Effectiveness of Hermetic Storage Using PICS Bags and Plastic Jars for Post-Harvest Preservation of <i>Acacia macrostachya</i>Seeds

In Burkina Faso, the availability of Acacia macrostachya “Zamnè” seeds throughout the year is threatened by the attacks of pests. So, the effectiveness of airtight (hermetic) storage for the preservation of these seeds was evaluated using 20-litre plastic jars and 50 kg PICS bags as hermetic containers with 50 kg polypropylene bags as controls. Seeds of Acacia macrostachya (17.5 kg) were stored in each of these storage devices for six months under ambient conditions in the laboratory. The number of storage pest Bruchidius silaceus increased significantly in polypropylene bags from 235 to 715 individuals on average/500 g of seeds. But in PICS bags and plastic drums, the number of this pest did not vary significantly (191 and 239 individuals on average/500 g of seeds for plastic jars and PICS bags respectively). In both hermetic devices, we found few individuals of another major storage pest Caryedon furcatus. However, polypropylene bags, haboured more pests’ in addition high numbers of C. furcatus and Oryzaephilus mercator which were not found in the hermetic devices. Seeds damage and weight loss increased significantly in polypropylene bags from 7.40% to 20.23% and 0.50% to 3% respectively compared to PICS bags and plastic jars. The germination rate of A. macrostachya seeds decreased significantly in PICS bags, plastic jars and polypropylene bags with average percentages of 14%;11% and 15% respectively compared to the initial average of 27%. PICS bags and plastic jars are therefore effective in preserving the quality of A. macrostachya seeds, but the effects of these hermetic devices on seed viability need to be explored further.

Reproductive Potential of Spermophagus niger (Coleoptera: Chrysomelidae: Bruchinae: Amblycerini) Developing on the Seeds of Two Roselle Varieties in Burkina Faso

In West Africa and particularly in Burkina Faso, Roselle, Hibiscus sabdariffa L. (Malvaceae) is receiving increasing attention as a crop with potential for making great socio-economic impacts. The biology of Spermophagus niger, recently identified as the main insect pest in the storage of roselle seeds, is poorly known. The present study aimed at comparing the reproductive potential of this insect on the seeds of two roselle varieties Altissima and Sabdariffa, mainly grown in Burkina Faso to identify susceptible/resistant variety to the pest. The results obtained are the first complete data on life history traits of S. niger in laboratory conditions. Overall, they indicated that both seed varieties have similar susceptibility to S. niger. The main life history traits measured did not differ significantly on both varieties (P 】0.05). However, the first generation individuals from the Altissima seeds were significantly larger (P = 0.0007 and P 【0.0001 for males and females respectively) and weighed more (P 【0.0001) than those from the other roselle variety. This result suggests that individuals from the Altissima variety may have a higher seed-damaging potential than those developed in the Sabdariffa variety and this potential might increase over successive generations. The consequences of such findings are discussed with a view to improving the post-harvest storage of roselle seeds and reducing losses in West Africa.