Effect of Thai neem leaf extracts on American bollworm, Heliothis armigera (Hubner)
1996
Ngampong Kongkathip | Kwanchai Sombatsiri (Kasetsart Univ., Bangkok (Thailand). Faculty of Science. Dept. of Chemistry)
Ground dried leaves of Thai neem (Azadirachta indica var. siamensis) were defated and removed off chlorophyll by soaking with hexane then extracted with 95 percent ethanol. The ethanol extract was partitioned with ethyl acetate and water to remove proteins and sugars. The ethyl acetate extract was fractionated by quick column chromatography to give 19 partially purified fractions. The crude extracts and partially purified fractions were evaluated for insecticidal activity. High performance liquid chromatography (HPLC) analysis showed no azadirachtin content in the leaves extracts. The crude extract at high concentration 0.44 percent w/v showed moderate stomach poison and antifeeding effect on the 2nd and 4th instar larvae of Heliothis armigera while both crude extract and partially purified fractions showed low effect on egg laying of H. armigera.
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