The control of Sitophilus zeamais (Motsch) in stored maize using crude bark and wood extracts of Cedrela odorata (L. Kennedy) and Pirimiphos-methyl.

Abstract

A laboratory tests was carried out using aqueous crude ethanol bark and wood extracts of Cedrela odorata (L. Kennedy) and a standard synthetic chemical (Primiphos-methyl) as a surface protectant against Sitophilus zeamais (Motsch) (Coleoptera:Curculionidae) infestation and damage in maize grains. The results of this investigation showed that the bark and wood extracts at 8,000 ppm gave the highest mean mortality of 16% and 24% for both topical application and residual action tests, compared to the pirimiphos-methyl standard formulation which achieved 96-100% mortality at the recommended dosage level of 4ppm. The standard solution, achieved 86-100% mortality of the adult weevils used as invaders of clean protected grains after 90 days storage, while the plant extract gave 32% mortality. The progeny emergence in the infested grains treated with bark extract was almost five times the progeny emergence in similar grains treated with pirimiphos-methyl formulation, and about half the number of progeny which emerged from the control. Subsequent grain damage was reduced from about 4.5% in the untreated control to 2.6% in the bark extract treated grains. The effect of the treatments on controlling the progress of attack in previously infected grains was also similar.
Key Words: Pest control; Insect pests; Maize weevil; Cedrela odorata; Sitophilus zeamais; Primiphos-methyl.