The effect of ground powders of two tropical plants, Lantana camara
L. and Tephrosia vogelii
Hook, on the level of insect damage and the grain quality parameters of stored maize were evaluated for five months. The evaluations were aimed at generating natural product treatments suitable for post-harvest grain protection and as sustainable alternatives to synthetic insecticides in the control of the maize weevil, Sitophilus zeamais
Motschulsky. Three rates (1.0, 2.5 and 5.0% w/w) of each plant powder, a synthetic insecticide, Actellic Super 2% dust at 0.05% w/w and an untreated control were used as treatments. Results showed that the plant powders significantly minimised the magnitude of depression in percent grain moisture content albeit at a lesser rate with high concentration and had no effect on the percent germination of maize grains when compared to the controls. The botanical treatments and synthetic insecticide were equally effective in reducing insect damage by 25%, but the level of damage was independent of the concentration applied. Grain colour and odour were unaffected by the botanicals. Results are discussed with regard to the use of botanicals by small-scale farmers as cost-effective and sustainable alternatives to synthetic insecticides in maize grain storage.