Evaluating Grain Protectant Efficacy of Some Botanicals against Maize Weevil, Sitophilus zeamais M

Abstract

The production of sorghum is threatened by a wide range of pre-and post harvest pests like stalk borer, sorghum chafer, and Sitophilus spp. Three botanical plants (Tagitus minuta, Datura stramonium and Carissa schimperi) with five concentrations were tested for efficacy to control maize weevil (Sitophilus zeamais Mostch) on stored sorghum seeds under laboratory conditions. The objective was to study the efficacy of some locally available botanicals to control Sitophilus zeamais Mostch and to determine the length of period the grain could be protected by the different treatments. For comparison, two more treatments-standard check Malathion 5% dust plus control (untreated check) were included; and the experiment was replicated three times. The experiment was conducted under room temperature at 25-28C and relative humidity at 70±5% in Kombolcha Plant Health Clinic Laboratory. Powders of each plant component were then mixed thoroughly with 500 gram grains in plastic jars roofed with muslin cloth and tightened with rubber band. Thirty adult weevils were released in each plastic jars. Number of dead weevils was recorded every 21, 42 and 84 days after the treatments were applied. The data was transformed to arcsine scale prior to analysis. Corrected observations were subjected to statistical analysis, factorial ANOVA. All botanicals significantly affected weevil mortality compared to untreated check, but not as effective as synthetic insecticides (Malathion 5% dust). Carissa schimperi (merez) 5% was significantly more effective than the rest botanical rates and the control (P <0.05). In general the result shows that treatment Carissa schimperi (merez) 5% and Tagitus minuta (gimi) 5% can solve poor resources farmers’ problems by integrating them with other cultural measures. However further research are needed to fix the rate graph and the long term effect in large stores of farmers conditions.