The threat of the larger grain borer, Prostephanus truncatus (Coleoptera: Bostrichidae) and practical control options for the pest.
It is about 40 years since Prostephanus truncatus, a devastating pest of stored maize and dried cassava, was accidentally introduced into Africa from meso-America. Losses of stored maize at least doubled because of the destructive nature of the pest. Prostephanus truncatus management measures generated and recommended then worked at that time. However, the pest remains a serious threat to food security in developing tropical countries as it continues to spread to other geographical areas. This paper reviews the status of scientific knowledge of the pest and practical control options in the context of reductions in synthetic pesticide use; pesticide resistance management; and consumer, worker and environmental safety, and in the process, identifies research and development gaps. We present a scenario of the threat of P. truncatus on stored-maize grain and dry cassava chips and discuss, critically analyse the economic feasibility of control methods that have been generated and applied through scientific research. This review reveals a clear paucity of reliable data on economic analysis of most interventions, a critical factor for farmer adoption. A gap is also identified in the uptake of some of the developed technologies; mainly ascribed to affordability issues and a lack of evidence-based economic analysis under the user's circumstances. There is a lack of reliable national postharvest loss data based on the measurement and currently, the most robust loss estimates for sub-Saharan Africa are available on the African Postharvest Loss Information System (APHLIS) online platform. Any emerging P. truncatus control methods should be evaluated for efficacy and cost-effectiveness under realistic circumstances together with the target end-users of the methods to assess appropriateness.