7.1 Introduction
In the global invasion literature published between 1980 and 2006, plants were the
subject of 44% of studies and vertebrates 15%, while invertebrates were the subject
of 36% of publications, despite their considerably greater diversity in terms of both
native and introduced species. Moreover, the vast majority of all studies analysed are
from North America, Europe and Australia, while Asia, and particularly Africa, were
greatly underrepresented in the literature (Pyšek et al. 2008). Most earlier work on
invertebrate invaders focused on agricultural pests, but even these studies were
undertaken later than corresponding studies for plants (Pyšek et al. 2008; Kenis
et al. 2009; Sutherst 2014).
Until recently, alien terrestrial invertebrates in South Africa received little
research attention compared to either alien vertebrates or plants. However, monographic assessments of alien species within several of the better-known invertebrate
groups have now been published, notably those for earthworms (Plisko 2010),
molluscs (Herbert 2010), and especially for pests of cultivated crops (Annecke and
Moran 1982; Visser 2009; Prinsloo and Uys 2015). Two recent publications have
also attempted to compile listings of all known alien and invasive animals reported
from South Africa (Picker and Griffiths 2011, 2017), while listings for all alien taxa,
derived from these and other sources, have also been compiled (van Wilgen and
Wilson 2018; van Wilgen et al. 2020, Chap. 1, Sect. 1.1). It is important to note that
discrepancies between the numbers of species listed in these various sources are
inevitable. This is not only because new introductions are constantly arriving or
being reported, but also because of differing definitions of the term ‘alien species’; of
the geographical area of coverage and, in the case of this review, the definition of
‘terrestrial’.
This chapter includes only species of terrestrial invertebrates that have been
introduced to mainland South Africa and have established self-sustaining
populations outside of captivity or cultivation. Our list therefore has considerably
fewer species than reported in the recent national status report on biological invasions in South Africa (van Wilgen and Wilson 2018). This is because the status
report lists many species that are not naturalised (status B1–C2 in their Table 4.3),
and hence did not fit our criteria for inclusion. It also included some species
which are invasive on the offshore Prince Edward Islands, but not to mainland
South Africa. The data set used here is thus that of Picker and Griffiths (2011),
updated to include those species recorded subsequent to that review. We define
terrestrial invertebrates as including all those that have at least one life stage
completed on land. The taxa considered thus include Collembola (springtails),
Insecta (insects), Myriapoda (millipedes and centipedes), Arachnida (spiders, ticks
and mites), Crustacea (woodlice and landhoppers), Nematoda (nematode worms),
Oligochaeta (earthworms), Gastropoda (slugs and snails) and Plathyhelminthes
(flatworms).
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In the global invasion literature published between 1980 and 2006, plants were the
subject of 44% of studies and vertebrates 15%, while invertebrates were the subject
of 36% of publications, despite their considerably greater diversity in terms of both
native and introduced species. Moreover, the vast majority of all studies analysed are
from North America, Europe and Australia, while Asia, and particularly Africa, were
greatly underrepresented in the literature (Pyšek et al. 2008). Most earlier work on
invertebrate invaders focused on agricultural pests, but even these studies were
undertaken later than corresponding studies for plants (Pyšek et al. 2008; Kenis
et al. 2009; Sutherst 2014).
Until recently, alien terrestrial invertebrates in South Africa received little
research attention compared to either alien vertebrates or plants. However, monographic assessments of alien species within several of the better-known invertebrate
groups have now been published, notably those for earthworms (Plisko 2010),
molluscs (Herbert 2010), and especially for pests of cultivated crops (Annecke and
Moran 1982; Visser 2009; Prinsloo and Uys 2015). Two recent publications have
also attempted to compile listings of all known alien and invasive animals reported
from South Africa (Picker and Griffiths 2011, 2017), while listings for all alien taxa,
derived from these and other sources, have also been compiled (van Wilgen and
Wilson 2018; van Wilgen et al. 2020, Chap. 1, Sect. 1.1). It is important to note that
discrepancies between the numbers of species listed in these various sources are
inevitable. This is not only because new introductions are constantly arriving or
being reported, but also because of differing definitions of the term ‘alien species’; of
the geographical area of coverage and, in the case of this review, the definition of
‘terrestrial’.
This chapter includes only species of terrestrial invertebrates that have been
introduced to mainland South Africa and have established self-sustaining
populations outside of captivity or cultivation. Our list therefore has considerably
fewer species than reported in the recent national status report on biological invasions in South Africa (van Wilgen and Wilson 2018). This is because the status
report lists many species that are not naturalised (status B1–C2 in their Table 4.3),
and hence did not fit our criteria for inclusion. It also included some species
which are invasive on the offshore Prince Edward Islands, but not to mainland
South Africa. The data set used here is thus that of Picker and Griffiths (2011),
updated to include those species recorded subsequent to that review. We define
terrestrial invertebrates as including all those that have at least one life stage
completed on land. The taxa considered thus include Collembola (springtails),
Insecta (insects), Myriapoda (millipedes and centipedes), Arachnida (spiders, ticks
and mites), Crustacea (woodlice and landhoppers), Nematoda (nematode worms),
Oligochaeta (earthworms), Gastropoda (slugs and snails) and Plathyhelminthes
(flatworms).
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C. Janion-Scheepers and C. L. Griffiths