The Performance of Prostephanus Truncatus (horn) on Different Sorghum Varieties Grown in Ghana.

ABSTRACT
Studies were carried out under ambient laboratory conditions of 32 °C ± 2 and 74 - 87 % r.h. to determine the suitability of sorghum grain as a substrate that would support both the feeding and breeding of Prostephanus truncatus (Horn). Three sorghum varieties (Framida, Mankaraga and Naga-White) and one maize variety (Obatanpa) grown in Ghana were used in thestudy. Three forms of the substrates: Whole grain, Coarsely-ground grain and Grain flour were used for bioassays. The Fj progeny and mean developmental periods recorded were used to determine susceptibility index for the different grain varieties. Mean weight of the insect progeny that emerged was also determined. Percentage damage due to P. truncatus infestation was assessed on the different grain varieties. Similarly, weight loss due to this beetle on the different grain varieties was determined using both the standard volume/weight method and the count and
weigh method for comparison. The effects of commodity compaction in storage, as well as disturbance on damage and weight loss were also determined. Furthermore, physical properties of grain, such as size, density, 100-grain weight, endosperm texture and grain hardness were determined to asses their influence on grain infestation by P. truncatus. Insect preference for the different grain varieties was also assessed.The results of the investigations revealed that P. truncatus can both feed and breed on sorghum grains. The mean developmental period and the mean weight of P. truncatus, as well as the grain susceptibility index were significantly (P