Evaluation of Some Insecticides against Melanagromyza sojae Zehnt. and Bemisia tabaci Genn. on Soybeen

Efficacy of thiamethoxam 70 WS and imidacloprid 70 WS, thiamethoxam 500 FS and thiamethoxam 350 FS, aaplied as seed treatment; carbofuran 3 G and phorate 10 G applied as seed dresssng at the time of fowing was evaluated in the field against natural incidence of major insect pests of soybean viz, stem fly, Melanagromyza sojae (Zehntner) and whitefly, Bemisia tabaci Gennadius during kharif 2005 ana 2006. The results revealea that thiamethoxam 70 WS @ 1.5 g kg⁻¹ seed, thiamethoxam 500 FS @ 1.5 g kg⁻¹ seed and imidacloprid 70 WS at 10 g kg⁻¹ seed were the most effective among all the treatments used during both seasons. Not only were all the three treatments effective in containing yellow mosaic virus disease incidence due to white fly B. tabaci but also reduced stem tunneling by M. sojae resulting in significant increase in grain yield. The residues of thiamethoxam and imidacloprid at harvest in the soybean grains analysed by HPLC-UV detector were below the detectable limits of 0.05 and 0.005 mg kg⁻¹, respectively.