Reproductive performance of the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on three different food hosts

Abstract

The reproductive performance, damage and weight loss of the Larger Grain Borer (LGB), Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on three food hosts namely cassava (TMS 30572, TME 419 and TMS98/0505), maize (SUWAN-1-SR-Y, BR 9943-DMR-SR and 2009 TZEWDT STR) and wood (Albizia glaberrima, Gmelina arborea and Tectona grandis) were investigated. Samples of 100g of the food host were weighed in four replicates into 250ml Kilner® jar and infested with 10 pairs of 1-5 day old LGB. The developmental period of LGB on each of the food host was noted and recorded. Similarly, weight loss and weight of damaged grains was determined as basis for determining the susceptibility of the food hosts to LGB infestation. Proximate composition of infested and un- infested food hosts of LGB were determined following the analytical procedures. Maize was the most preferred host, followed by cassava as indicated by the high number of adult LGB and grain damage recorded on them. The development of LGB was completed on all maize and cassava varieties but not on any of the wood species examined. Percent damage, weight loss, and percent dust were significantly (P<0.05) different among the food hosts. The mean percent damage (79.0), percent weight loss (57.0) and percent dust (25.0) recorded in cassava variety-TMS30572 was significantly (p<0.05) higher than on other food hosts. No weight loss was recorded on T. grandis. This study revealed the ability of P. truncatus to breed and feed on the maize and cassava varieties with no evidence of breeding on the three wood species. Carbohydrate contents were higher in the most preferred food host, maize (70.91) and less preferred food, cassava (82.02) than non-preferred wood species (13.56), indicating that carbohydrate was an essential component in most preferred food. Infestation of LGB caused significant reduction (P<0.05) in the nutritional component of the food hosts. This study showed that LGB still remains an economically important insect pest of maize and cassava. Considering the importance of these two crops to the livelihood of smallholder farmers, appropriate monitoring and control measures should therefore be put in place to safe guard maize and cassava from the ravages of this pest for the attendant enhancement of food security in Nigeria.