The Effect of Two Stored Sorghum Varieties Composition and Grain Coat Hardness to Feeding by Khapra Beetle and Lesser Grain Borer

Abstract

Insect pests of stored products cause much damage to stored sorghum grains. Considerable losses were recorded at Renk county, Upper Nile State, Southern Sudan and the surrounding areas. This study was conducted in the period of six months (January,2009-July,2009),to evaluate the effect of sorghum grain composition and seed coat hardness to feeding by Khapra beetle and lesser grain borer. The laboratory results showed that Fetterita cultivar had higher percentage of proteins (14%) and fat(2.43%) content than Gadamalhamam, while Gadamalhamam contained more crude fiber(6.90%) than Fetterita(5.53%),: This may partly explain why Gadamalhamam was more resistant to infestation by both the Khapra beetle(Trogoderma granarium) and Lesser grain borer(Rhyzopertha dominica) than Fetterita. The results also revealed that there was a positive relationship between coat hardness of the grain and degree of grain resistant to infestation by insect pests. The percentage weight loss of infested Fetterita grain was (14.4%) while, that of Gadamalhamam was (8.1%), and the degree of the seed coat resistance of Fetterita was (2.88kg/mm), while that of Gadamalhamam was (3.12kg/mm).