EVALUATION OF THE INSECTICIDAL PROPERTIES OF THE GREEN-ALGA, SCENEDESMUS-ACUTUS AGAINST THE EGYPTIAN COTTON LEAFWORM SPODOPTERA-LITTORALIS (BOISD)

Successive extraction of the green alga, Scenedesmus acutus 276-3a wit h different solvents indicated that the petroleum ether extract was th e most repellent to the hatched larvae of Spodoptera littoralis. The a pplication of spray emulsified 1% petroleum ether extract inhibited eg g laying. At 0.25% concentration the moths laid only 52.4 of their egg masses on the treated oviposition sites in comparison to the untreate d control. Concentration of 1% was protective against the immature sta ge by hindering the third instar larvae to feed on treated leaf discs. In addition, the water emulsion of petroleum ether extract was insect icidal. The percentage mortality was directly proportional to the conc entration applied and to the duration of exposure.