The Sweet potato weevils of the genus Cylas are the most destructive pests of sweet potato and are widely distributed in Africa. The aim of this study was to identify and document the species of Cylas occurring in sweet potato production zones in Ghana. A survey was conducted in 23 localities in 2015 from July to December in seven regions in Ghana in order to determine the identity of the pest. We collected nine thousand and two specimens from Central, Eastern, Greater-Accra, Northern, Volta, Upper-East, and the Upper-West regions. Two species were identified: Cylas brunneus Fabricius, 1797 and Cylas puncticollis Boheman, 1833. Cylas puncticollis occurred in all regions and represented 6,107 specimens (68%), while 2,895 of the specimens (32%) could be assigned to C. brunneus. The latter is restricted to the southern sector including Volta, Central, Eastern and Greater Accra Regions. When considering both species in the southern sector, the Volta Region accounted for 3,117 specimens (48%) followed by 1,447 (22%), 987 (15%), and 980 (15%), from the Central, Eastern, and Greater-Accra Regions, respectively. The dominant species in southern and northern sector was C. puncticollis.
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RBINS Staff Publications 2016
Ocean colour sensors have been capturing the state of the world's oceans for over a decade. They are typically installed on polar-orbiting satellites and cover the entire earth every 1 to 2 days. This temporal resolution is insufficient to observe oceanic processes occurring at a higher frequency, especially when taking cloud cover into account. Data from geostationary platforms can be obtained with a much better temporal resolution (images every 15 or 60 min), and thus are useful to study those processes. We show that by synergistically combining marine reflectance data from SEVIRI, a geostationary sensor, and MODIS Aqua, a polar orbiter, the resulting product is an improvement over both data sources. The synergy approach takes the reflectance from MODIS, with high quality and high spatial resolution, and modulates this over the day by the temporal variability of the SEVIRI reflectance, normalized to the SEVIRI reflectance at the time of MODIS overpass. The temporal frequency of the synergy product is much better than that of MODIS, and by using the latter's high quality data, the limited spatial and radiometric resolution of SEVIRI is enhanced. As the SEVIRI data is limited to a single broad red band (560-710 nm), the applications of the synergy product are limited to parameters that can be derived from this band, such as suspended particulate matter (SPM), turbidity (T) and the diffuse attenuation of photosynthetically available radiation (Kpar) in turbid waters. A geostationary ocean colour sensor over Europe will provide invaluable data concerning our marine environment. The cost of increasing the spatial resolution of a geostationary sensor is very high, and this study illustrates that a lower resolution geostationary ocean colour sensor combined with a high resolution polar orbiting sensor, can provide a high frequency synergetic product with high spatial resolution. (C) 2013 The Authors. Published by Elsevier Inc All rights reserved.
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