Control of the White Grub Liogenys fusca (Blanchard) (Coleoptera: Melolontidae) Using Insecticides on Seeds and in Soybean (Glycine max) Sowing Furrow

Abstract

Among soil pests that attack soybean crop, the white grubs complex has great importance during initial stage of crop development, and Liogenys fusca (Blanchard) is the most common species in Brazilian Western Central Region. The objective with this work was to evaluate the effect of some insecticides applied either to the soil or to the seed for control of L. fusca larvae in a soybean field. The study was carried out during 2006/07 crop season in Mato Grosso State, Brazil. In the furrow, the following insecticides were applied (g.ha-1): chlorpyrifos (576 and 720), endosulfan (1050), bifenthrin (40 and 60), imidacloprid (60), and fipronil (25). For seed treatment the following insecticides were applied: (g/100 kg of seeds): imidacloprid (60), clothianidin (60), fipronil (25 and 50), imidacloprid + thiodicarb (60 + 180), acephate (600) and thiamethoxam (42). Crop stand at 10 and 35 days after soybean emergency (DAE), plant height at 35 and 54 DAE and grain yield were measured to evaluate the effect of insecticides and the way of application. Chlorpyrifos (720 g.ha-1), endosulfan (1050) and fipronil (25), applied in the furrow, and imidacloprid (60 g.100kg-1), clothianidin (60) and fipronil (50), applied on seeds, provided the best initial establishment and development of the soybean crop. However there was no difference for grain yield between all insecticides applied either in soil or seeds, but these chemical treatments provided higher grain yield than the control treatment. It was concluded that insecticide application on seeds or in the furrow might be used as a strategy to larvae control of L. fusca in soybean fields.