Current status of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in five South-western States, Nigeria.

The study investigated the current distribution of the larger grain borer (LGB), Prostephanus truncatus, in five states of South-western Nigeria; Ogun, Oyo, Lagos, Ondo and Osun by visual observation of maize stored in cribs and using the synthetic aggregation pheromone of LGB as baits in survey traps for twenty days. The highest mean number of LGB was trapped in Ogun state, followed by catches from Lagos, Oyo, Ondo and Osun states respectively. The mean number of LGB trapped in Ogun state was significantly higher (P < 0.05) than mean catches in other states. In all the locations, the number of borers caught in the traps declined with days after the activation of the pheromone. In the crib survey, P. truncatus was not observed in any of the twenty cribs sampled across the states. However, other stored product insects were found in descending order; Sitophilus zeamais (L.) (60.0%), Oryzaephilus surinamensis (Motsch) (40.0%), Tribolium castaneum (Herbst.) (35.0%), Cryptolestes ferrugineus (Steph.) (25%) and Rhizopertha dominica F. (5.0%). Concerted efforts should be directed at preventing further spread of LGB in Nigeria, especially in Ogun and Lagos states that showed high presence of the borer.Keywords: Prostephanus Truncatus; Aggregation pheromone; Survey tra; Cribs; Distributio