Bothalia - African Biodiversity & Conservation ISSN: (Online) 2311-9284, (Print) 0006-8241 Page 1 of 19 Original Research Assessing the status of biological control as a management tool for suppression of invasive alien plants in South Africa Authors: Background: Biological control of invasive alien plants (IAPs) using introduced natural 1,2 Costas Zachariades enemies contributes significantly to sustained, cost-effective management of natural resources Iain D. Paterson3 Lorraine W. Strathie1 in South Africa. The status of, and prospects for, biological control is therefore integral to Martin P. Hill3 National Status Reports (NSRs) on Biological Invasions, the first of which is due in 2017. Brian W. van Wilgen4 Objectives: Our aim was to evaluate the status of, and prospects for, biological control of IAPs Affiliations: in South Africa. We discuss expansion of biological control and suggest indicators to be used 1 Plant Protection Research in the upcoming NSR to assess sufficient growth. Institute, Agricultural Research Council, South Africa Method: We used published literature, unpublished work and personal communication to assess the status of biological control of IAPs. We propose indicators based on the targets for biological 2 School of Life Sciences, control that were proposed in the 2014 ‘National Strategy for dealing with biological invasions in University of KwaZulu-Natal, South Africa South Africa’. To prioritise targets for future efforts, we used published lists of damaging IAPs and assessed the prospects for their biological control. Recommendations for using biological 3Department of Zoology and control as a management tool were made after discussion among the authors and with colleagues. Entomology, Rhodes University, South Africa Results: Significant control of several Cactaceae, Australian Acacia species and floating aquatic plants, and many other IAPs has been achieved in South Africa since 1913. Recently, biological 4Centre for Invasion Biology, control has benefited from improved international collaboration, a streamlined application Department of Botany and process for the release of new biological control agents (resulting in the approval of 19 agents Zoology, Stellenbosch University, South Africa against 13 IAP species since 2013), and increased funding and capacity. There is still a need to improve implementation and to better integrate biological control with other control Corresponding author: methods. In order to maximise benefits from biological control, increased investment is Costas Zachariades, required, particularly in implementation and post-release evaluation, and in targeting new [email protected] IAPs. Proposed targets for growth between 2017 and 2020 include an increase in financial Dates: investment in research by 29%, implementation by 28% and mass-rearing by 68%. Research Received: 15 Aug. 2016 capacity should increase by 29%, implementation capacity by 63% and mass-rearing capacity Accepted: 30 Nov. 2016 by 61%. New research projects should be initiated on 12 new IAP targets, while post-release Published: 31 Mar. 2017 monitoring efforts should be expanded to another 31 IAPs. How to cite this article: Zachariades, C., Paterson, Conclusion: Biological control of IAPs has contributed substantially to their management in I.D., Strathie, L.W., Hill, M.P. & South Africa, and continues to do so. Further investment in targeted aspects of IAP biological Van Wilgen, B.W., 2017, control will increase this contribution. ‘Assessing the status of biological control as a management tool for suppression of invasive alien Introduction plants in South Africa’, Biological control of invasive alien plant (IAP) species is the use of introduced, highly selective Bothalia 47(2), a2142. https://doi.org/10.4102/abc. natural enemies (usually herbivorous arthropods or pathogens) to control plants. It has been used v47i2.2142 in 130 countries as a valuable tool for the control of IAP species, with a total of over 550 biological control agents having been released (Winston et al. 2014). The benefits of biological control to Copyright: © 2017. The Authors. natural ecosystems are significant (Van Driesch et al. 2010), with some specific examples of Licensee: AOSIS. This work threatened indigenous species being protected by the action of biological control agents (Barton is licensed under the et al. 2007; Meyer, Fourdrigniez & Taputuarai 2011). Detailed analyses of programmes on biological Creative Commons Attribution License. control of IAPs have also clearly indicated that the risks of non-target effects from biological control agents are minimal (Fowler, Syrett & Hill 2000; Funasaki et al. 1988; Moran & Hoffmann Read online: 2015; Paynter et al. 2004; Pemberton 2000; Suckling & Sforza 2014). Less than 1% of all the Scan this QR agents released have a negative impact on non-target plant populations, and those that do code with your smart phone or could have been predicted to do so, and would not be released today (Suckling & Sforza 2014). mobile device to read online. Note: This paper was initially delivered at the 43rd Annual Research Symposium on the Management of Biological Invasions in South Africa, Goudini Spa, Western Cape, South Africa on 18-20 May 2016. http://www.abcjournal.org Open Access Page 2 of 19 Original Research Biological control of IAPs is therefore an environment- inefficient system by which agents were cleared for release friendly and safe control method that can result in effective through the relevant governmental departments. However, a and permanent control of IAPs, leading to the alleviation of far more effective system has been implemented (see section their economic and ecological impacts. ‘A streamlined biological control agent release process’) and approval for a total of 19 biological control agents for 13 IAP In 2013, South Africa marked its 100-year anniversary in species (or species complexes) has been granted since 2013. biological control of IAPs (Moran, Hoffmann & Zimmermann Of these, two agents were pathogens and the remainder were 2013). During the first few decades (1913 to the 1930s), insect agents. Most have already been released, and in some invasive Cactaceae were the targets of biological control cases establishment has been confirmed (Table 1). introductions (Klein 2011). These were all ‘transfer projects’, using insects that had already been successfully introduced In this article, we review the status of IAP biological control as biological control agents in other countries. In the 1950s in South Africa and the contribution of biological control and 1960s, transfer projects were initiated on Lantana camara towards the management of the most problematic and L. (Verbenaceae) and Hypericum perforatum L. (Clusiaceae), damaging IAPs. We also discuss successes and constraints, but the 1960s also saw the first novel South African projects, and prospects both for the control of the most damaging of on Hakea species (Proteaceae) and Leptospermum laevigatum South Africa’s IAPs and for the pro-active management of (Gaertn.) (Myrtaceae), which had predominantly invaded IAPs that are a threat but are not yet damaging to natural natural rather than agricultural ecosystems. During the 1970s resources. Indicators to assess the effectiveness of a substantial and 1980s, more groups of IAPs, in particular floating aquatic investment in biological control, with targets for future plants and Australian Acacia species (Mimosaceae), became national status reports, are proposed. the targets of biological control efforts (Klein 2011). This was facilitated by the formation of a dynamic group of young researchers by Dr David Annecke (Plant Protection Research Measures of success of IAP biological Institute, then under the national Department of Agriculture) control in South Africa in the early 1970s. Challenges during these decades included Control levels a paucity of funding and political restrictions on collecting In South Africa, biological control contributes significantly to candidate agents in many of the regions of origin. These the control of 34 of the 59 IAP species on which biological challenges have since been resolved. The advent of democracy control agents are established. Fourteen of these target in South Africa in 1994 led to normalised international species are considered to be under complete control, with no relations, and the inclusion of biological control in the need for any other control intervention (Klein 2011, updated funding model of the Working for Water programme (WfW) 2016; see Box 1). Many of the most obvious successes have [now one of the Natural Resource Management Programmes been against Australian Acacia species, cacti and floating (NRMP) within the national Department of Environmental aquatics (Klein 2011), although successes have certainly not Affairs (DEA)] in 1997 has led to substantial increases in the been limited to these groups (e.g. Gordon & Kluge 1991; funding available for biological control of IAPs over the past Hoffmann & Moran 1991). 20 years. To date, about 93 species of insects, mites and plant pathogens have been established on 59 IAP species in the The first-ever release of a biological control agent in South country (41 as primary targets and 18 as alternative hosts). Africa was the cochineal insect Dactylopius ceylonicus (Green) An additional 25 species of plants have been worked on, or (Hemiptera: Dactylopiidae) for the control of drooping are currently being investigated, but do not have biological prickly pear, Opuntia monacantha