Nonconventional insecticidal effects are exerted by preparations from the Neem tree, also called Indian lilac or Margosa tree (Azadirachta indica A. Juss, syn. Mefia azadirachta L. or Antefaea azadirachta L.) (Meliaceae). A closely related species, the chinaberry tree or Persian lilac (Mefia azedarach L.), is a source of substances with similar structures and insecticidal activity. However, the seed kernels, whole fruits or leaves of many M. azedarach chemotypes contain tetranortriterpenoids and other principles highly toxic to mammals (meliatoxins). The most prominent insecticidal constituent of Neem seed kernels i s the tetranortriterpenoid azadirachtin and related structures. Lesser concentrations of these active materials are found in the leaves and other parts of the tree. Third World farmers use crude Neern preparations, mainly seed kernel extracts or powders, as insecticides. An industrial Neem product, called Margosan-0, is in commercial use in the USA. The nonconventional effects of preparations or compounds isolated from Neem may be classified as follows: (i) partial reduction or complete inhibition of fecundity and/or sometimes egg hatchability; (ii) reduction of the life span of adults; (iii) oviposition repellence against females; (iv) direct ovicidal effects; (v) antifeedant effects against larvae (and nymphs) and adults; (vi) formation of permanent larvae; (vii) insect growth regulator effects at molting between larval (or nymphal) instars and especially in the prepupal stage; and (viii) analogous lesions during the emergence of adults. Phenomena (vii) and (viii) give rise to characteristic larval-pupal, nymphal-pupal, nymphal-adult and pupal-adult intermediates, and to crippled adults. Q 1993 WiIey-Liss, Inc.

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Physalisperuviana shrubs were not attacked by larvae of Spodoptera littoralis. It was demonstrated that withanolide E, a steroid isolated from P.peruviana, as well as several related steroids, have insect antifeedant properties.