The efficacy of the powder of a natural plant product (Acorus calamus L.) and two synthetic insecticides (i.e. Pirimiphos methyl and Rotenone) was compared in the laboratory for the control Sitophilus oryzea (L), Rhizopertha dominica (F) and Tribolium castaneum (Herbst) in stored wheat grains. Seven concentrations of the test chemicals (i.e. 1.25, 2.5, 5.0, 10.0, 15.0, 20.0 and 25g per kilogramme of wheat grains) were used. The control treatment consisted of 1kg untreated wheat grains. Percentage mortality was recorded cumulatively at 48h intervals for 16 days. Pirimiphos-methyl at 5g/kg of wheat grains gave 100% mortality of S. oryzea as against A. calamus powder and Rotenone that gave 46.56% and 26.44%, respectively. Mortality observed on R. dominica indicated that 25g of A. calamus powder resulted in significantly (P 0.05) higher percentage mortality 83.22% than pirimiphos-methyl that gave 56.65% and Rotenone with 36.4%. Only pirimiphos-methyl and Rotenone was toxic to T. castaneum, A. calamus powder was not.
KEY WORDS: Natural chemicals, synthetic insecticides, wheat grains, cereals.
Global Journal of Agricultural Sciences Vol.2(2) 2003: 94-97