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Biological invasions by agricultural pests can have serious negative impacts, including decreases in crop yield and economic losses. The MT-1 and MT-8 genotypes of the wheat curl mite (Aceria tosichella) (hereafter 'WCM' refers to these two genotypes) are globally distributed pests of wheat and maize that have not been recorded in South Africa. This study examined whether WCM could be introduced to, and establish in, South Africa. Trade data were used to determine whether viable pathways of introduction are present. A species distribution model and data on wheat and maize production were used to determine whether WCM could establish where its hosts are grown. WCM is most likely to be introduced to South Africa as a contaminant of maize from Argentina, Brazil, Uruguay, and USA; on live plant imports from China and Germany; and on seed imports from Brazil and Australia. Some of these pathways are not currently prominent, but could increase in the future. Parts of South Africa were predicted by the species distribution model to be climatically suitable for WCM, and within some of these areas the host crops are grown. Therefore, if WCM is introduced, it is likely to establish and cause extensive damage to agriculture. We recommend that WCM be considered for inclusion in South Africa's import conditions as a quarantine pest. [ABSTRACT FROM AUTHOR]

Alien species are introduced to new regions in many different ways and for different purposes. A number of frameworks have been developed to group such pathways of introduction into discrete categories in order to improve our understanding of biological invasions, provide information for interventions that aim to prevent introductions, enable reporting to national and international organisations and facilitate the prediction of threats. The introduction pathway classification framework proposed by the Convention on Biological Diversity (CBD) as a global standard is comprised of six main categories and 44 sub-categories. However, issues have arisen with its implementation. In this position paper, we outline five desirable properties of an introduction pathway classification framework - it should be compatible (i.e. the level of detail of the categories is similar to that of the available data), actionable (i.e. categories link to specific interventions), general (i.e. categories are applicable across the contexts that are of interest (e.g. taxa, habitats and regions)), equivalent (i.e. categories are equivalent in their level of detail) and distinct (i.e. categories are discrete and easily distinguished) - termed the CAGED properties. The six main categories of the CBD framework have all of the CAGED properties, but the detailed sub-categories have few. Therefore, while the framework has been proposed by the CBD as a global standard and efforts have been made to put it into practice, we argue that there is room for improvement. We conclude by presenting scenarios for how the issues identified could be addressed, noting that a hybrid model might be most appropriate. [ABSTRACT FROM AUTHOR]

Biological invasions often transcend political boundaries, but the capacity of countries to prevent invasions varies. How this variation in biosecurity affects the invasion risks posed to the countries involved is unclear. We aimed to improve the understanding of how the biosecurity of a country influences that of its neighbours. We developed six scenarios that describe biological invasions in regions with contiguous countries. Using data from alien species databases, socio‐economic and biodiversity data and species distribution models, we determined where 86 of 100 of the world's worst invasive species are likely to invade and have a negative impact in the future. Information on the capacity of countries to prevent invasions was used to determine whether such invasions could be avoided. For the selected species, we predicted 2,523 discrete invasions, most of which would have significant negative impacts and are unlikely to be prevented. Of these invasions, approximately a third were predicted to spread from the country in which the species first establishes to neighbouring countries where they would cause significant negative impacts. Most of these invasions are unlikely to be prevented as the country of first establishment has a low capacity to prevent invasions or has little incentive to do so as there will be no impact in that country. Regional biosecurity is therefore essential to prevent future harmful biological invasions. In consequence, we propose that the need for increased regional co‐operation to combat biological invasions be incorporated in global biodiversity targets. [ABSTRACT FROM AUTHOR]

Biosecurity schemes aim to prevent the introduction of species with a high invasion potential, without unduly restricting personal freedom and commercial activities. But invasive species risk assessments are time consuming, data intensive and expensive. Consequently, resource poor nations cannot implement these schemes. Here we develop a method for creating watch lists using the consistent predictors of invasion success—history of invasion, environmental suitability, and propagule pressure (measured respectively using the Global Invasive Species Database (GISD), environmental modelling, and tourism and trade data). We tested the approach for South Africa, at a national level for various taxa and at a provincial level for plants. Of 884 alien species listed in the GISD, 400 were potential invaders, with most occurring in high risk regions. When alien species in South Africa were evaluated there were many false-negatives (sensitivity of 32% for terrestrial and 40% for marine species), because the GISD is not comprehensive, but few false positives (specificity of 91% for terrestrial and 89% for marine species). The methodology was easy to apply at different political levels, but we found substantial overlaps between the national and provincial watch lists of plants. This simple technique is rapid, easily repeatable, flexible, transparent, works across taxa, and does not require substantial financial or scientific input. It can be used in any region of the world and at various political levels as an initial assessment of key threats. As such it may be an important step in developing biosecurity schemes for resource poor regions. [ABSTRACT FROM AUTHOR]