Biological control of Rubus alceifolius (Rosaceae) in La Reunion Island (Indian Ocean): from investigations on the plant to the release of the biological control agent Cibdela janthina (Argidae)

The giant bramble (Rubus alceifolius Poir.: Rosaceae), native to Southeast Asia, is one of the most invasive plants in La Reunion. A ten year research program was launched in 1997 with three components: i) genetic diversity, ii) development strategy, and iii) selection of biological control agents. Introduced populations in La Reunion, Mauritius, Mayotte and Australia were clonal and far from the highly variable native populations in Asia, while Madagascar populations appeared intermediate. Seed production is by apomixis in La Reunion Island and by allogamy in the native habitat. Fruit production occurs up to 1,100 m elevation while vegetative multiplication is possible up to 1,700 m. The plant grows in well lighted places, invading forest edges, and all open areas. From surveys of Rubus natural enemies in its native range, the sawfly Cibdela janthina (Klug) (Argidae) was selected as the most promising biological control agent and studied. The first population was thus released in La Reunion in early 2008 with the agreement of the local authorities for the biological control of R. alceifolius. It is now naturalized, spreading and under evaluation

Biological control of Rubus alceifolius (Rosaceae) in La Réunion Island (Indian Ocean): from investigations of the plant to the release of the biocontrol agent Cibdela janthina (Argidae)

The giant bramble (Rubus alceifolius Poir.: Rosaceae), native to Southeast Asia, is one of the most invasive plants in La Réunion. A ten year research program was launched in 1997 with three components: i) genetic diversity, ii) development strategy, and iii) selection of biological control agents. Introduced populations in La Réunion, Mauritius, Mayotte and Australia were clonal and far from the highly variable native populations in Asia, while Madagascar populations appeared intermediate. Seed production is by apomixis in La Réunion Island and by allogamy in the native habitat. Fruit production occurs up to 1,100 m elevation while vegetative multiplication is possible up to 1,700 m. The plant grows in well lighted places, invading forest edges, and all open areas. From surveys of Rubus natural enemies in its native range, the sawfly Cibdela janthina (Klug) (Argidae) was selected as the most promising biological control agent and studied. The first population was thus released in La Réunion in early 2008 with the agreement of the local authorities for the biological control of R. alceifolius. It is now naturalized, spreading and under evaluation

Le projet régional de malherbologie

Synthèse des recherches préliminaires sur la diversité et le développement des peuplements d'adventices suivant les facteurs écologiques (sols, pluviosité, altitude) et agronomiques (ancienneté de la culture, nature de la plante cultivée, intensification, utilisation d'herbicides), en vue d'optimiser les moyens de lutte intégré

AFROweeds: a collaborative and participative online network to enhance weed capacities in Africa

Weed competition cause high yield losses in African crop production systems. Conservative estimates show that even for rice alone weeds cost economies of sub-Saharan Africa (SSA) already a near $1.5 billion per year. For subsistence farmers in SSA there is only a limited range of affordable and effective control strategies. Due to the diversity of weed species, the complexity of crop – weed ecology and associated environmental and management interactions, as well as the socio-economic constraints of subsistence farming in Africa, few effective weed control strategies are developed so far. Moreover, even the limited number of control strategies, or component technologies currently available face limited dissemination and adoption among the (rice) farmer communities in SSA. The above described situation is largely the result of the sub-optimal capacities of agricultural research and development (R&D) organizations in SSA. The region has an extremely low ratio of trained weed scientists per farmer. Conversely, in the absence of weed scientists, students, R&D professionals or farmers looking for information on weeds, reliable, comprehensive and comprehensible sources are scant and scattered. The EU-ACP funded Afroweeds is an initiative of CIRAD and Africa Rice Center (AfricaRice) to link European and African botanists and weed scientists with the objective to enhance the regional capacities in these fields of expertise. Afroweeds is a network for professionals and students aimed at sharing knowledge on rice weeds. The modes operandi of Afroweeds is an open-access website (http://www.afroweeds.org/network). This online platform enables members to exchange information, discuss relevant issues and to access an increasingly extensive library of information and photos on weed species and management. The most eye-catching features of the Afroweeds collaborative platform are the extremely user-friendly weed species identification tools. They encompass image recognition software and a multiple-choice program (called 'plant robot') using schematic drawings of plant organs (e.g. leaves, flowers). Identification results can be cross-checked with a rich gallery of photos of fieldgrowing or herbarium specimen and information on ecology and biology, while the Afroweeds data base can also be consulted for effective management options. The strength of the Afroweeds collaborative site further lies in the fact that information and concerns can easily be shared with the other members of community for feed-back. By facilitating such exchange between actors who are otherwise isolated from each other, Afroweeds contributes towards spreading and enhancing knowledge on rice weeds and best weed management practices to improve the productivity of African rice-based cropping systems. (Texte intégral