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Although invasive alien species have long been recognized as a major threat to nature and people, until now there has been no comprehensive global review of the status, trends, drivers, impacts, management and governance challenges of biological invasions. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Thematic Assessment Report on Invasive Alien Species and Their Control (hereafter 'IPBES invasive alien species assessment') drew on more than 13,000 scientific publications and reports in 15 languages as well as Indigenous and local knowledge on all taxa, ecosystems and regions across the globe. Therefore, it provides unequivocal evidence of the major and growing threat of invasive alien species alongside ambitious but realistic approaches to manage biological invasions. The extent of the threat and impacts has been recognized by the 143 member states of IPBES who approved the summary for policymakers of this assessment. Here, the authors of the IPBES assessment outline the main findings of the IPBES invasive alien species assessment and highlight the urgency to act now., (© 2024. Springer Nature Limited.)

Our ability to predict the identity of future invasive alien species is largely based upon knowledge of prior invasion history. Emerging alien species-those never encountered as aliens before-therefore pose a significant challenge to biosecurity interventions worldwide. Understanding their temporal trends, origins, and the drivers of their spread is pivotal to improving prevention and risk assessment tools. Here, we use a database of 45,984 first records of 16,019 established alien species to investigate the temporal dynamics of occurrences of emerging alien species worldwide. Even after many centuries of invasions the rate of emergence of new alien species is still high: One-quarter of first records during 2000-2005 were of species that had not been previously recorded anywhere as alien, though with large variation across taxa. Model results show that the high proportion of emerging alien species cannot be solely explained by increases in well-known drivers such as the amount of imported commodities from historically important source regions. Instead, these dynamics reflect the incorporation of new regions into the pool of potential alien species, likely as a consequence of expanding trade networks and environmental change. This process compensates for the depletion of the historically important source species pool through successive invasions. We estimate that 1-16% of all species on Earth, depending on the taxonomic group, qualify as potential alien species. These results suggest that there remains a high proportion of emerging alien species we have yet to encounter, with future impacts that are difficult to predict., Competing Interests: The authors declare no conflict of interest.

Our study assessed the effectiveness of species debarking in controlling species invasion and the change in seedling dynamics after application of the different treatments. A split plots design was used in two forest reserves to assess the effectiveness of three debarking treatments: complete ring debarking, partial ring debarking and a control (no debarking). The results reveal that ring debarking has the potential to be used to control invasive species such as Cecropia peltata L. and Broussonetia papyrifera (L.) Vent. The efficiency, however, was influenced by the extent of the wound created and the size of tree, especially if trees are partially debarked. The control method also stimulated natural regeneration of native species with higher regeneration of native species recorded compared to invasive species. Also, plots that had completely debarked trees had higher species diversity than the partially debarked and the control plots in one of the reserve. The fact that none of the trees in the control plots died is indication of the effectiveness of debarking in the control of invasive species considered here. The effectiveness of this method suggests it is a suitable option for killing small to medium size trees with little cost to the environment compared to the application of arboricides for instance and is therefore worth revisiting in silvicultural treatments where minimum environmental disturbance is required. We recommend more studies to compare the effectiveness of the control approaches on different invasive species and monitor how the native communities respond including in terms of species diversity and functional groups, since removal methods may impact differently on these plant community traits. [ABSTRACT FROM AUTHOR]

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]

The introduction of a non-native fish species into an aquatic ecosystem presents significant ecological risks if the species is able to successfully integrate into the ecosystem. Lake Bosomtwe in Ghana is an impact crater lake which contains an endemic and a near-endemic cichlid species. Following the establishment of an intensive Nile tilapia (Oreochromis niloticus) cage aquaculture facility on the Lake in 2012 and it closure in 2015, there have been several unconfirmed reports of the capture of O. niloticus from Lake Bosomtwe by local fishermen. On 6th February 2020, the first documented observations of O. niloticus in the natural environment of Lake Bosomtwe were made using seine net catches. Nine more seining activities were carried out between 6th February and 17th April, 2020, and the presence of the O. niloticus was confirmed during all sampling events. Oreochromis niloticus constituted between 2 and 10% of the captured cichlid species composition. The introduction of the species warrants larger-scale comprehensive studies on the possible detrimental interactions with native species, and on changes to ecosystem function. [ABSTRACT FROM AUTHOR]

When traveling in cars, we can unintentionally carry and disperse weed seed; but which species, and where are they a problem? To answer these questions, we systematically searched the scientific literature to identify all original research studies that assess seed transported by cars and listed the species with seed on/in cars. From the 13 studies that fit these criteria, we found 626 species from 75 families that have seed that can be dispersed by cars. Of these, 599 are listed as weeds in some part of the world, with 439 listed as invasive or naturalized alien species in one or more European countries, 248 are invasive/noxious weeds in North America, 370 are naturalized alien species in Australia, 167 are alien species in India, 77 are invasive species in China and 23 are declared weeds/invaders in South Africa. One hundred and one are classified as internationally important environmental weeds. Although most (487) were only recorded once, some species such as Chenopodium album, Poa pratensis and Trifolium repens were common among studies. Perennial graminoids seem to be favoured over annual graminoids while annual forbs are favoured over perennial forbs. Species characteristics including seed size and morphology and where the plants grew affected the probability that their seed was transported by cars. Seeds can be found in many different places on cars including under the chassis, front and rear bumpers, wheel wells and rims, front and back mudguards, wheel arches, tyres and on interior floor mats. With increasing numbers of cars and expanding road networks in many regions, these results highlight the importance of cars as a dispersal mechanism, and how it may favour invasions by some species over others. Strategies to reduce the risk of seed dispersal by cars include reducing seed on cars by mowing road verges and cleaning cars. [ABSTRACT FROM AUTHOR]