The pet trade has been a major pathway for the introduction of vertebrate invaders, but little is known about its role in invertebrate invasions. Here we assess the trade in terrestrial invertebrates (excluding spiders) in South Africa and the potential of this trade to result in biological invasions and impacts. Pet stores, websites, and expositions were visited, and a list of the taxa traded was compiled. DNA barcoding was used to determine if the species were correctly identified in the trade. Information on invasion history and impact elsewhere was used to assess the potential for species to become invasive and have impact in South Africa. We found 53 alien terrestrial invertebrate taxa that were traded, although only 36 of these matched a valid species name. Of 11 species tested using DNA barcoding nine were correctly identified. Species accumulation curves were produced, but did not reach an asymptote, suggesting there are many species in the trade that were not recorded. The most common species were used as food for pets, rather than as pets themselves. None of the species were reported to be invasive elsewhere, and few had records of causing negative impacts (the exception being moderate impacts to human health caused by venomous scorpions). Therefore, there is little evidence that the invertebrates traded pose a significant threat to South Africa. However, given uncertainties in which taxa are traded and the lack of data on invasiveness and impact, there might be a significant invasion debt. We recommend continued monitoring and engagement with the industry.

Many countries define nativity at a country-level—taxa are categorised as either alien species or native species. However, there are often substantial within-country biogeographical barriers and so a taxon can be native and alien to different parts of the same country. Here, we use the term ‘native-alien populations’ as a short-hand for populations that result from the human-mediated dispersal of individuals of a species beyond a biogeographical barrier to a point beyond that species’ native range, but that is still within the same political entity as parts of the species’ native range. Based on these criteria, we consider native-alien populations to be biological invasions. However, we argue that, in comparison to other alien populations, native-alien populations: 1) are likely to be closer geographically to their native range; 2) are likely to be phylogenetically and ecologically more similar to native species in their introduced range; and 3) options to control their introduction or manage them will likely be more limited. We argue this means native-alien populations tend to differ from other alien populations in the likelihood of invasion, the types of impacts they have, and in how they can be most effectively managed. We also argue that native-alien populations are similarly a distinct phenomenon from native populations that are increasing in abundance or range extent. And note that native-alien populations are expected to be particularly common in large, ecologically diverse countries with disjunct biomes and ecoregions. Reporting, monitoring, regulating and managing native-alien populations will, we believe, become an increasingly important component of managing global change.

Species can be both native and alien to a given administrative region. Here we present the first consolidated inventory of these ‘native-alien populations’ for South Africa, and provide an overview of the data it contains. To gather data, literature searches were performed and experts were consulted both directly and via an on-line survey. Putative native-alien populations were then scored based on a newly developed protocol. The final inventory contains information on 77 native species from 49 families across nine classes that have formed 132 native-alien populations across the terrestrial, freshwater, and marine environments. The phenomenon is rare when compared to the prevalence of related phenomena, such as alien species introduced from other countries (2033 alien species in South Africa), but is under-reported. However, they pose a specific problem for regulators and managers and their importance will likely increase with global change. These data will be integrated with an existing alien species list and, we hope, will provide a useful foundation to address the issue. We encourage those working on biodiversity to contribute more records.

The House Sparrow Passer domesticus is recognised as one of the commonest avian invasive species globally, with its occurrence associated with human existence. However, relatively little on population sizes of this species in rural landscapes has been documented. The study on House Sparrows was conducted in three areas in a rural landscape of Limpopo province, South Africa where it is an invasive, to 1) determine population numbers of the House Sparrow between the years 2014 and 2016, and 2) investigate the interaction between the number of House Sparrows and the number of their active nests. The House Sparrow population numbers showed no significant differences between 2014, 2015 and 2016. The House Sparrow numbers were influenced by the number of active nests in 2014 and 2016. The current study showed that the presence of House Sparrows was not affected by the house type they roosted in, and the number of active nests was not influenced by the house types available in each area. The results also showed that the House Sparrow occurs across a rural landscape with variation in numbers across seasons. The evidence reported provides significant insight into how invasive House Sparrows are well established in rural landscapes around human habitation, and it is recommended that this should be incorporated into the management of such alien invasive birds. Nombre de Moineaux DomestiquesPasser domesticus, espèce invasive, dans le paysage rural de la province de Limpopo, Afrique du Sud Le Moineau Domestique Passer domesticus est considéré comme l'une des espèces aviaires communes à caractère invasif la plus répandue dans le monde, sa présence étant généralement associée à l'activité humaine. Cependant, la densité de population de cette espèce dans le paysage rural a très peu été documentée. Notre étude relative au Moineau Domestique a été menée dans trois zones rurales de la province de Limpopo, en Afrique du Sud afin de 1) dénombrer la population de Moineaux Domestiques entre 2014 et 2016 et 2) d'étudier les interactions entre le nombre de Moineaux Domestiques et le nombre de leurs nids actifs. Il n'y a pas de différence significative entre la population de Moineaux Domestiques en 2014, 2015 et 2016. Le nombre de Moineaux Domestiques a été influencé par le nombre de nids actifs en 2014 et 2016. Nous estimons que la présence des Moineaux Domestiques n'est pas liée au type d'habitation dans laquelle ils s'abritent et que le nombre de nids actifs n'est pas influencé par le type d'habitation présent dans chaque zone. Nos résultats montrent que le nombre de Moineaux Domestiques présents dans un paysage rural varie en fonction des saisons. L'étude menée prouve de manière significative que l'espèce invasive des Moineaux Domestiques est bien établie dans le paysage rural, à proximité des habitations humaines. Il est recommandé d'intégrer cela dans le management de cette espèce exotique invasive aviaire.

The scarlet sage, Salvia coccinea, was first detected in Northern Province, South Africa in 1905, in what is now Limpopo Province. However, its presence and suitability in South Africa remains undocumented. We conducted vegetation surveys to determine the actual distribution and to incorporate species distribution modelling in order to determine the potential distribution of this species. Twelve populations were documented from different localities. The species distribution model was successful in predicting areas that are climatically suitable for this species to survive in South Africa. The wide distribution and high density suggest a long residency time. Thus we conclude that its recent invasion of the wild has most probably originated in gardens.

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