Resistance of Some Hybrid Maize (Zea mays L.) to Damage by Maize Weevil Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae) and Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Damage to stored maize grains by Sitophilus zeamais and Prostephanus truncatus is enormous and could be total if the insects are not controlled timely and appropriately. Control of the insects with host plant resistance has advantages over other control measures because of its lasting effect, friendliness to the environment and safety to natural enemies among others. This study assessed host resistance of 11 maize varieties to infestation and damage by S. zeamais and P. truncatus. One hundred gram maize grains each of the maize varieties were weighed into 250 cm3 glass jars and separately infested with twenty, 1-5 days old S. zeamais or P. truncatus. Percentage grain damage, weight loss, adult mortality, grain dust and number of insects were determined and integrated to define the resistance of the maize varieties to the insects. Eight of the 11 maize varieties were either resistant or moderately resistant to damage by S. zeamais and P. truncatus, while three were susceptible. The basis of resistance is antibiosis conferred by the ash, carbohydrate and fat content of the maize grains. The resistance varieties could be planted to mitigate infestation and damage by the insects. The factors conferring resistance can be used as environmentally friendly source of resistance to breed maize grains for resistance to the insects.