Bioefficacy of Plant Extracts Against Tobacco Caterpillar, Spodoptera Litura in Bay Islands

Studies were conducted at the Central Agricultural Research Institute, Port Blair, to assess the biological activity of aqueous leaf extracts of Noni (Morinda citrifolia), cloves (Syzygium aromaticum) and Amomum aculeatum against tobacco caterpillar, Spodoptera litura under laboratory conditions using ‘leaf dip method’. Leaf extracts inhibited the growth and development and affected the larval and pupal survival and adult emergence in a dose-dependent manner. Ninety per cent of the larvae died due to M. citrifolia and S. aromaticum intoxication, hence the larval population could not reach the crucial late instar stage, which is actually responsible for crop damage. Consequently, the survival was also reduced as it was only 11.89 in highest concentration of M. citrifolia, 12.22 in S. aromaticum and 26.2 in A. aculeatum, respectively, whereas in control it was as high as 76.50%.