Biodiversity information on weeds, covering species descriptions and distribution, is essential for understanding the ecology and distribution of weeds and their management. WIKWIO (Weed Identification and Knowledge in the Western Indian Ocean http://www.wikwio.org), a European Union African Caribbean Pacific Science & Technology II programme funded project, is focused on the Western Indian Ocean region to develop species information systems on weeds in food and cash crops. WIKWIO aims to assimilate weed knowledge through its participatory portal (http://portal.wikwio.org) to strengthen a science and technology network of stakeholders such as scientists, extension agents, and farmers in the African region. During the computer demonstration, this project's two major citizen science applications will be showcased. The graphically driven weed species identification system (http://www.wikwio.org/idao) helps users to identify about 345 weed species, without requiring prior knowledge in taxonomy. The citizen science application (http://portal.wikwio.org/observation/list/) facilitates uploading images of weed species, with a time and location. Both of these applications are available on web and mobile (https://play.google.com/store/apps/developer?id=Project+Wikwio) platforms. (Texte intégral)