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
A review of the biocontrol programmes against aquatic weeds in South Africa
- Coetzee, Julie A, Bownes, Angela, Martin, Grant D, Miller, Benjamin E, Smith, Rosalie, Weyl, Philip S R, Hill, Martin P
- Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D , Miller, Benjamin E , Smith, Rosalie , Weyl, Philip S R , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406965 , vital:70326 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a18"
- Description: Biological control (biocontrol) against invasive macrophytes is one of the longest standing programmes in South Africa, initiated in the 1970s against water hyacinth, Pontederia crassipes Mart. (Pontederiaceae). Since then, 15 agent species (13 insects, one mite and one pathogen) have been released against six weeds, most of which are floating macrophytes, with excellent levels of success. The release of the water hyacinth planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae) in particular, has improved biocontrol prospects for water hyacinth since 2018. In the last decade, however, a new suite of submerged and rooted emergent invasive macrophytes has been targeted. The first release against a submerged macrophyte in South Africa, and the first release against Brazilian waterweed, Egeria densa Planch. (Hydrocharitaceae), anywhere in the world, was achieved with the release of a leafmining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae). Yellow flag, Iris pseudacorus L. (Iridaceae) and Mexican waterlily, Nymphaea mexicana Zucc. (Nymphaeaceae), have also been targeted for biocontrol for the first time worldwide, and are in the early stages of agent development. Post-release evaluations, long term monitoring and controlled experiments have highlighted the need for a more holistic approach to managing aquatic invasive plants in South Africa, whose presence is largely driven by eutrophication, resulting in regime shifts between floating and submerged invaded states.
- Full Text:
- Date Issued: 2021
- Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D , Miller, Benjamin E , Smith, Rosalie , Weyl, Philip S R , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406965 , vital:70326 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a18"
- Description: Biological control (biocontrol) against invasive macrophytes is one of the longest standing programmes in South Africa, initiated in the 1970s against water hyacinth, Pontederia crassipes Mart. (Pontederiaceae). Since then, 15 agent species (13 insects, one mite and one pathogen) have been released against six weeds, most of which are floating macrophytes, with excellent levels of success. The release of the water hyacinth planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae) in particular, has improved biocontrol prospects for water hyacinth since 2018. In the last decade, however, a new suite of submerged and rooted emergent invasive macrophytes has been targeted. The first release against a submerged macrophyte in South Africa, and the first release against Brazilian waterweed, Egeria densa Planch. (Hydrocharitaceae), anywhere in the world, was achieved with the release of a leafmining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae). Yellow flag, Iris pseudacorus L. (Iridaceae) and Mexican waterlily, Nymphaea mexicana Zucc. (Nymphaeaceae), have also been targeted for biocontrol for the first time worldwide, and are in the early stages of agent development. Post-release evaluations, long term monitoring and controlled experiments have highlighted the need for a more holistic approach to managing aquatic invasive plants in South Africa, whose presence is largely driven by eutrophication, resulting in regime shifts between floating and submerged invaded states.
- Full Text:
- Date Issued: 2021
Advances in the regulation of weed biological control in South Africa
- Ivey, Philip, Hill, Martin P, Zachariades, Costas
- Authors: Ivey, Philip , Hill, Martin P , Zachariades, Costas
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416819 , vital:71388 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a24"
- Description: Regulation of biological control (biocontrol) is essential to ensure its continued safety and to enhance its acceptability as a key contributor to the management of damaging invasive alien plants in South Africa. Local researchers were concerned that regulators may become risk averse and over-cautious, thus preventing introductions of safe biocontrol agents, as bureaucratic impediments have contributed to the decline in the number of biocontrol releases in several other countries. In South Africa, the introduction of a transparent and inclusive review process has averted these concerns. Legislation in South Africa enables departments concerned with protecting environmental and agricultural resources, to work together to regulate potential risks. An interdepartmental committee, advised by independent specialists, facilitate the review of research into the safety of potential biocontrol agents. Regulators have reviewed and timeously assessed 26 potential biocontrol agents between 2013 and 2020. This has ensured that the considerable benefits from safe biocontrol agents are available for management of some of South Africa’s worst invasive alien plants. We review the system in South Africa and suggest possible improvements to the regulatory framework.
- Full Text:
- Date Issued: 2021
- Authors: Ivey, Philip , Hill, Martin P , Zachariades, Costas
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416819 , vital:71388 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a24"
- Description: Regulation of biological control (biocontrol) is essential to ensure its continued safety and to enhance its acceptability as a key contributor to the management of damaging invasive alien plants in South Africa. Local researchers were concerned that regulators may become risk averse and over-cautious, thus preventing introductions of safe biocontrol agents, as bureaucratic impediments have contributed to the decline in the number of biocontrol releases in several other countries. In South Africa, the introduction of a transparent and inclusive review process has averted these concerns. Legislation in South Africa enables departments concerned with protecting environmental and agricultural resources, to work together to regulate potential risks. An interdepartmental committee, advised by independent specialists, facilitate the review of research into the safety of potential biocontrol agents. Regulators have reviewed and timeously assessed 26 potential biocontrol agents between 2013 and 2020. This has ensured that the considerable benefits from safe biocontrol agents are available for management of some of South Africa’s worst invasive alien plants. We review the system in South Africa and suggest possible improvements to the regulatory framework.
- Full Text:
- Date Issued: 2021
Agathis bishopi (Hymenoptera: Braconidae) as a potential tool for detecting oranges infested with Thaumatotibia leucotreta (Lepidoptera: Tortricidae)
- Zimba, Kennedy J, Hill, Martin P, Moore, Sean D, Heshula, Unathi
- Authors: Zimba, Kennedy J , Hill, Martin P , Moore, Sean D , Heshula, Unathi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423955 , vital:72108 , xlink:href="https://doi.org/10.1007/s10905-015-9526-0"
- Description: In South Africa, Thaumatotibia leucotreta is a key pest of citrus impacting its production and trade. Detection of newly infested fruit by visual inspection is challenging and poses a risk of packing infested with healthy fruit for export. Agathis bishopi is a larval endoparasitoid of T. leucotreta, attacking early larval instars. Understanding how A. bishopi parasitoids locate fruit infested with their host is of interest for developing an efficient detector for T. leucotreta infested fruit. The response of female adult A. bishopi parasitoids to olfactory and visual cues associated with T. leucotreta infested fruit were evaluated using a Y-tube olfactometer and flight tunnel. Agathis bishopi parasitoids were strongly attracted to infested fruit over healthy fruit, either when only olfactory or combinations of visual and olfactory cues were offered. Among the four synthetic compounds tested, D-limonene and ocimene elicited a strong attraction to parasitoids with response rates of 92 % and 72 % respectively. A blend of four synthetic compounds simulating T. leucotreta infested fruit odour equally elicited strong attraction to parasitoids (84 % response rate). Attraction of parasitoids to infested fruit cues was heightened by prior experience, suggesting the occurrence of associative learning. Results from this study indicate that A. bishopi parasitoids mainly rely on olfactory cues in host habitat location and that D-limonene and ocimene are the major attractants in infested fruit volatiles. These findings and the potential for manipulating A. bishopi for detection of infested fruit in the packhouse are discussed.
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy J , Hill, Martin P , Moore, Sean D , Heshula, Unathi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423955 , vital:72108 , xlink:href="https://doi.org/10.1007/s10905-015-9526-0"
- Description: In South Africa, Thaumatotibia leucotreta is a key pest of citrus impacting its production and trade. Detection of newly infested fruit by visual inspection is challenging and poses a risk of packing infested with healthy fruit for export. Agathis bishopi is a larval endoparasitoid of T. leucotreta, attacking early larval instars. Understanding how A. bishopi parasitoids locate fruit infested with their host is of interest for developing an efficient detector for T. leucotreta infested fruit. The response of female adult A. bishopi parasitoids to olfactory and visual cues associated with T. leucotreta infested fruit were evaluated using a Y-tube olfactometer and flight tunnel. Agathis bishopi parasitoids were strongly attracted to infested fruit over healthy fruit, either when only olfactory or combinations of visual and olfactory cues were offered. Among the four synthetic compounds tested, D-limonene and ocimene elicited a strong attraction to parasitoids with response rates of 92 % and 72 % respectively. A blend of four synthetic compounds simulating T. leucotreta infested fruit odour equally elicited strong attraction to parasitoids (84 % response rate). Attraction of parasitoids to infested fruit cues was heightened by prior experience, suggesting the occurrence of associative learning. Results from this study indicate that A. bishopi parasitoids mainly rely on olfactory cues in host habitat location and that D-limonene and ocimene are the major attractants in infested fruit volatiles. These findings and the potential for manipulating A. bishopi for detection of infested fruit in the packhouse are discussed.
- Full Text:
- Date Issued: 2015
Agathis bishopi, a larval parasitoid of false codling moth Thaumatotibia leucotreta: laboratory rearing and effect of adult food on parasitism and longevity
- Zimba, Kennedy J, Moore, Sean D, Heshula, LU, Hill, Martin P
- Authors: Zimba, Kennedy J , Moore, Sean D , Heshula, LU , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406985 , vital:70328 , xlink:href="https://hdl.handle.net/10520/EJC185849"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae) is a koinobiont larval endoparasitoid of false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of economic importance on citrus in South Africa. In the field Agathis bishopi was found to parasitise up to 34 % of FCM larvae in fruit, reflecting reasonable biocontrol potential. Improving the rearing of A. bishopi would therefore complement the existing biocontrol strategies for FCM. In several parasitic wasps, sugar concentration and feeding duration has been shown to influence parasitism and longevity. However, their effect on parasitism and longevity of A. bishopi is unknown. In the present study a rearing protocol for A. bishopi is described, including evaluation of the effects of honey concentration on parasitoid longevity. On average, 18.2%of FCM larvae in rearing containers were parasitised under the rearing protocol described. Cotton wool, instead of paper towelling, as honey carrier for feeding parasitoids in rearing containers significantly increased parasitism and yield of offspring. Furthermore, longevity significantly increased with higher concentrations of honey. Maximum lifespan duration for male and female parasitoids was achieved when parasitoids were fed on 36 % (w/v) honey. Results from this study indicate that A. bishopi requires a sufficient concentration of sugar, coupled with frequent and prolonged feeding on a cotton wool substrate, in order to achieve maximum parasitism and longevity. Such information provides a basis for optimising mass-rearing and longevity of A. bishopi and parasitism of FCM in orchards.
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy J , Moore, Sean D , Heshula, LU , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406985 , vital:70328 , xlink:href="https://hdl.handle.net/10520/EJC185849"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae) is a koinobiont larval endoparasitoid of false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of economic importance on citrus in South Africa. In the field Agathis bishopi was found to parasitise up to 34 % of FCM larvae in fruit, reflecting reasonable biocontrol potential. Improving the rearing of A. bishopi would therefore complement the existing biocontrol strategies for FCM. In several parasitic wasps, sugar concentration and feeding duration has been shown to influence parasitism and longevity. However, their effect on parasitism and longevity of A. bishopi is unknown. In the present study a rearing protocol for A. bishopi is described, including evaluation of the effects of honey concentration on parasitoid longevity. On average, 18.2%of FCM larvae in rearing containers were parasitised under the rearing protocol described. Cotton wool, instead of paper towelling, as honey carrier for feeding parasitoids in rearing containers significantly increased parasitism and yield of offspring. Furthermore, longevity significantly increased with higher concentrations of honey. Maximum lifespan duration for male and female parasitoids was achieved when parasitoids were fed on 36 % (w/v) honey. Results from this study indicate that A. bishopi requires a sufficient concentration of sugar, coupled with frequent and prolonged feeding on a cotton wool substrate, in order to achieve maximum parasitism and longevity. Such information provides a basis for optimising mass-rearing and longevity of A. bishopi and parasitism of FCM in orchards.
- Full Text:
- Date Issued: 2015
Agents sans frontiers: cross-border aquatic weed biological control in the rivers of southern Mozambique
- Langa, Sílvia da Fátima, Hill, Martin P, Compton, Stephen G
- Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
- Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
- Full Text:
- Date Issued: 2020
- Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
- Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
- Full Text:
- Date Issued: 2020
An analysis of the fruit-sucking and fruit-piercing moth complex in citrus orchards in South Africa
- Goddard, M, Hill, Martin P, Moore, Sean D
- Authors: Goddard, M , Hill, Martin P , Moore, Sean D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407000 , vital:70329 , xlink:href="https://hdl.handle.net/10520/EJC-15072d6de5"
- Description: Fruit-piercing moths are a sporadic pest of citrus, especially in the Eastern Cape Province of South Africa, where the adults can cause significant damage in outbreak years. However, growers confuse fruit-piercing moths with fruit-sucking moths that do not cause primary damage. In this study we trapped these moths during the 2013–2015 growing seasons. A large number of diverse fruit-feeding moths were collected through weekly sampling in citrus orchards in the Eastern Cape and northern Limpopo provinces. Twenty-three species of fruit-feeding moth were trapped. However, only two were fruit-piercing species, capable of causing primary damage, namely Serrodes partita (Fabricius) (Erebidae) and Eudocima divitiosa (Walker) (Erebidae). Surprisingly S. partita, which has been reported as the main fruit-piercing moth pest of citrus in South Africa, comprised only 6.9 % of trap catches. The categorisation of moths as fruit-piercing or fruit-sucking (causing secondary damage) was confirmed by examining the morphological structures (tearing hooks and erectile barbs) of these moths’ proboscides. This study has shown that in non-outbreak seasons, S. partita comprised only a small percentage of fruit-feeding moths in citrus orchards. However, growers may misidentify the harmless fruit-sucking species as fruit-piercing species, and thus overestimate the density of fruit-piercing moths.
- Full Text:
- Date Issued: 2019
- Authors: Goddard, M , Hill, Martin P , Moore, Sean D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407000 , vital:70329 , xlink:href="https://hdl.handle.net/10520/EJC-15072d6de5"
- Description: Fruit-piercing moths are a sporadic pest of citrus, especially in the Eastern Cape Province of South Africa, where the adults can cause significant damage in outbreak years. However, growers confuse fruit-piercing moths with fruit-sucking moths that do not cause primary damage. In this study we trapped these moths during the 2013–2015 growing seasons. A large number of diverse fruit-feeding moths were collected through weekly sampling in citrus orchards in the Eastern Cape and northern Limpopo provinces. Twenty-three species of fruit-feeding moth were trapped. However, only two were fruit-piercing species, capable of causing primary damage, namely Serrodes partita (Fabricius) (Erebidae) and Eudocima divitiosa (Walker) (Erebidae). Surprisingly S. partita, which has been reported as the main fruit-piercing moth pest of citrus in South Africa, comprised only 6.9 % of trap catches. The categorisation of moths as fruit-piercing or fruit-sucking (causing secondary damage) was confirmed by examining the morphological structures (tearing hooks and erectile barbs) of these moths’ proboscides. This study has shown that in non-outbreak seasons, S. partita comprised only a small percentage of fruit-feeding moths in citrus orchards. However, growers may misidentify the harmless fruit-sucking species as fruit-piercing species, and thus overestimate the density of fruit-piercing moths.
- Full Text:
- Date Issued: 2019
Assessing the status of biological control as a management tool for suppression of invasive alien plants in South Africa
- Zachariades, Costas, Paterson, Iain D, Strathie, Lorraine W, Hill, Martin P, van Wilgen, Brian W
- Authors: Zachariades, Costas , Paterson, Iain D , Strathie, Lorraine W , Hill, Martin P , van Wilgen, Brian W
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59762 , vital:27646 , https://doi.org/10.4102/abc.v47i2.2142
- Description: Biological control of invasive alien plant (IAP) species is the use of introduced, highly selective natural enemies (usually herbivorous arthropods or pathogens) to control plants. It has been used in 130 countries as a valuable tool for the control of IAP species, with a total of over 550 biological control agents having been released (Winston et al. 2014). The benefits of biological control to natural ecosystems are significant (Van Driesch et al. 2010), with some specific examples of threatened indigenous species being protected by the action of biological control agents (Barton et al. 2007; Meyer, Fourdrigniez & Taputuarai 2011). Detailed analyses of programmes on biological control of IAPs have also clearly indicated that the risks of non-target effects from biological control agents are minimal (Fowler, Syrett & Hill 2000; Funasaki et al. 1988; Moran & Hoffmann 2015; Paynter et al. 2004; Pemberton 2000; Suckling & Sforza 2014). Less than 1% of all the agents released have a negative impact on non-target plant populations, and those that do could have been predicted to do so, and would not be released today (Suckling & Sforza 2014).
- Full Text:
- Date Issued: 2017
- Authors: Zachariades, Costas , Paterson, Iain D , Strathie, Lorraine W , Hill, Martin P , van Wilgen, Brian W
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59762 , vital:27646 , https://doi.org/10.4102/abc.v47i2.2142
- Description: Biological control of invasive alien plant (IAP) species is the use of introduced, highly selective natural enemies (usually herbivorous arthropods or pathogens) to control plants. It has been used in 130 countries as a valuable tool for the control of IAP species, with a total of over 550 biological control agents having been released (Winston et al. 2014). The benefits of biological control to natural ecosystems are significant (Van Driesch et al. 2010), with some specific examples of threatened indigenous species being protected by the action of biological control agents (Barton et al. 2007; Meyer, Fourdrigniez & Taputuarai 2011). Detailed analyses of programmes on biological control of IAPs have also clearly indicated that the risks of non-target effects from biological control agents are minimal (Fowler, Syrett & Hill 2000; Funasaki et al. 1988; Moran & Hoffmann 2015; Paynter et al. 2004; Pemberton 2000; Suckling & Sforza 2014). Less than 1% of all the agents released have a negative impact on non-target plant populations, and those that do could have been predicted to do so, and would not be released today (Suckling & Sforza 2014).
- Full Text:
- Date Issued: 2017
Baculovirus-based strategies for the management of insect pests: a focus on development and application in South Africa
- Knox, Caroline M, Moore, Sean D, Luke, Garry, Hill, Martin P
- Authors: Knox, Caroline M , Moore, Sean D , Luke, Garry , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416829 , vital:71389 , xlink:href="https://doi.org/10.1080/09583157.2014.949222"
- Description: There is growing concern among governments, scientists, agricultural practitioners and the general public regarding the negative implications of widespread synthetic chemical pesticide application for the control of crop pests. As a result, baculovirus biopesticides are gaining popularity as components of integrated pest management (IPM) programmes in many countries despite several disadvantages related to slow speed of kill, limited host range and complex large scale production. In South Africa, baculoviruses are incorporated into IPM programmes for the control of crop pests in the field, and recent bioprospecting has led to the characterisation of several novel isolates with the potential to be formulated as commercial products. This contribution will provide an overview of the use of baculoviruses against insect pests in South Africa, as well as research and development efforts aimed at broadening their application as biocontrol agents. Challenges faced by researchers in developmental projects as well as potential users of baculoviruses as biopesticides in the field are also discussed.
- Full Text:
- Date Issued: 2015
- Authors: Knox, Caroline M , Moore, Sean D , Luke, Garry , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416829 , vital:71389 , xlink:href="https://doi.org/10.1080/09583157.2014.949222"
- Description: There is growing concern among governments, scientists, agricultural practitioners and the general public regarding the negative implications of widespread synthetic chemical pesticide application for the control of crop pests. As a result, baculovirus biopesticides are gaining popularity as components of integrated pest management (IPM) programmes in many countries despite several disadvantages related to slow speed of kill, limited host range and complex large scale production. In South Africa, baculoviruses are incorporated into IPM programmes for the control of crop pests in the field, and recent bioprospecting has led to the characterisation of several novel isolates with the potential to be formulated as commercial products. This contribution will provide an overview of the use of baculoviruses against insect pests in South Africa, as well as research and development efforts aimed at broadening their application as biocontrol agents. Challenges faced by researchers in developmental projects as well as potential users of baculoviruses as biopesticides in the field are also discussed.
- Full Text:
- Date Issued: 2015
Beauveria and Metarhizium against false codling moth (Lepidoptera: Tortricidae): a step towards selecting isolates for potential development of a mycoinsecticide
- Coombes, Candice A, Hill, Martin P, Moore, Sean D, Dames, Joanna F, Fullard, T
- Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F , Fullard, T
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405757 , vital:70203 , xlink:href="https://hdl.handle.net/10520/EJC167505"
- Description: False codling moth, Thaumatotibia leucotreta Meyrick (1912) (Lepidoptera: Tortricidae), can cause both pre- and post-harvest damage to citrus fruit. Not only can this result in reduced crop yield, but more importantly because of the moth's endemism to sub-Saharan Africa, it is classified as a phytosanitary pest by many export markets. An entire consignment of citrus may be rejected in the presence of a single moth (Moore 2012). Since the bulk of citrus fruit production in South Africa is exported, the control of T. leucotreta is critical (Citrus Growers Association, South Africa 2012). Traditionally, control has been achieved through the use of chemical insecticides; however, residue restrictions, resistance development and concerns about environmental pollution have substantially reduced the dependence on chemical pesticides in citrus. Research on T. leucotreta control has therefore focused on the use of biological organisms (e.g. parasitoids and viruses), which are used as control agents within an integrated pest management (IPM) programme in citrus. These biological control agents, however, only targeted the aboveground life stages of the pest, not the soil-dwelling life stages (late fifth instars, prepupae, pupae), which is the subject of this contribution (Moore 2012).
- Full Text:
- Date Issued: 2015
- Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F , Fullard, T
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405757 , vital:70203 , xlink:href="https://hdl.handle.net/10520/EJC167505"
- Description: False codling moth, Thaumatotibia leucotreta Meyrick (1912) (Lepidoptera: Tortricidae), can cause both pre- and post-harvest damage to citrus fruit. Not only can this result in reduced crop yield, but more importantly because of the moth's endemism to sub-Saharan Africa, it is classified as a phytosanitary pest by many export markets. An entire consignment of citrus may be rejected in the presence of a single moth (Moore 2012). Since the bulk of citrus fruit production in South Africa is exported, the control of T. leucotreta is critical (Citrus Growers Association, South Africa 2012). Traditionally, control has been achieved through the use of chemical insecticides; however, residue restrictions, resistance development and concerns about environmental pollution have substantially reduced the dependence on chemical pesticides in citrus. Research on T. leucotreta control has therefore focused on the use of biological organisms (e.g. parasitoids and viruses), which are used as control agents within an integrated pest management (IPM) programme in citrus. These biological control agents, however, only targeted the aboveground life stages of the pest, not the soil-dwelling life stages (late fifth instars, prepupae, pupae), which is the subject of this contribution (Moore 2012).
- Full Text:
- Date Issued: 2015
Best of both worlds: The thermal physiology of Hydrellia egeriae, a biological control agent for the submerged aquatic weed, Egeria densa in South Africa
- Smith, Rosali, Coetzee, Julie A, Hill, Martin P
- Authors: Smith, Rosali , Coetzee, Julie A , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417913 , vital:71494 , xlink:href="https://doi.org/10.1007/s10526-022-10142-w"
- Description: The submerged aquatic weed, Egeria densa Planch. (Hydrocharitaceae) or Brazilian waterweed, is a secondary invader of eutrophic freshwater systems in South Africa, following the successful management of floating aquatic weeds. In 2018, the leaf and stem-mining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae), was released against E. densa, the first agent released against a submerged aquatic weed in South Africa. During its life stages, the biological control agent is exposed to two environments, air and water. The thermal physiology of both life stages was investigated to optimize agent establishment through fine-tuned release strategies. The thermal physiological limits of H. egeriae encompassed its host plant’s optimal temperature range of 10 to 35 °C, with lower and upper critical temperatures of 2.6 to 47.0 °C, lower and upper lethal temperatures of − 5.6 and 40.6 °C for adults, and − 6.3 to 41.3 °C for larvae. Results from development time experiments and degree-day accumulation showed that the agent is capable of establishing at all E. densa sites in South Africa, with between 6.9 and 8.3 generations per year. However, cold temperatures (14 °C) prolonged the agent’s development time to three months, allowing it to only develop through one generation in winter. Predictions obtained from laboratory thermal physiology experiments corroborates field data, where the agent has established at all the sites it was released.
- Full Text:
- Date Issued: 2022
- Authors: Smith, Rosali , Coetzee, Julie A , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417913 , vital:71494 , xlink:href="https://doi.org/10.1007/s10526-022-10142-w"
- Description: The submerged aquatic weed, Egeria densa Planch. (Hydrocharitaceae) or Brazilian waterweed, is a secondary invader of eutrophic freshwater systems in South Africa, following the successful management of floating aquatic weeds. In 2018, the leaf and stem-mining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae), was released against E. densa, the first agent released against a submerged aquatic weed in South Africa. During its life stages, the biological control agent is exposed to two environments, air and water. The thermal physiology of both life stages was investigated to optimize agent establishment through fine-tuned release strategies. The thermal physiological limits of H. egeriae encompassed its host plant’s optimal temperature range of 10 to 35 °C, with lower and upper critical temperatures of 2.6 to 47.0 °C, lower and upper lethal temperatures of − 5.6 and 40.6 °C for adults, and − 6.3 to 41.3 °C for larvae. Results from development time experiments and degree-day accumulation showed that the agent is capable of establishing at all E. densa sites in South Africa, with between 6.9 and 8.3 generations per year. However, cold temperatures (14 °C) prolonged the agent’s development time to three months, allowing it to only develop through one generation in winter. Predictions obtained from laboratory thermal physiology experiments corroborates field data, where the agent has established at all the sites it was released.
- Full Text:
- Date Issued: 2022
Best practices in the use and exchange of microorganism biological control genetic resources
- Mason, Peter G, Hill, Martin P, Smith, David, Silvestri, Luciano C, Weyl, Philip S R, Brodeur, Jacques, Vitorino, Marcello Diniz
- Authors: Mason, Peter G , Hill, Martin P , Smith, David , Silvestri, Luciano C , Weyl, Philip S R , Brodeur, Jacques , Vitorino, Marcello Diniz
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417927 , vital:71495 , xlink:href="https://doi.org/10.1007/s10526-023-10197-3"
- Description: The Nagoya Protocol actions the third objective of the Convention on Biological Diversity and provides a framework to effectively implement the fair and equitable sharing of benefits arising out of the use of genetic resources. This includes microorganisms used as biological control agents. Thus biological control practitioners must comply with access and benefit-sharing regulations that are implemented by countries providing microbial biological control agents. A review of best practices and guidance for the use and exchange of microorganisms used for biological control has been prepared by the IOBC Global Commission on Biological Control and Access and Benefit-Sharing to demonstrate commitment to comply with access and benefit-sharing requirements, and to reassure the international community that biological control is a very successful and environmentally safe pest management strategy that uses biological resources responsibly and sustainably. We propose that best practices include the following elements: collaboration to facilitate information exchange about the availability of microbial biological control agents and where they may be sourced; freely sharing available knowledge in databases about successes and failures; collaborative research with provider countries to develop capacity; and production technology transfer to provide economic opportunities. We recommend the use of model concept agreements for accessing microorganisms for scientific research and non-commercial release into nature where access and benefit-sharing regulations exist and where regulations are not restrictive or do not exist. We also recommend a model agreement for deposition of microbial biological control agents into culture collections.
- Full Text:
- Date Issued: 2023
- Authors: Mason, Peter G , Hill, Martin P , Smith, David , Silvestri, Luciano C , Weyl, Philip S R , Brodeur, Jacques , Vitorino, Marcello Diniz
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417927 , vital:71495 , xlink:href="https://doi.org/10.1007/s10526-023-10197-3"
- Description: The Nagoya Protocol actions the third objective of the Convention on Biological Diversity and provides a framework to effectively implement the fair and equitable sharing of benefits arising out of the use of genetic resources. This includes microorganisms used as biological control agents. Thus biological control practitioners must comply with access and benefit-sharing regulations that are implemented by countries providing microbial biological control agents. A review of best practices and guidance for the use and exchange of microorganisms used for biological control has been prepared by the IOBC Global Commission on Biological Control and Access and Benefit-Sharing to demonstrate commitment to comply with access and benefit-sharing requirements, and to reassure the international community that biological control is a very successful and environmentally safe pest management strategy that uses biological resources responsibly and sustainably. We propose that best practices include the following elements: collaboration to facilitate information exchange about the availability of microbial biological control agents and where they may be sourced; freely sharing available knowledge in databases about successes and failures; collaborative research with provider countries to develop capacity; and production technology transfer to provide economic opportunities. We recommend the use of model concept agreements for accessing microorganisms for scientific research and non-commercial release into nature where access and benefit-sharing regulations exist and where regulations are not restrictive or do not exist. We also recommend a model agreement for deposition of microbial biological control agents into culture collections.
- Full Text:
- Date Issued: 2023
Biological control of Salvinia molesta in South Africa revisited
- Martin, Grant D, Coetzee, Julie A, Weyl, Philip S R, Parkinson, Matthew C, Hill, Martin P
- Authors: Martin, Grant D , Coetzee, Julie A , Weyl, Philip S R , Parkinson, Matthew C , Hill, Martin P
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103878 , vital:32318 , https://doi.org/10.1016/j.biocontrol.2018.06.011
- Description: The aquatic weed Salvinia molesta D.S. Mitch. (Salviniaceae) was first recorded in South Africa in the early 1900s, and by the 1960s was regarded as one of South Africa’s worst aquatic weeds. Following the release of the weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae) in 1985, the weed is now considered under successful biological control. However, the post-release evaluation of this biological control programme has been ad hoc, therefore, to assess the efficacy of the agent, annual quantitative surveys of South African freshwater systems have been undertaken since 2008. Over the last ten years, of the 57 S. molesta sites visited annually in South Africa, the weevil has established at all of them. Eighteen sites are under successful biological control, where the weed no longer poses a threat to the system and 19 are under substantial biological control, where biological control has reduced the impact of the weed. Since 2008, the average percentage weed cover at sites has declined significantly from 51–100% cover to 0–5% cover in 2017 (R2 = 0.78; P < 0.05). Observations of site-specific characteristics suggest that biological control is most effective at small sites and more difficult at larger and shaded sites. Our findings show that S. molesta remains under good biological control in South Africa, however, some sites require intermittent strategic management, such as augmentative releases of C. salviniae.
- Full Text:
- Date Issued: 2018
- Authors: Martin, Grant D , Coetzee, Julie A , Weyl, Philip S R , Parkinson, Matthew C , Hill, Martin P
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103878 , vital:32318 , https://doi.org/10.1016/j.biocontrol.2018.06.011
- Description: The aquatic weed Salvinia molesta D.S. Mitch. (Salviniaceae) was first recorded in South Africa in the early 1900s, and by the 1960s was regarded as one of South Africa’s worst aquatic weeds. Following the release of the weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae) in 1985, the weed is now considered under successful biological control. However, the post-release evaluation of this biological control programme has been ad hoc, therefore, to assess the efficacy of the agent, annual quantitative surveys of South African freshwater systems have been undertaken since 2008. Over the last ten years, of the 57 S. molesta sites visited annually in South Africa, the weevil has established at all of them. Eighteen sites are under successful biological control, where the weed no longer poses a threat to the system and 19 are under substantial biological control, where biological control has reduced the impact of the weed. Since 2008, the average percentage weed cover at sites has declined significantly from 51–100% cover to 0–5% cover in 2017 (R2 = 0.78; P < 0.05). Observations of site-specific characteristics suggest that biological control is most effective at small sites and more difficult at larger and shaded sites. Our findings show that S. molesta remains under good biological control in South Africa, however, some sites require intermittent strategic management, such as augmentative releases of C. salviniae.
- Full Text:
- Date Issued: 2018
Biological control of water lettuce, Pistia stratiotes L., facilitates macroinvertebrate biodiversity recovery: a mesocosm study
- Coetzee, Julie A, Langa, Susana D, Motitsoe, Samuel F, Hill, Martin P
- Authors: Coetzee, Julie A , Langa, Susana D , Motitsoe, Samuel F , Hill, Martin P
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423967 , vital:72112 , xlink:href="https://doi.org/10.1007/s10750-020-04369-w"
- Description: Floating aquatic weed infestations have negative socio-economic and environmental consequences to the ecosystems they invade. Despite the long history of invasion by macrophytes, only a few studies focus on their impacts on biodiversity, while the ecological benefits of biological control programmes against these species have been poorly quantified. We investigated the process of biotic homogenization following invasion by Pistia stratiotes on aquatic biodiversity, and recovery provided by biological control of this weed. Biotic homogenization is the increased similarity of biota as a result of introductions of non-native species. The study quantified the effect of P. stratiotes, and its biological control through the introduction of the weevil, Neohydronomus affinis on recruitment of benthic macroinvertebrates to artificial substrates. Mats of P. stratiotes altered the community composition and reduced diversity of benthic macroinvertebrates in comparison to an uninvaded control. However, reduction in percentage cover of the weed through biological control resulted in a significant increase in dissolved oxygen, and recovery of the benthic macroinvertebrate community that was comparable to the uninvaded state. This highlights the process of homogenization by an invasive macrophyte, providing a justification for sustained ecological and restoration efforts in the biological control of P. stratiotes where this plant is problematic.
- Full Text:
- Date Issued: 2020
- Authors: Coetzee, Julie A , Langa, Susana D , Motitsoe, Samuel F , Hill, Martin P
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423967 , vital:72112 , xlink:href="https://doi.org/10.1007/s10750-020-04369-w"
- Description: Floating aquatic weed infestations have negative socio-economic and environmental consequences to the ecosystems they invade. Despite the long history of invasion by macrophytes, only a few studies focus on their impacts on biodiversity, while the ecological benefits of biological control programmes against these species have been poorly quantified. We investigated the process of biotic homogenization following invasion by Pistia stratiotes on aquatic biodiversity, and recovery provided by biological control of this weed. Biotic homogenization is the increased similarity of biota as a result of introductions of non-native species. The study quantified the effect of P. stratiotes, and its biological control through the introduction of the weevil, Neohydronomus affinis on recruitment of benthic macroinvertebrates to artificial substrates. Mats of P. stratiotes altered the community composition and reduced diversity of benthic macroinvertebrates in comparison to an uninvaded control. However, reduction in percentage cover of the weed through biological control resulted in a significant increase in dissolved oxygen, and recovery of the benthic macroinvertebrate community that was comparable to the uninvaded state. This highlights the process of homogenization by an invasive macrophyte, providing a justification for sustained ecological and restoration efforts in the biological control of P. stratiotes where this plant is problematic.
- Full Text:
- Date Issued: 2020
Biology and rearing of Ectomyeolis ceratoniae Zeller (Lepidoptera: Pyralidae) carob moth, a pest of multiple crops in South Africa
- Thackeray, S R, Moore, Sean D, Strathie, Lorraine W, Kirkman, W, Hill, Martin P
- Authors: Thackeray, S R , Moore, Sean D , Strathie, Lorraine W , Kirkman, W , Hill, Martin P
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59799 , vital:27652 , https://doi.org/10.4001/003.025.0474
- Description: Ectomyeolis ceratoniae Zeller (Lepidoptera: Pyralidae), carob moth, is a pest of several crops in South Africa. A laboratory culture was established from field-collected larvae infesting mummified pecan nuts. Biological parameters of larvae reared on an artificial diet were measured. The insect goes through five larval instars, and the head capsule sizes of the five instars were determined to be <0.34 mm, 0.35-0.64 mm, 0.65-0.94 mm, 0.95-1.14 mm and >0.15 mm for the five instars, respectively. The insect was reared individually and communally in glass vials, the latter to develop a mass-rearing technique. Developmental time from neonate to pupa was significantly slower when larvae were individually reared (38.18 ±1.2 days) compared to when they were communally reared (24.6 ± 0.65 days). A microsporidian infection (Nosema sp.) was recorded in the culture, causing significantly (fy6 = 14.99, P = 0.0082) higher mortality of communally reared larvae (76.25 % ± 11.87) than individually reared larvae (24.9 % ± 9.6).
- Full Text:
- Date Issued: 2017
- Authors: Thackeray, S R , Moore, Sean D , Strathie, Lorraine W , Kirkman, W , Hill, Martin P
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59799 , vital:27652 , https://doi.org/10.4001/003.025.0474
- Description: Ectomyeolis ceratoniae Zeller (Lepidoptera: Pyralidae), carob moth, is a pest of several crops in South Africa. A laboratory culture was established from field-collected larvae infesting mummified pecan nuts. Biological parameters of larvae reared on an artificial diet were measured. The insect goes through five larval instars, and the head capsule sizes of the five instars were determined to be <0.34 mm, 0.35-0.64 mm, 0.65-0.94 mm, 0.95-1.14 mm and >0.15 mm for the five instars, respectively. The insect was reared individually and communally in glass vials, the latter to develop a mass-rearing technique. Developmental time from neonate to pupa was significantly slower when larvae were individually reared (38.18 ±1.2 days) compared to when they were communally reared (24.6 ± 0.65 days). A microsporidian infection (Nosema sp.) was recorded in the culture, causing significantly (fy6 = 14.99, P = 0.0082) higher mortality of communally reared larvae (76.25 % ± 11.87) than individually reared larvae (24.9 % ± 9.6).
- Full Text:
- Date Issued: 2017
Changes in chemical composition of essential oils from leaves of different Lantana camara L. (Verbenaceae) varieties after feeding by the introduced biological control agent, Falconia intermedia Distant (Hemiptera: Miridae)
- Ngxande-Koza, S W, Heshula, L U P, Hill, Martin P
- Authors: Ngxande-Koza, S W , Heshula, L U P , Hill, Martin P
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59834 , vital:27664 , https://doi.org/10.4001/003.025.0462
- Description: Lantana camara L. (Verbenaceae) is one of the most problematic plant invaders in South Africa and has been targeted for biological control for over 50 years. Essential oil constituents which often change in response to insect herbivory are reported to play a crucial role in plant-insect interactions. However, nothing is known about the chemical profiles of essential oils of L. camara varieties in South Africa and how this changes under herbivory. Therefore, essential oils were collected using hydrodistillation from undamaged and insect-damaged leaves of four L. camara varieties and analysed using gas chromatography-mass spectrometry to elucidate their chemical profiles. A total of 163 compounds were identified from the undamaged leaves of the various L. camara varieties. Feeding by the biocontrol agent Falconia intermedia Distant (Hemiptera: Miridae) resulted in changes in the quality and quantity of chemical constituents of the essential oils. Only 75 compounds were identified from the insect-damaged leaves of L. camara varieties. Terpenes were the major components across the varieties, while caryophyllene, hexane, naphthalene, copaene and a-caryophyllene were common in all the varieties tested from both undamaged and insect-damaged leaves. Results from this study indicated the chemical distinctiveness of the Whitney Farm variety from other varieties. The changes in chemical concentrations indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. These inductions following the feeding by F. intermedia could be having a negative impact on the success of biological control against L. camara varieties. However, the focus of this paper is to report on the chemical baseline of L. camara varieties. Hence, comparisons of chemical compound concentrations of L. camara essential oils tested and the feeding-induced changes with respect to their quality and quantity are discussed.
- Full Text:
- Date Issued: 2017
- Authors: Ngxande-Koza, S W , Heshula, L U P , Hill, Martin P
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59834 , vital:27664 , https://doi.org/10.4001/003.025.0462
- Description: Lantana camara L. (Verbenaceae) is one of the most problematic plant invaders in South Africa and has been targeted for biological control for over 50 years. Essential oil constituents which often change in response to insect herbivory are reported to play a crucial role in plant-insect interactions. However, nothing is known about the chemical profiles of essential oils of L. camara varieties in South Africa and how this changes under herbivory. Therefore, essential oils were collected using hydrodistillation from undamaged and insect-damaged leaves of four L. camara varieties and analysed using gas chromatography-mass spectrometry to elucidate their chemical profiles. A total of 163 compounds were identified from the undamaged leaves of the various L. camara varieties. Feeding by the biocontrol agent Falconia intermedia Distant (Hemiptera: Miridae) resulted in changes in the quality and quantity of chemical constituents of the essential oils. Only 75 compounds were identified from the insect-damaged leaves of L. camara varieties. Terpenes were the major components across the varieties, while caryophyllene, hexane, naphthalene, copaene and a-caryophyllene were common in all the varieties tested from both undamaged and insect-damaged leaves. Results from this study indicated the chemical distinctiveness of the Whitney Farm variety from other varieties. The changes in chemical concentrations indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. These inductions following the feeding by F. intermedia could be having a negative impact on the success of biological control against L. camara varieties. However, the focus of this paper is to report on the chemical baseline of L. camara varieties. Hence, comparisons of chemical compound concentrations of L. camara essential oils tested and the feeding-induced changes with respect to their quality and quantity are discussed.
- Full Text:
- Date Issued: 2017
Characterisation of novel CrleGV isolates for false codling moth control-lessons learnt from codling moth resistance to CpGV.
- Opoku-Debrah, John, Moore, Sean, Hill, Martin P, Knox, Caroline
- Authors: Opoku-Debrah, John , Moore, Sean , Hill, Martin P , Knox, Caroline
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425414 , vital:72237 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20133257674"
- Description: Recently some codling moth, Cydia pomonella, populations in Europe developed resistance to CpGV. In order to prepare for the possibility of a similar occurrence with the false codling moth, Thaumatotibia leucotreta, in South Africa, a search was conducted for novel CrleGV isolates. Through overcrowding, outbreaks of novel isolates were recorded from laboratory populations of five geographically distinct host populations. The genetic novelty of these and two commercially available isolates was confirmed through restriction enzyme analysis and sequence analysis of the granulin and egt genes. Phylogenetic analysis showed the existence of two CrleGV-SA genome types. Significant differences in virulence were also shown between certain isolates against certain host populations.
- Full Text:
- Date Issued: 2013
- Authors: Opoku-Debrah, John , Moore, Sean , Hill, Martin P , Knox, Caroline
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425414 , vital:72237 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20133257674"
- Description: Recently some codling moth, Cydia pomonella, populations in Europe developed resistance to CpGV. In order to prepare for the possibility of a similar occurrence with the false codling moth, Thaumatotibia leucotreta, in South Africa, a search was conducted for novel CrleGV isolates. Through overcrowding, outbreaks of novel isolates were recorded from laboratory populations of five geographically distinct host populations. The genetic novelty of these and two commercially available isolates was confirmed through restriction enzyme analysis and sequence analysis of the granulin and egt genes. Phylogenetic analysis showed the existence of two CrleGV-SA genome types. Significant differences in virulence were also shown between certain isolates against certain host populations.
- Full Text:
- Date Issued: 2013
Chlorophyll fluorometry as a method of determining the effectiveness of a biological control agent in post-release evaluations
- Miller, Benjamin E, Coetzee, Julie A, Hill, Martin P
- Authors: Miller, Benjamin E , Coetzee, Julie A , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417438 , vital:71453 , xlink:href="https://doi.org/10.1080/09583157.2019.1656165"
- Description: The impact of the planthopper Megamelus scutellaris, a biocontrol agent of water hyacinth in South Africa, was assessed using chlorophyll fluorometry in a greenhouse study under two different eutrophic nutrient treatments and agent densities (high and low). The results indicated that plants grown in low nutrients with high densities of M. scutellaris showed the greatest reduction in the fluorescence parameters Fv/Fm and PIabs. The successful use of chlorophyll fluorometry for the detection of subtle insect damage to water hyacinth leaves could have future application in post-release studies to measure the impact of M. scutellaris in the field.
- Full Text:
- Date Issued: 2019
- Authors: Miller, Benjamin E , Coetzee, Julie A , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417438 , vital:71453 , xlink:href="https://doi.org/10.1080/09583157.2019.1656165"
- Description: The impact of the planthopper Megamelus scutellaris, a biocontrol agent of water hyacinth in South Africa, was assessed using chlorophyll fluorometry in a greenhouse study under two different eutrophic nutrient treatments and agent densities (high and low). The results indicated that plants grown in low nutrients with high densities of M. scutellaris showed the greatest reduction in the fluorescence parameters Fv/Fm and PIabs. The successful use of chlorophyll fluorometry for the detection of subtle insect damage to water hyacinth leaves could have future application in post-release studies to measure the impact of M. scutellaris in the field.
- Full Text:
- Date Issued: 2019
Community entomology: insects, science and society
- Weaver, Kim N, Hill, Jaclyn M, Martin, Grant D, Paterson, Iain D, Coetzee, Julie A, Hill, Martin P
- Authors: Weaver, Kim N , Hill, Jaclyn M , Martin, Grant D , Paterson, Iain D , Coetzee, Julie A , Hill, Martin P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123343 , vital:35429 , https://hdl.handle.net/10520/EJC-c859bebd5
- Description: Educative outreach programmes have been found to be effective ways in which to raise awareness around basic scientific concepts. The Biological Control Research Group (BCRG) in the Department of Zoology and Entomology at Rhodes University, South Africa, is involved in community engaged initiatives that aim to be interactive and informative around entomology, and more specifically, the use of biological control against invasive alien plants. As a higher education institution, Rhodes University has a civic responsibility to engage with local communities and work with them around local challenges. Three groups of activities undertaken by the BCRG in partnership with local schools and other community partners are described and assessed in this paper as a way of assessing them and exploring future research areas around the aims and outcomes of these programmes.
- Full Text:
- Date Issued: 2017
- Authors: Weaver, Kim N , Hill, Jaclyn M , Martin, Grant D , Paterson, Iain D , Coetzee, Julie A , Hill, Martin P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123343 , vital:35429 , https://hdl.handle.net/10520/EJC-c859bebd5
- Description: Educative outreach programmes have been found to be effective ways in which to raise awareness around basic scientific concepts. The Biological Control Research Group (BCRG) in the Department of Zoology and Entomology at Rhodes University, South Africa, is involved in community engaged initiatives that aim to be interactive and informative around entomology, and more specifically, the use of biological control against invasive alien plants. As a higher education institution, Rhodes University has a civic responsibility to engage with local communities and work with them around local challenges. Three groups of activities undertaken by the BCRG in partnership with local schools and other community partners are described and assessed in this paper as a way of assessing them and exploring future research areas around the aims and outcomes of these programmes.
- Full Text:
- Date Issued: 2017
Comparison of the biology of geographically distinct populations of the citrus pest, Thaumatotibia leucotreta (Meyrick)(Lepidoptera: Tortricidae)
- Opoku-Debrah, John K, Hill, Martin P, Knox, Caroline M, Moore, Sean D
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405769 , vital:70204 , xlink:href="https://hdl.handle.net/10520/EJC160246"
- Description: Baculovirus biopesticides are an important component of integrated pest management programmes worldwide. One such example is the Cryptophlebia leucotreta granulovirus (CrleGV) which is used for the control of false codling moth, Thaumatotibia (= Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus and other crops in South Africa. A potential problem associated with constant application of viral biopesticides is the differing susceptibility to the virus observed between different geographic populations of the insect host. This could be related to a number of factors, including biological performance and fitness of the target insect population. This study compared a variety of phenotypic traits between geographically distinct T. leucotreta populations collected from the Addo, Marble Hall, Citrusdal and Nelspruit regions of South Africa, and reared under laboratory conditions for several generations. Traits including pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and developmental time were used as parameters to measure biological performance and fitness. Insects from the Citrusdal region of the Western Cape exhibited significantly lower pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and the longest duration in larval and pupal development compared to the other colonies investigated. This is the first study to report differences in the performance of laboratory reared T. leucotreta from different geographic locations, and the findings may have important implications for the application of viral biopesticides for the control of this pest in South Africa.
- Full Text:
- Date Issued: 2014
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405769 , vital:70204 , xlink:href="https://hdl.handle.net/10520/EJC160246"
- Description: Baculovirus biopesticides are an important component of integrated pest management programmes worldwide. One such example is the Cryptophlebia leucotreta granulovirus (CrleGV) which is used for the control of false codling moth, Thaumatotibia (= Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus and other crops in South Africa. A potential problem associated with constant application of viral biopesticides is the differing susceptibility to the virus observed between different geographic populations of the insect host. This could be related to a number of factors, including biological performance and fitness of the target insect population. This study compared a variety of phenotypic traits between geographically distinct T. leucotreta populations collected from the Addo, Marble Hall, Citrusdal and Nelspruit regions of South Africa, and reared under laboratory conditions for several generations. Traits including pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and developmental time were used as parameters to measure biological performance and fitness. Insects from the Citrusdal region of the Western Cape exhibited significantly lower pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and the longest duration in larval and pupal development compared to the other colonies investigated. This is the first study to report differences in the performance of laboratory reared T. leucotreta from different geographic locations, and the findings may have important implications for the application of viral biopesticides for the control of this pest in South Africa.
- Full Text:
- Date Issued: 2014