Impact of differing population levels of Rhyzopertha dominica (F.) on milling and physicochemical properties of sorghum kernel and flour

The effects of different population levels of Rhyzopertha dominica (F.), the lesser grain borer, on physiochemical properties of sorghum kernels and flour, were investigated through a laboratory study at 27 and 32 °C, and 57% relative humidity. Initial population level and temperature, and their interaction, were significant for the number of F1 progeny and feeding damage (P<0.01). A strong positive correlation was also found between initial population size, number of F1 progeny, percentage of insect-damaged kernels (IDKs) and feeding damage. The impact of R. dominica on the milling quality of sorghum was seen through a reduction in abrasive hardness, milling yield, and kafirin content. Initial population and temperature affected most pasting properties, and overall pasting viscosity increased with initial population, number of F1 progeny, and percentage of IDK at 32 °C. Results show that R. dominica can potentially impact the milling quality of sorghum and also alter the physicochemical properties of sorghum flour.