Morphological and biological characterization of Spermophagus niger (Motschulsky, 1866) (Coleoptera: Chrysomelidae) from four West African countries.

In Burkina Faso and many West African countries, Spermophagus niger (L.) is the main insect pest of Hibiscus sabdariffa seeds stored with considerable damage. Variations in bioclimatic conditions can lead to significant changes in the morphology and biology of populations of the same insect species, leading to strains that are morphologically and biologically different and that would react differently to a given control method. In this study, strains of S. niger from Niger (Niamey), Ghana (Navrongo), Benin (Parakou) and five localities in Burkina Faso (Diébougou, Banfora, Saaba, Mani, and Manga) are studied under controlled conditions (32 °C ± 0.1, 43% ± 1 r.h., L: D 12:12). The results showed that males from Niamey and Parakou lived longer, while females from Niamey and Diébougou had a statistically high longevity. The larval survival rate of the Niamey strain was significantly lower than Manga, Parakou, and Navrongo. The Niamey strain recorded adults compared to the other strains. In terms of weight, the females and males from Banfora and Niamey were statistically heavier than other strains. At the end of the study, S. niger' strains showed different morphologies in terms of weight. Furthermore, adult longevity, larval survival rate, and emergence rate were strain dependent.