Pesticide Research Journal

The relative efficacy of eleven insecticides against the aphid, Rhopalosiphum maidis (Fitch) revealed that dimethoate emulsion (0.03%) was the most effective followed by imidacloprid (0.005% solution), thiamethoxam (0.025% dispersion) and acephate (0.037% solution). Vertimec (9.5 mg a.i. L⁻¹ emulsion), spinosad (0.01% suspension) and diflubenzuron (0.05% emulsion) ranked in the middle order of effectiveness. Metarrhizium anisopliae (1×10⁸ spores L⁻¹), Beauveria bassiana (1 ×10⁸ spores L⁻¹), karanj seed extract (5 mL L⁻¹), and neem seed kernel extract (5 mL L⁻¹) were the least effective. The maximum yield was recorded from the plots treated with dimethoate (7.79 q ha⁻¹) followed by imidacloprid and thiamethoxam and the minimum from M. Anisopliae (5.37 q ha⁻¹). The highest benefit:cost ratio (39.51:1) was obtained in dimethoate treatment followed by acephate (36.92:1) and imidacloprid (24.84:1). Plots treated with spinosad showed negative benefit:cost ratio (0.28:1).