Background: Invasive weeds pose a serious threat to agricultural systems worldwide and the management of such species requires information on their distribution. Objective: This research work aimed at assessing the evolution in the distribution of Siaw weed across biogeographical zones in Benin as first step toward the development of management policy and to give insight into the threat it poses to agriculture and biodiversity. Methods: Field and roadside surveys were carried out to record the presence of the species. Geographical coordinates were collected and incorporated in GIS software to map the distribution of the plant. Abundance data were submitted to analysis of variance to compare infestation level across biogeographical zones, and correlation of the species distribution with environmental factors was examined. Results:The extent of occurrence of the species has increased and fell within latitudes 6°30' and just beyond 10° North and range from about 0 m to 438 m in elevation, covering the entire area from south to center, and in part the north of the country. This weed is significantly more abundant in sudano-guinean zone (7.28 ± 0.18) than guinean zone (4.72 ± 0.20) and sudanian zone (3.5 ± 0.5). The species distribution is significantly correlated to the major climate variables and soil pH. Conclusion:The distribution of Siam weed mapped here shows progress in its occurrence points. Further studies are needed to better investigate the importance of soil and climate variables in its distribution and the vulnerability of the center zone ecosystems.

REMERCIEMENTSLes auteurs remercient le Centre Régional de Recherche et d'Education pour un Développement Intégré (CREDI-ONG) pour avoir financé cette étude. RESUMELa transition agroécologique en cours dans le monde nécessite le développement des alternatives de production saine, notamment concernant la gestion des nuisibles de cultures. La présente étude vise à évaluer en milieu réel, l'effet herbicide des composés allélopathiques de Chromoleana odorata sur les mauvaises herbes à travers son thé de compost. Le dispositif expérimental est un bloc aléatoire complet avec quatre répétitions. Les données collectées ont porté sur la diversité, la taille et la biomasse aérienne des mauvaises herbes. De l'analyse de variances effectuée, il ressort que le thé de compost a significativement (p ˂ 0,05) réduit la taille et la biomasse aérienne des mauvaises herbes sans pour autant affecter leur richesse spécifique. Le thé de compost de C. odorata a ainsi réduit l'enherbement et serait donc une piste potentielle pour le développement de biointrants en agroécologie. Effect of Chromoleana odorata L. compost tea on the development of weeds ABSTRACTThe ongoing agroecological transition needs the development of alternative methods of production as far as the pests management is concerned. This study aims to assess on farm the herbicide effect of Chromoleana odorata L. allelochemicals through the compost tea. The experimental design is a Fisher block with four replications. The data collected relate to the diversity, the height and weight of weeds. After performing the ANOVA, we can realize that the compost tea has significantly (p ˂ 0.05) reduced the height and the weight of weeds without affecting their diversity. The compost tea of C. odorata has thereby controlled the weeds and is a potential source of bio inputs in agroecology.

Rice vampireweed belongs to the Orobanchaceae and is found in Africa and Australia. It is a hemiparasitic weed of lowland rice genotypes and causes losses of 40 to 100% of rice grain yield. Our study addressed the genetic diversity of rice vampireweed in Benin and Senegal. The specific objectives of this research were to study the genetic diversity of rice vampireweed accessions in Benin and Senegal and the relationship between the different genotypes of rice vampireweed through agroecological areas. To achieve these objectives, the genetic diversity of rice vampireweed accessions using the AFLP technique was studied. Based on our results, dendrogram classification has distinguished four different genetic groups. The populations of Benin and Senegal are genetically diverse. Substantial genetic differentiation (GST) exists among agroecological areas within Benin and Senegal (GST = 0.17). The high genetic diversity of rice vampireweed in Benin and Senegal presents a challenge for the development of resistant rice germplasm.