ANTIFEEDANT ACTIVITY OF METABOLITES OF ARISTOLOCHIA-ALBIDA AGAINST THE TOBACCO CUTWORM, SPODOPTERA-LITURA

The antifeedant activity of the metabolites of Aristolochia albida roo t extracts was examined against tobacco cutworm larvae (Spodoptera lit ura, Noctuidae) using a leaf-disk choice bioassay. The antifeedant act ivities of the crude methanolic extract and aristolochic acid were ver y strong. 6-Hydroxyaristolochic acid showed moderate activity, while a ristolic acid, aristolactam, and aristolone did not demonstrate any an tifeedant activity at a 0. 1 % concentration. Methyl aristolochiate an d methyl 6-hydroxyaristolochiate prepared by diazomethane treatment of the acids showed significantly lower activities when compared with th e parent acids. When the carboxylic acid group of aristolochic acid wa s decarboxylated or reduced to the benzyl alcohol or to the aldehyde, significantly lower antifeedant activities were observed for the compo unds. These results suggest that a free carboxylic acid group in close proximity to a nitro group in the aristolochic acid ring structure is important to antifeedant activity. In a comparative experiment, arist olochic acid demonstrated a level of activity comparable to azadiracht in, a potent natural antifeedant.