Comparative study of the biology of the larger grain borer, Prostephanus truncatus (Coleoptera: Bostrichidae) on potential host grains grown in Burkina Faso

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The recent records of Prostephanus truncatus Horn (Coleoptera: Bostrichidae) in certain regions of Burkina Faso make it a potential pest for maize, its preferred host, and for other cereals grown in the country. To estimate the extent of its possible large-scale invasion, we determined its survival and reproductive parameters on grains of maize, red sorghum, millet, and paddy rice. Bioassays consisted of infesting healthy grains from each of the four cereals, contained in Petri dishes, with a pair of P. truncatus aged up to 24 h old. Observations were made daily to replace the grains and collect data until the pair died and the F1 generation of insects emerged. Then the main biological parameters of P. truncatus were determined on each cereal. The results showed that female P. truncatus generally lived longer than males, regardless of the cereal used as food substrate. However, longevity was higher on maize than on red sorghum, millet, and paddy rice, respectively. There was no oviposition activity on paddy rice unlike other cereals. Female P. truncatus laid more eggs on maize than on other cereals. Red sorghum and millet did not allow for the complete development of the larvae. The pest developed successfully on maize, and a sex ratio biased in favor of females was observed. Given these results, significant damage by P. truncatus could occur on maize grains. Further studies should focus on climatic adaptation of P. truncatus and its other possible alternative hosts including woody and tuberous plants growing in Burkina Faso.