Abstract

                                The present study aimed to find the toxicity of aqueous and methanol extracts of three different brown macroalgae viz., Padina tetrastromatica, Sargassum wightii and Turbinaria conoides against tobacco cutworm, Spodoptera litura. Larval mortality was noticed in both the extracts at all the concentrations tested in a dose-dependent increase after 96 h of exposure with 73.33, 56.66, and 50.00 per cent in aqueous extract; and 50.00, 46.66 and 43.33 per cent in methanol extracts at 10 % concentration in S. wightii, T. conoides and P. tetrastromatica, respectively. Pre-pupal and pupal mortality were recorded in all the concentrations showing malformations during the growth. Pupation and adult emergence were also affected by the extracts of S. wightii. From the results, it is surmised that brown macroalgae possess insecticidal potential and growth inhibitory properties which can be exploited for eco-friendly management of Spodoptera litura and possibly other lepidopteran larvae as well.

Key words : Brown macroalgae; Padina tetrastromatica; Sargassum wightii; Turbinaria conoides; Spodoptera litura; Eco-friendly management