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Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is native to Asia, and was widely introduced as a biocontrol agent of aphids and coccids in Europe and North America. In Europe, H. axyridis is considered to be an invasive alien species because of its potential to disrupt native ladybird communities. Since 1999, the Belgian Ladybird Working Group mapped all Belgian Coccinellidae and recorded data on substratum plants and habitat. The first feral H. axyridis population in Belgium was recorded in 2001, but the expansion rate is decreasing because it now colonised the whole country. Recorded occupancy in Belgium showed an average rate of increase of 189% between 2002 and 2006. In Belgium, H. axyridis occurred in a wide range of habitats, including those of high conservation value. However, habitat and land cover analysis showed that H. axyridis is more frequently found in urbanised landscapes than in semi-natural landscapes. A niche overlap analysis based on plant use data showed that the potential to affect native species is higher for generalist, deciduous and coniferous tree ladybird species than for heathland and wetland specialist species. Phenology data showed that H. axyridis is able to reproduce later in the year than native species. Based on recorded distribution, ecology and phenology, we discuss the potential of H. axyridis to disrupt native ladybird assemblages in Belgium. [ABSTRACT FROM AUTHOR]

In the context of the optimization of the mechanical platform of a virtual reality system involving a haptic device, this paper introduces two tools in order to help the designer for obtaining the best positioning of the device respect to the application workspace. With this purpose we have defined a measure called Average Volumetric Manipulability, of how the application workspace fits in with the volume where haptic device provides its best performance. Also, we have defined other measure called Useful Manipulability which takes in account the frequency with which each zone of the application workspace is visited during the simulation process. The practical use of these measures is demonstrated using them during the design and development of a real application. [ABSTRACT FROM AUTHOR]