White grubs (Schyzonycha spp.)
Whitegrubs are the larvae of scarab "chafer" beetles. They are white, C-shaped with a brown head and three pairs of legs. Many species of white grubs are associated with groundnut damage in parts of sub-Saharan Africa. The most important are Schyzonycha species.
White grubs attack plants at all stages of growth. They eat roots and damage pods of groundnuts. White grubs feed mainly on the taproots and/or peripheral roots leading to stunting or death. They inflict cuts in the crown region of taproots; these lesions are often invaded by rot-causing fungi. White grubs also cut out pods from the base of groundnut pegs and destroy larger, soft pods. Plants are often attacked in a row. White grubs seem to prefer soils with sandy or loamy sand textures and are seldom observed in clay soils.
- Allow enough time between manure application and planting of groundnut. The excessive use of organic manure in groundnut farms has been observed to increase the incidence of white grubs, especially when manure is applied during the cropping season.
- Deep ploughing or hand hoe tillage exposes soil pests to desiccation and to predators, thus helping to reduce their numbers and damage.