DefinePK

Abstract

In West Africa, bruchid beetles are responsible for major losses of cowpeas during storage. Small-scale farmers from Burkina Faso often use leaves of a shrub, Boscia senegalensis (Lamarck) (Capparaceae), to protect stored cowpeas. The effectiveness of this practice combined with augmentation of the larval parasitoid Dinarmus basalis was investigated in two regions of Burkina Faso. Two bruchid species, Callosobruchus maculatus (Fabricius) and Bruchidius atrolineatus (Pic), emerged from cowpea seeds harvested in both regions of study but only C. maculatus developed during the whole period of cowpea storage. The Pteromalid D. basalis (Rondani) was the only larval parasitoid in the Bobo-Dioulasso region. In the Ouagadougou region, another larval parasitoid, Eupelmus vuilleti (Crawford) (Eupelmidae), appeared and competed with D. basalis. Interspecific competition between the two parasitoids species involved low levels of parasitism that favoured the increase in bruchid population. Augmentation of D. basalis adults during the first two months of storage reduced bruchid populations and reduced seed weight losses in both regions. The introduction of B. senegalensis leaves reduced bruchid numbers during the first three months of storage only, but the pest population drastically increased from this period onwards. The seed losses were finally higher than those of the control after six months of storage. The use of B. senegalensis influenced the interspecific relations between parasitoid species at Ouagadougou and could improve the biological control using augmentation of D. basalis adults. The results are discussed in a prospect of integrated pest management in stored cowpeas.