Toxicity of Synthetic Pyrethroids against Cirphis loreyi Dupt. (Lepidoptera: Noctuidae) on Sunflower

The efficacy of four different synthetic pyrethroids viz., deltamethrin, cypermethrin, fenvalerate and permethrin was evaluated against the Cirphis loreyi Dupt., a serious pest of sunflower crop. The LC₅₀ estimated were 0.0000953, 0.0002945, 0.0009870, 0.0012260% and LD₅₀ 0.03592, 0.07854, 0.13510 and 0.16920 µg/g of body weight of third instar larvae for these insecticides, respectively. The data reveals that the deltamethrin is most toxic and permethrin is least toxic. The relative persistent toxicity was taken as a parameter for final comparison of the bioefficacy on newly hatched caterpillars. The LT₅₀ recorded was maximum for deltamethrin (7.99 d), followed by cypermethrin (6.33 d), fenvalerate (4.27 d) and permethrin (4.22 d). The order of relative efficacy based on LT₅₀ values of these insecticides were deltamethrin 0.001, cypermethrin 0.01, fenvalerate 0.01 and permethrin 0.05%.