RESUMEN
In assessing the pesticidal activity of soosan, P. maritimum, the bulbs and leaves were extracted using acetone/ethanol and ethanol as solvents and mosquito larvae C. pipiens, as a test organism. The acetone/ethanol extract of bulbs was more toxic [LC50, 25 ppm] than that of the leaves [LC50, 75 ppm]. Crude alkaloids, lycorine, terpenes and sterols and fixed oil were isolated from soosan bulb. Their percentages were 0.193, 0.02, 0.13 and 3.3%, respectively. The acetone/ethanol extract showed a strong aphicidal activity to Aphis gossypii with LC50 of 0.028% followed by lycorine, soosan oil and crude alkaloids with LC50 values of 0.07, 0.28 and 0.3%, respectively. Also, the acetone/ethanol extract showed high toxicity to Spodoptera littoralis 4th instar larvae, with LD50 value of 2 mg/larva. In addition, the crude alkaloids ethanol extract and the oil of soosan bulbs showed acaricidal activity against the two spotted spider mite, Tetranychus urticae with LC50 values of 0.2, 0.36, and 1.5%, respectively. Synergism studies on the A. gosspii indicated that lycorine, the principal alkaloid of soosan bulbs, strongly synergized, the OP insecticide cyanophos and reducing its LC50 values from 120 to 48 ppm. On the other hand, the aqueous extract of soosan bulbs synergized the toxicity of Actellic and Permethrin in Tribolium castaneum which reduced their LC50 values from 80 to 46 ppm and from 1000 to 550 ppm, respectively. Also, ethanol and petroleum ether extracts synergized the toxicity of Reldan and Permethrin, respectively, in the same insect