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
Comparisons of isotopic niche widths of some invasive and indigenous fauna in a South African river
- Hill, Jaclyn M, Jones, Roy W, Hill, Martin P, Weyl, Olaf L F
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Date Issued: 2015
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Date Issued: 2015
Conceptualizing, categorizing and recording the outcomes of biological control of invasive plant species, at a population level
- Hoffman, John H, Moran, Cliff V, Hill, Martin P
- Authors: Hoffman, John H , Moran, Cliff V , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423315 , vital:72047 , xlink:href="https://doi.org/10.1016/j.biocontrol.2019.02.005"
- Description: Rates of establishment of agents, their population dynamics after release, and measures of the damage they inflict on their target hosts are all useful indicators of progress and success in weed biological control but cannot account for the overall degree and extent of weed biocontrol achievements (i.e. outcomes) at a plant population level. Current conventions that describe weed biocontrol outcomes as ‘negligible’, ‘partial’, ‘substantial’ or ‘complete’, are often idiosyncratic and imprecise and are inadequate for describing the complexities involved. Using selected examples from South Africa, an extension of the present system is proposed for conceptualizing and categorizing weed biocontrol outcomes more easily; it incorporates four different invasion parameters i.e. density, area, biomass and number of propagules, for different regions and habitats. This approach should help to provide weed biocontrol practitioners with a shared basis for describing, succinctly and with greater precision, the results of their weed biocontrol programs, at a plant population level.
- Full Text:
- Date Issued: 2019
- Authors: Hoffman, John H , Moran, Cliff V , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423315 , vital:72047 , xlink:href="https://doi.org/10.1016/j.biocontrol.2019.02.005"
- Description: Rates of establishment of agents, their population dynamics after release, and measures of the damage they inflict on their target hosts are all useful indicators of progress and success in weed biological control but cannot account for the overall degree and extent of weed biocontrol achievements (i.e. outcomes) at a plant population level. Current conventions that describe weed biocontrol outcomes as ‘negligible’, ‘partial’, ‘substantial’ or ‘complete’, are often idiosyncratic and imprecise and are inadequate for describing the complexities involved. Using selected examples from South Africa, an extension of the present system is proposed for conceptualizing and categorizing weed biocontrol outcomes more easily; it incorporates four different invasion parameters i.e. density, area, biomass and number of propagules, for different regions and habitats. This approach should help to provide weed biocontrol practitioners with a shared basis for describing, succinctly and with greater precision, the results of their weed biocontrol programs, at a plant population level.
- Full Text:
- Date Issued: 2019
Cryptic species of a water hyacinth biological control agent revealed in South Africa: host specificity, impact, and thermal tolerance
- Paterson, Iain D, Coetzee, Julie A, Weyl, Philip, Griffith, Tamzin C, Voogt, Nina, Hill, Martin P
- Authors: Paterson, Iain D , Coetzee, Julie A , Weyl, Philip , Griffith, Tamzin C , Voogt, Nina , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423982 , vital:72113 , xlink:href="https://doi.org/10.1111/eea.12812"
- Description: The discovery that cryptic species are more abundant than previously thought has implications for weed biological control, as there is a risk that cryptic species may be inadvertently released with consequences for the safety of the practice. A cryptic species of a biological control agent released for the control of the invasive alien macrophyte, water hyacinth, Eichhornia crassipes (C. Mart.) Solms. (Pontederiaceae), was recently discovered in South Africa. The two species were considered a single species prior to genetic analysis and interbreeding experiments. The original biological control agent retains the name Eccritotarsus catarinensis (Carvalho) (Heteroptera: Miridae) whereas the new species has been described as Eccritotarsus eichhorniae Henry. In this study, we compared the host specificity, efficacy, and thermal physiologies of the two species. The host specificity of the two species within the Pontederiaceae was very similar and both are safe for release in South Africa. Comparison of the per capita impact of the two species indicated that E. eichhorniae was the more damaging species but this is likely to be influenced by temperature, with E. catarinensis being more effective under lower temperatures and E. eichhorniae being more effective under higher temperatures. Releasing the correct species for the thermal environment of each release site will improve the level of control of water hyacinth in South Africa. This example highlights the need to keep populations of biological control agents from different native range collection localities separate, and to screen for host specificity and efficacy.
- Full Text:
- Date Issued: 2019
- Authors: Paterson, Iain D , Coetzee, Julie A , Weyl, Philip , Griffith, Tamzin C , Voogt, Nina , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423982 , vital:72113 , xlink:href="https://doi.org/10.1111/eea.12812"
- Description: The discovery that cryptic species are more abundant than previously thought has implications for weed biological control, as there is a risk that cryptic species may be inadvertently released with consequences for the safety of the practice. A cryptic species of a biological control agent released for the control of the invasive alien macrophyte, water hyacinth, Eichhornia crassipes (C. Mart.) Solms. (Pontederiaceae), was recently discovered in South Africa. The two species were considered a single species prior to genetic analysis and interbreeding experiments. The original biological control agent retains the name Eccritotarsus catarinensis (Carvalho) (Heteroptera: Miridae) whereas the new species has been described as Eccritotarsus eichhorniae Henry. In this study, we compared the host specificity, efficacy, and thermal physiologies of the two species. The host specificity of the two species within the Pontederiaceae was very similar and both are safe for release in South Africa. Comparison of the per capita impact of the two species indicated that E. eichhorniae was the more damaging species but this is likely to be influenced by temperature, with E. catarinensis being more effective under lower temperatures and E. eichhorniae being more effective under higher temperatures. Releasing the correct species for the thermal environment of each release site will improve the level of control of water hyacinth in South Africa. This example highlights the need to keep populations of biological control agents from different native range collection localities separate, and to screen for host specificity and efficacy.
- Full Text:
- Date Issued: 2019
Development of a Postharvest Cold Treatment for Cryptophlebia peltastica (Lepidoptera: Tortricidae) for Export of Litchis From South Africa
- Moore, Sean D, Kirkman, Wayne, Peyper, Mellissa, Thackeray, Sean R, Marsberg, Tamryn, Albertyn, Sonnica, Hill, Martin P
- Authors: Moore, Sean D , Kirkman, Wayne , Peyper, Mellissa , Thackeray, Sean R , Marsberg, Tamryn , Albertyn, Sonnica , Hill, Martin P
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423729 , vital:72089 , xlink:href="https://doi.org/10.1093/jee/toy287"
- Description: The litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae), is endemic to sub-Saharan Africa and certain Indian Ocean islands. It is an important pest of litchis and to a lesser extent macadamias. Litchis are exported to certain markets that consider C. peltastica as a phytosanitary pest. Consequently, an effective postharvest phytosanitary treatment is required. This study sought to develop a cold disinfestation treatment for this purpose. First, it was established that the fifth instar was the most cold-tolerant larval stage, as it was the only instar for which there was still some survival after 12 d at 1°C. It was then determined that cold treatment trials could be conducted in artificial diet, as there was no survival of fifth instar C. peltastica in litchis after only 9 d at 1°C, whereas it took 15 d at this temperature before no survival of fifth instar C. peltastica was recorded in artificial diet. Consequently, cold susceptibility of fifth instar C. peltastica and the most cold-tolerant larval stages (fourth and fifth instar) of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), were compared in artificial diet. There was no survival of C. peltastica after 13 d at 1°C, whereas this was only so for T. leucotreta after 16 d. Consequently, it can be concluded that any cold treatment that has been proven effective against T. leucotreta would be as effective against C. peltastica. Finally, it was confirmed that the cold susceptibility of T. leucotreta in artificial diet did not overestimate the effect of cold on T. leucotreta larvae in litchis.
- Full Text:
- Date Issued: 2018
- Authors: Moore, Sean D , Kirkman, Wayne , Peyper, Mellissa , Thackeray, Sean R , Marsberg, Tamryn , Albertyn, Sonnica , Hill, Martin P
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423729 , vital:72089 , xlink:href="https://doi.org/10.1093/jee/toy287"
- Description: The litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae), is endemic to sub-Saharan Africa and certain Indian Ocean islands. It is an important pest of litchis and to a lesser extent macadamias. Litchis are exported to certain markets that consider C. peltastica as a phytosanitary pest. Consequently, an effective postharvest phytosanitary treatment is required. This study sought to develop a cold disinfestation treatment for this purpose. First, it was established that the fifth instar was the most cold-tolerant larval stage, as it was the only instar for which there was still some survival after 12 d at 1°C. It was then determined that cold treatment trials could be conducted in artificial diet, as there was no survival of fifth instar C. peltastica in litchis after only 9 d at 1°C, whereas it took 15 d at this temperature before no survival of fifth instar C. peltastica was recorded in artificial diet. Consequently, cold susceptibility of fifth instar C. peltastica and the most cold-tolerant larval stages (fourth and fifth instar) of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), were compared in artificial diet. There was no survival of C. peltastica after 13 d at 1°C, whereas this was only so for T. leucotreta after 16 d. Consequently, it can be concluded that any cold treatment that has been proven effective against T. leucotreta would be as effective against C. peltastica. Finally, it was confirmed that the cold susceptibility of T. leucotreta in artificial diet did not overestimate the effect of cold on T. leucotreta larvae in litchis.
- Full Text:
- Date Issued: 2018
Developmental and reproductive performance of a specialist herbivore depend on seasonality of, and light conditions experienced by, the host plant
- Zachariades, Uyi O O,, Heshula, L U P, Hill, Martin P
- Authors: Zachariades, Uyi O O, , Heshula, L U P , Hill, Martin P
- Date: 2018
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59845 , vital:27667 , https://doi.org/10.1371/journal.pone.0190700
- Description: Host plant phenology (as influenced by seasonality) and light-mediated changes in the phenotypic and phytochemical properties of leaves have been hypothesised to equivocally influence insect herbivore performance. Here, we examined the effects of seasonality, through host plant phenology (late growth-season = autumn vs flowering-season = winter) and light environment (shade vs full-sun habitat) on the leaf characteristics of the invasive alien plant, Chromolaena odorata. In addition, the performance of a specialist folivore, Pareuchaetes insulata, feeding on leaves obtained from both shaded and full-sun habitats during autumn and winter, was evaluated over two generations. Foliar nitrogen and magnesium contents were generally higher in shaded plants with much higher levels during winter. Leaf water content was higher in shaded and in autumn plants. Total non-structural carbohydrate (TNC) and phosphorus contents did not differ as a function of season, but were higher in shaded foliage compared to full-sun leaves. Leaf toughness was noticeably higher on plants growing in full-sun during winter. With the exception of shaded leaves in autumn that supported the best performance [fastest development, heaviest pupal mass, and highest growth rate and Host Suitability Index (HSI) score], full-sun foliage in autumn surprisingly also supported an improved performance of the moth compared to shaded or full-sun leaves in winter. Our findings suggest that shaded and autumn foliage are nutritionally more suitable for the growth and reproduction of P. insulata. However, the heavier pupal mass, increased number of eggs and higher HSI score in individuals that fed on full-sun foliage in autumn compared to their counterparts that fed on shaded or full-sun foliage in winter suggest that full-sun foliage during autumn is also a suitable food source for larvae of the moth. In sum, our study demonstrates that seasonal and light-modulated changes in leaf characteristics can affect insect folivore performance in ways that are not linear.
- Full Text:
- Date Issued: 2018
- Authors: Zachariades, Uyi O O, , Heshula, L U P , Hill, Martin P
- Date: 2018
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59845 , vital:27667 , https://doi.org/10.1371/journal.pone.0190700
- Description: Host plant phenology (as influenced by seasonality) and light-mediated changes in the phenotypic and phytochemical properties of leaves have been hypothesised to equivocally influence insect herbivore performance. Here, we examined the effects of seasonality, through host plant phenology (late growth-season = autumn vs flowering-season = winter) and light environment (shade vs full-sun habitat) on the leaf characteristics of the invasive alien plant, Chromolaena odorata. In addition, the performance of a specialist folivore, Pareuchaetes insulata, feeding on leaves obtained from both shaded and full-sun habitats during autumn and winter, was evaluated over two generations. Foliar nitrogen and magnesium contents were generally higher in shaded plants with much higher levels during winter. Leaf water content was higher in shaded and in autumn plants. Total non-structural carbohydrate (TNC) and phosphorus contents did not differ as a function of season, but were higher in shaded foliage compared to full-sun leaves. Leaf toughness was noticeably higher on plants growing in full-sun during winter. With the exception of shaded leaves in autumn that supported the best performance [fastest development, heaviest pupal mass, and highest growth rate and Host Suitability Index (HSI) score], full-sun foliage in autumn surprisingly also supported an improved performance of the moth compared to shaded or full-sun leaves in winter. Our findings suggest that shaded and autumn foliage are nutritionally more suitable for the growth and reproduction of P. insulata. However, the heavier pupal mass, increased number of eggs and higher HSI score in individuals that fed on full-sun foliage in autumn compared to their counterparts that fed on shaded or full-sun foliage in winter suggest that full-sun foliage during autumn is also a suitable food source for larvae of the moth. In sum, our study demonstrates that seasonal and light-modulated changes in leaf characteristics can affect insect folivore performance in ways that are not linear.
- Full Text:
- Date Issued: 2018
DNA-based identification of Lepidoptera associated with citrus in South Africa
- Marsberg, Tamryn, Hill, Martin P, Moore, Sean D, Timm, A E
- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, A E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
- Full Text:
- Date Issued: 2015
- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, A E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
- Full Text:
- Date Issued: 2015
Do thermal requirements of Dichrorampha odorata, a shoot-boring moth for the biological control of Chromolaena odorata, explain its failure to establish in South Africa?
- Nqayi, Slindile B, Zachariades, Costas, Coetzee, Julie A, Hill, Martin P, Chidwanyika, Frank, Uyi, Osariyekemwen O, McConnachie, Andrew J
- Authors: Nqayi, Slindile B , Zachariades, Costas , Coetzee, Julie A , Hill, Martin P , Chidwanyika, Frank , Uyi, Osariyekemwen O , McConnachie, Andrew J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416851 , vital:71391 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v31_n1_a14"
- Description: Chromolaena odorata (L.) RM King and H Rob. (Asteraceae) has been subject to a biological control programme in South Africa for over three decades. A shoot-tip boring moth, Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae), originating from Jamaica, was released as a biological control agent in 2013 but despite the release of substantial numbers of the insect, it has not established a permanent field population. Because climate incompatibility is a major constraint for classical biological control of invasive plants, and based on the differences in climate between Jamaica and South Africa and field observations at release sites, aspects of the thermal physiology of D. odorata were investigated to elucidate reasons for its failure to establish. Developmental time decreased with increasing temperatures ranging from 20 °C to 30 °C, with incomplete development for immature stages at 18 °C and 32 °C. The developmental threshold, t, was calculated as 8.45 °C with 872.4 degree-days required to complete development (K). A maximum of 6.5 generations per year was projected for D. odorata in South Africa, with the heavily infested eastern region of the country being the most eco-climatically suitable for establishment. The lower lethal temperature (LLT50) of larvae and adults was –4.5 and 1.8 °C, respectively. The upper lethal temperature (ULT50) for larvae was 39.6 °C whilst that of adults was 41.0 °C. Larvae thus had better cold tolerance compared to adults whereas adults had better heat tolerance compared to larvae. The critical thermal (CT) limits for adults were 3.4 ± 0.07 to 43.7 ± 0.12 °C. Acclimation at 20 °C for 7 days resulted in increased cold and heat tolerance with a CTmin and CTmax of 1.9 ± 0.06 and 44.4 ± 0.07 °C respectively, compared to the relative control, acclimated at 25 °C. Acclimation at 30 °C improved neither cold (CTmin: 5.9 ± 0.08 °C) nor heat tolerance (CTmax: 42.9 ± 0.10 °C). These results suggest that thermal requirements fall within field temperatures and are thus not the main constraining factor leading to poor establishment of D. odorata in South Africa.
- Full Text:
- Date Issued: 2023
- Authors: Nqayi, Slindile B , Zachariades, Costas , Coetzee, Julie A , Hill, Martin P , Chidwanyika, Frank , Uyi, Osariyekemwen O , McConnachie, Andrew J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416851 , vital:71391 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v31_n1_a14"
- Description: Chromolaena odorata (L.) RM King and H Rob. (Asteraceae) has been subject to a biological control programme in South Africa for over three decades. A shoot-tip boring moth, Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae), originating from Jamaica, was released as a biological control agent in 2013 but despite the release of substantial numbers of the insect, it has not established a permanent field population. Because climate incompatibility is a major constraint for classical biological control of invasive plants, and based on the differences in climate between Jamaica and South Africa and field observations at release sites, aspects of the thermal physiology of D. odorata were investigated to elucidate reasons for its failure to establish. Developmental time decreased with increasing temperatures ranging from 20 °C to 30 °C, with incomplete development for immature stages at 18 °C and 32 °C. The developmental threshold, t, was calculated as 8.45 °C with 872.4 degree-days required to complete development (K). A maximum of 6.5 generations per year was projected for D. odorata in South Africa, with the heavily infested eastern region of the country being the most eco-climatically suitable for establishment. The lower lethal temperature (LLT50) of larvae and adults was –4.5 and 1.8 °C, respectively. The upper lethal temperature (ULT50) for larvae was 39.6 °C whilst that of adults was 41.0 °C. Larvae thus had better cold tolerance compared to adults whereas adults had better heat tolerance compared to larvae. The critical thermal (CT) limits for adults were 3.4 ± 0.07 to 43.7 ± 0.12 °C. Acclimation at 20 °C for 7 days resulted in increased cold and heat tolerance with a CTmin and CTmax of 1.9 ± 0.06 and 44.4 ± 0.07 °C respectively, compared to the relative control, acclimated at 25 °C. Acclimation at 30 °C improved neither cold (CTmin: 5.9 ± 0.08 °C) nor heat tolerance (CTmax: 42.9 ± 0.10 °C). These results suggest that thermal requirements fall within field temperatures and are thus not the main constraining factor leading to poor establishment of D. odorata in South Africa.
- Full Text:
- Date Issued: 2023
Economic evaluation of water loss saving due to the biological control of water hyacinth at New Year’s Dam, Eastern Cape province, South Africa
- Fraser, Gavin C G, Hill, Martin P, Martin, J A
- Authors: Fraser, Gavin C G , Hill, Martin P , Martin, J A
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69341 , vital:29502 , https://doi.org/10.2989/16085914.2016.1151765
- Description: Water hyacinth Eichhornia crassipes is considered the most damaging aquatic weed in the world. However, few studies have quantified the impact of this weed economically and ecologically, and even fewer studies have quantified the benefits of its control. This paper focuses on water loss saving as the benefit derived from biological control of this plant between 1990 and 2013 at New Year’s Dam, Alicedale, Eastern Cape, South Africa. Estimates of water loss due to evapotranspiration from water hyacinth vary significantly; therefore, the study used three different rates, high, medium and low. A conservative raw agriculture value of R 0.26 per m3 was used to calculate the benefits derived by the water saved. The present benefit and cost values were determined using 10% and 5% discount rates. The benefit/cost ratio at the low evapotranspiration rate was less than one, implying that biological control was not economically viable but, at the higher evapotranspiration rates, the return justified the costs of biological control. However, at the marginal value product of water, the inclusion of the costs of damage to infrastructure, or the adverse effects of water hyacinth on biodiversity, would justify the use of biological control, even at the low transpiration rate.
- Full Text: false
- Date Issued: 2016
- Authors: Fraser, Gavin C G , Hill, Martin P , Martin, J A
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69341 , vital:29502 , https://doi.org/10.2989/16085914.2016.1151765
- Description: Water hyacinth Eichhornia crassipes is considered the most damaging aquatic weed in the world. However, few studies have quantified the impact of this weed economically and ecologically, and even fewer studies have quantified the benefits of its control. This paper focuses on water loss saving as the benefit derived from biological control of this plant between 1990 and 2013 at New Year’s Dam, Alicedale, Eastern Cape, South Africa. Estimates of water loss due to evapotranspiration from water hyacinth vary significantly; therefore, the study used three different rates, high, medium and low. A conservative raw agriculture value of R 0.26 per m3 was used to calculate the benefits derived by the water saved. The present benefit and cost values were determined using 10% and 5% discount rates. The benefit/cost ratio at the low evapotranspiration rate was less than one, implying that biological control was not economically viable but, at the higher evapotranspiration rates, the return justified the costs of biological control. However, at the marginal value product of water, the inclusion of the costs of damage to infrastructure, or the adverse effects of water hyacinth on biodiversity, would justify the use of biological control, even at the low transpiration rate.
- Full Text: false
- Date Issued: 2016
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
Efforts towards engaging communities to promote the benefits of biological control research and implementation in South Africa
- Weaver, Kim N, Hill, Martin P, Byrne, Marcus J, Ivey, Philip J
- Authors: Weaver, Kim N , Hill, Martin P , Byrne, Marcus J , Ivey, Philip J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414428 , vital:71146 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a23"
- Description: In the last decade, biological control in South Africa has evolved from a classical applied science, allied to an extension service, to a more community engagement-based activity. Therefore, capacity building is important for the sustainability of biological control research and its implementation. In South Africa, a broad approach has been taken to build capacity in weed biological control, starting at grass-roots level with primary and secondary school learner programmes, through to developing research capacity at the tertiary level and enhancing technical capacity through adult education. Non-specialists are empowered through access to knowledge. The dissemination of accurate information through the most appropriate outlets has become increasingly important, including non-traditional science communication through the internet and, more importantly, social media, which has the potential to reach a far wider audience. Public understanding of biological control has the potential to contribute significantly to the green and knowledge economies of South Africa, but relies on government support for the sustainability of this discipline.
- Full Text:
- Date Issued: 2021
- Authors: Weaver, Kim N , Hill, Martin P , Byrne, Marcus J , Ivey, Philip J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414428 , vital:71146 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a23"
- Description: In the last decade, biological control in South Africa has evolved from a classical applied science, allied to an extension service, to a more community engagement-based activity. Therefore, capacity building is important for the sustainability of biological control research and its implementation. In South Africa, a broad approach has been taken to build capacity in weed biological control, starting at grass-roots level with primary and secondary school learner programmes, through to developing research capacity at the tertiary level and enhancing technical capacity through adult education. Non-specialists are empowered through access to knowledge. The dissemination of accurate information through the most appropriate outlets has become increasingly important, including non-traditional science communication through the internet and, more importantly, social media, which has the potential to reach a far wider audience. Public understanding of biological control has the potential to contribute significantly to the green and knowledge economies of South Africa, but relies on government support for the sustainability of this discipline.
- Full Text:
- Date Issued: 2021
Entomopathogenic fungi as control agents of Thaumatotibia leucotreta in citrus orchards: field efficacy and persistence
- Coombes, Candice A, Hill, Martin P, Moore, Sean D, Dames, Joanna F
- Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417956 , vital:71497 , xlink:href="https://doi.org/10.1007/s10526-016-9756-x"
- Description: Entomopathogenic fungal isolates Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) strain G Ar 17 B3 and Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) strain FCM Ar 23 B3 have been identified as effective control agents of the important citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) wandering fifth instars under laboratory conditions. This study is the first report on the ability of these isolates to persist and reduce T. leucotreta infestation in commercial citrus orchards in South Africa. A reduction in pest infestation of between 28 and 82 % upon trial completion was reported. Both isolates were recovered from soil samples collected five months post-application with high host density and moderate to high soil moisture favouring recovery. Low soil moisture negatively influenced the persistence of both isolates and the control efficiency of B. bassiana. These results provide evidence and support for the future use of these isolates against T. leucotreta thus warranting further investigation.
- Full Text:
- Date Issued: 2016
- Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417956 , vital:71497 , xlink:href="https://doi.org/10.1007/s10526-016-9756-x"
- Description: Entomopathogenic fungal isolates Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) strain G Ar 17 B3 and Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) strain FCM Ar 23 B3 have been identified as effective control agents of the important citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) wandering fifth instars under laboratory conditions. This study is the first report on the ability of these isolates to persist and reduce T. leucotreta infestation in commercial citrus orchards in South Africa. A reduction in pest infestation of between 28 and 82 % upon trial completion was reported. Both isolates were recovered from soil samples collected five months post-application with high host density and moderate to high soil moisture favouring recovery. Low soil moisture negatively influenced the persistence of both isolates and the control efficiency of B. bassiana. These results provide evidence and support for the future use of these isolates against T. leucotreta thus warranting further investigation.
- Full Text:
- Date Issued: 2016
Evidence for a new regime shift between floating and submerged invasive plant dominance in South Africa
- Strange, Emily F, Hill, Martin P, Coetzee, Julie A
- Authors: Strange, Emily F , Hill, Martin P , Coetzee, Julie A
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423993 , vital:72114 , xlink:href="https://doi.org/10.1007/s10750-018-3506-2"
- Description: Classical biological control for the management of floating invasive plants has been highly successful in South Africa. However, restoring ecosystem services has been compromised by a new suite of submerged invasive plants. This study proposes that biological control of floating invasive macrophytes acts as a catalyst in a regime shift between floating and submerged invasive plant dominance. Regime shifts are large and sudden changes in the structure and functioning of ecosystems. The proposed shift is driven by the rapid decomposition of floating plants and subsequent increase in availability of nutrients and light. A mesocosm experiment explored the effect of biological control on floating Pistia stratiotes L. (Araceae) upon the growth of invasive submerged Egeria densa Planch. (Hydrocharitaceae), and native submerged plant species of the same family; Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae). The results revealed a cascade effect of biological control of P. stratiotes on the availability of nitrogen, resulting in increased relative growth rates and invasive capacity for E. densa. In contrast, the native L. major could not compete with healthy or damaged P. stratiotes. These findings highlight the vulnerability of South African freshwater systems to submerged plant invasions and demonstrate the importance of a more holistic approach to invasive plant management.
- Full Text:
- Date Issued: 2018
- Authors: Strange, Emily F , Hill, Martin P , Coetzee, Julie A
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423993 , vital:72114 , xlink:href="https://doi.org/10.1007/s10750-018-3506-2"
- Description: Classical biological control for the management of floating invasive plants has been highly successful in South Africa. However, restoring ecosystem services has been compromised by a new suite of submerged invasive plants. This study proposes that biological control of floating invasive macrophytes acts as a catalyst in a regime shift between floating and submerged invasive plant dominance. Regime shifts are large and sudden changes in the structure and functioning of ecosystems. The proposed shift is driven by the rapid decomposition of floating plants and subsequent increase in availability of nutrients and light. A mesocosm experiment explored the effect of biological control on floating Pistia stratiotes L. (Araceae) upon the growth of invasive submerged Egeria densa Planch. (Hydrocharitaceae), and native submerged plant species of the same family; Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae). The results revealed a cascade effect of biological control of P. stratiotes on the availability of nitrogen, resulting in increased relative growth rates and invasive capacity for E. densa. In contrast, the native L. major could not compete with healthy or damaged P. stratiotes. These findings highlight the vulnerability of South African freshwater systems to submerged plant invasions and demonstrate the importance of a more holistic approach to invasive plant management.
- Full Text:
- Date Issued: 2018
Genetic and biological characterisation of a novel Plutella xylostella granulovirus, PlxyGV-SA
- Abdulkadir, Fatima, Knox, Caroline M, Marsberg, Tamryn, Hill, Martin P, Moore, Sean D
- Authors: Abdulkadir, Fatima , Knox, Caroline M , Marsberg, Tamryn , Hill, Martin P , Moore, Sean D
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417971 , vital:71498 , xlink:href="https://doi.org/10.1007/s10526-015-9666-3"
- Description: Plutella xylostella granulovirus (PlxyGV) has been isolated from insect populations in many countries and is considered a potential biopesticide for sustainable control of P. xylostella (L.) (Lepidoptera: Plutellidae). Several PlxyGV isolates have been genetically characterised, and the full genome sequence of PlxyGV-Japan is available for comparison with novel isolates. A South African PlxyGV was recently recovered from an overcrowded laboratory P. xylostella colony and identified as a genetically distinct isolate by sequencing of the granulin gene and restriction endonuclease (REN) analysis of genomic DNA. In this report, PlxyGV-SA was further characterised by PCR amplification and sequencing of egt, lef-8 and lef-9 genes, and several amino acid substitutions were observed. The PstI REN profile of PlxyGV-SA was different from that of PlxyGV-Japan in terms of band size and number, thereby confirming its novel genetic identity. Surface dose bioassays showed that PlxyGV-SA is pathogenic to neonate but not late instar larvae at the same and higher virus doses, indicating that a biopesticide should be targeted at early larval stages in the field.
- Full Text:
- Date Issued: 2015
- Authors: Abdulkadir, Fatima , Knox, Caroline M , Marsberg, Tamryn , Hill, Martin P , Moore, Sean D
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417971 , vital:71498 , xlink:href="https://doi.org/10.1007/s10526-015-9666-3"
- Description: Plutella xylostella granulovirus (PlxyGV) has been isolated from insect populations in many countries and is considered a potential biopesticide for sustainable control of P. xylostella (L.) (Lepidoptera: Plutellidae). Several PlxyGV isolates have been genetically characterised, and the full genome sequence of PlxyGV-Japan is available for comparison with novel isolates. A South African PlxyGV was recently recovered from an overcrowded laboratory P. xylostella colony and identified as a genetically distinct isolate by sequencing of the granulin gene and restriction endonuclease (REN) analysis of genomic DNA. In this report, PlxyGV-SA was further characterised by PCR amplification and sequencing of egt, lef-8 and lef-9 genes, and several amino acid substitutions were observed. The PstI REN profile of PlxyGV-SA was different from that of PlxyGV-Japan in terms of band size and number, thereby confirming its novel genetic identity. Surface dose bioassays showed that PlxyGV-SA is pathogenic to neonate but not late instar larvae at the same and higher virus doses, indicating that a biopesticide should be targeted at early larval stages in the field.
- Full Text:
- Date Issued: 2015
Heterogeneity in virulence relationships between Cryptophlebia leucotreta granulovirus isolates and geographically distinct host populations: Lessons from codling moth resistance to CpGV-M
- 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: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417998 , vital:71500 , xlink:href="https://doi.org/10.1007/s10526-016-9728-1"
- Description: In South Africa, the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV) is used to control the citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). However, the risk associated with continuous application of a single active ingredient is resistance. In order to manage resistance should it occur in field populations of T. leucotreta in South Africa, five new CrleGV genotypes from geographically distinct insect populations which were shown to exhibit some degree of phenotypic variation were recovered and genetically characterized. In droplet bioassays using seven CrleGV isolates against five T. leucotreta populations, some isolates were found to show higher virulence to some host populations than others. There were marked differences in the LD50 values of isolates and the number of occlusion bodies required per larva ranged between 0.79 and 3.12. The significance of these findings with respect to the application of CrleGV biopesticides and the management of resistance is discussed.
- Full Text:
- Date Issued: 2016
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417998 , vital:71500 , xlink:href="https://doi.org/10.1007/s10526-016-9728-1"
- Description: In South Africa, the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV) is used to control the citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). However, the risk associated with continuous application of a single active ingredient is resistance. In order to manage resistance should it occur in field populations of T. leucotreta in South Africa, five new CrleGV genotypes from geographically distinct insect populations which were shown to exhibit some degree of phenotypic variation were recovered and genetically characterized. In droplet bioassays using seven CrleGV isolates against five T. leucotreta populations, some isolates were found to show higher virulence to some host populations than others. There were marked differences in the LD50 values of isolates and the number of occlusion bodies required per larva ranged between 0.79 and 3.12. The significance of these findings with respect to the application of CrleGV biopesticides and the management of resistance is discussed.
- Full Text:
- Date Issued: 2016
Host searching and oviposition behaviour of Agathis bishopi (Hymenoptera: Braconidae), a larval parasitoid of false codling moth, Thaumatotibia leucotreta (Lepidoptera: Tortricidae): a potential proxy indicator for fruit infestation
- Zimba, Kennedy J, Heshula, LU, Moore, Sean D, Hill, Martin P
- Authors: Zimba, Kennedy J , Heshula, LU , Moore, Sean D , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407019 , vital:70330 , xlink:href="https://hdl.handle.net/10520/EJC195073"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae)is an arrhenotokous larval endoparasitoid of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) (Gendall 2007; Hofmeyr et al. 2015) commonly known as false codling moth (FCM), a major pest of citrus in South Africa (Moore et al. 2004; Malan et al. 2011). Under field conditions, A. bishopi was identified attacking more than 34% of FCM larvae in fruit, showing good biocontrol potential (Gendall 2007). Preference by A. bishopi for parasitising the early instars of its concealed host suggests that the parasitoid has strong natural host location ability (Sishuba 2003; Gendall 2007).
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy J , Heshula, LU , Moore, Sean D , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407019 , vital:70330 , xlink:href="https://hdl.handle.net/10520/EJC195073"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae)is an arrhenotokous larval endoparasitoid of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) (Gendall 2007; Hofmeyr et al. 2015) commonly known as false codling moth (FCM), a major pest of citrus in South Africa (Moore et al. 2004; Malan et al. 2011). Under field conditions, A. bishopi was identified attacking more than 34% of FCM larvae in fruit, showing good biocontrol potential (Gendall 2007). Preference by A. bishopi for parasitising the early instars of its concealed host suggests that the parasitoid has strong natural host location ability (Sishuba 2003; Gendall 2007).
- Full Text:
- Date Issued: 2015
Host stage preference and performance of Dolichogenidea gelechiidivoris (Hymenoptera: Braconidae), a candidate for classical biological control of Tuta absoluta in Africa
- Aigbedion-Atalor, Pascal O, Mohamed, Samira A, Hill, Martin P, Zalucki, Myron P, Azrag, Abdelmutalab G A, Srinivasan, Ramasamy, Ekesi, Sunday
- Authors: Aigbedion-Atalor, Pascal O , Mohamed, Samira A , Hill, Martin P , Zalucki, Myron P , Azrag, Abdelmutalab G A , Srinivasan, Ramasamy , Ekesi, Sunday
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423516 , vital:72068 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104215"
- Description: Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is native to South America but has invaded the Afro-Eurasian supercontinent where it is currently the most devastating invasive arthropod pest of tomato. As a part of the first classical biological control programme against T. absoluta in Africa, a larval parasitoid, Dolichogenidea gelechiidivoris Marsh. (Syn.: Apanteles gelechiidivoris Marsh) (Hymenoptera: Braconidae), of T. absoluta was imported from Peru into the quarantine facility of the International Centre of Insect Physiology and Ecology, Kenya. We report on the host larval preference of D. gelechiidivoris and the host suitability, and the parasitoid’s reproductive strategy, including lifetime fecundity and egg maturation dynamics. Dolichogenidea gelechiidivoris females preferentially oviposited in early (1st and 2nd) larval instars of T. absoluta but parasitized and completed development in all four instars of the host. Host instar did not affect D. gelechiidivoris sex-ratio but females reared on the first instar had significantly fewer eggs than when reared in late larval instars (3rd and 4th). Females of the parasitoid emerged with a high mature egg load which peaked 2 d post eclosion. The females of D. gelechiidivoris survived 8.51 ± 0.65 d and produced 103 ± 8 offspring per female at 26 ± 4 °C (range: 24 to 29 °C) and 50–70% relative humidity (RH) with males present and fed honey-water (80% honey). Increasing maternal age decreased the proportion of female offspring. Under the aforementioned laboratory conditions, the Gross and Net reproductive rates were 72 and 39.5 respectively, while the mean generation time was 20 d. The potential intrinsic rate of natural increase was 0.18. This study shows that D. gelechiidivoris is a potential biological control agent of T. absoluta and should be considered for release in Kenya and across Africa following host specificity testing and risk assessments.
- Full Text:
- Date Issued: 2020
- Authors: Aigbedion-Atalor, Pascal O , Mohamed, Samira A , Hill, Martin P , Zalucki, Myron P , Azrag, Abdelmutalab G A , Srinivasan, Ramasamy , Ekesi, Sunday
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423516 , vital:72068 , xlink:href="https://doi.org/10.1016/j.biocontrol.2020.104215"
- Description: Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is native to South America but has invaded the Afro-Eurasian supercontinent where it is currently the most devastating invasive arthropod pest of tomato. As a part of the first classical biological control programme against T. absoluta in Africa, a larval parasitoid, Dolichogenidea gelechiidivoris Marsh. (Syn.: Apanteles gelechiidivoris Marsh) (Hymenoptera: Braconidae), of T. absoluta was imported from Peru into the quarantine facility of the International Centre of Insect Physiology and Ecology, Kenya. We report on the host larval preference of D. gelechiidivoris and the host suitability, and the parasitoid’s reproductive strategy, including lifetime fecundity and egg maturation dynamics. Dolichogenidea gelechiidivoris females preferentially oviposited in early (1st and 2nd) larval instars of T. absoluta but parasitized and completed development in all four instars of the host. Host instar did not affect D. gelechiidivoris sex-ratio but females reared on the first instar had significantly fewer eggs than when reared in late larval instars (3rd and 4th). Females of the parasitoid emerged with a high mature egg load which peaked 2 d post eclosion. The females of D. gelechiidivoris survived 8.51 ± 0.65 d and produced 103 ± 8 offspring per female at 26 ± 4 °C (range: 24 to 29 °C) and 50–70% relative humidity (RH) with males present and fed honey-water (80% honey). Increasing maternal age decreased the proportion of female offspring. Under the aforementioned laboratory conditions, the Gross and Net reproductive rates were 72 and 39.5 respectively, while the mean generation time was 20 d. The potential intrinsic rate of natural increase was 0.18. This study shows that D. gelechiidivoris is a potential biological control agent of T. absoluta and should be considered for release in Kenya and across Africa following host specificity testing and risk assessments.
- Full Text:
- Date Issued: 2020
Identity and origins of introduced and native Azolla species in Florida
- Madeira, Paul T, Center, Ted D, Coetzee, Julie A, Pemberton, Robert W, Purcell, Matthew F, Hill, Martin P
- Authors: Madeira, Paul T , Center, Ted D , Coetzee, Julie A , Pemberton, Robert W , Purcell, Matthew F , Hill, Martin P
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419313 , vital:71634 , xlink:href="https://doi.org/10.1016/j.aquabot.2013.07.009"
- Description: Azolla pinnata, an introduced aquatic fern, is spreading rapidly causing concern that it may displace native Azolla. It is now present in the Arthur R. Marshall Loxahatchee National Wildlife Refuge, the northernmost portion of the Florida Everglades. Because A. pinnata subspecies are native to Africa, Southeast Asia, and Australia, determining the actual geographic origin of the Florida exotic is important to the discovery of efficacious biological control agents. Both the exotic and native Azollas were examined using morphological and molecular criteria. Both criteria distinguished three A. pinnata subspecies with the Florida exotic matching the Australian A. pinnata subsp. pinnata. Molecular divergence between the A. pinnata subspecies indicates the three types should be considered separate species. The Florida native was characterized by both molecular and morphological methods as Azolla caroliniana. The discovery of a previously uncharacterized Ecuadorian Azolla, which appears to be a paternal ancestor of A. caroliniana, indicates that A. caroliniana is a hybrid species.
- Full Text:
- Date Issued: 2013
- Authors: Madeira, Paul T , Center, Ted D , Coetzee, Julie A , Pemberton, Robert W , Purcell, Matthew F , Hill, Martin P
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419313 , vital:71634 , xlink:href="https://doi.org/10.1016/j.aquabot.2013.07.009"
- Description: Azolla pinnata, an introduced aquatic fern, is spreading rapidly causing concern that it may displace native Azolla. It is now present in the Arthur R. Marshall Loxahatchee National Wildlife Refuge, the northernmost portion of the Florida Everglades. Because A. pinnata subspecies are native to Africa, Southeast Asia, and Australia, determining the actual geographic origin of the Florida exotic is important to the discovery of efficacious biological control agents. Both the exotic and native Azollas were examined using morphological and molecular criteria. Both criteria distinguished three A. pinnata subspecies with the Florida exotic matching the Australian A. pinnata subsp. pinnata. Molecular divergence between the A. pinnata subspecies indicates the three types should be considered separate species. The Florida native was characterized by both molecular and morphological methods as Azolla caroliniana. The discovery of a previously uncharacterized Ecuadorian Azolla, which appears to be a paternal ancestor of A. caroliniana, indicates that A. caroliniana is a hybrid species.
- Full Text:
- Date Issued: 2013
Impact of Access and Benefit Sharing implementation on biological control genetic resources
- Mason, Peter G, Barratt, Barbara I P, Mc Kay, Fernando, Klapwijk, Johannette N, Silvestri, Luciano C, Hill, Martin P, Hinz, Hariet L, Sheppard, Andy, Brodeur, Jacques, Vitorino, Marcello Diniz, Weyl, Philip S R, Hoelmer, Kim A
- Authors: Mason, Peter G , Barratt, Barbara I P , Mc Kay, Fernando , Klapwijk, Johannette N , Silvestri, Luciano C , Hill, Martin P , Hinz, Hariet L , Sheppard, Andy , Brodeur, Jacques , Vitorino, Marcello Diniz , Weyl, Philip S R , Hoelmer, Kim A
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418013 , vital:71501 , xlink:href="https://doi.org/10.1007/s10526-023-10176-8"
- Description: The third objective of the Convention on Biological Diversity, the fair and equitable sharing of benefits arising out of the use of genetic resources was further developed when the Nagoya Protocol on Access and Benefit Sharing came into effect in 2014. Interpretation of how this agreement is being implemented is wide-ranging and there are implications for biological control. A survey of biological control workers indicated that while some countries have facilitated access to biological control genetic resources, requirements in other countries have impeded biological control implementation. There was consensus that benefits to provider countries should be in the form of supporting local research communities. There was also agreement that the free use and exchange of biological control genetic resources has provided benefits to the global community, including to both providers and recipients of the agents. It is recommended that consideration of the free use and exchange principal should be a key element of Access and Benefit Sharing measures for the future.
- Full Text:
- Date Issued: 2023
- Authors: Mason, Peter G , Barratt, Barbara I P , Mc Kay, Fernando , Klapwijk, Johannette N , Silvestri, Luciano C , Hill, Martin P , Hinz, Hariet L , Sheppard, Andy , Brodeur, Jacques , Vitorino, Marcello Diniz , Weyl, Philip S R , Hoelmer, Kim A
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418013 , vital:71501 , xlink:href="https://doi.org/10.1007/s10526-023-10176-8"
- Description: The third objective of the Convention on Biological Diversity, the fair and equitable sharing of benefits arising out of the use of genetic resources was further developed when the Nagoya Protocol on Access and Benefit Sharing came into effect in 2014. Interpretation of how this agreement is being implemented is wide-ranging and there are implications for biological control. A survey of biological control workers indicated that while some countries have facilitated access to biological control genetic resources, requirements in other countries have impeded biological control implementation. There was consensus that benefits to provider countries should be in the form of supporting local research communities. There was also agreement that the free use and exchange of biological control genetic resources has provided benefits to the global community, including to both providers and recipients of the agents. It is recommended that consideration of the free use and exchange principal should be a key element of Access and Benefit Sharing measures for the future.
- Full Text:
- Date Issued: 2023