Evaluation of granular insecticides against white grubs (Coleoptera: Scarabaeidae) infesting soybean crop

Abstract

The experiment was carried out to study the efficacy of various insecticides viz., Carbofuran 3G @ 750g a.i./ha, Clothianidin 50WDG @ 120g a.i./ha, Fipronil 0.3G @ 50g a.i./ha, Thiamethoxam 25WG @ 80g a.i./ha, Imidacloprid 70WG @ 300g a.i./ha, Chlorantraniliprole 0.4 GR @100g a.i./ha, Fipronil 40% + Imidacloprid 40% WG @ 300g a.i./ha Chlorpyrifos 10G @ 300g a.i./ha and Emamectin benzoate 5SG @ 12.5g a.i./ha against white grubs infesting soybean crops. All treatments were shown to be significantly superior to the control. During the 2019 and 2020 cropping seasons, Fipronil 40% + Imidacloprid 40% WG @ 300g a.i./ha was shown to be the most effective in terms of percent decrease over the control, i.e., 81.95 and 79.31%, respectively, followed by Clothianidin 50WDG @ 120g a.i./ha (78.95 and 77.46%). Emamectin benzoate 5SG at 12.5g a.i./ha was found to be less effective, reducing plant damage by 30.07% during the previous year and 39.37% during the next years. The maximum soybean yield and cost benefit ratio was obtained from the plot treated with Fipronil 40% + Imidacloprid 40% WG @ 300g a.i./ha, while the lowest was obtained from the plot treated with Emamectin benzoate 5SG @ 12.5g a.i./ha. Observations recorded on the following application of insecticides revealed that there was no evidence of phytotoxicity in any of the treated soybean plots. Experimental results demonstrated that Fipronil 40% + Imidacloprid 40% WG applied at 300g a.i./ha was effective for the control of white grub in soybean crop without harming natural enemies.