Effect of leaf feeding by Melanaphis sacchari (Zehntner) (Homoptera: Aphididae), on sorghum grain quality

Abstract

A study was conducted to determine the effect of leaf feeding by the aphid, Melanaphis sacchari, on grain quality of sorghum. A field trial was planted with two sub-blocks. Each sub-block was planted with ten similar sorghum hybrids. One sub-block was protected from aphid infestation by means of insecticide application while the other was allowed to become infested by aphids. Plots consisted of four rows of 10 m with three replicates of each hybrid. Grain was harvested from the central two rows per plot. The effect of aphid feeding on sorghum grain quality was evaluated by comparing the germinative vigor, germinative energy, diastatic power, percentage malt loss and percentage water uptake during malting as well as the milling performance in terms of dehulling index and abrasive hardness index of grain harvested from aphid infested and uninfested sub-blocks. Diastatic power, malt loss and abrasive hardness index were significantly reduced in grain harvested from aphid infested plants. Results indicated that aphid damage has a significant economic impact on the quality of sorghum grain used in the beer brewing and milling industry. Using grain from aphid infested plants may result in reduced efficiency of the brewing process. Reduced grain hardness resulting from aphid feeding may result in increased flour losses during the milling process. © 2003 Taylor & Francis Group, LLC.