Host-specificity testing of the leaf-feeding flea beetle, Phenrica guerini, a biological control agent for the invasive alien cactus, Pereskia aculeata
- Dixon, Elizabeth, Paterson, Iain D, Muskett, Philippa, McConnachie, Andrew
- Authors: Dixon, Elizabeth , Paterson, Iain D , Muskett, Philippa , McConnachie, Andrew
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417687 , vital:71478 , xlink:href="https://doi.org/10.1080/09583157.2023.2214342"
- Description: Pereskia aculeata Miller (Cactaceae) is an environmentally damaging invasive alien plant in South Africa and Australia. The flea-beetle, Phenrica guerini Bechyné (Coleoptera: Chrysomelidae), has been used in South Africa as a biological control agent against the plant for more than 30 years but updated host-specificity testing was required to determine its suitability as an agent in Australia. No-choice larval survival tests were conducted on 26 test plant species from 11 families, with survival to the adult stage only being recorded on the target weed, P. aculeata. No-choice oviposition testing with adult P. guerini was conducted on six test plant species. No adult feeding was recorded on any test plants and significantly more eggs were oviposited on P. aculeata (158.8 SE ± 21.4) than on Talinum caffrum (5.2 SE ± 5.2), which was the only test plant on which they oviposited. The adults survived on average 27 days longer on P. aculeata than on any test plant species. In a multiple-choice trial that included all three species that supported any larval feeding as well as P. aculeata, oviposition and feeding was only recorded on target weed. Phenrica guerini is suitably host specific for consideration in Australia as a biological control agent against P. aculeata.
- Full Text:
- Date Issued: 2023
- Authors: Dixon, Elizabeth , Paterson, Iain D , Muskett, Philippa , McConnachie, Andrew
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417687 , vital:71478 , xlink:href="https://doi.org/10.1080/09583157.2023.2214342"
- Description: Pereskia aculeata Miller (Cactaceae) is an environmentally damaging invasive alien plant in South Africa and Australia. The flea-beetle, Phenrica guerini Bechyné (Coleoptera: Chrysomelidae), has been used in South Africa as a biological control agent against the plant for more than 30 years but updated host-specificity testing was required to determine its suitability as an agent in Australia. No-choice larval survival tests were conducted on 26 test plant species from 11 families, with survival to the adult stage only being recorded on the target weed, P. aculeata. No-choice oviposition testing with adult P. guerini was conducted on six test plant species. No adult feeding was recorded on any test plants and significantly more eggs were oviposited on P. aculeata (158.8 SE ± 21.4) than on Talinum caffrum (5.2 SE ± 5.2), which was the only test plant on which they oviposited. The adults survived on average 27 days longer on P. aculeata than on any test plant species. In a multiple-choice trial that included all three species that supported any larval feeding as well as P. aculeata, oviposition and feeding was only recorded on target weed. Phenrica guerini is suitably host specific for consideration in Australia as a biological control agent against P. aculeata.
- Full Text:
- Date Issued: 2023
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
- Sutton, Guy F, Paterson, Iain D, Compton, Stephen G, Paynter, Quentin
- 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.
- Full Text:
- Date Issued: 2017
- 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.
- Full Text:
- Date Issued: 2017
Effect of water trophic level on the impact of the water hyacinth moth Niphograpta albiguttalis on Eichhornia crassipes
- Canavan, Kim N, Coetzee, Julie A, Hill, Martin P, Paterson, Iain D
- Authors: Canavan, Kim N , Coetzee, Julie A , Hill, Martin P , Paterson, Iain D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423740 , vital:72090 , xlink:href="https://doi.org/10.2989/16085914.2014.893225"
- Description: 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. The impact of N. albiguttalis on water hyacinth growth was quantified under low-, medium- and high-nutrient concentrations in a greenhouse experiment. Niphograpta albiguttalis was damaging to water hyacinth in all three nutrient treatments, but significant damage in most plant parameters was found only under high-nutrient treatments. However, E. crassipes plants grown in high-nutrient water were healthier, and presumably had higher fitness, than plants not exposed to herbivory at lower-nutrient levels. Niphograpta albiguttalis is likely to be most damaging to water hyacinth in eutrophic water systems, but the damage will not result in acceptable levels of control because of the plant's high productivity under these conditions. Niphograpta albiguttalis is a suitable agent for controlling water hyacinth infestations in eutrophic water systems, but should be used in combination with other biological control agents and included in an integrated management plan also involving herbicidal control and water quality management.
- Full Text:
- Date Issued: 2014
- Authors: Canavan, Kim N , Coetzee, Julie A , Hill, Martin P , Paterson, Iain D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423740 , vital:72090 , xlink:href="https://doi.org/10.2989/16085914.2014.893225"
- Description: 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. The impact of N. albiguttalis on water hyacinth growth was quantified under low-, medium- and high-nutrient concentrations in a greenhouse experiment. Niphograpta albiguttalis was damaging to water hyacinth in all three nutrient treatments, but significant damage in most plant parameters was found only under high-nutrient treatments. However, E. crassipes plants grown in high-nutrient water were healthier, and presumably had higher fitness, than plants not exposed to herbivory at lower-nutrient levels. Niphograpta albiguttalis is likely to be most damaging to water hyacinth in eutrophic water systems, but the damage will not result in acceptable levels of control because of the plant's high productivity under these conditions. Niphograpta albiguttalis is a suitable agent for controlling water hyacinth infestations in eutrophic water systems, but should be used in combination with other biological control agents and included in an integrated management plan also involving herbicidal control and water quality management.
- Full Text:
- Date Issued: 2014
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 s
- Canavan, Kim N, Paterson, Iain D, Hill, Martin P
- Authors: Canavan, Kim N , Paterson, Iain D , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406155 , vital:70243 , xlink:href="https://hdl.handle.net/10520/EJC155690"
- Description: 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 and Leishman 2004; Puliafico et al. 2008). The release from natural enemies may benefit alien plants more than simply reducing herbivory because, according to the Evolution of Increased Competitive Ability (EICA) hypothesis, without pressure from herbivores more resources that were previously allocated to defence can be allocated to reproduction (Blossey and Notzold 1995). Alien invasive plants are therefore expected to have simpler herbivore communities with fewer specialist herbivores (Frenzel and Brandl 2003; Heleno et al. 2008; Heger and Jeschke 2014).
- Full Text:
- Date Issued: 2014
- Authors: Canavan, Kim N , Paterson, Iain D , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406155 , vital:70243 , xlink:href="https://hdl.handle.net/10520/EJC155690"
- Description: 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 and Leishman 2004; Puliafico et al. 2008). The release from natural enemies may benefit alien plants more than simply reducing herbivory because, according to the Evolution of Increased Competitive Ability (EICA) hypothesis, without pressure from herbivores more resources that were previously allocated to defence can be allocated to reproduction (Blossey and Notzold 1995). Alien invasive plants are therefore expected to have simpler herbivore communities with fewer specialist herbivores (Frenzel and Brandl 2003; Heleno et al. 2008; Heger and Jeschke 2014).
- Full Text:
- Date Issued: 2014
A promising biological control agent for the invasive alien plant, Pereskia aculeata Miller (Cactaceae), in South Africa
- Paterson, Iain D, Mdodana, Lumka A, Mpekula, Ongezwa, Mabunda, Bheki D, Hill, Martin P
- Authors: Paterson, Iain D , Mdodana, Lumka A , Mpekula, Ongezwa , Mabunda, Bheki D , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416806 , vital:71387 , xlink:href="https://doi.org/10.1080/09583157.2014.919439"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien plant from Central and South America that has become a problematic environmental weed in South Africa. A potential biological control agent, the stem-wilter, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), was collected in southern Brazil and imported into quarantine in South Africa. Field host range data suggested that C. schaffneri has a host range restricted to P. aculeata. No-choice nymph survival tests were then conducted on 27 test plant species in 9 families. Survival to the adult stage was only recorded on P. aculeata and the closely related Pereskia grandifolia Haw. (Cactaceae). Mortality was significantly higher on P. grandifolia with only 3% of the nymphs reaching the adult stage compared with 74% on P. aculeata indicating that P. aculeata is the primary host plant. P. grandifolia is native in South America and is of no agricultural importance in South Africa so any feeding on P. grandifolia in South Africa would have no negative environmental or economic consequences. In other tests, adult survival on P. aculeata [25.8 days (SE ± 3.74)] was significantly longer than on other test plant species [4.3 days (SE ± 0.36)] further confirming the host specificity of the species. Impact studies conducted in quarantine indicated that C. schaffneri is damaging to P. aculeata, significantly reducing the number of leaves and the shoot lengths of plants, even at relatively low insect densities. C. schaffneri is safe for release in South Africa and is likely to be a damaging and effective agent.
- Full Text:
- Date Issued: 2014
- Authors: Paterson, Iain D , Mdodana, Lumka A , Mpekula, Ongezwa , Mabunda, Bheki D , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416806 , vital:71387 , xlink:href="https://doi.org/10.1080/09583157.2014.919439"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien plant from Central and South America that has become a problematic environmental weed in South Africa. A potential biological control agent, the stem-wilter, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), was collected in southern Brazil and imported into quarantine in South Africa. Field host range data suggested that C. schaffneri has a host range restricted to P. aculeata. No-choice nymph survival tests were then conducted on 27 test plant species in 9 families. Survival to the adult stage was only recorded on P. aculeata and the closely related Pereskia grandifolia Haw. (Cactaceae). Mortality was significantly higher on P. grandifolia with only 3% of the nymphs reaching the adult stage compared with 74% on P. aculeata indicating that P. aculeata is the primary host plant. P. grandifolia is native in South America and is of no agricultural importance in South Africa so any feeding on P. grandifolia in South Africa would have no negative environmental or economic consequences. In other tests, adult survival on P. aculeata [25.8 days (SE ± 3.74)] was significantly longer than on other test plant species [4.3 days (SE ± 0.36)] further confirming the host specificity of the species. Impact studies conducted in quarantine indicated that C. schaffneri is damaging to P. aculeata, significantly reducing the number of leaves and the shoot lengths of plants, even at relatively low insect densities. C. schaffneri is safe for release in South Africa and is likely to be a damaging and effective agent.
- Full Text:
- Date Issued: 2014
Addressing the red flags in cochineal identification: The use of molecular techniques to identify cochineal insects that are used as biological control agents for invasive alien cacti
- van Steenderen, Clarke J M, Paterson, Iain D, Edwards, Shelley, Day, M D
- Authors: van Steenderen, Clarke J M , Paterson, Iain D , Edwards, Shelley , Day, M D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423282 , vital:72044 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104426"
- Description: Invasive Cactaceae cause considerable damage to ecosystem function and agricultural practices around the world. The most successful biological control agents used to combat this group of weeds belong to the genus Dactylopius (Hemiptera: Dactylopiidae), commonly known as ‘cochineal’. Effective control relies on selecting the correct species, or in some cases, the most effective intraspecific lineage, of cochineal for the target cactus species. Many of the Dactylopius species are so morphologically similar, and in the case of intraspecific lineages, identical, that numerous misidentifications have been made in the past. These errors have resulted in failed attempts at the biological control of some cactus species. This study aimed to generate a multi-locus genetic database to enable the accurate identification of dactylopiids. Genetic characterization was achieved through the nucleotide sequencing of three gene regions (12S rRNA, 18S rRNA, and COI) and two inter-simple sequence repeats (ISSR). Nucleotide sequences were very effective for species-level and D. tomentosus lineage-level identification, but could not distinguish between the two lineages within D. opuntiae commonly used for biological control of various Opuntia spp. Fragment analysis through the use of ISSRs successfully addressed this issue. This is the first time that a method has been developed that can distinguish between these two D. opuntiae lineages. Using the methods developed in this study, biological control practitioners can ensure that the most effective agent species and lineages are used for each cactus target weed, thus maximizing the level of control.
- Full Text:
- Date Issued: 2021
- Authors: van Steenderen, Clarke J M , Paterson, Iain D , Edwards, Shelley , Day, M D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423282 , vital:72044 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104426"
- Description: Invasive Cactaceae cause considerable damage to ecosystem function and agricultural practices around the world. The most successful biological control agents used to combat this group of weeds belong to the genus Dactylopius (Hemiptera: Dactylopiidae), commonly known as ‘cochineal’. Effective control relies on selecting the correct species, or in some cases, the most effective intraspecific lineage, of cochineal for the target cactus species. Many of the Dactylopius species are so morphologically similar, and in the case of intraspecific lineages, identical, that numerous misidentifications have been made in the past. These errors have resulted in failed attempts at the biological control of some cactus species. This study aimed to generate a multi-locus genetic database to enable the accurate identification of dactylopiids. Genetic characterization was achieved through the nucleotide sequencing of three gene regions (12S rRNA, 18S rRNA, and COI) and two inter-simple sequence repeats (ISSR). Nucleotide sequences were very effective for species-level and D. tomentosus lineage-level identification, but could not distinguish between the two lineages within D. opuntiae commonly used for biological control of various Opuntia spp. Fragment analysis through the use of ISSRs successfully addressed this issue. This is the first time that a method has been developed that can distinguish between these two D. opuntiae lineages. Using the methods developed in this study, biological control practitioners can ensure that the most effective agent species and lineages are used for each cactus target weed, thus maximizing the level of control.
- Full Text:
- Date Issued: 2021
Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
- Paterson, Iain D, Mangan, Rose, Downie, Douglas A, Coetzee, Julie A, Hill, Martin P, Burke, Ashley M, Downey, Paul O, Henry, Thomas J, Compton, Stephen G
- Authors: Paterson, Iain D , Mangan, Rose , Downie, Douglas A , Coetzee, Julie A , Hill, Martin P , Burke, Ashley M , Downey, Paul O , Henry, Thomas J , Compton, Stephen G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424877 , vital:72191 , xlink:href="https://doi.org/10.1002/ece3.2297"
- Description: There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. 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. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.
- Full Text:
- Date Issued: 2016
- Authors: Paterson, Iain D , Mangan, Rose , Downie, Douglas A , Coetzee, Julie A , Hill, Martin P , Burke, Ashley M , Downey, Paul O , Henry, Thomas J , Compton, Stephen G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424877 , vital:72191 , xlink:href="https://doi.org/10.1002/ece3.2297"
- Description: There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. 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. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.
- Full Text:
- Date Issued: 2016
Molecular identification of Azolla invasions in Africa: The Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist
- Madeira, P T, Dray, F Allen, Coetzee, Julie A, Paterson, Iain D, Tipping, Philip W
- Authors: Madeira, P T , Dray, F Allen , Coetzee, Julie A , Paterson, Iain D , Tipping, Philip W
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424765 , vital:72182 , xlink:href="https://doi.org/10.1016/j.sajb.2016.03.007"
- Description: 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. It is notoriously difficult to determine Azolla species based on morphology so genetic analyses were required to confirm the identity of the Azolla used by the agent. Extensive sampling was conducted and samples were sequenced at the trnL-trnF and trnG-trnR chloroplastic regions and the nuclear ITS1 region. Current literature reported A. filiculoides as the only Section Azolla species in southern Africa but 24 samples were identified as Azolla cristata, an introduced species within Section Azolla that was not used during host specificity trials. A. pinnata subsp. africana was only located at one site in southern Africa, while the alien A. pinnata subsp. asiatica was located at three. What was thought to be A. pinnata subsp. africana was in fact A. cristata, a closer relative of A. filiculoides and a suitable host according to specificity trials. This study confirms that S. rufinasus is a proficient Azolla taxonomist but also supports the use of molecular techniques for resolving taxonomic conundrums.
- Full Text:
- Date Issued: 2016
- Authors: Madeira, P T , Dray, F Allen , Coetzee, Julie A , Paterson, Iain D , Tipping, Philip W
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424765 , vital:72182 , xlink:href="https://doi.org/10.1016/j.sajb.2016.03.007"
- Description: 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. It is notoriously difficult to determine Azolla species based on morphology so genetic analyses were required to confirm the identity of the Azolla used by the agent. Extensive sampling was conducted and samples were sequenced at the trnL-trnF and trnG-trnR chloroplastic regions and the nuclear ITS1 region. Current literature reported A. filiculoides as the only Section Azolla species in southern Africa but 24 samples were identified as Azolla cristata, an introduced species within Section Azolla that was not used during host specificity trials. A. pinnata subsp. africana was only located at one site in southern Africa, while the alien A. pinnata subsp. asiatica was located at three. What was thought to be A. pinnata subsp. africana was in fact A. cristata, a closer relative of A. filiculoides and a suitable host according to specificity trials. This study confirms that S. rufinasus is a proficient Azolla taxonomist but also supports the use of molecular techniques for resolving taxonomic conundrums.
- Full Text:
- Date Issued: 2016
Eight decades of invasion by Chromolaena odorata (Asteraceae) and its biological control in West Africa: the story so far
- Aigbedion-Atalor, Pascal O, Adom, Medetissi, Day, Michael D, Uyi, Osariyekemwen, Egbon, Ikponmwosa N, Idemudia, I, Igbinosa, Igho B, Paterson, Iain D, Braimah, Haruna, Wilson, David D, Zachariades, Costas
- Authors: Aigbedion-Atalor, Pascal O , Adom, Medetissi , Day, Michael D , Uyi, Osariyekemwen , Egbon, Ikponmwosa N , Idemudia, I , Igbinosa, Igho B , Paterson, Iain D , Braimah, Haruna , Wilson, David D , Zachariades, Costas
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417450 , vital:71454 , xlink:href="https://doi.org/10.1080/09583157.2019.1670782"
- Description: Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae) is a perennial weedy shrub of neotropical origin and a serious biotic threat in its invasive range. The Asian-West Africa (AWA) biotype of C. odorata present in West Africa is both morphologically and genetically different from the southern African (SA) biotype. The AWA biotype was first introduced into Nigeria in the late 1930s and rapidly spread across West Africa. Currently, 12 of the 16 countries in West Africa have been invaded, with significant negative effects on indigenous flora and fauna. However, locals in West Africa have found several uses for the weed. As chemical, physical and other conventional methods were unsustainable, costly and largely ineffective, three biological control agents, Apion brunneonigrum (Coleoptera: Brentidae), Pareuchaetes pseudoinsulata (Lepidoptera: Erebidae) and Cecidochares connexa (Diptera: Tephritidae), have been released in West Africa between the 1970s and the early 2000s. However, only C. connexa and P. pseudoinsulata established, contributing to the control of the weed, in six and four countries in West Africa respectively. Limited research funding, the absence of post-release evaluations of the established agents, and the ‘conflict of interest’ status of C. odorata (i.e. being beneficial for local use but damaging to ecosystem services and agriculture), are serious factors deterring the overall biological control effort. Here, using historical records and field surveys, we examine the invasion history, spread, impacts, and management of C. odorata in West Africa and make recommendations for the sustainable management of C. odorata in the region.
- Full Text:
- Date Issued: 2019
- Authors: Aigbedion-Atalor, Pascal O , Adom, Medetissi , Day, Michael D , Uyi, Osariyekemwen , Egbon, Ikponmwosa N , Idemudia, I , Igbinosa, Igho B , Paterson, Iain D , Braimah, Haruna , Wilson, David D , Zachariades, Costas
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417450 , vital:71454 , xlink:href="https://doi.org/10.1080/09583157.2019.1670782"
- Description: Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae) is a perennial weedy shrub of neotropical origin and a serious biotic threat in its invasive range. The Asian-West Africa (AWA) biotype of C. odorata present in West Africa is both morphologically and genetically different from the southern African (SA) biotype. The AWA biotype was first introduced into Nigeria in the late 1930s and rapidly spread across West Africa. Currently, 12 of the 16 countries in West Africa have been invaded, with significant negative effects on indigenous flora and fauna. However, locals in West Africa have found several uses for the weed. As chemical, physical and other conventional methods were unsustainable, costly and largely ineffective, three biological control agents, Apion brunneonigrum (Coleoptera: Brentidae), Pareuchaetes pseudoinsulata (Lepidoptera: Erebidae) and Cecidochares connexa (Diptera: Tephritidae), have been released in West Africa between the 1970s and the early 2000s. However, only C. connexa and P. pseudoinsulata established, contributing to the control of the weed, in six and four countries in West Africa respectively. Limited research funding, the absence of post-release evaluations of the established agents, and the ‘conflict of interest’ status of C. odorata (i.e. being beneficial for local use but damaging to ecosystem services and agriculture), are serious factors deterring the overall biological control effort. Here, using historical records and field surveys, we examine the invasion history, spread, impacts, and management of C. odorata in West Africa and make recommendations for the sustainable management of C. odorata in the region.
- Full Text:
- Date Issued: 2019
Grasses as suitable targets for classical weed biological control
- Sutton, Guy F, Day, Michael D, Den Breeyen, Alana, Goolsby, J A, Cristofaro, M, McConnachie, Andrew J, Paterson, Iain D
- 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.
- Full Text:
- Date Issued: 2019
- 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.
- Full Text:
- Date Issued: 2019
The potential for biological control on cryptic plant invasions
- Canavan, Kim, Canavan, Susan, Harms, Nathan E, Lambertini, Carla, Paterson, Iain D, Thum, Ryan
- Authors: Canavan, Kim , Canavan, Susan , Harms, Nathan E , Lambertini, Carla , Paterson, Iain D , Thum, Ryan
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423562 , vital:72072 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104243"
- Description: Cryptic invasions can be defined as ‘the occurrence of an invasive species or genotype that was not previously recognised as alien in origin or not distinguished from other aliens’. Such invasions can result in negative impacts on the recipient ecosystems and disturb the evolutionary history of native plant populations. Many cryptic invasions have become so problematic that there is a need to implement control measures. This paper explores the potential for biological control to be implemented as a means of managing cryptic invasions. Firstly, the paper defines the different forms of cryptic invasion, differentiating between interspecific and intraspecific invasions; this hierarchy influences how to detect, study and ultimately implement biological control when cryptic invasions occur. Secondly, unique challenges associated with biological control programmes for cryptic invasions are addressed, including: the need for intraspecific level host specificity in agents, the occurrence of hybridisation between native species/lineages and the target weed, the role of enemy release in cryptic invasions in the presence of closely related native plant species/lineages, and a review of potential stakeholder conflicts of interest and legislation. Biological control of cryptic invasions has been shown to be possible, however the process will be more difficult and complex than controlling traditional targets and will likely take up more time and resources. If these challenges are overcome, then biological control programmes against cryptic invasions should be able to proceed and maintain the same standards as traditional biological control programmes.
- Full Text:
- Date Issued: 2020
- Authors: Canavan, Kim , Canavan, Susan , Harms, Nathan E , Lambertini, Carla , Paterson, Iain D , Thum, Ryan
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423562 , vital:72072 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104243"
- Description: Cryptic invasions can be defined as ‘the occurrence of an invasive species or genotype that was not previously recognised as alien in origin or not distinguished from other aliens’. Such invasions can result in negative impacts on the recipient ecosystems and disturb the evolutionary history of native plant populations. Many cryptic invasions have become so problematic that there is a need to implement control measures. This paper explores the potential for biological control to be implemented as a means of managing cryptic invasions. Firstly, the paper defines the different forms of cryptic invasion, differentiating between interspecific and intraspecific invasions; this hierarchy influences how to detect, study and ultimately implement biological control when cryptic invasions occur. Secondly, unique challenges associated with biological control programmes for cryptic invasions are addressed, including: the need for intraspecific level host specificity in agents, the occurrence of hybridisation between native species/lineages and the target weed, the role of enemy release in cryptic invasions in the presence of closely related native plant species/lineages, and a review of potential stakeholder conflicts of interest and legislation. Biological control of cryptic invasions has been shown to be possible, however the process will be more difficult and complex than controlling traditional targets and will likely take up more time and resources. If these challenges are overcome, then biological control programmes against cryptic invasions should be able to proceed and maintain the same standards as traditional biological control programmes.
- Full Text:
- Date Issued: 2020
Thermal plasticity and microevolution enhance establishment success and persistence of a water hyacinth biological control agent
- Griffith, Tamzin C, Paterson, Iain D, Owen, Candice A, Coetzee, Julie A
- Authors: Griffith, Tamzin C , Paterson, Iain D , Owen, Candice A , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424866 , vital:72190 , xlink:href="https://doi.org/10.1111/eea.12814"
- Description: Aspects of the thermal physiology of the water hyacinth biological control agent Eccritotarsus catarinensis Carvalho (Hemiptera: Miridae) have been extensively investigated over the past 20 years to understand and improve post-release establishment in the field. Thermal physiology studies predicted that the agent would not establish at a number of cold sites in South Africa, where it has nonetheless subsequently established and thrived. Recently, studies have begun to incorporate the plastic nature of insect thermal physiology into models of agent establishment. This study determined whether season and locality influenced the thermal physiology of two field populations of E. catarinensis, one collected from the hottest site where the agent has established in South Africa, and one from the coldest site. The thermal physiology of E. catarinensis was significantly influenced by season and site, demonstrating a degree of phenotypic plasticity, and that some post-release local adaptation to climatic conditions has occurred through microevolution. We then determined whether cold acclimation under laboratory conditions was possible. Successfully cold-acclimated E. catarinensis had a significantly lower critical thermal minimum (CTmin) compared to the field cold-acclimated population. This suggests that cold acclimation of agents could be conducted in the laboratory before future releases to improve their cold tolerance, thereby increasing their chance of establishment at cold sites and allowing further adaptation to colder climates to occur in the field. Although the thermal tolerance of E. catarinensis is limited by local adaptations to climatic conditions in the native range, the plastic nature of the insect's thermal physiology has allowed it to survive in the very different climatic conditions of the introduced range, and there has been some adaptive change to the insect's thermal tolerance since establishment. This study highlights the importance of plasticity and microevolutionary processes in the success of biological control agents under the novel climatic conditions in the introduced range.
- Full Text:
- Date Issued: 2019
- Authors: Griffith, Tamzin C , Paterson, Iain D , Owen, Candice A , Coetzee, Julie A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424866 , vital:72190 , xlink:href="https://doi.org/10.1111/eea.12814"
- Description: Aspects of the thermal physiology of the water hyacinth biological control agent Eccritotarsus catarinensis Carvalho (Hemiptera: Miridae) have been extensively investigated over the past 20 years to understand and improve post-release establishment in the field. Thermal physiology studies predicted that the agent would not establish at a number of cold sites in South Africa, where it has nonetheless subsequently established and thrived. Recently, studies have begun to incorporate the plastic nature of insect thermal physiology into models of agent establishment. This study determined whether season and locality influenced the thermal physiology of two field populations of E. catarinensis, one collected from the hottest site where the agent has established in South Africa, and one from the coldest site. The thermal physiology of E. catarinensis was significantly influenced by season and site, demonstrating a degree of phenotypic plasticity, and that some post-release local adaptation to climatic conditions has occurred through microevolution. We then determined whether cold acclimation under laboratory conditions was possible. Successfully cold-acclimated E. catarinensis had a significantly lower critical thermal minimum (CTmin) compared to the field cold-acclimated population. This suggests that cold acclimation of agents could be conducted in the laboratory before future releases to improve their cold tolerance, thereby increasing their chance of establishment at cold sites and allowing further adaptation to colder climates to occur in the field. Although the thermal tolerance of E. catarinensis is limited by local adaptations to climatic conditions in the native range, the plastic nature of the insect's thermal physiology has allowed it to survive in the very different climatic conditions of the introduced range, and there has been some adaptive change to the insect's thermal tolerance since establishment. This study highlights the importance of plasticity and microevolutionary processes in the success of biological control agents under the novel climatic conditions in the introduced range.
- Full Text:
- Date Issued: 2019
Population genetics of invasive and native Nymphaea mexicana Zuccarini: Taking the first steps to initiate a biological control programme in South Africa
- Reid, Megan, Naidu, Prinavin, Paterson, Iain D, Mangan, Rosie, Coetzee, Julie A
- Authors: Reid, Megan , Naidu, Prinavin , Paterson, Iain D , Mangan, Rosie , Coetzee, Julie A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419375 , vital:71638 , xlink:href="https://doi.org/10.1016/j.aquabot.2021.103372"
- Description: Nymphaea mexicana Zuccarini (Nympheaceae) (Mexican waterlily) is a rooted floating-leaved aquatic plant native to southern USA and Mexico that has become a problematic invasive alien plant in South Africa. Biological control is considered a desirable management strategy for the plant in South Africa. A good understanding of the genetic structure of invasive populations has been useful in other biological control programmes because taxonomic uncertainty about the target plant can result in natural enemies that are not adapted to the invasive populations being considered as potential agents. For N. mexicana, hybrids exist in the wild and horticultural trade, but identification is difficult, so understanding the genetic structure of populations is required to ensure that potential agents are collected off plants similar to invasive populations in South Africa. ISSR (inter-simple sequence repeats) analysis was used to determine whether invasive N. mexicana populations from South Africa were genetically similar to native range populations from USA or whether they were hybrids. Results from these analyses were matched with the morphotypes of each population based on petal colour, shape, and size. The genotypes suggested by the ISSR analyses corroborated the presence of both hybrid and pure forms of N. mexicana in South Africa. Populations of N. mexicana in the invaded range that are genetically similar to native range populations are more likely to be suitable for biological control, while other populations are likely to be hybrids formed by crossing of parents from the native range or within the horticultural trade, which may present difficulties for management using biocontrol.
- Full Text:
- Date Issued: 2021
- Authors: Reid, Megan , Naidu, Prinavin , Paterson, Iain D , Mangan, Rosie , Coetzee, Julie A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419375 , vital:71638 , xlink:href="https://doi.org/10.1016/j.aquabot.2021.103372"
- Description: Nymphaea mexicana Zuccarini (Nympheaceae) (Mexican waterlily) is a rooted floating-leaved aquatic plant native to southern USA and Mexico that has become a problematic invasive alien plant in South Africa. Biological control is considered a desirable management strategy for the plant in South Africa. A good understanding of the genetic structure of invasive populations has been useful in other biological control programmes because taxonomic uncertainty about the target plant can result in natural enemies that are not adapted to the invasive populations being considered as potential agents. For N. mexicana, hybrids exist in the wild and horticultural trade, but identification is difficult, so understanding the genetic structure of populations is required to ensure that potential agents are collected off plants similar to invasive populations in South Africa. ISSR (inter-simple sequence repeats) analysis was used to determine whether invasive N. mexicana populations from South Africa were genetically similar to native range populations from USA or whether they were hybrids. Results from these analyses were matched with the morphotypes of each population based on petal colour, shape, and size. The genotypes suggested by the ISSR analyses corroborated the presence of both hybrid and pure forms of N. mexicana in South Africa. Populations of N. mexicana in the invaded range that are genetically similar to native range populations are more likely to be suitable for biological control, while other populations are likely to be hybrids formed by crossing of parents from the native range or within the horticultural trade, which may present difficulties for management using biocontrol.
- Full Text:
- Date Issued: 2021
Pereskiophaga brasiliensis, a natural enemy of the invasive alien cactus Pereskia aculeata, is not suitably host specific for biological control in South Africa
- Paterson, Iain D, Muskett, Phillipa A, Mdodana, LL, Vitorino, M D
- Authors: Paterson, Iain D , Muskett, Phillipa A , Mdodana, LL , Vitorino, M D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417498 , vital:71458 , xlink:href="https://doi.org/10.1080/09583157.2019.1581132"
- Description: The stem-mining weevil, Pereskiophaga brasiliensis, was a candidate biological control agent for the invasive cactus Pereskia aculeata in South Africa. In host specificity trials, it developed on two indigenous test plant species under choice and no-choice conditions. Pereskiophaga brasiliensis is therefore not suitably host specific for release in South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Paterson, Iain D , Muskett, Phillipa A , Mdodana, LL , Vitorino, M D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417498 , vital:71458 , xlink:href="https://doi.org/10.1080/09583157.2019.1581132"
- Description: The stem-mining weevil, Pereskiophaga brasiliensis, was a candidate biological control agent for the invasive cactus Pereskia aculeata in South Africa. In host specificity trials, it developed on two indigenous test plant species under choice and no-choice conditions. Pereskiophaga brasiliensis is therefore not suitably host specific for release in South Africa.
- Full Text:
- Date Issued: 2019
Field-based ecological studies to assess prospective biological control agents for invasive alien plants: An example from giant rat's tail grass
- Sutton, Guy F, Canavan, Kim N, Day, Michael M, Paterson, Iain D
- 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.
- Full Text:
- Date Issued: 2021
- 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.
- Full Text:
- Date Issued: 2021
Interactions between two biological control agents and their target weed: a beetle, a bug and a cactus weed
- Mnqeta, Zezethu, Paterson, Iain D
- Authors: Mnqeta, Zezethu , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417475 , vital:71456 , xlink:href="https://doi.org/10.1080/09583157.2019.1631960"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien shrub introduced into South Africa from Brazil. The leaf-feeding beetle, Phenrica guerini Bechyne (Chrysomelidae), was released as a biological control agent in South Africa in 1991 followed by the stem-wilting bug, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), in 2014. This study investigated the interactions between the two agents under laboratory conditions. Potted plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species together. Four densities, ranging from 2 to 12 insects per plant were used. Cathorhitha schaffneri alone at low to moderate densities resulted in the same reduction in number of leaves and shoot length as when combine with P. guerini. At the highest density, C. schaffneri reduced the number of leaves significantly more than any treatment. Mortality of P. guerini was significantly higher than C. schaffneri at the highest density when in combination. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. It is recommended that C. schaffneri should be released at sites where P. guerini is not present. Extrapolation of laboratory-based studies into the field is often challenging, so mass-rearing and releases of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Date Issued: 2019
- Authors: Mnqeta, Zezethu , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417475 , vital:71456 , xlink:href="https://doi.org/10.1080/09583157.2019.1631960"
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien shrub introduced into South Africa from Brazil. The leaf-feeding beetle, Phenrica guerini Bechyne (Chrysomelidae), was released as a biological control agent in South Africa in 1991 followed by the stem-wilting bug, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), in 2014. This study investigated the interactions between the two agents under laboratory conditions. Potted plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species together. Four densities, ranging from 2 to 12 insects per plant were used. Cathorhitha schaffneri alone at low to moderate densities resulted in the same reduction in number of leaves and shoot length as when combine with P. guerini. At the highest density, C. schaffneri reduced the number of leaves significantly more than any treatment. Mortality of P. guerini was significantly higher than C. schaffneri at the highest density when in combination. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. It is recommended that C. schaffneri should be released at sites where P. guerini is not present. Extrapolation of laboratory-based studies into the field is often challenging, so mass-rearing and releases of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Date Issued: 2019
Evaluating the efficacy of Hypogeococcus sp. as a biological control agent of the cactaceous weed Cereus jamacaru in South Africa
- Sutton, Guy F, Klein, H, Paterson, Iain D
- Authors: Sutton, Guy F , Klein, H , 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.
- Full Text:
- Date Issued: 2018
- Authors: Sutton, Guy F , Klein, H , 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.
- Full Text:
- Date Issued: 2018
Prospects for biological control of cactus weeds in Namibia
- Paterson, Iain D, Manheimmer, C A, Zimmermann, H C
- Authors: Paterson, Iain D , Manheimmer, C A , Zimmermann, H C
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417522 , vital:71460 , xlink:href="https://doi.org/10.1080/09583157.2018.1562040"
- Description: Australia and South Africa have a long history of sharing successful biocontrol agents for cactus weeds but other countries, such as Namibia, could also benefit. There are four biological control agents that are widely utilised in South Africa and/or Australia for the control of 10 invasive alien Cactaceae in Namibia.
- Full Text:
- Date Issued: 2018
- Authors: Paterson, Iain D , Manheimmer, C A , Zimmermann, H C
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417522 , vital:71460 , xlink:href="https://doi.org/10.1080/09583157.2018.1562040"
- Description: Australia and South Africa have a long history of sharing successful biocontrol agents for cactus weeds but other countries, such as Namibia, could also benefit. There are four biological control agents that are widely utilised in South Africa and/or Australia for the control of 10 invasive alien Cactaceae in Namibia.
- Full Text:
- Date Issued: 2018
Encompassing the relative non-target risks from agents and their alien plant targets in biological control assessments
- Downey, Paul O, Paterson, Iain D
- Authors: Downey, Paul O , Paterson, Iain D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417940 , vital:71496 , xlink:href="https://doi.org/10.1007/s10526-016-9744-1"
- Description: Criticisms about the safety of biological control of alien plants has resulted in a risk-averse approach, where the risks posed by the agent are paramount and the risks posed by the alien plant are neglected. We argue that the risk associated with non-target damage from agents needs to be assessed relative to that of their target alien plants. A literature review of the non-target risks associated with biological control agents was undertaken in terms of the risk to native species from agents relative to the risk to native species from their alien plant targets. We then developed a framework that compares the consequence with the likelihood of non-target damage for both agents and their targets to provide an overall risk rating. Assessments of the risk of damage from both agents and their target alien plants will enable researchers, managers and policy makers to better assess the risks from biological control.
- Full Text:
- Date Issued: 2016
- Authors: Downey, Paul O , Paterson, Iain D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417940 , vital:71496 , xlink:href="https://doi.org/10.1007/s10526-016-9744-1"
- Description: Criticisms about the safety of biological control of alien plants has resulted in a risk-averse approach, where the risks posed by the agent are paramount and the risks posed by the alien plant are neglected. We argue that the risk associated with non-target damage from agents needs to be assessed relative to that of their target alien plants. A literature review of the non-target risks associated with biological control agents was undertaken in terms of the risk to native species from agents relative to the risk to native species from their alien plant targets. We then developed a framework that compares the consequence with the likelihood of non-target damage for both agents and their targets to provide an overall risk rating. Assessments of the risk of damage from both agents and their target alien plants will enable researchers, managers and policy makers to better assess the risks from biological control.
- Full Text:
- Date Issued: 2016
West African arthropods hold promise as biological control agents for an invasive tree in the Pacific Islands
- Paterson, Iain D, Paynter, Quentin, Neser, Stefan, Akpabey, FJ, Compton, Stephen G
- Authors: Paterson, Iain D , Paynter, Quentin , Neser, Stefan , Akpabey, FJ , Compton, Stephen G
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407119 , vital:70338 , xlink:href="https://hdl.handle.net/10520/EJC-639c91613"
- Description: African tulip tree, Spathodea campanulata Beauv. (Bignoniaceae), is a large tree of secondary forests, forest edges and savannas that is indigenous to Central and West Africa (Bidgood 1994). It has been widely utilised as an ornamental plant due to its beautiful flowers, fast growth and relative ease of cultivation, as a shade tree in parks and coffee plantations, and as a living fencepost (Francis 1990). Naturalisation has often followed cultivation of the plant, which is now established outside of the native range in Africa (Hedberg et al. 2006), the Caribbean (Francis 1990; Labrada and Medina 2009) and many Pacific islands (Meyer 2004), including Hawaii, Papua New Guinea, Fiji, Samoa, Tonga,Vanuatu and Tahiti (Lowe et al. 2000; Dovey et al. 2004; Labrada and Medina 2009). On some of these islands it has become a destructive weed, invading indigenous forests and having a severe impact on agricultural production (Labrada and Medina 2009; Larrue et al. 2014). This has resulted in African tulip tree being recognised as one of the 100 worst alien invasive species worldwide, along with only 30 other terrestrial plants (Lowe et al. 2000).
- Full Text:
- Date Issued: 2017
- Authors: Paterson, Iain D , Paynter, Quentin , Neser, Stefan , Akpabey, FJ , Compton, Stephen G
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407119 , vital:70338 , xlink:href="https://hdl.handle.net/10520/EJC-639c91613"
- Description: African tulip tree, Spathodea campanulata Beauv. (Bignoniaceae), is a large tree of secondary forests, forest edges and savannas that is indigenous to Central and West Africa (Bidgood 1994). It has been widely utilised as an ornamental plant due to its beautiful flowers, fast growth and relative ease of cultivation, as a shade tree in parks and coffee plantations, and as a living fencepost (Francis 1990). Naturalisation has often followed cultivation of the plant, which is now established outside of the native range in Africa (Hedberg et al. 2006), the Caribbean (Francis 1990; Labrada and Medina 2009) and many Pacific islands (Meyer 2004), including Hawaii, Papua New Guinea, Fiji, Samoa, Tonga,Vanuatu and Tahiti (Lowe et al. 2000; Dovey et al. 2004; Labrada and Medina 2009). On some of these islands it has become a destructive weed, invading indigenous forests and having a severe impact on agricultural production (Labrada and Medina 2009; Larrue et al. 2014). This has resulted in African tulip tree being recognised as one of the 100 worst alien invasive species worldwide, along with only 30 other terrestrial plants (Lowe et al. 2000).
- Full Text:
- Date Issued: 2017