Search

Invasive alien species (IAS) continue to shape the global landscape through their effects on biological diversity and agricultural productivity. The effects are particularly pronounced in Sub-Saharan Africa, which has seen the arrival of many IAS in recent years. This has been attributed to porous borders, weak cross border biosecurity, and inadequate capacity to limit or stop invasions. Prediction and early detection of IAS, as well as mechanisms of containment and eradication, are needed in the fight against this global threat. Horizon scanning is an approach that enables gathering of information on risk and impact that can support IAS management. A study was conducted in Ghana to establish two ranked lists of potential invasive alien plant pest species that could be harmful to agriculture, forestry, and the environment, and to rank them according to their potential threat. The ultimate objective was to enable prioritization of actions including pest risk analysis, prevention, surveillance and contingency plans. Prioritisation was carried out using an adapted version of horizon scanning and consensus methods developed for ranking IAS worldwide. Following a horizon scan of invasive alien species not yet officially present in Ghana, a total of 110 arthropod and 64 pathogenic species were assessed through a simplified pest risk assessment. Sixteen species, of which 14 were arthropods and two pathogens, had not been recorded on the African continent at the time of assessment. The species recorded in Africa included 19 arthropod and 46 pathogenic species which were already recorded in the neighbouring countries of Burkina Faso, Côte d'Ivoire, and Togo. The majority of arthropod species were likely to arrive as contaminants on commodities, followed by a sizable number which were likely to arrive as stowaways, while some species were capable of long distance dispersal unaided. The main actions suggested for species that scored highly included full pest risk analyses and, for species recorded in neighbouring countries, surveys to determine their presence in Ghana were recommended. [ABSTRACT FROM AUTHOR]

This study investigated the position of staminodes around the style of cocoa flowers and the stability of cocoa flowers relative to pollination and seasonality. Cocoa flowers were categorized into converging, ≤1.20mm; parallel, 1.21-2.40mm, and splay ≥2.41mm, depending on the distance between the staminode and style. Some flowers were hand pollinated while others were not and were excluded from insect visitors. Proportions of flowers of converging (56.0%), parallel (37.5%), and splay (6.5%) remained similar along the vertical plane of cocoa trees. Although pollination rates of flowers with splay staminodes were the lowest, the overall pollination success of cocoa trees was not significantly affected because of the small proportion of splay flowers. The stability of the cocoa flowers depended on both the season and pollination. During the dry season, unpollinated flowers of cocoa trees showed a flower-stability ratio of 72% on the second day, while the flower-stability ratio was 94% in the wet season. Pollinated (senescent) flowers had a stability ratio of 95% after 5 days during the wet season, but all pollinated flowers dropped after 5 days in the dry season, indicating that seasonal factors, such as water stress, can have dramatic effects on cocoa yields. [ABSTRACT FROM AUTHOR]