Etude de l’effet rémanent de Mavi MNPV dans un champ de niébé

Le niebe est l’une des legumineuses alimentaires la plus importante dans toutes les regions de l’Afrique Sub-saharienne. L’objectif de ce travail etait d’etudier l’effet remanent de Mavi Multinucleo polyhedrovirus (Mavi MNPV) apres la recolte du niebe au champ. Le champ a ete traite 5 fois au biopesticide Mavi MNPV a la frequence de sept jours. Deux semaines apres la recolte, deux plants ainsi que les graines de chaque traitement sur chaque unite parcellaire ayant recu les traitements de Mavi MNPV de 107, 108 et 109 virions/ml ont ete collectes et amenes au laboratoire avec le substrat de developpement de la plante (sable). Aucune des formulations issues des substrats sable, racines, feuilles, tiges et graines n’a affecte la mortalite des larves L2 et L3 de Maruca vitrata et aucune difference significative n’a ete observee entre les traitements et le temoin. Quels que soient les traitements, le taux d’emergence des adultes est eleve ; ce qui signifie que la variation de la concentration de Mavi MNPV ne conditionne pas sa presence dans le sol, les tiges, les feuilles, les racines et les graines. Le biopesticide Mavi MNPV n’est pas persistant dans la nature.Mots cles : Niebe, Mavi MNPV, Maruca vitrata, Effet remanent   English Title: Study of the residual effect of Mavi MNPV in a cowpea field Cowpea is one of the most important food legumes in all regions of Sub-Saharan Africa. The objective of this research work was to study the persistence effect of Mavi Multinucleus polyhedrovirus (Mavi MNPV) after field harvest of the cowpea. The field was treated 5 times with Mavi MNPV biopesticide at seven days. Two weeks after harvest, two plants as well as the seeds from each treatment on each plot unit that received Mavi MNPV treatments of 107, 108 and 109 virions / ml were removed and brought to the laboratory with the plant development substrate (sand). None of the formulations from sand, root, leaf, stem and seed substrates did not affect the mortality of L2 and L3 larvae of Maruca vitrata and no significant difference was observed between treatments and control. Regardless of the treatments, the rate of emergence of adults is high; this means that the variation in the concentration of Mavi MNPV does not condition its presence in soil, stems, leaves, roots and seeds. Mavi MNPV biopesticide is not persistent in nature.Keywords: Cowpea, Mavi MNPV, Maruca vitrata, Residual effect.