Control Effects of Different Application Methods of Imidacloprid and Thiamethoxam against Rape Aphids and Their Safety to Rape

The control effects of 70% imidacloprid WS( active ingredient 420 g / ha,600 g / ha) and 70%thiamethoxam WS( active ingredient 420 g / ha) applied in sowing time on rape aphids during the whole growing seasons,the residues of imidacloprid and thiamethoxam in rape in different growing stages,and the yield of rapeseed were investigated for evaluating the control effects of these two insecticides. The results showed that by spreading 70% imidacloprid WS 420—600 g / ha and 70% thiamethoxam WS 420 g / ha in the sowing ditch and by spreading 70% thiamethoxam WS 420 g / ha on the topsoil after covered,they all had good control effects against rape aphids,with 98. 98% —100. 00% from prosperous beginning period to decline period of rape aphids in seedling stage,and 79. 61% —98. 51% from returning green stage to flowering stage,and had good yield-increasing rate with 17. 47% —27. 19%. The residue in rapeseed of imidacloprid by spreading 420 g / ha in the sowing ditch was lower than the highest limited standard inUSA( 0. 05 mg / kg). The treatments spreading 70% imidacloprid WS 420 g / ha or 70% thiamethoxam WS420 g / ha in the sowing ditch and 70% thiamethoxam WS 420 g / ha on the topsoil after covered were safe to rape,had good control efficacy on rape aphids and significant yield-increasing rate,and remained lower residues in products.