Variation in the phytochemical composition of Chromolaena odorata (L.) King and Robinson (Asteraceae) across climatic zones in Benin (West Africa)

Chromolaena odorata (L.) King and Robinson (Asteraceae) is a tropical shrub with interesting chemical potential widely used in agriculture and medical science and which can be affected by several geographic and climatic conditions. Therefore, we investigated the phytochemical composition of this plant across climatic zones in Benin. The plant material collected from different locations was phytochemically screened by staining and precipitation tests. The total phenolic, flavonoid and tannin contents were determined using, the colorimetric method of Folin-Ciocalteu, the method of aluminum chloride and the method of vanillin, respectively, then the obtained data were subjected to analysis of variance. The phytochemical analysis revealed the presence of the main chemical groups such as alkaloids, free anthracene, coumarins, flavonoids, mucilage, tannins, reducing compounds, saponins, quinone derivatives, steroids. There was a significant difference (P < 0.05) in the phytochemical contents across geographical sites. In comparing the levels of phytochemicals among geographical locations, the raw material collected from the north climatic zone contained the highest phenolic and flavonoid contents, 147.59 ± 3.04 mg/g and 17.17 ±0.31 mg/g, respectively, compared to others. Overall, the study highlighted the potential of C. odorata as source of natural products. There was no difference in the phytochemical markers whereas the phytochemical contents vary across climatic zones. These results can be of use in the development of biopesticides from the raw material of C. odorata

Facteurs de développement des plantes invasives dans les systèmes agricoles au Bénin et implications pour une gestion durable

The periodic outbreak of invasive plants is one of the problems the West African agroecosystems, especially Beninese, are faced. The objective of this review is to analyze the approaches and the results of studies obtained on several models of invasive plants in Benin with an emphasis on the factors that favor their establishment in agricultural environments. From the evaluation of the bioecological adaptation potential of invasive plants, it resulted that there are intrinsic and extrinsic factors of distribution of invasive exotic species. The intrinsic factors are linked to the genetic and biological potential of plants while these extrinsic ones relate to anthropogenic actions and environmental conditions. The biology of invasive species, the anthropogenic actions and climate are the key factors of success in biological invasions. Improvement in agricultural systems and prediction models of infestation linked to climate change can, among other things, help limit resurgence’s impacts. Key words: Exotic invasive species, weed, agriculture, climate, BeninLa résurgence des plantes invasives est l’un des problèmes des systèmes agricoles en Afrique Sub-Saharienne, notamment au Bénin. Il est important de porter un regard analytique sur les causes des invasions de plantes en agriculture, pour une meilleure orientation dans le choix des moyens de lutte. Cette revue a pour objectif d’analyser les approches et résultats d’études obtenus sur plusieurs plantes invasives au Bénin, en ressortant les facteurs qui favorisent leur distribution dans les milieux agricoles. Il se dégage, à partir de l’évaluation du potentiel bioécologique d’adaptation des plantes invasives, qu’il y a des facteurs intrinsèques et extrinsèques qui concourent à leur distribution dans les systèmes agricoles. Les facteurs intrinsèques sont liés aux potentiels génétiques et biologiques des plantes invasives tandis que ceux extrinsèques se rapportent pour la plupart aux actions anthropiques et aux conditions environnementales du milieu. La biologie des plantes invasives, les actions anthropiques et le climat sont les facteurs clés de succès des invasions biologiques végétales. L’amélioration des systèmes de cultures, et les prédictions des infestations en lien avec le changement climatique peuvent entre autres aider à limiter les chocs de résurgence des plantes invasives dans les systèmes agricoles. Mots clés: Espèces exotiques envahissantes, mauvaises herbes, agriculture, climat, Béni