Indoor Toxicity of Emamectin Benzoate and Chlorantraniliprole Against Spodoptera litura and Their Residues on Lotus Plants
Spodoptera litura is the most threatening pest in lotus production,seriously affecting the lotus yield and quality.Emamectin benzoate and chlorantraniliprole,the main insecticides for controlling S.litura on vegetables,are widely used by farmers to control S.litura on lotus plants.To determine the application concentrations,control effects,and safety of the two insecticides in lotus fields,indoor experiments were conducted to determine the control effects of 200 g/L chlorantraniliprole(SC)and 5%emamectin benzoate(WDG),and the residues of the two insecticides in the water,lotus leaves,and lotus seeds after field application were determined by HPLC-MS/MS.The indoor experiment results showed that chlorantraniliprole and emamectin benzoate both had good control effects on S.litura,with the median lethal concentrations(LC50)of 17.700 and 1.694 mg/L,respectively.After unmanned aerial vehicle spraying of emamectin benzoate at 20 g/667m2,there was no residue of emamectin benzoate in the water or lotus leaves after 5 d.After spraying of chlorantraniliprole at 20 mL/667m2,the residual amounts in the water and lotus leaves after 9 d were 0.005 and 0.007 mg/L,respectively.No residue of the two insecticides was detected in lotus seeds(dry and fresh)2 h after spraying.Therefore,it was recommended that chlorantraniliprole and emamectin benzoate can be used to control S.litura in lotus fields during the growth period,while attention should be paid to the application interval for safety.Considering the safe harvesting of lotus seeds and leaves,it was recommended that the preharvest intervals of chlorantraniliprole and 5%emamectin benzoate should be 9 d.
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