Additive effect of certain chemicals on the efficacy of Bacillus Thuringiensis var. Kurstaki Ber. against Spodoptera Litura (Fab.)
2002
Latha, E.Sree | Krishnayya, P.V. | Subbaratnam, G.V.(Agricultural College Bapatla (India) Department of Entomology)
Four groups of chemical viz. inorganic salts (calcium carbonate and calcium sulphate), protein solubilizing agents (tween 80 and sodium dodecyl sulphate), amino acids (aspartic acid lysine) and amides (acetamide and benzamide) were tested @ 0.05% for their additive effect on activity of Bacillus thuringiensis var. kurstaki (Btk dipel 8L) against Spodoptera litura. The median lethal concentrations were fixed after allowing third instar larvae of Spodoptera. litura to feed on treated castor leaves continiously for three days in the laboratory. addition of these chemicals increased the efficacy of Btk by reducing the L 50 values by 1.80 to 2.83 fold. Additive chemicals potentiated the insecticidal activity of Btk by resulting in quick toxic effect, increased inhibition of feeding, reduction in larval and pupal weights, malformation of pupae and adults and reduction in adult emergence.
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