Bio-efficacy, persistence and residual toxicity of different insecticides against soybean pod borer Helicoverpa armigera (Hubner) infesting soybean

The studies on the bio-efficacy, persistence and residual toxicity of different insecticides viz., chlorantraniliprole 0.004 per cent, ethion 0.100 per cent, triazophos 0.050 per cent, indoxacarb 0.010 per cent, emamectin benzoate 0.001 per cent, quinalphos 0.050 per cent and profenophos 0.100 per cent against Helicoverpa armigera (Hubner) infesting soybean were conducted at the Research Farm of Department of Agril. Entomology, College of Agriculture, Latur (MS). The overall result revealed that all the insecticidal treatments were significantly superior over untreated control in minimizing the larval population of H. armigera infesting soybean. Among the treatments, chlorantraniliprole 0.004 per cent was found to be the most effective insecticide in reducing larval population of H. armigera on soybean (1.22 and 1.44 larvae per mrl) followed by emamectin benzoate 0.001 per cent (1.33 and 1.78 larvae per mrl), indoxacarb 0.010 per cent (2.22 and 1.89 larvae per mrl), quinalphos 0.050 per cent (2.41 and 2.00 larvae per mrl), profenophos 0.100 per cent (3.67 and 2.22 larvae per mrl), triazophos 0.050 per cent (3.78 and 2.67 larvae per mrl) and ethion 0.100 per cent (4.11 and 2.78 larvae per mrl) after first and second spray, respectively. The highest soybean yield was achieved by chlorantraniliprole 0.004 per cent (34.87 q per ha) while quinalphos 0.050 per cent (1:19.72) registered highest incremental cost benefit ratio. The results on residual toxicity of different insecticides against H. armigera infesting soybean indicated that chlorantraniliprole 0.004 per cent and emamectin benzoate 0.001 per cent illustrated highest persistent toxicity index (PT) (953.68 and 913.48 and; 885.64 and 875.80, respectively) and LT50 values (7.93 and 7.78 and; 7.06 and 7.09 days, respectively) against third instar larvae of H. armigera after first and second spray as compared to the other insecticides.