Contribution of insects to low groundnut yields in southern Africa
1989
Wightman, J.A.
An assessment of the importance of insects as constraints to groundnut production in five countries of the SADCC region of southern Africa was made during the 1986/87 groundnut growing season. The survey showed that white grubs were a particular problem in Zimbabwe as pod and root eaters, where the sandy soils rendered the short-duration crop particularly vulnerable. Termites were a major problem in Botswana where they were primarily associated with the drought conditions. They also caused severe crop loss in dry areas of other countries. Many pod-boring species caused crop loss, the most important being millipedes, followed by wireworms, false wireworms, and doryline ants. White grubs and termites also damaged pods. Insecticides increased the damage caused by some species of termites, because predatory ants were more susceptible to the insecticides than the target species. The application of a soil insecticide increased the seed yield by 23.8 per cent, 53.1 per cent, and 60.1 per cent at three sites in Malawi and had no effect at two others. Soil insects as a whole caused as much yield loss in the region as pathogens, the main differences being the greater number of species involved and the variability between farms, districts, and seasons
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