Abstract

Robert Mwaruwari Morgan

Use of plant compounds in grain protection has shown great potential as an alternative to synthetic insecticides in Sub-Saharan Africa. This study investigated the efficacy of Eucalyptus grandis and Tagetes minuta ground leaf powders as grain protectants against Sitophilus zeamais in stored maize. Effect of leaf powders were evaluated on percent germination, percent weight loss of grain, insect infestation, grain colour and odour over 192 days (≈six months) duration. Leaf powders (2.5 and 5 g/kg), synthetic pesticide (Actellic Chirindamatura dust (0.5 g/kg)) and an untreated control were used as treatments. All plant powders significantly minimized grain damage and infestation 96 days post treatment (≈three months) and had no effect on percent germination of maize grains when compared to controls. However, variable responses dependent upon botanical plant cultivars and rate of application were observed from three to six months after application. Grain colour and odour were not affected by plant powders over six months of storage. E. grandis and T. minuta significantly reduce grain damage and insect infestation with no adverse effects on seed germination, colour and odour hence can be used as sustainable alternatives to synthetic insecticides in maize storage especially by smallholder farmers.