First investigations of insecticidal effects of methanolic extracts from the leaves and bark of the Philippine neem tree, Azadirachta integrifoliola Merr., and comparison of these effects to those of extracts from Azadirachta indica (A. Juss) and Melia azedarach L.
1989
Schmutterer, H. (Giessen Univ. (Germany, F.R.). Inst. fuer Phytopathologie und Angewandte Zoologie)
Crude methanolic extracts from the leaves and bark of Azadirachta integrifoliola, A. indica and Melia azedarach were compared in biotests using Epilachna varivestis as the test insects. Leaf extracts were applied in Petri dishes at concentrations of 50, 100, 200 and 400 ppm - in one experiment, also of 800 ppm. In causing the mortality of test insects during their metamorphosis, and inducing morphogenetic defects in adults, such as malformed hindwings, the leaf extracts of A. integrifoliola were superior to those from M. azedarach. The extracts from A. indica leaves were least effective. The same sequence of effectiveness was observed in cage tests, but higher concentrations (800 ppm) were needed to obtain effect comparable to those in Petri dishes. The A. indica extract was only slightly effective at this concentration. Crude methanolic extracts from the bark of the three species of Meliaceae were somewhat different in efficacy to those from the leaves. Concentrations of 200 and 400 ppm from A. integrifoliola and A. indica extracts were about equally effective, whereas the same concentrations of M. azedarach extracts had no effect and even that of 800 ppm was only slightly effective. The symptoms caused by extracts of A. integrifoliola on larvae and pupae were identical to those of A. indica and M. azedarach, including, for instance, dark thoracic spots on fourth instar larvae of E. varivestis. The possible potential of A. integrifoliola as a source of growth-regulating natural pesticides in high rainfall areas of the tropics is discussed
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