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Stellenbosch, South Africa

R. Garnas J.,University of Pretoria | Auger-Rozenberg M.-A.,French National Institute for Agricultural Research | Roques A.,French National Institute for Agricultural Research | Bertelsmeier C.,University of Lausanne | And 4 more authors.
Biological Invasions

The advent of simple and affordable tools for molecular identification of novel insect invaders and assessment of population diversity has changed the face of invasion biology in recent years. The widespread application of these tools has brought with it an emerging understanding that patterns in biogeography, introduction history and subsequent movement and spread of many invasive alien insects are far more complex than previously thought. We reviewed the literature and found that for a number of invasive insects, there is strong and growing evidence that multiple introductions, complex global movement, and population admixture in the invaded range are commonplace. Additionally, historical paradigms related to species and strain identities and origins of common invaders are in many cases being challenged. This has major consequences for our understanding of basic biology and ecology of invasive insects and impacts quarantine, management and biocontrol programs. In addition, we found that founder effects rarely limit fitness in invasive insects and may benefit populations (by purging harmful alleles or increasing additive genetic variance). Also, while phenotypic plasticity appears important post-establishment, genetic diversity in invasive insects is often higher than expected and increases over time via multiple introductions. Further, connectivity among disjunct regions of global invasive ranges is generally far higher than expected and is often asymmetric, with some populations contributing disproportionately to global spread. We argue that the role of connectivity in driving the ecology and evolution of introduced species with multiple invasive ranges has been historically underestimated and that such species are often best understood in a global context. © 2016, Springer International Publishing Switzerland. Source

Saccaggi D.L.,Plant Health Diagnostic Services | Saccaggi D.L.,Stellenbosch University | Karsten M.,Stellenbosch University | Robertson M.P.,University of Pretoria | And 6 more authors.
Biological Invasions

Biological invasions are increasing and are strongly associated with negative agricultural, economic and ecological impacts. It is increasingly recognized that the primary focus in minimizing biological invasions should be to prevent initial entry of alien species. However, exclusion of terrestrial arthropods such as insects and mites is difficult, in part because of their relatively small size, cryptic habits, broad physiological tolerances and close association with various internationally traded goods. Here we discuss methods, approaches, management and intervention systems used by border biosecurity agencies to prevent entry of inadvertently transported arthropods. We examine the at-border systems that exist for the detection and identification of and response to alien arthropods, and discuss the constraints and challenges present in these systems. We critically review current border biosecurity systems and discuss their relative efficacy. We then discuss additional measures and key areas that could be addressed that may further improve these systems. These include: (1) the application of appropriate sampling strategies; (2) employment of suitable inspection methods adequate to detect small and hidden arthropods; and (3) thorough recording of methods, organisms detected and both negative and positive results of inspections. We emphasize that more research is needed on taxonomy, biology, genetics, distribution, host and disease associations, impacts and pathways of introductions for invasive arthropods. Of critical importance is the compilation of complete and accurate invasive species lists and high-risk species watch-lists. The adoption of these recommendations will contribute to improved biosecurity systems for the exclusion of alien, invasive and pest arthropods. © 2016 Springer International Publishing Switzerland Source

Saccaggi D.L.,Plant Health Diagnostic Services | Pieterse W.,Plant Health Diagnostic Services
Journal of Economic Entomology

South Africa imports plant budwood (dormant cuttings for propagation) from various countries. Phytosanitary measures, including inspections at points of entry, are implemented to minimize the chance of a pest being introduced on the budwood. This study presents the inspections and interceptions of mites and insects on budwood imported to South Africa from 2004 to 2011. The study presents crops and countries from which South Africa imports budwood, and gives data on the type of imports more often infested with arthropods. Interceptions of insects and mites are reported, including interceptions of phytosanitary, economically important and nonphytophagous mites. The arthropod taxa intercepted are listed, and it is noted that the majority of interceptions are of mites, particularly of Eriophyoidea. These data are discussed in the context of quarantine and research. © 2013 Entomological Society of America. Source

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