Insecticidal and Developmental Inhibitory Properties of Some Plant Extracts on Culex Pipiens and Spodoptera Littoralis

Four plants belonging to four families were evaluated for insecticidal activity toward Culex pipiens and Spodoptera littoralis. Crude gradient extracts were obtained from the powder of Ipomoea cairica, Sesbania sesban, Acacia nilotica and Cymbopogon proximus using different solvents. Against C. pipiens, the petroleum ether and hexane extracts of C. proximus and I. cairica showed a strong insecticidal activity with LC50 = 0.39 and 0.67 mg/ml, respectively. Against S. littoralis, the hexane extract of S. sesban was the most toxic with 80% mortality. A complete pupation (100%) resulted from 1, 5 and 10 mg/ml of hexane extract of S. sesban. In contrast, a significant decrease in pupation was achieved with 25 mg/ml of hexane extract of I. cairica (63.33%). In addition, the adult emergence was significantly decreased with water: ethanol extract of A. nilotica (26.98%). The effect of extracts on growth of S. littoralis showed that petroleum ether and hexane extracts of C. proximus and I. cairica were the most potent (22.20 and 22.13%, respectively).