Biological control of South African plants that are invasive elsewhere in the world: A review of earlier and current programmes
- Authors: Olckers, Terence , Coetzee, Julie A , Egli, Daniella , Martin, Grant D , Paterson, Iain D , Sutton, Guy F , Wood, Alan R
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414336 , vital:71137 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a21"
- Description: South Africa supports a rich floral diversity, with 21 643 native plant taxa that include a high proportion (76.3%) of endemic species, and many of these favoured as ornamentals, both locally and globally. Consequently, South Africa has contributed substantially to global plant invasions, with 1093 native taxa (5% of all species) naturalized in other countries. At least 80 taxa are invasive in natural or semi-natural ecosystems elsewhere, while an additional 132 taxa are potentially invasive. Of the global naturalized flora, 8.2% originate from South Africa and largely comprise species of Poaceae, Asteraceae, Iridaceae and Fabaceae. Australia, in particular, but also Europe and North America are major recipients of South African weeds. However, few countries have targeted South African plants for biological control (biocontrol), with most efforts undertaken by Australia. Previous and current targets have involved only 26 species with 17 agents (15 insects, one mite and one rust fungus) of South African origin released on five target species in Australia and the United States of America. South Africa’s history of weed biocontrol, together with a large cohort of active scientists, is currently facilitating several internationally funded programmes targeting invasive plants of South African origin. In particular, the recently inaugurated Centre for Biological Control at Rhodes University and the University of KwaZulu-Natal have provided the impetus for novel efforts on five new target species and renewed efforts on four previously targeted species. In this contribution, we review the history of earlier biocontrol programmes against weeds of South African origin and the status of projects currently in progress in South Africa.
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- Date Issued: 2021
Field-based ecological studies to assess prospective biological control agents for invasive alien plants: An example from giant rat's tail grass
- Authors: Sutton, Guy F , Canavan, Kim N , Day, Michael M , Paterson, Iain D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423756 , vital:72091 , xlink:href="https://doi.org/10.1111/1365-2664.13834"
- Description: Biological control (biocontrol) of invasive alien plants is a widely utilised weed management tool. Prospective biocontrol agents are typically assessed through host specificity testing and pre-release efficacy studies performed in quarantine. However, rearing of the potential biocontrol agents and/or test plants is often difficult or impossible under quarantine conditions. Moreover, practitioners may attain laboratory artefacts in quarantine, which may result in the potential agent being needlessly rejected. Field-based studies in the weed's indigenous distribution could overcome these issues.
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- Date Issued: 2021
Climate modelling suggests a review of the legal status of Brazilian pepper Schinus terebinthifolia in South Africa is required:
- Authors: Martin, Grant D , Magengelele, Nwabisa L , Paterson, Iain D , Sutton, Guy F
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148606 , vital:38754 , https://doi.org/10.1016/j.sajb.2020.04.019
- Description: Brazilian pepper (Schinus terebinthifolia) is a tree native to subtropical South America that was introduced into South Africa in the early 1900s as an ornamental plant. The tree has since escaped cultivation and has invaded ruderal and pristine habitats along the eastern coast of South Africa. Brazilian Pepper is also one of the most problematic invasive alien plants in Florida, USA. We modelled the climatically suitable area for this species in South Africa using MaxEnt, with five distinct datasets: incorporating both the native and the invaded range of the species, as well as different backgrounds.
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- Date Issued: 2020
Grasses as suitable targets for classical weed biological control
- Authors: Sutton, Guy F , Day, Michael D , den Breeyen, Alana , Goolsby, J A , Cristofaro, M , McConnachie, Andrew J , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417984 , vital:71499 , xlink:href="https://doi.org/10.1007/s10526-019-09968-8"
- Description: Grasses are amongst the most abundant and environmentally damaging invasive weeds worldwide. Biological control is frequently employed as a sustainable and cost-effective management strategy for many weeds. However, grasses have not been actively pursued as targets for classical weed biological control due to a perceived lack of sufficiently specialised and damaging natural enemies to use as biological control agents. There are also concerns that the risk posed to economically important crop/pasture species and closely-related native species is too great to consider implementing biological control for invasive grasses. In this paper, we review the literature and demonstrate that grasses can possess suitably host-specific and damaging natural enemies to warrant consideration as potential biological control agents. The risk of grass biological control is no greater than for other weedy taxa if practitioners follow appropriately rigorous risk assessments protocols.
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- Date Issued: 2019
Evaluating the efficacy of Hypogeococcus sp. as a biological control agent of the cactaceous weed Cereus jamacaru in South Africa
- Authors: Sutton, Guy F , Klein, Hildegard , Paterson, Iain D
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423350 , vital:72051 , xlink:href="https://doi.org/10.1007/s10526-018-9887-3"
- Description: We evaluated the efficacy of Hypogeococcus sp. (Hemiptera: Pseudococcidae) as a biological control agent of the cactaceous weed Cereus jamacaru De Candolle (Queen of the Night cactus) in South Africa. This weed has been described as being under complete biological control due to the action of Hypogeococcus sp., although no formal post-release evaluation had been conducted prior to this study. Biological control was associated with significant reductions in fruiting, plant survival and plant densities, while plant population age structures were negatively affected. Weed populations infected by Hypogeococcus sp. were typified by low or non-existent recruitment and are expected to diminish with time. Populations where Hypogeococcus sp. was absent displayed extensive recruitment, and are predicted to expand or self-replace, if left unchecked. These data indicate that Hypogeococcus sp. has a significant negative effect on C. jamacaru at the individual plant and population level, and given sufficient time provides complete biological control over this weed in South Africa.
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- Date Issued: 2018
Genetic matching of invasive populations of the African tulip tree, Spathodea campanulata Beauv.(Bignoniaceae), to their native distribution: Maximising the likelihood of selecting host-compatible biological control agents
- Authors: Sutton, Guy F , Paterson, Iain D , Paynter, Quentin
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405797 , vital:70207 , xlink:href="https://doi.org/10.1016/j.biocontrol.2017.08.015"
- Description: Spathodea campanulata Beauv (Bignoniaceae) has become a highly damaging environmental and agricultural weed in the Pacific Islands. It has been targeted for biological control due to the costly and inefficient nature of physical and chemical control methods. Determining the origin of weed populations has been increasingly recognised as an important component of successful biological control programmes, and may be important for the biological control of S. campanulata due to the high degree of morphological variability within the species, as well as the broad native distribution. Genetic matching, using inter-simple sequence repeats (ISSR’s), and morphological data found support for invasive Pacific Island S. campanulata plants originating from West Africa. Pacific and West African plants were genetically most similar, and were differentiated from native plants from East/Central Africa by PCA and Bayesian-clustering (STRUCTURE) analyses. Genetic data was corroborated by morphological data which showed that West African and Pacific Islands plants had more sparsely pubescent leaves compared to plants from East/Central Africa. Populations in South Africa, where the plant is introduced but not problematic, originated from a different source population than those in the Pacific Islands, probably in East/Central Africa. A greater sampling effort is required before the origin of the South African populations can be determined with certainty. Herbivores and pathogens for the Pacific Islands should be collected from West Africa as they are more likely to be compatible with S. campanulata plants in this region.
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- Date Issued: 2017
Predicting the risk of non-target damage to a close relative of a target weed using sequential no-choice tests, paired-choice tests and olfactory discrimination experiments
- Authors: Sutton, Guy F , Paterson, Iain D , Compton, Stephen G , Paynter, Quentin
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417511 , vital:71459 , xlink:href="https://doi.org/10.1080/09583157.2015.1118615"
- Description: We investigated host-plant utilisation by the candidate biocontrol agent Paradibolia coerulea (Coleoptera: Chrysomelidae) on the target plant Spathodea campanulata Beauv. (Bignoniaceae) and a closely related non-target plant, Kigelia africana (Lam.) Benth. (Bignoniaceae). Paired-choice and sequential no-choice experiments were performed and coupled with olfactory discrimination experiments to test the insects’ responses to volatiles from both plant species as well as to cues from conspecific beetles. Although K. africana was utilised by P. coerulea, S. campanulata was preferred for both adult feeding and oviposition. Interestingly, whereas females were attracted to olfactory cues emitted by S. campanulata, males demonstrated no such olfactory discrimination. Females were also attracted to cues deposited by males, and males were deterred by cues from other males, but neither sex responded to female olfactory cues. Very few eggs were recorded on K. africana and none of the larvae that hatched on K. africana survived the first instar. Both S. campanulata and K. africana are suitable for adult feeding, but persistent utilisation of K. africana in the field is unlikely because larval development is only possible on S. campanulata and because the adult females are strongly attracted to volatiles emitted by the target plant. Nevertheless, if P. coerulea is released as a biocontrol agent, spill-over adult feeding could potentially occur on K. africana growing sympatrically with S. campanulata. Because P. coerulea cannot complete its development on K. africana, non-target damage will only occur where the target plant is present, with an intensity dependent on densities of adult beetles locally.
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- Date Issued: 2017