Interaction between the root-feeding beetle, Longitarsus bethae (Coleoptera: Chrysomelidae) and the root-knot nematode, Meloidogyne javanica (Nematoda: Heteroderidae): Implications for the biological control of Lantana camara L. (Verbenaceae) in South Africa
- Authors: Musedeli, Jufter
- Date: 2019
- Subjects: Insect-plant relationships , Insects -- Host plants , Flea beetles , Symbiosis , Longitarsus , Chrysomelidae , Lantana camara -- Biological control -- South Africa , Heteroderidae , Root-knot nematodes , Weeds -- Biological control -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71130 , vital:29788
- Description: Plants often are simultaneously attacked by several herbivores that can affect each other’s performance, and their interaction may affect their host plant fitness. The current study was conducted to determine the interaction between the root-feeding beetle, Longitarsus bethae Savini & Escalona (Coleoptera: Chrysomelidae) and a root-knot nematode, Meloidogyne javanica (Treub) Chitwood (Tylenchida: Heteroderidae), with implications for the biological control of Lantana camara L. (Verbenaceae) in South Africa. The studies were conducted under quarantine conditions at the Agricultural Research Council-PHP, Roodeplaat, Pretoria, South Africa. Specifically, the study determined; (i) whether root damage by the flea beetle enhanced infection by M. javanica, (ii) whether L. camara roots infected with the nematode enhanced the performance of the beetle, (iii) whether single or combined effect of the two organisms (i.e. L. bethae and M. javanica) had an overall effect on the growth and biomass of their shared host, L. camara, and (iv) the susceptibility of 10 L. camara varieties that are commonly found in South Africa to M. javanica. The study found that galling on the roots of L. camara by the nematode occurs at the highest inoculation of 300 eggs of L. bethae per plant, and no galling occurred at inoculation of 200 eggs per plant and below. The findings also showed that L. bethae performed better on M. javanica-infected than on healthy L. camara roots, and that more L. bethae adult progeny with slightly bigger body size emerged from M. javanica-infected, than from healthy plants. Fresh weight (galls) of plant roots from treatments where both species (i.e., L. bethae and M. javanica) were combined was significantly higher than that from plants infected with the nematode only, suggesting that the combination of both species induces more galling than the nematode does alone. The above-ground dry biomass was significantly lower both in combined and M. javanica only treatments, than in L. bethae only treatment. The study also found that selected L. camara varieties were infected with M. javanica, albeit at varying degrees of infection. Among the 10 L. camara varieties, Orange Red OR 015 was the most susceptible. Other susceptible varieties included Light Pink 009 LP, Total Pink 021 TP and Dark Pink 018 DP, and these, together with variety Orange Red OR 015, constituted 40% of the L. camara varieties evaluated in the current study. Fifty percent of the varieties displayed slight to moderate susceptibility to M. javanica, while 10% displayed lack of susceptibility. The study concluded that the symbiotic relationship between L. bethae and M. javanica was mutual, resulting in increase in the fitness of the beetle. The combined herbivory by L. bethae and M. javanica was also found to be additive on one of the most common varieties of L. camara in South Africa, and therefore co-infestation by both species might enhance the biological control of this weed in South Africa. The study further concluded that the suitability of some invasive L. camara cultivars such as Light Pink 009 LP and Orange Red 015 OR for M. javanica, might also contribute towards biological control of this weed in South Africa, particularly in areas where the two herbivores species co-exist.
- Full Text:
- Authors: Musedeli, Jufter
- Date: 2019
- Subjects: Insect-plant relationships , Insects -- Host plants , Flea beetles , Symbiosis , Longitarsus , Chrysomelidae , Lantana camara -- Biological control -- South Africa , Heteroderidae , Root-knot nematodes , Weeds -- Biological control -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71130 , vital:29788
- Description: Plants often are simultaneously attacked by several herbivores that can affect each other’s performance, and their interaction may affect their host plant fitness. The current study was conducted to determine the interaction between the root-feeding beetle, Longitarsus bethae Savini & Escalona (Coleoptera: Chrysomelidae) and a root-knot nematode, Meloidogyne javanica (Treub) Chitwood (Tylenchida: Heteroderidae), with implications for the biological control of Lantana camara L. (Verbenaceae) in South Africa. The studies were conducted under quarantine conditions at the Agricultural Research Council-PHP, Roodeplaat, Pretoria, South Africa. Specifically, the study determined; (i) whether root damage by the flea beetle enhanced infection by M. javanica, (ii) whether L. camara roots infected with the nematode enhanced the performance of the beetle, (iii) whether single or combined effect of the two organisms (i.e. L. bethae and M. javanica) had an overall effect on the growth and biomass of their shared host, L. camara, and (iv) the susceptibility of 10 L. camara varieties that are commonly found in South Africa to M. javanica. The study found that galling on the roots of L. camara by the nematode occurs at the highest inoculation of 300 eggs of L. bethae per plant, and no galling occurred at inoculation of 200 eggs per plant and below. The findings also showed that L. bethae performed better on M. javanica-infected than on healthy L. camara roots, and that more L. bethae adult progeny with slightly bigger body size emerged from M. javanica-infected, than from healthy plants. Fresh weight (galls) of plant roots from treatments where both species (i.e., L. bethae and M. javanica) were combined was significantly higher than that from plants infected with the nematode only, suggesting that the combination of both species induces more galling than the nematode does alone. The above-ground dry biomass was significantly lower both in combined and M. javanica only treatments, than in L. bethae only treatment. The study also found that selected L. camara varieties were infected with M. javanica, albeit at varying degrees of infection. Among the 10 L. camara varieties, Orange Red OR 015 was the most susceptible. Other susceptible varieties included Light Pink 009 LP, Total Pink 021 TP and Dark Pink 018 DP, and these, together with variety Orange Red OR 015, constituted 40% of the L. camara varieties evaluated in the current study. Fifty percent of the varieties displayed slight to moderate susceptibility to M. javanica, while 10% displayed lack of susceptibility. The study concluded that the symbiotic relationship between L. bethae and M. javanica was mutual, resulting in increase in the fitness of the beetle. The combined herbivory by L. bethae and M. javanica was also found to be additive on one of the most common varieties of L. camara in South Africa, and therefore co-infestation by both species might enhance the biological control of this weed in South Africa. The study further concluded that the suitability of some invasive L. camara cultivars such as Light Pink 009 LP and Orange Red 015 OR for M. javanica, might also contribute towards biological control of this weed in South Africa, particularly in areas where the two herbivores species co-exist.
- Full Text:
An investigation into the bacterial communities associated with pyrroloiminoquinone-producing South African latrunculid sponges
- Authors: Hilliar, Storm Hannah
- Date: 2018
- Subjects: Sponges South Africa Algoa Bay , Betaproteobacteria , Spirochaeta , Symbiosis , Bacterial communities
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/62112 , vital:28128
- Description: Marine sponges belonging to the family Latrunculiidae are known for their production of cytotoxic pyrroloiminoquinone alkaloids and the South African coast provides a unique environment for the exploitation of these potent bioactive compounds. The isolation of structurally similar pyrroloiminoquinone compounds from unrelated, non poriferan sources has led to the suggestion that South African latrunculid pyrroloiminoquinones may be secondary metabolites produced by sponge associated microbial symbionts. Previous studies investigating the bacterial communities of South African latrunculid sponges have shown the conservation of distinct microbial populations with unusual bacterial taxa dominated by a novel betaproteobacterial and spirochete species. This study describes the further investigation into these associated bacterial communities, their conservation and sponge microbiome comparisons across spatial, temporal and environmental scales. The bacterial communities associated with seven latrunculid species representing three genera (Tsitsikamma, Cyclacanthia and Latrunculia) were characterized as well as a Mycale and Tethya rubra species. Latrunculid sponge microbiomes were significantly different from those associated with sympatric outlier sponge species and the surrounding environment. The bacterial communities associated with latrunculid sponges appear host specific with the conservation of two dominant bacterial symbionts which mirror the phylogeny of their host species. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2018
- Full Text:
- Authors: Hilliar, Storm Hannah
- Date: 2018
- Subjects: Sponges South Africa Algoa Bay , Betaproteobacteria , Spirochaeta , Symbiosis , Bacterial communities
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/62112 , vital:28128
- Description: Marine sponges belonging to the family Latrunculiidae are known for their production of cytotoxic pyrroloiminoquinone alkaloids and the South African coast provides a unique environment for the exploitation of these potent bioactive compounds. The isolation of structurally similar pyrroloiminoquinone compounds from unrelated, non poriferan sources has led to the suggestion that South African latrunculid pyrroloiminoquinones may be secondary metabolites produced by sponge associated microbial symbionts. Previous studies investigating the bacterial communities of South African latrunculid sponges have shown the conservation of distinct microbial populations with unusual bacterial taxa dominated by a novel betaproteobacterial and spirochete species. This study describes the further investigation into these associated bacterial communities, their conservation and sponge microbiome comparisons across spatial, temporal and environmental scales. The bacterial communities associated with seven latrunculid species representing three genera (Tsitsikamma, Cyclacanthia and Latrunculia) were characterized as well as a Mycale and Tethya rubra species. Latrunculid sponge microbiomes were significantly different from those associated with sympatric outlier sponge species and the surrounding environment. The bacterial communities associated with latrunculid sponges appear host specific with the conservation of two dominant bacterial symbionts which mirror the phylogeny of their host species. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2018
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