic larvicides in the aquatic environment.

• Haribalan Perumalsamy(Entomology Major, Department of Agricultural Biotechnology, Seoul National University)
• Jun-Ran Kim(Research Institute for Agriculture and Life Science, Seoul National University)
• Murugan Kadarkarai(Department of Zoology, Bharathiar Univerisity, Coimbatore, India)
• Young-Joon Ahn(WCU Biomodulation Major, Department of Agricultural Biotechnology, Seoul National University)