The potential larvicidal activity of leaf, bark and seed extracts of two indigenous plants, Aegle marmelos and Pongamia pinnata was studied against the third and fourth instars of Culex quinquefasciatus Say larvae. Larval mortality was observed after 24 hours of application. Both the two plants had shown effectiveness as larvicide against the C. quinquefasciatus larvae. Based on probit analysis, the larvicidal LC50 values of leaf extracts of A. marmelos at the application doses for Distilled Water (1,000-13,000 ppm), 50% Ethyl Alcohol (500-7,000 ppm), Methanol (250-1,250 ppm) and Acetone (200-1,000 ppm) were 3281.914, 1895.087, 682.865 and 486.026 ppm respectively. Those for A. marmelos bark extracts, the LC50 at the application dosages for Distilled Water (1,000-8,000 ppm), 50% Ethyl Alcohol (400-1,200 ppm), Methanol (300-900 ppm) and Acetone (100-900 ppm) were 2322.444, 680.016, 557.446 and 384.368 ppm respectively. Those also of A. marmelos seed extracts for Distilled Water (800-5,600 ppm), 50% Ethyl Alcohol (700-1,900 ppm), Methanol (200-1,400 ppm) and Acetone (100-700 ppm) were 2042.614, 1104.960, 446.143 and 270.939 ppm respectively. Again based on probit analysis, the larvicidal LC50 values of leaf extracts of P. pinnata at the application doses for Distilled Water (2,000-10,000 ppm), 50% Ethyl Alcohol (400-2,800 ppm), Methanol (300-1,900 ppm) and Acetone (150-850 ppm) were 4150.342, 957.269, 755.738 and 376.902 ppm respectively. Those for P. pinnata bark extracts, the LC50 at the application dosages for Distilled Water (3,000-11,000 ppm), 50% Ethyl Alcohol (600-2,200 ppm), Methanol (400-1,000 ppm) and Acetone (200-800 ppm) were 5777.03, 1046.046, 633.661 and 385.998 ppm respectively. Finally, those also of P. pinnata seed extracts for Distilled Water (700-3,500 ppm), 50% Ethyl Alcohol (500-1,700 ppm), Methanol (2001,000 ppm) and Acetone (100-500 ppm) were 1586.479, 910.066, 396.973 and 216.717 ppm respectively. Of the two plants, leaf and seed extracts of P. pinnata were more effective than A. marmelos but for bark extract A. marmelos showed more larvicidal activity than P. pinnata as observed from LC50 and relative potency values.

Key words: Aegle marmelos, Pongamia pinnata, plant parts, Culex quinquefasciatus, larvicidal effects.