of propagules from multiple sources increases propagule pressure and the potential for
introducing high genetic diversity, which in turn increases the likelihood of successful
establishment and, in some instances, invasion (Wilson et al. 2009).
Unfortunately, some of the pathways that are important for the introduction of
alien taxa are difficult to manage, or are becoming increasingly difficult to manage
(for an example see Box 12.5). There has been a recent increase in trade between
South Africa and other African countries (Ahwireng-Obeng and McGowan 1998),
which means that there has likely been an increase in the movement of alien taxa
from these countries to South Africa. Indeed within a year (July 2016–February
2017), three agriculturally important alien pest species [Raoiella indica (Red Palm
Mite), Tuta absoluta (Tomato Leaf Miner), and Spodoptera frugiperda (Fall Armyworm)] dispersed into South Africa from other African countries (International Plant
Protection Convention 2016; Agricultural Research Council-Plant Protection
Research Institute 2017; Visser et al. 2017a). Alien organisms that disperse unaided
into the country can enter South Africa anywhere along the 4862 km land borderline,
while those transported intentionally or accidentally by humans could enter the
country at 54 land border posts. It is, therefore, extremely difficult to prevent alien
organisms from dispersing into South Africa from neighbouring countries (Faulkner
et al. 2017a). The development of e-commerce has also made it very easy to find and
purchase alien ornamental plants and pets, and many taxa that are prohibited for
import into South Africa, or that have already been introduced to the country and are
invasive or harmful, are sold online by South African traders (Martin and Coetzee
2011). Such online commerce is difficult to control, because improved transport and
packaging technology has made it easy to move taxa purchased online between
countries, and made it very difficult to enforce regulations (Martin and Coetzee
2011) (also see Boxes 12.4 and 12.5). As a consequence, the rate of introduction
continues to increase (Fig. 12.5) despite existing control measures (Faulkner and
Wilson 2018).
South Africa’s extensive transport networks (Fig. 12.11) facilitate the transportation of a high and increasing volume of goods and number of people and, for
instance, there has been a recent increase in the number of domestic airline passengers (Fig. 12.12, see Faulkner and Wilson 2018). Alien and native taxa are currently
dispersed within the country through a wide range of pathways, and these transport
networks often facilitate these movements. For example, taxa are sold (e.g. on
web-sites like EBay) and transported throughout the country by the public (Martin
and Coetzee 2011; van Rensburg et al. 2011; Taylor et al. 2015), marine alien taxa
[such as Caprella mutica (Japanese Skeleton Shrimp) (Peters and Robinson 2017)]
are unintentionally transported along the coast attached to the hulls and niche areas
of vessels (see Box 12.3) and, despite existing control measures (see Box 12.5), pests
of agriculture or forestry are often transported around the country in infested plant
material (Faulkner and Wilson 2018) [like Sirex noctilio (Sirex Woodwasp) (Picker
and Griffiths 2011; Hurley et al. 2012) and the recently introduced Euwallacea
fornicatus (Polyphagous Shot Hole Borer) and its fungal symbiont Fusarium
euwallaceae (Eatough Jones and Paine 2015; International Plant Protection Convention 2018)] (see Box 11.3 in Potgieter et al. 2020, Chap. 11).
342
K. T. Faulkner et al.
introducing high genetic diversity, which in turn increases the likelihood of successful
establishment and, in some instances, invasion (Wilson et al. 2009).
Unfortunately, some of the pathways that are important for the introduction of
alien taxa are difficult to manage, or are becoming increasingly difficult to manage
(for an example see Box 12.5). There has been a recent increase in trade between
South Africa and other African countries (Ahwireng-Obeng and McGowan 1998),
which means that there has likely been an increase in the movement of alien taxa
from these countries to South Africa. Indeed within a year (July 2016–February
2017), three agriculturally important alien pest species [Raoiella indica (Red Palm
Mite), Tuta absoluta (Tomato Leaf Miner), and Spodoptera frugiperda (Fall Armyworm)] dispersed into South Africa from other African countries (International Plant
Protection Convention 2016; Agricultural Research Council-Plant Protection
Research Institute 2017; Visser et al. 2017a). Alien organisms that disperse unaided
into the country can enter South Africa anywhere along the 4862 km land borderline,
while those transported intentionally or accidentally by humans could enter the
country at 54 land border posts. It is, therefore, extremely difficult to prevent alien
organisms from dispersing into South Africa from neighbouring countries (Faulkner
et al. 2017a). The development of e-commerce has also made it very easy to find and
purchase alien ornamental plants and pets, and many taxa that are prohibited for
import into South Africa, or that have already been introduced to the country and are
invasive or harmful, are sold online by South African traders (Martin and Coetzee
2011). Such online commerce is difficult to control, because improved transport and
packaging technology has made it easy to move taxa purchased online between
countries, and made it very difficult to enforce regulations (Martin and Coetzee
2011) (also see Boxes 12.4 and 12.5). As a consequence, the rate of introduction
continues to increase (Fig. 12.5) despite existing control measures (Faulkner and
Wilson 2018).
South Africa’s extensive transport networks (Fig. 12.11) facilitate the transportation of a high and increasing volume of goods and number of people and, for
instance, there has been a recent increase in the number of domestic airline passengers (Fig. 12.12, see Faulkner and Wilson 2018). Alien and native taxa are currently
dispersed within the country through a wide range of pathways, and these transport
networks often facilitate these movements. For example, taxa are sold (e.g. on
web-sites like EBay) and transported throughout the country by the public (Martin
and Coetzee 2011; van Rensburg et al. 2011; Taylor et al. 2015), marine alien taxa
[such as Caprella mutica (Japanese Skeleton Shrimp) (Peters and Robinson 2017)]
are unintentionally transported along the coast attached to the hulls and niche areas
of vessels (see Box 12.3) and, despite existing control measures (see Box 12.5), pests
of agriculture or forestry are often transported around the country in infested plant
material (Faulkner and Wilson 2018) [like Sirex noctilio (Sirex Woodwasp) (Picker
and Griffiths 2011; Hurley et al. 2012) and the recently introduced Euwallacea
fornicatus (Polyphagous Shot Hole Borer) and its fungal symbiont Fusarium
euwallaceae (Eatough Jones and Paine 2015; International Plant Protection Convention 2018)] (see Box 11.3 in Potgieter et al. 2020, Chap. 11).
342
K. T. Faulkner et al.