We conclude that even small degrees of suppression of plant fitness, or reductions
in the size of populations through biological control will be compounded over the
years. In most cases, biological control will reduce the costs of other interventions
and will make successful management of the problem more likely and easier. If there
are any doubts about what has been achieved with biological control against invasive
alien plants in South Africa over the years, the fundamental counterfactual question
is: ‘what would be the extent of the alien plant invasions if there had been no
biological controls?’
Acknowledgements Our thanks and respects are extended to past and present invasive plant
biological control practitioners in South Africa. Not all of them can be recorded as authors, but
their work is the foundation for many of the cases and outcomes reported here. We appreciate the
valuable inputs from the reviewers and the editors. We are also grateful to the Working for Water
programme of the Department of Water Affairs and Forestry, subsequently the Department of
Environmental Affairs, Natural Resources Management Programmes, for their generous financial
support since 1995, which has put South Africa in the forefront of endeavours in biological control
against invasive alien plants worldwide.
References
Annecke DP, Moran VC (1978) Critical reviews of biological pest control in South Africa. 2. The
prickly pear, Opuntia ficus-indica (L.) Miller. J Entomol Soc South Afr 41:161–188
Anonymous (1999) Appendix. Releases of introduced biological control agents against weeds in
South Africa. Afr Entomol Mem 1:175–182
Beinart W, Wotshela L (2011) Prickly pear, the social history of a plant in the Eastern Cape. Wits
University Press, Johannesburg. https://doi.org/10.18772/22011115300
Cilliers CJ (1987) The evaluation of three insect natural enemies for the biological control of the
weed Lantana camara L. J Entomol Soc South Afr 50:15–34
Cilliers CJ (1999) Biological control of parrot’s feather, Myriophyllum aquaticum (Vell.) Verdc.
(Haloragaceae), in South Africa. Afr Entomol Mem 1:113–118
Cilliers CJ, Neser S (1991) Biological control of Lantana camara (Verbenaceae) in South Africa.
Agric Ecosyst Environ 37:57–75. https://doi.org/10.1016/0167-8809(91)90139-O
Coetzee JA, Hill MP, Byrne MJ et al (2011a) A review of the biological control programmes on
Eichhornia crassipes (C.Mart.) Solms (Pontederiaceae), Salvinia molesta D.S.Mitch.
(Salviniaceae), Pistia stratiotes L. (Araceae), Myriophyllum aquaticum (Vell.) Verdc.
(Haloragaceae) and Azolla filiculoides (Lam.) (Azollaceae) in South Africa. Afr Entomol
19:451–468. https://doi.org/10.4001/003.019.0202
Coetzee JA, Bownes A, Martin GD (2011b) Prospects for the biological control of submerged
macrophytes in South Africa. Afr Entomol 19:469–487. https://doi.org/10.4001/003.019.0203
Crawley MJ (1989) Plant life-history and the success of weed biological control projects. In:
Delfosse ES (ed) Proceedings of the VII international symposium on biological control of
weeds, Rome, 1988. CSIRO, Melbourne, pp 17–26
De Lange WJ, van Wilgen BW (2010) An economic assessment of the contribution of biological
control to the management of invasive alien plants and to the protection of ecosystem services in
South Africa. Biol Invasions 12:4113–4124. https://doi.org/10.1007/s10530-010-9811-y
Dennill GB, Donnelly D (1991) Biological control of Acacia longifolia and related weed species
(Fabaceae) in South Africa. Agric Ecosyst Environ 37:115–135. https://doi.org/10.1016/01678809(91)90142-K
568
M. P. Hill et al.
in the size of populations through biological control will be compounded over the
years. In most cases, biological control will reduce the costs of other interventions
and will make successful management of the problem more likely and easier. If there
are any doubts about what has been achieved with biological control against invasive
alien plants in South Africa over the years, the fundamental counterfactual question
is: ‘what would be the extent of the alien plant invasions if there had been no
biological controls?’
Acknowledgements Our thanks and respects are extended to past and present invasive plant
biological control practitioners in South Africa. Not all of them can be recorded as authors, but
their work is the foundation for many of the cases and outcomes reported here. We appreciate the
valuable inputs from the reviewers and the editors. We are also grateful to the Working for Water
programme of the Department of Water Affairs and Forestry, subsequently the Department of
Environmental Affairs, Natural Resources Management Programmes, for their generous financial
support since 1995, which has put South Africa in the forefront of endeavours in biological control
against invasive alien plants worldwide.
References
Annecke DP, Moran VC (1978) Critical reviews of biological pest control in South Africa. 2. The
prickly pear, Opuntia ficus-indica (L.) Miller. J Entomol Soc South Afr 41:161–188
Anonymous (1999) Appendix. Releases of introduced biological control agents against weeds in
South Africa. Afr Entomol Mem 1:175–182
Beinart W, Wotshela L (2011) Prickly pear, the social history of a plant in the Eastern Cape. Wits
University Press, Johannesburg. https://doi.org/10.18772/22011115300
Cilliers CJ (1987) The evaluation of three insect natural enemies for the biological control of the
weed Lantana camara L. J Entomol Soc South Afr 50:15–34
Cilliers CJ (1999) Biological control of parrot’s feather, Myriophyllum aquaticum (Vell.) Verdc.
(Haloragaceae), in South Africa. Afr Entomol Mem 1:113–118
Cilliers CJ, Neser S (1991) Biological control of Lantana camara (Verbenaceae) in South Africa.
Agric Ecosyst Environ 37:57–75. https://doi.org/10.1016/0167-8809(91)90139-O
Coetzee JA, Hill MP, Byrne MJ et al (2011a) A review of the biological control programmes on
Eichhornia crassipes (C.Mart.) Solms (Pontederiaceae), Salvinia molesta D.S.Mitch.
(Salviniaceae), Pistia stratiotes L. (Araceae), Myriophyllum aquaticum (Vell.) Verdc.
(Haloragaceae) and Azolla filiculoides (Lam.) (Azollaceae) in South Africa. Afr Entomol
19:451–468. https://doi.org/10.4001/003.019.0202
Coetzee JA, Bownes A, Martin GD (2011b) Prospects for the biological control of submerged
macrophytes in South Africa. Afr Entomol 19:469–487. https://doi.org/10.4001/003.019.0203
Crawley MJ (1989) Plant life-history and the success of weed biological control projects. In:
Delfosse ES (ed) Proceedings of the VII international symposium on biological control of
weeds, Rome, 1988. CSIRO, Melbourne, pp 17–26
De Lange WJ, van Wilgen BW (2010) An economic assessment of the contribution of biological
control to the management of invasive alien plants and to the protection of ecosystem services in
South Africa. Biol Invasions 12:4113–4124. https://doi.org/10.1007/s10530-010-9811-y
Dennill GB, Donnelly D (1991) Biological control of Acacia longifolia and related weed species
(Fabaceae) in South Africa. Agric Ecosyst Environ 37:115–135. https://doi.org/10.1016/01678809(91)90142-K
568
M. P. Hill et al.