Farmers’ Practices and Combinations of Malathion and Neem Seed Powder Management Options against Sorghum and Maize Insect Pests during Storage at Bako, West Shoa Zone, Ethiopia

Abstract

Some farmersf practices (layering of teff grain over sorghum grain in 20% proportion, mixing sorghum with teff at 30% w/w, mixing sorghum with partially ground hot pepper at the rate of 2and 1% w/w) including Malathion 5% D (50g/quintal) and untreated check were evaluated against stored sorghum insect pests at Bako Research Center, Western Ethiopia, during 2004/2005-2005/2006. Besides, combinations of different rates (T1 = 0% (0 g)+ 00% (4 g), T2 = 10% (0.01 g) + 50% (2 g), T3 = 20% (0.02 g) + 40% (1.6 g), T4 = 30% (0.03 g) + 30% (1.2 g), T5 = 40% (0.04 g) + 20% ( 0.8 g), T6 = 50% (0.05 g) + 10% ( 0.4 g), T7 = 100% (0.1 g) + 0 % (standard check) and T8 = untreated check) of Malathion 5% D and neem seed powder were separately evaluated against maize weevils Sitophilus zeamais Mostch in the laboratory at Bako from February to July 2006. Data collected include number of dead and alive species of insect pests in each treatment/sample, number and weight of damaged and undamaged grain, as well as percent weight losses/sample. Number and weight of damaged grains were significantly (P . 0.05) higher after layering of teff over sorghum with 20% w/w, followed by mixing sorghum with teff at 30% w/w and untreated check when compared to the other treatments. Number and weight of undamaged kernels was significantly (P . 0.05) higher with mixing sorghum mixed with hot pepper at 2 and 1% w/w than the other treatments. Similarly, percent weight losses were significantly (P . 0.05) lower in mixing sorghum with hot pepper at 2 and 1% w/w than the other treatments, which were similar to the standard check. With respect to combined treatments, mortality in case of all combinations ranged between 3.33 to 100%, while that of the untreated check ranged between 0 to 5.33% following 90 days of exposure. Number of progeny weevils emerged, percentages of grain damaged and kernel weight losses in all of the treatment combinations were significantly lower than that of the untreated check 90 days after infestation. Number of progeny weevils emerged, percentages of grain damaged and kernel weight losses for all these treatments were also found significantly lower than that of the untreated check. Significantly (P . 0.05) higher percentages of mortality, lower percentages of damaged grains and kernel weight losses were observed with Malathion dust treatment at 40 and 50% combined with neem seed powder than that of the other treatments next to the standard check 156 days following infestation. It could be thus concluded that mixing sorghum grain with partially ground hot pepper at the rates of 2 and 1% w/w can be used to suppress stored sorghum insect pests, and combinations of Malathion and neem seed powder at 40+20, and 50+10%, respectively, can be used to protect maize from the weevil. However, further study for one more additional year may be required for further validation of the results.

Keywords: Farmers Practices; Neem Seed Powder; Maize Insect Pest Mortality; Progeny; Stored Sorghum and Teff; Weevil