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The Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera, Bostrichidae), already familiar for a considerable time as a post-harvest pest, has been increasing in significance internationally since 1981 due to its accidentally introduction into Africa, where it has now become firmly established.
The countries afflicted were Tanzania in East Africa and Togo in West Africa. Both countries reported extremely high losses in maize storage caused by the Larger Grain Borer. In very intense cases of infestation, the stored maize was practically completely destroyed, resulting in the loss of staple food for farmers. This prompted national authorities in Tanzania to request help in solving the problem from the Federal Ministry for Economic Cooperation of the FRG. Thus, the pilot project ''Biological-integrated control of the Larger Grain Borer", a project of the GTZ (Deutsche Gesellschaft für Technische Zusammenarbeit GmbH), was born. The objective of the project was to develop a method of biological or integrated control of the pest and to provide this method for use in Africa. In the process of reaching this objective, research work was conceived and subsequently carried out in the Federal Republic of Germany and in the appropriate institutions in partner countries in each case.
This publication is an abridged version of a dissertation on the ecology of the pest P. truncatus in its new habitat, Togo. Particular themes of this work are its population dynamics in maize stores, the damage and loss it causes and its interaction with useful endemic insects. In addition, the aspect of bridging over periods without sufficient nourishment with regard to the epidemiology of the Larger Grain Borer was also of significance. The method of biological control selected for the Larger Grain Borer by local plant protection services and the GTZ was the release of the predator Teretriosoma nigrescens LEWIS (Coleoptera, Histeridae). Prior to releasing the predator, it was essential to gather information on its efficacy under controlled, near-to-practical conditions similar to those in the natural environment in Togo. It was also essential to gain further knowledge of any possible undesired side-effects of releasing the insect.