Effectiveness of the global protected area network in representing species diversity

The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planet's land surface. This surpasses the 10% target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform—that is, 'one size fits all'—conservation targets

Bemisia tabaci (Hemiptera : Aleyrodidae) trap catches in a cassava field in Côte d'Ivoire in relation to environmental factors and the distribution of African cassava mosaic disease

African cassava mosaic virus (ACMV), vectored by the whitefly, #Bemisia tabaci (Gennadius), is considered the most damaging pathogen of any African crop. Information about vector movement is important for understanding the epidemiology of this disease and the experiments reported here were designed to examine #B. tabaci flight activity both in and around a cassava crop in relation to time of day, crop growth stage, wind direction and speed, and to the resulting pattern of infected plants within the field at harvest. At wind speeds of < 1.4 m/s, adult #B. tabaci approached the yellow traps by flying upwind. At greater wind speeds, significantly fewer #B. tabaci adults approached the traps from downwind, thus reversing the directionality of the catch. When the direction of the prevailing south-west wind reversed, so did the directionality of the catch. #Bemisia tabaci adults were flight active throughout the day and the greatest percentage were caught above the canopy between 06.00-08.00 h, when wind speeds were lowest. Trap height and position significantly affected catch with the greatest numbers caught on the lowest traps. More than three times as many #B. tabaci adults were caught on traps situated downwind from the field compared to those upwind, suggesting that the field was acting as a source of whiteflies. In both years, African cassava mosaic disease (ACMD) incidence was highest and lowest, respectively, on the edges and in the middle of the trials, with the highest incidence occurring on the edges facing the prevailing wind direction. These results are discussed in relation to the epidemiology of ACMD and to potential cultural control methods such as the use of ACMD-resistant guard rows to protect a mainly susceptible crop. (Résumé d'auteur