species (freshwater crabs or prawns), disturbance of reproductive activity and
nesting success of substrate-spawning fishes and broad influences on food-web
structure (Nunes et al. 2017). The currently known parasites of crayfishes, such as
D. boschmai (Fig. 6.5b–d), are not known to have spread to native biota.
6.2.8 Insecta
Several insects have been introduced either purposefully for biological control, or
accidentally as stowaways (Table 6.1). In this chapter we consider only insects that
are dependent on the aquatic environment for parts of their life cycle. The
intentionally-introduced insects include mostly biological control agents for invasive
aquatic plants (Janion-Scheepers and Griffiths 2020, Chap. 7; Hill et al. 2020a, b,
Chap 19). Before introduction, candidate biological control agents are subject to
intensive testing to ensure that they do not impact on non-target taxa. While these
organisms fulfil the criteria of being fully invasive sensu Blackburn et al. (2011),
their impacts are beneficial as they are confined to the control of the relevant aquatic
plant species, with no evidence of spread to native species.
Knowledge of the introduction history of other insects not introduced for biological control is scant, because they generally arrive as stowaways and, as is the case
for many other invertebrates, reports of their presence in the wild are often dependent
on their discovery by specialists in unrelated surveys, rather than on arrival dates.
The Asian tiger mosquito Aedes albopictus, which was first reported in Cape Town
in 1990, was most likely a stowaway in imports from Asia (Picker and Griffiths
2011). For other species, such as the water boatman Trichocorixa verticalis, current
knowledge is limited to occurrence records.
6.2.9 Teleostei
Fishes are among the most commonly intentionally introduced organisms in the
world (Gozlan et al. 2010). The origins, vectors, and invasion status of naturalised
alien fishes are summarised in Table 6.1, and their current distributions are illustrated
in Fig. 6.6.
Centrarchidae
The fish family Centrarchidae includes popular North American fishes of the genus
Micropterus that were introduced to develop opportunities for angling. Four species,
Largemouth Bass Micropterus salmoides, Smallmouth Bass Micropterus dolomieu,
Spotted Bass Micropterus punctulatus and Florida Bass Micropterus floridanus have
naturalised and most river basins in the country contain at least one of these species
(Hargrove et al. 2019; Weyl et al. 2017a, b). These are the focus of a large
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O. L. F. Weyl et al.
nesting success of substrate-spawning fishes and broad influences on food-web
structure (Nunes et al. 2017). The currently known parasites of crayfishes, such as
D. boschmai (Fig. 6.5b–d), are not known to have spread to native biota.
6.2.8 Insecta
Several insects have been introduced either purposefully for biological control, or
accidentally as stowaways (Table 6.1). In this chapter we consider only insects that
are dependent on the aquatic environment for parts of their life cycle. The
intentionally-introduced insects include mostly biological control agents for invasive
aquatic plants (Janion-Scheepers and Griffiths 2020, Chap. 7; Hill et al. 2020a, b,
Chap 19). Before introduction, candidate biological control agents are subject to
intensive testing to ensure that they do not impact on non-target taxa. While these
organisms fulfil the criteria of being fully invasive sensu Blackburn et al. (2011),
their impacts are beneficial as they are confined to the control of the relevant aquatic
plant species, with no evidence of spread to native species.
Knowledge of the introduction history of other insects not introduced for biological control is scant, because they generally arrive as stowaways and, as is the case
for many other invertebrates, reports of their presence in the wild are often dependent
on their discovery by specialists in unrelated surveys, rather than on arrival dates.
The Asian tiger mosquito Aedes albopictus, which was first reported in Cape Town
in 1990, was most likely a stowaway in imports from Asia (Picker and Griffiths
2011). For other species, such as the water boatman Trichocorixa verticalis, current
knowledge is limited to occurrence records.
6.2.9 Teleostei
Fishes are among the most commonly intentionally introduced organisms in the
world (Gozlan et al. 2010). The origins, vectors, and invasion status of naturalised
alien fishes are summarised in Table 6.1, and their current distributions are illustrated
in Fig. 6.6.
Centrarchidae
The fish family Centrarchidae includes popular North American fishes of the genus
Micropterus that were introduced to develop opportunities for angling. Four species,
Largemouth Bass Micropterus salmoides, Smallmouth Bass Micropterus dolomieu,
Spotted Bass Micropterus punctulatus and Florida Bass Micropterus floridanus have
naturalised and most river basins in the country contain at least one of these species
(Hargrove et al. 2019; Weyl et al. 2017a, b). These are the focus of a large
168
O. L. F. Weyl et al.