Morphological identification and assessment of biodemographic parameters of Spermophagus niger motschulsky (Coleoptera: Chrysomelidae), insect pest of kenaf (Hibiscus cannabinus L.) seeds during post-harvest storage in Burkina Faso: First report.

Abstract

Spermophagus niger L. is a well-known pest of roselle (Hibiscus sabdariffa L.) seeds in West Africa and responsible of mostly damage. This study first reported the presence of S. niger Motschulsky in kenaf (Hibiscus cannabinus L.) seeds stored. Samples of kenaf seeds collected at four locations in Burkina Faso. In the laboratory, the seeds were incubated until adults' insects emerged. The emerged insects were first identified morphologically and their biodemographic parameters studied under controlled conditions (32°C ± 0.1, 43% ± 1 r.h.). The results showed that S. niger (Coleoptera: Chrysomelidae) was the only pest encountered on H. cannabinus seeds in storage and was able to complete its development cycle there. Over the course of its life, which lasts an average of 7 days, the female laid around 40 eggs, resulting in 24 individuals dominated by females. The embryonic and total development time were average 5 and 26 days, respectively. Spermophagus niger population doubled in 6 days, with an intrinsic rate of natural increase of 0.105. The finite rate of increase and the generation time averaged 1.11 and 31.86 days, respectively. This study pointed out for the first time that S. niger is able to evolve successfully on H. cannabinus seeds in storage conditions and therefore, could be a serious pest of this important crop. The data from this study could therefore be used as a basis for the post-harvest management of H. cannabinus seeds.