Biological Control of the Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Biological control was first considered shortly after the accidental introduction of Prostephanus truncatus in Africa in the early 1980's. This article reviews first the history of the biological control efforts with a focus on the results and recommendations of the initial international meetings and foreign exploration projects, followed by a discussion of the more important biocontrol agents, in particular the histerid Teretrius nigrescens. Since the release of T. nigrescens in Africa a number of techniques have been employed by different research groups to measure the effect of the natural enemy on P. truncatus, including pheromone trapping, field experiments, gut analysis grain store surveys, simulation modelling, and statistical and economic analysis the conclusions of these various studies have been largely equivocal, and the results of studies with recent data suggest that uncertainty is growing. Further resources and time are needed both for a proper evaluation and for the further development of control strategies compatible with biological control.