The ability of P. truncatus to attack sorghum grain, the extent of grain damage and consequent dry weight loss was investigated in the laboratory. At the end of 90 days storage, mean percentage grain damage ranged from 19.01% to 37.75%. Mean percentage dry weight loss observed was between 5.18% and 19.81%. The quantity of grain dust produced weighed between 5.92g and 28.60g. Live adult beetles (0.00 to 77.00) were also recovered, especially on the high-yield improved sorghum cultivars. The total number of adult beetles (22 and 94) emerged were higher on the high-yield improved sorghum cultivars than on the native one. Thus, sorghum grain can suffer considerable destruction by P. truncatus, especially the high-yield improved sorghum cultivars. High-yield improved sorghum cultivars have relatively soft pericarp and soft endosperm which offer low resistance to tunneling, feeding or breeding activities by these beetles. Efforts should be made to keep this beetle from assuming a pest status on sorghum grain by both improving grain storage qualities through breeding and by observing necessary preventive sanitary measures in storage.

Keywords: Prostephanus truncatus, sorghum grain, grain damage, dry weight loss, grain dust, high-yield improved cultivars