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These are academic papers relating to invasive species in South Africa. They include current research and projects such as biological control, invasive species traits, invasion biology and the detrimental effects invasive species have on biodiversity, water resources and the economy. They are listed according to year in which they were published.
A vision for global monitoring of biological invasions
Managing biological invasions relies on good global coverage of species distributions. This study presents a vision for global observation and monitoring of biological invasions. The authors show how the architecture for tracking biological invasions is provided by a minimum information set of Essential Variables, global collaboration on data sharing and infrastructure, and strategic contributions by countries.
Guillaume Latombe, Petr Pyšek, Jonathan M. Jeschke, Tim M. Blackburn, Sven Bacher, César Capinha, Mark J. Costello, Miguel Fernández, Richard D. Gregory, Donald Hobern, Cang Hui, Walter Jetz, Sabrina Kumschick, Chris McGrannachan, Jan Pergl, Helen E. Roy, Riccardo Scalera, Zoe E. Squires, John R.U.Wilson, Marten Winter, Piero Genovesi, Melodie A. McGeoch.
How repeatable is the Environmental Impact Classification of Alien Taxa (EICAT)? Comparing independent global impact assessments of amphibians
The magnitude of impacts some alien species cause to native environments makes them targets for regulation and management. However, which species to target is not always clear, and comparisons of a wide variety of impacts are necessary. This study assesses the newly proposed Environmental Impact Classification for Alien Taxa (EICAT) used for amphibians and test how outcomes differ between assessors.
Sabrina Kumschick, G. John Measey, Giovanni Vimercati, F. Andre de Villiers, Mohlamatsane M. Mokhatla, Sarah J. Davies, Corey J. Thorp, Alexander D. Rebelo, Tim M. Blackburn, Fred Kraus.
Senna didymobotrya - Flowering Plants of Africa
Senna Mill. Ia a large genus in the Fabaceae family, subfamily Caesalpinioideae, tribe Cassieae with approximately 350 species. This classification has been supported by a number of studies of these genera based on morphology, ontogenetic charactersitics, molecular systematics and cytogenetics (Resende et al. 2013).
Jaca, T. P. & Condy,G.
A description of the naturalised Clusia rosea Jacq. (Clusiaceae) populations in South Africa
The invasive nature of C. rosea was brought to the attention of environmentalists by a local conservation group in southern KwaZulu-Natal (KZN) in 2010. It was added to the Durban Early Detection and Rapid Response website (www.durbaninvasives.org.za) and featured in a Southern African Plant Invaders Atlas (SAPIA) newsletter (Henderson 2013) to create awareness about the species and encourage sighting reports.
Michael D. Cheek, Reshnee Lalla
The balance of trade in alien species between South Africa and the rest of Africa
Alien organisms are not only introduced from one biogeographical region to another but also spread within regions. The aim of this study was to gain a greater understanding of the introduction of alien species into Africa and the spread of species between South Africa and other African countries.
Katelyn T. Faulkner, Brett P. Hurley, Mark P. Robertson, Mathieu Rouget, John R.U. Wilson
Changes in the composition and distribution of alien plants in South Africa: An update from the Southern African Plant Invaders Atlas
Data on alien species status and occurrence are essential variables for the monitoring and reporting of biological invasions. This study aims to document changes in the alien plant taxa recorded in SAPIA, assess trends in invasive distributions and explore effects of management and regulations.
Lesley Henderson, John R.U. Wilson
A proposed national strategic framework for the management of Cactaceae in South Africa
South Africa has a long history of managing biological invasions. The aim of this study is to guide the future management of cactus invasions, a national strategic framework was developed by the South African Cactus Working Group. The overarching aim of this framework is to reduce the negative impacts of cacti to a point where their benefits significantly outweigh the losses.
Haylee Kaplan, John R.U. Wilson, Hildegard Klein, Lesley Henderson, Helmuth G. Zimmermann, Phetole Manyama, Philip Ivey, David M. Richardson, Ana Novoa
Promise and challenges of risk assessment as an approach for preventing the arrival of harmful alien species
Harmful alien species continue to be a major driver of biodiversity change across the globe, as well as causing enormous economic costs and impacts to human health and livelihoods. A range of approaches to Risk Assessment tool development have emerged, each relying on different assumptions about the relationships between traits and species impacts, and each requiring different levels and types of data.
Reuben P. Keller, Sabrina Kumschick
Evaluating invasion risk for freshwater fishes in South Africa
South Africa, as a signatory of the Convention on Biological Diversity, has an obligation to identify, prioritise and manage invasive species and their introduction pathways. This study aims to evaluate the Fish Invasiveness Screening Kit (FISK) to predict the invasion risk posed by fish species proposed for introduction into South Africa.
Sean M. Marr, Bruce R. Ellender, Darragh J. Woodford, Mhairi E. Alexander, Ryan J. Wasserman, Philip Ivey, Tsungai Zengeya, Olaf L.F. Weyl
Grasses as invasive plants in South Africa revisited: Patterns, pathways and management
In many countries around the world, the most damaging invasive plant species are grasses. However, the status of grass invasions in South Africa has not been documented recently. This study aims to update Sue Milton’s 2004 review of grasses as invasive alien plants in South Africa, provide the first detailed species level inventory of alien grasses in South Africa and assess the invasion dynamics and management of the group.
Vernon Visser, John R.U. Wilson, Kim Canavan, Susan Canavan, Lyn Fish, David Le Maitre, Ingrid Nänni, Caroline Mashau, Tim G. O’Connor, Philip Ivey, Sabrina Kumschick, David M. Richardson
Contributions to the National Status Report on Biological Invasions in South Africa
South Africa has committed to producing a National Status Report on Biological Invasions by October 2017 and thereafter every three years. This will be the first status report at a national level specifically on biological invasions.
John R.U. Wilson, Mirijam Gaertner, David M. Richardson, Brian W. van Wilgen
Optimising invasive fish management in the context of invasive species legislation in South Africa
South Africa hosts a large number of non-native freshwater fishes that were introduced for various industries. This study assesses the history and status of national legislation pertaining to invasive freshwater fishes, and the practical implications of the legislation for managing different species with contrasting distributions, impacts and utilisation value.
Darragh J. Woodford, Phillip Ivey, Martine S. Jordaan, Peter K. Kimberg, Tsungai Zengeya, Olaf L.F. Weyl
Managing conflict-generating invasive species in South Africa: Challenges and trade-offs
This paper reviewed the benefits and negative impacts of alien species that are currently listed in the Alien and Invasive Species Regulations of the National Environmental
Management: Biodiversity Act (Act no 10 of 2004) and certain alien species that are not yet listed in the regulations for which conflicts of interest complicate management.
Tsungai Zengeya, Philip Ivey, Darragh J. Woodford, Olaf Weyl, Ana Novoa, Ross Shackleton, David Richardson, Brian van Wilgen
The global distribution of bamboos: assessing correlates of introduction and invasion
There is a long history of species being moved around the world by humans. These introduced species can provide substantial benefits, but they can also have undesirable consequences. We explore the importance of human activities on the processes of species dissemination and potential invasions using the Poaceae subfamily Bambusoideae (‘bamboos’), a group that contains taxa that are widely utilised and that are often perceived as weedy.
Aliens in the nursery: assessing the attitudes of nursery managers to invasive species regulations
The horticultural industry is recognised as a major pathway for the introduction and spread of invasive alien plants (IAPs). The Conservation of Agricultural Resources Act (CARA) of 1983 (Act No. 43 of 1983) listed and categorised invasive species with an aim to curb their spread.
Assessing and managing the threat posed by Epipremnum aureum in
The predictive success of risk assessments is still largely a function of invasiveness elsewhere. Therefore, species
that are invasive elsewhere should be prioritised for management, and where possible eradicated.We set out to
investigate the threat posed by the alien climber Epipremnum aureum (Araceae) and assess techniques for controlling
the spread of the species in South Africa.
Impact assessment with different scoring tools: How well do alien amphibian assessments match?
Classification of alien species’ impacts can aid policy making through evidence based listing and management recommendations. We highlight differences and a number of potential difficulties with two scoring tools, the Environmental Impact Classification of Alien Taxa (EICAT) and the Generic Impact Scoring System (GISS) using amphibians as a case study. Generally, GISS and EICAT assessments lead to very similar impact levels, but scores from the schemes are not equivalent.
Economic evaluation of water loss saving due to the biological control of water hyacinth at New Year’s Dam, Eastern Cape province, South Africa
Water hyacinth Eichhornia crassipes is considered the most damaging aquatic weed in the world. However, few studies have quantified the impact of this weed economically and ecologically, and even fewer studies have quantified the benefits of its control.
GCG Fraser1, MP Hill and JA Martin
Molecular identification of Azolla invasions in Africa: The Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist
Biological control of Azolla filiculoides in South Africa with the Azolla specialist Stenopelmus rufinasus has been highly successful. However, field surveys showed that the agent utilized another Azolla species, thought to be the native Azolla pinnata subsp. africana, which contradicted host specificity trials.
P.T. Madeira, M.P. Hill, F.A. Dray Jr., J.A. Coetzee, I.D. Paterson, P.W. Tipping
Unravelling the biogeographic origins of the Eurasian watermilfoil (Myriophyllum spicatum) invasion in North America
Using phylogeographic analyses to determine the geographic origins of biological invaders is important for identifying environmental adaptations and genetic composition in their native range as well as biocontrol agents among indigenous herbivores.
Michael L. Moody, Nayell Palomino, Philip S.R. Weyl, Julie A. Coetzee, Raymond M. Newman, Nathan E. Harms, Xing Liu, and Ryan A. Thum
Macroinvertebrate communities associated with duckweed in two Eastern Cape Rivers, South Africa
The functional feeding groups and diversity of macroinvertebrate communities associated with duckweed mats in the New Year’s River (two sites) and Bloukrans River (two sites), Eastern Cape Province, South Africa, were assessed.
PC Muskett, JM Hill & PSR Weyl
Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept.
The cryptic species are of special interest because they were discovered within biological control agent populations.
Iain D. Paterson, Rosie Mangan, Douglas A. Downie, Julie A. Coetzee, Martin P. Hill,
Ashley M. Burke, Paul O. Downey, Thomas J. Henry & Stephe G. Compton
The interaction between insect population density and culture age of fungus on the control of invasive weed water hyacinth
The possibilities of a positive or negative impact the biocontrol agents may have on each other as well as on the control of the weed itself, inspired these scientists to study the interactions between the mirid, Eccritotarsus catarinensis and the phytopathogen, Acremonium zonatum, biocontrol agents of water hyacinth (Eichhornia crassipes).
Puja Ray. Martin P. Hill
Naturally occurring phytopathogens enhance biological control of water hyacinth (Eichhornia crassipes) by Megamelus scutellaris (Hemiptera: Delphacidae), even in eutrophic water
Insect biological control agents directly damage target weeds by removal of plant biomass, but herbivorous insects have both direct and indirect impacts on their host plants and can also facilitate pathogen infection. Scientists compared the impact of fungicide surface-sterilised and unsterilised Megamelus scutellaris individuals and water hyacinth leaves on growth of the weed at two nutrient levels.
G.F. Sutton, S.G. Compton, J.A. Coetzee
Have grass carp driven declines in macrophyte occurrence and diversity in the Vaal River, South Africa?
Grass carp invasions worldwide have been shown to have severe impacts on macrophyte biodiversity and ecosystem functioning. This fish is an aggressive feeder on submerged macrophytes, as well as being an ecosystem engineer that can change water and sediment chemistry.
PSR Weyl & GD Martin
Was Myriophyllum spicatum L. (Haloragaceae) recently introduced to South Africa from Eurasia?
The aim of this study was to determine if Myriophyllum spicatum was recently introduced from Eurasia by reconstructing the genetic relationships between South African and Eurasian M. spicatum using both a nuclear roboso-mal (ITS1-5.8S-ITS2-26S) and a chloroplast intron (trnQ-rps16) sequence from 40 populations.
P.S.R. Weyl, R.A. Thum, M.L. Moody, R.M. Newman, and J.A. Coetzee
Invasive estuarine grass
The invasive estuarine grass Spartina alterniflora was first detected in the Great Brak Estuary in 2004. Using herbicide treatment, this invasive grass has almost been eliminated from the estuary.
A global assessment of alien amphibian impacts in a formal framework
The aim of this study is to score impacts of all known alien amphibians, compare them to other taxonomic groups and determine the magnitude of their ecological and socio-economic impacts and how these scores relate to key traits.
Application of the Environmental Impact Classification for Alien Taxa (EICAT) to a global assessment of alien bird impacts
To apply the recently published EICAT protocol to an assessment of the magnitude of environmental impacts of alien bird species established worldwide.
Understanding invasive species pathways
In order to effectively prevent biological invasions, the pathways of introduction need to be understood and managed. This paper looks at pathways of introduction using South Africa as a case study.
Invasive aquatic plants in the pet trade
DNA barcoding techniques by researchers at the University of Johannesburg has revealed that several NEMBA-listed aquatic plants are known to be traded in the South African aquarium industry.
Pollinators in seed germination
This paper discusses the role and importance of pollinators in seed germination of invasive plants in the family Proteaceae, as well as that of autonomous self-fertilisation.
E-commerce trade in invasive plants
Among many introduction pathways of non-native species, horticulture is a particularly important driver of plant invasions. In recent decades, the horticultural industry expanded globally and changed structurally through the emergence of new distribution channels, including internet trade (e-commerce).
Franziska Humair, Luc Humair, Fabian Kuhn, and Christoph Kueffer
Comparisons of isotopic niche widths of some invasive and indigenous fauna in a South African river
Biological invasions threaten ecosystem integrity and biodiversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in direct competition with native species for dietary resources.
Jaclyn m. Hill, Roy w. Jones, Martin p. Hill and Olaf l. F. Weyl
Responses of adult Hydrellia lagarosiphon to a revised diet: implications for life cycle studies and laboratory culturing techniques
Preservation of an insect culture under laboratory conditions is essential for its study. Numerous diets have been developed for entomophagous insects undergoing screening as biological control agents in attempts to improve the nutritional quality of food provided in laboratory settings.
Rosie Mangan, 1 Tara Dirilgen & Jan-Robert Baars
Morphological variations in southern African populations of Myriophyllum spicatum: Phenotypic plasticity or local adaptation?
Variability in aquatic plant morphology is usually driven by phenotypic plasticity and local adaptations to environmental conditions experienced. This study aimed to elucidate which of these drivers is responsible for the morphological variation exhibited by three populations of Myriophyllum spicatum L. (Haloragaceae), a submerged aquatic plant whose status as native or exotic within southern Africa is uncertain.
P.S.R.Weyl, J.A. Coetzee
Discovery of Melaleuca quinquenervia in SA
Small naturalised populations of the broadleaf paperbark tree (Melaleuca quinquenervia) were been discovered in SA in 2009. This prompted an evaluation of the species’ distribution across South Africa. The tree is native to part Australia and parts of Indonesia, New Caledonia and Papua New Guinea.
First Record: Mimosa albida var. albida in Africa
A first official record of a naturalised population of Mimosa albida var. albida in Africa, a woody shrub indigenous to Central and South America. A total of 61 plants were recorded along 1.5 km arc of the Mkhomazi River in KwaZulu-Natal, South Africa. Efforts are underway to eradicate the population. The paper is a first formal report of the species outside of cultivation in Africa.
Legislative approaches for preventing invasions
Using cacti in South Africa as a case study, the authors develop a framework for assisting decision-makers in developing effective non-native species policies. The rate of transportation, introduction, dissemination, and spread of non-native species is increasing despite growing global awareness of the extent and impact of biological invasions. Effective policies are needed to prevent an increase in the negative environmental and economic impacts caused by invasive species.
Aliens in the nursery
The horticultural industry is recognised as one of the major pathways for the introduction and spread of invasive alien plants (IAPs) around the world. The paper assesses the awareness and attitudes of Cape Town nursery managers in regard to invasive species regulations.
New invasive cactus in the Tugela River basin
A new invasive cactus species (Echinopsis oxygona) is discovered in the Tugela River basin in KwaZulu-Natal, and new records of Opuntia microdasys are highlighted.
Biogeographical factors in the role of invasive plant distribution
This paper looks as biogeographical factors in the role of invasive species distribution in plants, from a South African perspective.
Effect of nutrient quality and leaf age of water hyacinth, Eichhornia crassipes, on the development of its co-evolved herbivore, Eccritotarsus catarinensis (Hemiptera: Miridae)
Specialist herbivores have evolved adaptations to overcome plant defensive chemicals and thus prefer younger leaves with their higher nutritional value, whereas generalist herbivores are unable to overcome these chemical defences, and opt for older leaves which have fewer nutrients, but are less defended (Center & Wright 1990).
A.M. Burke*, J.A. Coetzee & M.P. Hill
Effect of water trophic level on the impact of the water hyacinth moth Niphograpta albiguttalis on Eichhornia crassipes
Eutrophication contributes to the proliferation of alien invasive weed species such as water hyacinth (Eichhornia crassipes). Although the South American moth Niphograpta albiguttalis was released in South Africa in 1990 as a biological control agent against water hyacinth, no post-release evaluations have yet been conducted here.
K Canavan, JA Coetzee, MP Hill & ID Paterson
The herbivorous arthropods associated with the invasive alien plant, Arundo donax, and the native analogous plant, Phragmites australis, in the Free State Province, South Africa
The Enemy Release Hypothesis (ERH) predicts that when plant species are introduced outside their native range there is a release from natural enemies resulting in the plants becoming problematic invasive alien species (Lake & Leishman 2004; Puliafico et al. 2008).
K. Canavan, I. Paterson* & M.P. Hill
Water hyacinth, Eichhornia crassipes (Pontederiaceae), reduces benthic macroinvertebrate diversity in a protected subtropical lake in South Africa
The socio-economic impacts of the free-floating aquatic plant water hyacinth (Eichhornia crassipes) on aquatic systems are well documented, yet the impacts on aquatic biodiversity, particularly invertebrate biodiversity, are less well understood. This study aimed to determine whether the presence of water hyacinth altered the diversity and assemblage structure of benthic macroinvertebrates in a conservation area.
Julie A. Coetzee • Roy W. Jones • Martin P. Hill
Investigations of growth metrics and 15N values of water hyacinth (Eichhornia crassipes, (Mart.) Solms-Laub) in relation to biological control
The success of biological control for Eichhornia crassipes (Mart) Solms-Laub has been varied, with failure attributed to various factors including increased eutrophication in freshwater systems. Studies have shown that high N-loads are associated with enriched 15N values of aquatic biota.
Jaclyn M. Hill
Competition between two aquatic macrophytes, Lagarosiphon major and Myriophyllum spicatum Linnaeus as influenced by substrate sediment and nutrients
Competition between two globally economic and ecologically important submerged aquatic macro-phytes, Lagarosiphon major (Rid.) Moss ex Wager and Myriophyllum spicatum L., was studied in response to growing in different substrate nutrient and sediment treatments. Addition series experiments were conducted with mixed plantings of L. major and M. spicatum grown under two soil nutrient concentrations (high vs. low) and two sediment treatments (sand vs. loam).
G.D. Martin, J.A. Coetzee
The invasion status of Myriophyllum spicatum L. in southern Africa
The submerged aquatic macrophyte Myriophyllum spicatum L. (Haloragaceae) has been recorded in southern Africa since 1829. It was first considered problematic in 2005 on the Vaal River, which has highlighted the need for an assessment of the invasion status and an appropriate management strategy to be identified.
Philip S.R. Weyl and Julie A. Coetzee
An integrated remote sampling approach for aquatic invertebrates associated with submerged Macrophytes
A sampling method and apparatus for collecting meaningful and quantifiable samples of aquatic macroinvertebrates, and the macrophytes they are associated with, are presented. Where physical danger from wildlife is a significant factor, especially in Africa, this apparatus offers some safety in that it can be operated from a boat.
PSR Weyl & JA Coetzee
Melaleuca parvistaminea in South Africa
The rough-barked honey myrtle (Melaleuca parvistaminea) is endemic to Victoria and New Sales Wales in Australia. The study documents and assesses management options for the first reported invasion of Melaleuca parvistaminea in the world, in the context of a South African wetland ecosystem.
Invasive cactus species – a global review
The cactus family (Cactaceae), is a very popular horticultural plant group. Hundreds of cactus species have been introduced outside their native ranges; a few of them are among the most damaging and invasive plant species in the world. In this paper, the authors aim to compile a list of species in the family of Cacatceae, determine their current native and invasive ranges and determine the potential future ranges of invasive taxa.
Site-specific conditions influence plant naturalisation
The outcome of plant introductions is often considered in binary terms, invasive or non-invasive. Most species experience a time lag before naturalisation occurs, and many species become naturalised at some sites but not at others. This study aims, among others, to determine the invasion status of introduced Proteaceae species in South Africa which are not classified as major invaders.
Ecological impacts of alien species
Despite ongoing and intensive research over the past decade on the effects of alien species, invasion science still lacks the capacity to accurately predict the impacts of those species and to provide timely advice to managers on where limited resources should be allocated. The authors review different strategies, including specific experimental and observational approaches, for detecting and quantifying the ecological impacts of alien species.
Forestry trial data – evaluating climate-based SDMs in predicting tree invasions
Predicting which species will escape from forestry plantations and become invasive remains a challenge in invasion biology. Climate is frequently used to predict the outcome of species introductions based on the results from species distribution models (SDMs). The authors discuss the potential for using historical forestry trials to assess the performance of climate-based SDMs. The study identified the climatic factors required for successful invasion of acacias, and accentuates the importance of integration of status elsewhere for risk assessment.
Nutrient-mediated effects on Cornops aquaticum Brüner (Orthoptera: Acrididae), a potential biological control agent of water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae)
Host plant quality for phytophagous insects, of which nitrogen is one of the most crucial components, is highly variable and can be a major determinant of their performance. This has implications in insectweed biological control systems where host plant quality can affect establishment, survival and population growth rates of the biocontrol agents.
Angela Bownes, Martin P. Hill, Marcus J. Byrne
Impacts of a sub-lethal dose of glyphosate on water hyacinth nutrients and its indirect effects on Neochetina weevils
A sub-lethal dose of a herbicide under field conditions was applied to determine if it stimulates an increase in water hyacinth nutrients, thereby increasing feeding intensity by Neochetina spp. weevils used as biocontrol agents of the weed.
N. Katembo, M.P. Hill & M.J. Byrne
Identity and origins of introduced and native Azolla species in Florida
Azolla pinnata, an introduced aquatic fern, is spreading rapidly causing concern that it may displace native Azolla. It is now present in the Arthur R. Marshall Loxahatchee National Wildlife Refuge, the northernmost portion of the Florida Everglades.
Paul T. Madeira, Ted D. Center, Julie A. Coetzee, Robert W. Pembertona, Matthew F. Purcell, Martin P. Hill
Interactions within pairs of biological control agents on water hyacinth, Eichhornia crassipes
Water hyacinth (Eichhornia crassipes) is an invasive aquatic plant in South Africa where seven biological control agents have been released on the weed. Combined herbivory by these multiple agents may cause greater damage than any of the agents acting alone.
Danica Marlin, Martin P. Hill, Marcus J. Byrne
The effect of herbivory by the mite Orthogalumna terebrantis on the growth and Photosynthetic performance of water hyacinth (Eichhornia crassipes)
Eutrophication of fresh water systems is one of the most important factors contributing to the invasion of fresh water bodies by water hyacinth, Eichhornia crassipes. The South American mite, Orthogalumna terebrantis, established on the weed in South Africa in the late 1980s, but the impact of mite herbivory on the weed has never been quantified.
Danica Marlina, Martin P. Hill, Brad S. Ripley, Abram J. Strauss, Marcus J. Byrne
Comparisons of the thermal physiology of water hyacinth biological control agents: predicting establishment and distribution pre- and post-release
Investigations into the thermal physiology of weed biological control agents may elucidate reasons for establishment failure following release. Such studies have shown that the success of water hyacinth biological control in South Africa remains variable in the high-lying interior Highveld region, because the control agents are restricted to establishment and development due to extreme winter conditions.
Bronwen May & Julie Coetzee
Microbial agents for control of aquatic weeds and their role in integrated management
Aquatic ecosystems throughout the world are threatened by the presence of invasive aquatic plants, both floating and submerged. This paper discusses some of the major microbial agents associated with aquatic weeds and their increasing role in integrated weed management.
Puja Ray and Martin P. Hill
Weevil borne microbes contribute as much to the reduction of photosynthesis in water hyacinth as does herbivory
Arthropods released for weed biocontrol can have effects other than simply removing biomass and frequently decrease photosynthetic rate more than can be attributed to the mere loss of photosynthetic surface area. Some of this effect may result because biological control agents facilitate the transfer and ingress of deleterious microbes into plant tissues on which they feed.
Nic Venter, Martin P. Hill, Sarah-Leigh Hutchinson, Brad S. Ripley
Invasive aquatic plants: a field guide
A field guide comprising categorised, new and similar indigenous species. This pictorial guide features 20 aquatic invasives. Also includes images of indigenous aquatic plants that should not be confused with invasives.
Invasion dynamics of Banksia ericifolia – the absence of fire can cause a lag phase
Transition from a species introduction to an invasion often spans many decades and is known as a lag phase. Few studies have determined the mechanisms underlying lag phases. This study examines Banksia ericifolia. The researchers identified 18 sites where the species has been planted. The invasions originated from about 100 individuals planted 35 years ago. After several fires, the population has grown to around 10,000 plants in 127 hectares.
Invasion success in woody plants – test case: Proteaceae
Proteaceae is a large family of flowering plants occurring predominantly in the southern hemisphere with its greatest diversity in Australia and southern Africa. The family is associated with nutrient-poor soils and many species have adaptations for surviving in these conditions. The authors use Proteaceae as a test case and ask questions around the introduction of the plants globally and the invasion status of these introduced species.
Montpellier broom and Spanish broom in South Africa
The legumes Genista monspessulana (French or Montpellier broom) and Spartium junceum (Spanish broom) are major invaders in several other parts of the world, but not yet so in South Africa. Both are native to Europe, with the Spanish broom native to the Mediterranean region in southern Europe.
Petiveria alliacea in KwaZulu-Natal, South Africa
A first record of naturalisation of guinea hen weed (Petiveria alliacea). Petiveria alliacea has a wide natural distribution from Texas and Florida in the southern United States, southward to Ecuador, Argentina and a number of Caribbean islands. It is cultivated as an ornamental garden plant in South Africa, with the earliest recorded collection dating back to 1883 from the Durban Botanical Gardens.
Misleading criticisms of invasion science: a field guide
Invasion science is the study of the causes and consequences of the introduction of organisms to the areas outside their native ranges. Despite much evidence on its importance to science and society, invasion science has been the target of criticisms from a relatively small but vocal number of scientists and academics.
A standardised set of metrics to assess and monitor tree invasions
Functional and effective metrics are required by scientists, managers and policy-makers to improve understanding and management of biological invasions. The authors outlines key characteristics of tree invasions, discuss how these change with time and examine potential metrics to describe and monitor them.
Incorporating risk mapping into eradication management plans
The management of an invasive species is most effective when invasions are detection early and control measures quickly implemented. Factors important for detection depend on the spatial scale examined. The authors propose a protocol for developing risk maps at national, landscape, and local scales to improve detection rates of invasive plant species. Test case: Acacia stricta in South Africa.
A new national unit for invasive species detection, assessment and eradication planning
Biological invasions are a major threat to biodiversity and economic livelihoods in South Africa. Invasive plants cost South Africa an estimated R6.5 billion every year but if left unmanaged overall impacts on ecosystem services are likely to rise sharply. Even with no new introductions, the number of biological invasions in South Africa will increase as introduced species naturalise and become invasive. The authors describe the establishment in 2008 of a unit funded by the Working for Water Programme as part of the South African National Biodiversity Institute's Invasive Species Programme (SANBI ISP).
Distribution and management of Acacia implexa in South Africa
Is A. implexa a suitable target for eradiation? The first detailed assessment of an invasion by the screw-pod-wattle (Acacia implexa) anywhere in the world. Approximately 30,000 individuals were found in three geographically distinct populations, all in the Western Cape. The study concludes that the costs of eradicating A.implexa are within feasible limits and the plant should remain a target for eradiation.
Plant traits and spread of Spartina alterniflora
Smooth cordgrass (Spartina alterniflora) was discovered growing in the Great Brak Estuary on the southern Cape coast of South Africa in 2004. It is a recognised aggressive invader of estuaries and salt marsh around the world. This is the first record of this invasive plant in Africa as well as its first occurrence in an estuary that closes to the sea. The study illustrates the adaptive potential of this invasive marsh plant and indicates the possibility of invasion in seasonally closed estuaries in other global locations.
Impacts of invasive alien plants on water quality, with particular emphasis on South Africa
Invasive alien plants are a significant environmental problem in South Africa’s terrestrial and freshwater ecosystems. Over 200 introduced plant species are regarded as invasive. The authors review the current state of knowledge of quantified impacts of invasive alien plants on water quality, with a focus on South Africa.
A biological control agent for Parthenium hysterophorus in Australia
Parthenium weed (Parthenium hysterophorus), a major weed causing economic, environmental and human and animal health problems in Australia and several countries in Asia, Africa, and the Pacific, has been a target for biological control in Australia since the mid-1970s. Nine species of insects and two rust fungi have been introduced as biological control agents into Australia.
Assessment: national plant control strategy in SA
Alien plant invasions are a large and growing threat to ecosystems around the world. The paper presents an assessment of a large, national-scale alien plant control program that has operated in South Africa for 15 years. The authors review data from three national-level estimates of the extent of invasion, records of the costs and spatial extent of invasive species control operations, assessments of the effectiveness of biological control, and smaller-scale studies.
Australian acacia: Contain or eradicate?
Learn more about a decision analysis framework to analyse the best management goal for an invasive species population (eradication, containment or take no action) when knowledge about the current extent is uncertain. For the kangaroo thorn or hedge wattle (A. paradoxa) in South Africa, attempting to eradicate is likely to be cost-effective, especially if resources are allocated to better understand and improve management efficacy.
Australian acacias around the world
Australian acacias, about 1000 species native to Australia, have been moved around the world by humans over the past 250 years. This has created an opportunity to explore how evolutionary, ecological, historical and sociological factors interact and affect the distribution, usage, invasiveness and perceptions of a globally important group of plants.
Global efforts to limit Australian acacia invasions
Many Australian acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. The authors review global efforts to minimise the risk and limit the impact of invasions in this widely used plant group.
Trees and shrubs as invasive alien species
Until fairly recently woody plants were not widely considered to be important invasive alien species. Thousands of species of trees and shrubs have been moved around the world. The article presents a list of invasive alien trees and shrubs and discusses key issues regarding the invasions of non-native woody plants around the world.
Estimating stream-flow reduction due to invasive alien plants
Alien vegetation, especially large invasive trees such as eucalyptus, pines and wattles, is known to reduce streamflow to less than that which would occur under naturally vegetated conditions. There are numerous models, methods and rules-of-thumb to estimate streamflow reduction due to invasive alien plants (IAPs) currently being applied within South Africa. The paper describes a fundamental hydrological principle against which streamflow reduction due to IAPs can be tested.
Initiation of biological control against Parthenium hysterophorus in South Africa
The annual herbaceous plant Parthenium hysterophorus, commonly known as parthenium, famine or rag weed has been a major weed of global significance for several decades, with wide-ranging impacts on agriculture, biodiversity conservation, and human and animal health. In 2003, South Africa became the first African country and only the third country worldwide to implement a biological control programme against the weed. In 2005, the South African biological control programme was extended to Ethiopia through an international co-operative programme.
Aquatic weeds in the pet trade
An evaluation of the risks posed by the aquarium trade, aquarists and the internet trade in South Africa. These avenues were investigated as vectors for the introduction of invasives into the country. Online and manual surveys were conducted and used to determine the extent of the movement of various invasive as well as indigenous submerged plant species in SA. 34 pet stores and 23 aquarists were interviewed.
Biological control: water hyacinth & grasshopper
The water hyacinth grasshopper (Cornops aquaticum) is being considered for release in South Africa as a biocontrol agent for water hyacinth (Eichhornia crassipes), a species native to the Amazon basin. It is one of South Africa’s most environmentally, socially and ecologically problematic aquatic weeds.
Water hyacinth & grasshopper – assessment
Water hyacinth (Eichhornia crassipes) is a highly invasive aquatic weed in South Africa. The study looks at the relationship between insect density and plant damage of grasshopper (Cornops aquaticum), a candidate biological control agent and the invasive water hyacinth. The results showed that Cornops aquaticum should be considered for release in South Africa, based on its host specificity and potential impact on E.crassipes.
Molecular systematics and ecology of invasive kangaroo paws in
Most legislation pertaining to non-native organisms is implicitly focussed at the individual
species level. However, in some cases interspecific hybrids can be more invasive than any of the parent species. The authors explore these issues in the context of the need to manage naturalised populations of kangaroo paws (Anigozanthos species) in South Africa.
Population dynamics of Parthenium hysterophorus
Phytosociological analysis performed over 2005 to 2009 revealed that coffee weed (Cassia occidentalis) is a dominant species at three of four sites in Agra district, India, that were previously observed to be dominated by heavy populations of Parthenium hysterophorus. This study was performed to determine the cumulative effects of C. occidentalis on the growth and possible suppression of Parthenium hysterophorus
Impact of Parthenium hysterophorus on grazing land in Ethiopia
An investigation into the impact of Parthenium hysterophorus infestation was conducted in 2007 in the north-eastern grazing lands of Ethiopia. The investigation was undertaken to determine the impact of P. hysterophorus on the above-ground native herbaceous species diversity and community evenness, as well as the soil seedbank structure, in Kobo district, north-eastern Ethiopia.
Effects of Parthenium hysterophorus on rats
Most legislation pertaining to non-native organisms is implicitly focussed at the individual species level. However, in some cases interspecific hybrids can be more invasive than any of the parent species. The authors explore these issues in the context of the need to manage naturalised populations of kangaroo paws (Anigozanthos species) in South Africa.
Current and potential geographical distribution of Parthenium hysterophorus
Parthenium hysterophorus, commonly known as parthenium weed or famine weed, is of South American origin and considered to be one of the world’s most serious invasive plants, invading Australia, Asia and Africa. This study increases the current understanding of the distribution of P. hysterophorus and develops a baseline from which to monitor future spread and abundance of the plant.
Evaluating the invasiveness of Acacia paradoxa in South Africa
A first detailed survey of a population of kangaroo thorn in SA. Many of the Australian acacia species, introduced to South Africa during the 19th and 20th centuries, have become highly invasive are among the most widespread invasive plant species in South Africa. In this paper the authors present an assessment of the population of A. paradoxa growing in Table Mountain National Park.
Candidate biological control agent Cornops aquaticum
The water hyacinth was introduced into South Africa as an ornamental aquarium plant in the early 1900’s. By the 1970’s it had reached pest proportions in dams and rivers around the country. The study aims at determining the potential efficacy of grasshopper (Cornops aquaticum) for water hyacinth (Eichhornia crassipes).
Formulation of phytotoxins from Phoma sp. for the management of Parthenium hysterophorus
Parthenium hysterophorus is a pernicious weed, imposing deleterious economic effects on humans and livestock. Biological control is a relatively cheap and most feasible long-term approach for controlling deadly weeds. Research on adjuvant and formulation technology for eco-friendly agrochemicals has advanced rapidly in recent years. Phoma is a well-known phytopathogen responsible for many diseases in plants and is known to produce an array of bioactive extracellular toxic compounds.
Payments for ecosystem services – addressing poverty and ecosystem service delivery
A payments for ecosystem services (PES) system came about in South Africa with the establishment of the government-funded Working for Water (WfW) Programme in 1995. The success of the programme is largely attributed to it being mainly funded as a poverty-relief initiative, although water users also contribute through their water fees. The authors examine ways in which the South African situation may develop into a model which could be valuable in other developing countries.
Remote sensing tools for monitoring the benefits of the WfW Programme
The Working for Water (WfW) Programme was launched in 1995. One of its aims is to protect the water resources of South Africa through controlling invasive alien plants (AIPs). Control takes place across the country and targets a number of species. The paper looks at the development of remote sensing tools for monitoring the hydrological benefits of the Working for Water programme.
Control of ragweed with herbicides
Ragweed parthenium, also called parthenium weed (Parthenium hysterophorus) is an annual herb in the Asteraceae family. It is a troublesome and noxious weed native to tropical and subtropical America and widely distributed in North and South America, Africa, Asia and Australia. The article looks at the control of ragweed with pre-emergence and post-emergence herbicides.
Introduced species as evolutionary traps
Predications that invasive alien plants would use significant amounts of water were a major factor in the establishment of South Africa’s Working for Water Programme. The aim of the programme is to protect water resources by clearing out these plants. In this paper, the authors assess the state of knowledge in the field of hydrology in South Africa, with specific reference to the effects on invasive alien plants.
Invasive alien plants and water resources in South Africa
Invasive species can alter environments in such a way that normal behavioural decision making rules of native species are no longer adaptive. The evolutionary trap concept provides a useful framework for predicting and managing the impact of harmful invasive species. In this paper the authors discuss how native species respond to changes in their selective regime via evolution or learning.
Social benefits in the Working for Water Programme as a public works initiative
The Working for Water public works and conservation initiative has broken new ground in addressing urgent social needs in South Africa. In this paper the authors outline the programme’s context and social factors that helped to shape it over the first seven years, the development of social interventions, and the identification of research priorities for the future.
Growth, reproduction and photosynthesis of ragweed parthenium
Ragweed parthenium (Parthenium hysterophorus) is an aggressive, herbaceous weed with an almost worldwide occurrence. This investigation was designed to study growth and reproductive performance of parthenium with respect to seasons and photosynthetic gas exchange behaviour at different levels of CO2, temperature, light and relative humidity (RH), to understand the likely effects of these variables on the adaptation of the species.
Hydrological impacts of invasive alien plants
Invasive alien species, particularly trees, use much more water when compared with native vegetation. Perhaps less well understood are the reasons for this increased water usage and whether it should be expected from all species of invading alien trees under all environmental conditions. The authors examine the reasons for increased water use from trees as compared with short crops.
Predicting species invasions using ecological niche modelling
Invasions can be unpredictable – which species will invade and which invaders will become serious problems? Alien plants, animals and microbes have flooded the United States, disrupting natural systems, extinguishing species, compromising agriculture and damaging resources. A new approach to ecological niche modelling, based on new tools drawn from biodiversity informatics, is applied to the challenge of predicting potential species’ invasions.
Water shortage, deforestation and development SA’s Working for Water Programme
Alien trees and plants have invaded many parts of the country, taking land away from indigenous species. These alien species consume much more water that indigenous vegetation, threating biodiversity and constituting a significant fire hazard. The Working for Water Programme commenced in 1995, with the aim to clear away alien vegetation from large areas of land and in doing so to improve the water supply to both rural and urban areas.
Characterisation of a toxin from Parthenium hysterophorus and its mode of excretion in animals
Several species of the compositae family are known to be toxic when consumed by animals. Incorporation of Parthenium hysterophorus into the diet of livestock was found to cause chronic or acute toxicity, dependent on how much weed was ingested. The results of studies done on the characterisation of the toxic principle from the weed and fate of the administered toxin in animals are presented in this paper.