Soil Pests of Groundnut in West Africa—Species Diversity, Damage and Estimation of Yield Losses

Among the major arthropods in soil and plant samples taken from groundnut farms during the 1996 cropping season in Mali, Burkina-Faso, Niger, and Nigeria, termites in the genus Microtermes (Isoptera: Termitidae) were the most abundant and widely distributed species of economic importance. None of the termite species identified on trees in the surveyed farms attacked groundnuts. At plant maturity, termites were less frequently observed in soils taken from bare ground but were predominantly found on plants. Residues of previous cereal crops in the fields contributed to termite spread. Most of the whitegrub (Coleoptera: Scarabaeidae) and millipede (Myriapoda: Odontopygidae) species identified belonged to the genera of Schyzonycha and Peridontopyge respectively. There was a general decrease in both their population densities and the percentages of farms they infested at plant maturity compared to the early stages of the crop. Mean percentages of plants attacked by termites, whitegrubs and millipedes in the surveyed groundnut fields were 39.4, 10.9, and 9.3% respectively. Yield loss due to termites, which predominantly damaged harvested kernels, was estimated at 9.6–30.4%, and was significantly correlated with percentage of plants damaged by termites (r2 = 0.73).