Insecticidal Activity of Some Plant Extracts

Natural insecticides have been used in Egypt and some other locations for pest control in crops, offering an effective alternative to synthetic pesticides.  To determine the active principles in the plant materials used in Egypt, three species of the Chenopodiaceae family [Atriplex farinosa Forssk., Atriplex nummularia Lindl., and Haloxylon salicornicum (Moq.) Bunge ex Boiss.] and one species in the Resedaceae family (Ochradenus baccatus Delile) were investigated.  Plant material from each of the target species was ground and the constituents separated by column chromatography.  Insecticidal activity of the isolated compounds was tested in feeding, contact, and egg hatchability tests using Helicoverpa zea (Boddie), a major agricultural pest that as a larvae feeds on numerous crops, including cotton (cotton bollworm), corn (corn earworm), and tomato (tomato fruitworm).  Highest mortality of the larvae occurred when the larvae were in contact with extracts from A. farinosa.  Extracts from A. nummularia and H. salicornicum also exhibited activity against the larvae.  Similar trends were determined on the hatchability of eggs, but no significant effects were detected in feeding tests.