Identification and Control Methods for White Grub Infestation in Codonopsis pilosula
Belonging to the order Coleoptera, family Scarabaeidae. It is the larva of the scarab beetle, mainly active in the soil, damaging the roots of Codonopsis pilosula. White grubs generally have one generation per year, with larvae or adults overwintering in the soil. After temperatures rise in the following spring, white grubs gradually move upward in the soil; when the soil temperature reaches above 15°C, they move into the topsoil layer above 10cm to feed. When summer temperatures rise and the soil dries out, they descend to deeper soil layers and stop feeding or moving. In autumn they return to the topsoil layer to be active, and after October they successively burrow down below 30cm to overwinter. In summer with abundant rain, high soil moisture, and heavier application of barnyard manure, the infestation is severe.
Control methods: apply thoroughly decomposed organic fertilizer to prevent attracting adults to lay eggs; manual capture and killing. When white grub damage appears in the field, dig out the larvae near the root zone of the affected plants; water the plant roots with a 1500-fold diluted phoxim solution.