Understanding and managing the introduction pathways of alien taxa: South Africa as a case study
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For the effective prevention of biological invasions, the pathways responsible for introductions must be understood and managed. However introduction pathways, particularly for developing nations, have been understudied. Using the Hulme et al. (J Appl Ecol 45:403–414, 2008) pathway classification, we assessed the South African introduction pathways in terms of the number of introductions, the invasion success of introduced taxa, how the pathways have changed over time, and how these factors vary for vertebrates, invertebrates and plants. Pathway and date of introduction, region of origin, distribution and invasion status data for 2111 alien taxa were extracted from databases. Most alien and invasive taxa were deliberately introduced and subsequently escaped captivity or cultivation. Pathway prominence also varied temporally and across organism types. Vertebrates and plants were largely escapes and although most plant escapes have become invasive, this is not the case for vertebrates. However the number of new plant and vertebrate escapes has increased over time. Invertebrates have been deliberately released or unintentionally introduced as contaminants or stowaways. For invertebrates the number of release, contaminant and stowaway introductions has increased, and most contaminants and stowaways have become invasive. As effective screening procedures are in place for invertebrates released for biological control, the major threats for South Africa are from vertebrate and plant escapes and invertebrate contaminants and stowaways. We recommend improvements to risk assessment and education to prevent escapes, and prioritised inspection strategies to reduce stowaway and contaminant introductions. Finally, as introduction pathways and introduced taxa change temporally, biosecurity decisions need to be informed by information on current and future pathways.
KeywordsBiological invasions Biosecurity Pre-border control Invasion success Mode of introduction Date of introduction
This work was supported by the South African National Department of Environment Affairs through its funding of the South African National Biodiversity Institute’s Invasive Species Programme. Additional funding was provided by the DST-NRF Centre for Invasion Biology. MR acknowledges funding from the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation of South Africa. We thank Dian Spear for advice on data collection as well as Hildegard Klein and Angela Bownes for their help with additional information on biological control agents.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Essl F, Bacher S, Blackburn TM, Booy O, Brundu G, Brunel S, Cardoso A-C, Eschen R, Gallardo B, Galil B, García-Berthou E, Genovesi P, Groom Q, Harrower C, Hulme PE, Katsanevakis S, Kenis M, Kühn I, Kumschick S, Martinou AF, Nentwig W, O’Flynn C, Pagad S, Pergl J, Pyšek P, Rabitsch W, Richardson DM, Roques A, Roy HE, Scalera R, Schindler S, Seebens H, Vanderhoeven S, Vilá M, Wilson JRU, Zenetos A, Jeschke JM (2015) Crossing frontiers in tackling pathways of biological invasions. Bioscience 65:769–782Google Scholar
- Faulkner KT, Spear D, Robertson MP, Rouget M, Wilson JRU (2015) An assessment of the information content of South African alien species databases. Bothalia: Afr Biodivers Conserv 45:1–11. doi: 10.4102/abc.v45i1.1103
- Gonzalez-Nuñez X (2008) 15-year review: trade policy in South Africa. Trade and Industrial Policy Strategies, PretoriaGoogle Scholar
- Hastie T (2013) gam: generalized additive models. http://cran.r-project.org/package=gam. Accessed 3 July 2014
- Herbert DG (2010) The introduced terrestrial mollusca of South Africa. South African National Biodiversity Institute, PretoriaGoogle Scholar
- Kraus F (2007) Using pathway analysis to inform prevention strategies for alien reptiles and amphibians. Manag Vertebr Invasive Species 21:94–103Google Scholar
- Mack RN (2005) Predicting the identity of plant invaders: future contributions from horticulture. HortScience 40:1168–1174Google Scholar
- R Core Team (2013) R: a language and environment for statistical computing. http://www.r-project.org/. Accessed 23 April 2014
- Richardson DM, Cambray JA, Chapman RA, Dean WRJ, Griffiths CL, Le Maitre DC, Newton DJ, Winstanley TJ (2003) Vectors and pathways of biological invasions in South Africa—past, present and future. In: Ruiz GM, Carlton JT (eds) Invasive species: vectors and management strategies. Island Press, Washington, pp 292–349Google Scholar
- Simberloff D (2006) Risk assessments, blacklists, and white lists for introduced species: Are predictions good enough to be useful? Agric Resour Econ Rev 35:1–10Google Scholar
- Williams PA, Newfield M (2002) A weed risk assessment system for new conservation weeds in New Zealand. Department of Conservation, WellingtonGoogle Scholar
- Wittenberg R, Cock MJW (2005) Best practices for the prevention and management of invasive alien species. In: Mooney HA, Mack RN, McNeely JA, Neville LE, Schei PJ, Wage JK (eds) Invasive alien species: a new synthesis. Island Press, Washington, pp 209–232Google Scholar
- Wojtasik EM (2013) Richness and diversity of alien ethnomedicinal plant taxa used and sold for traditional medicine in South Africa. Dissertation, University of WitwatersrandGoogle Scholar