invasion patterns and processes as well as management and remediation (van Wilgen
et al. 2014).
The account is centred on idiosyncratically-chosen and divergent initiatives and
programmes that ran, often concurrently, in the twentieth century and beyond, and
that are dealt with in chronological order according to the date of their inception. The
overviews are selective, but they cover, in my opinion, the most important contributions that have been made to invasion science, and the people that have made
them. This chapter focusses on invasion science in South Africa, i.e. scientific
studies relating to alien species and biological invasions, and it does not cover the
history of introductions of alien species themselves, as this is covered elsewhere in
this book (Faulkner et al. 2020, Chap. 12). There has been legislation of aspects of
the problem in South Africa since 1861, and the development of policy and
legislation in this regard is also covered elsewhere in this book (Lukey and Hall
2020, Chap. 18). My focus here is also restricted to studies that relate to alien species
and does not include studies of native species that have spread, for example bush
encroachment by native trees and shrubs, or range expansion by native animals.
Finally, this account is restricted to studies of alien species that invade natural
ecosystems and does not address weeds or pests of agricultural systems.
2.2 Biological Control of Invasive Plants: Research
and Implementation 1913–Present
The practice of controlling invasive alien plants by using host-specific insects, mites
or pathogens from the target plants’ native range has a long history in South Africa,
starting with the introduction in 1913 of the cochineal insect Dactylopius ceylonicus
as a biological control agent against Opuntia monacantha (Drooping Prickly Pear).
At the time, the cactus was highly invasive along the coast from the Western Cape to
Durban (Lounsbury 1915; Moran et al. 2013). This was followed by further projects
that sought to control other invasive cacti in South Africa in the 1930s. However, it
was not until the late 1960s that attempts to locate, introduce and establish biological
control agents on alien plants that invaded natural ecosystems began in earnest.
There have been many notable successes, and the latest assessment (van Wilgen and
Wilson 2018) shows that biological control agents have been established on 60 invasive alien plant species in South Africa, with 15 alien plant species now under
complete control, with a further 19 species under a substantial degree of control (see
also Zachariades et al. 2017; Hill et al. 2020, Chap. 19). Today, biological control is
practiced in over 90 countries worldwide, with South Africa being one of five
nations that have been at the forefront of development in this field (the others are
Australia, Canada, New Zealand and the United States of America; Moran and
Hoffmann 2015).
36
B. W. van Wilgen
et al. 2014).
The account is centred on idiosyncratically-chosen and divergent initiatives and
programmes that ran, often concurrently, in the twentieth century and beyond, and
that are dealt with in chronological order according to the date of their inception. The
overviews are selective, but they cover, in my opinion, the most important contributions that have been made to invasion science, and the people that have made
them. This chapter focusses on invasion science in South Africa, i.e. scientific
studies relating to alien species and biological invasions, and it does not cover the
history of introductions of alien species themselves, as this is covered elsewhere in
this book (Faulkner et al. 2020, Chap. 12). There has been legislation of aspects of
the problem in South Africa since 1861, and the development of policy and
legislation in this regard is also covered elsewhere in this book (Lukey and Hall
2020, Chap. 18). My focus here is also restricted to studies that relate to alien species
and does not include studies of native species that have spread, for example bush
encroachment by native trees and shrubs, or range expansion by native animals.
Finally, this account is restricted to studies of alien species that invade natural
ecosystems and does not address weeds or pests of agricultural systems.
2.2 Biological Control of Invasive Plants: Research
and Implementation 1913–Present
The practice of controlling invasive alien plants by using host-specific insects, mites
or pathogens from the target plants’ native range has a long history in South Africa,
starting with the introduction in 1913 of the cochineal insect Dactylopius ceylonicus
as a biological control agent against Opuntia monacantha (Drooping Prickly Pear).
At the time, the cactus was highly invasive along the coast from the Western Cape to
Durban (Lounsbury 1915; Moran et al. 2013). This was followed by further projects
that sought to control other invasive cacti in South Africa in the 1930s. However, it
was not until the late 1960s that attempts to locate, introduce and establish biological
control agents on alien plants that invaded natural ecosystems began in earnest.
There have been many notable successes, and the latest assessment (van Wilgen and
Wilson 2018) shows that biological control agents have been established on 60 invasive alien plant species in South Africa, with 15 alien plant species now under
complete control, with a further 19 species under a substantial degree of control (see
also Zachariades et al. 2017; Hill et al. 2020, Chap. 19). Today, biological control is
practiced in over 90 countries worldwide, with South Africa being one of five
nations that have been at the forefront of development in this field (the others are
Australia, Canada, New Zealand and the United States of America; Moran and
Hoffmann 2015).
36
B. W. van Wilgen