International plant virus epidemiology workshop : resistance to viruses and vectors, temperate and tropical plants

La mouche blanche #Bemisia tabaci (#Homoptera : #Aleyrodidae$) est le seul insecte connu vecteur de la mosaïque africaine du manioc. Des essais aux champs sont en cours en basse Côte d'Ivoire pour étudier l'écologie des populations aux stades immatures sur le manioc. Des données préliminaires sur la vitesse de développement et le taux de mortalité de chaque stade, la distribution à l'intérieur de la plante et l'évolution des populations dans le temps, sont présentées ici. Les mensurations morphomètriques ont révélé qu'on peut distinguer entre les sexes au dernier stade larvaire. (Résumé d'auteur

International plant virus epidemiology workshop : resistance to viruses and vectors, temperate and tropical plants

The whitefly #Bemisia tabaci is a well known vector of African Cassava Mosaic in tropical countries. By using isozyme electrophoresis (esterase patterns) and host-range studies, tow types of #B. tabaci were characterised : one breeding mainly on cassava, the other breeding on all plants other than cassava. Each types shows a different esterase pattern. (Résumé d'auteur

An Assessment of Land Cover and Threats in Important Bird Areas in Africa

Over 1,200 Important Bird Areas (IBAs) have been identified in Africa, each meeting at least one of four objective criteria that identify it as an area of high conservation importance for birds. Despite their biodiversity value, many IBAs are threatened by habitat degradation and a high proportion lack legal protection.We integrate an inventory of these IBAs with remote sensing data to identify patterns that could be used to assess priorities for monitoring and conservation. Land cover composition in IBAs differed significantly from that in buffer zones of the same area immediately surrounding them and was significantly more homogeneous. Agriculture and deforestation were the most prevalent threats to IBAs, particularly in IBAs containing a high proportion of dense forest or shrub. Human population density within IBAs was no lower than that immediately outside IBAs, and was around three times higher than the average for sub-Saharan Africa. However, projected human population growth was lower than the average for sub-Saharan Africa, with the projected increase greatest in IBAs with a high proportional cover of dense forest and mosaic woodland and lowest in IBAs with a higher grassland component.JRC.H.3-Global environement monitorin

Coverage provided by the global protected-area system: Is it enough?

Protected-area targets of 10% of a biome, of a country, or of the planet have often been used in conservation planning. The new World Database on Protected Areas shows that terrestrial protected-area coverage now approaches 12% worldwide. Does this mean that the establishment of new protected areas can cease? This was the core question of the "Building Comprehensive Protected Area Systems" stream of the Fifth World Parks Congress in Durban, South Africa, in 2003. To answer it requires global gap analysis, the subject of the special section of BioScience for which this article serves as an introduction. We also provide an overview of the extraordinary data sets now available to allow global gap analysis and, based on these, an assessment of the degree to which existing protected-area systems represent biodiversity. Coverage varies geographically, but is less than 2% for some bioregions, and more than 12% of 11,633 bird, mammal, amphibian, and turtle species are wholly unrepresented. The global protected-area systems are far from complete