With an increasing realization that many agrochemicals are hazardous to animals and humans, came the desire to replace these chemical agents with biological approaches that are more friendly to the environment and human health. Microorganisms play an important role in plant disease control, as naturally occurring antagonists. Microorganisms may also have beneficial effects on plant development when applied to plant roots. Research efforts worldwide have recorded successes in biological control and growth stimulation on many crops, particularly when using members of the genera Bacillus and Trichoderma. Their use on citrus rootstock could be advantageous to nurserymen and growers in reducing the incidence of seedling mortality and increasing production. To achieve these objectives, laboratory and tunnel experiments were conducted to develop effective biocontrol agents for citrus seedlings and cuttings. Nineteen 0 ut 0 f 23 Trichoderma isolates tested in vitro against Phytophthora p arasitica sp showed antagonistic activity by hyperparasitism and four out of eight Bacillus isolates resulted in antagonism by forming inhibition zones. The positive in vitro activity of Trichoderma and Bacillus isolates on Phytophthora provided motivation step for further trials in the greenhouse to evaluate their biological control activity on citrus seedlings and cuttings. A greenhouse trial was carried out to evaluate the biological control potential of 23 Trichoderma isolates (drenched at 5 x 105 spores / rnI) and two Bacillus isolates (drenched at 1 X 106 or 1 X 108 colony forming units (CFU) / rnI) to suppress Phytophthora parasitica sp. of rough lemon (Citrus jambhirini Lush.) seedlings. Five isolates ofTrichoderma (AA12, AA5, Trichoderma harzianum (AA16), SY3F and Eco-T~ were highly effective in suppressing Phytophthora root rot, with AA12 providing the best control. The Bacillus isolates also suppressed the pathogen but were not as effective as the Trichoderma isolates. This trial was used to test for growth stimulation activity by some of the biocontrol agents. To verify these results, a further trial was carried out to evaluate growth stimulation capabilities in the absence of any pathogen. Trichoderma Isolates AA13 and AA17 caused no 111 change in seedling growth, while other Trichoderma and Bacillus isolates had an inhibitory effect on the seedling growth. This trial indicated that the biocontrol activity was affected by inoculum densities, and as a result in vitro sporulation capacity was evaluated. TrichodermaIsolate AA16 was the largest spore producer, followed by Eco-T®. Spore production was lowest from Trichoderma isolates AA4 and AA12. Growth stimulation responses of Trichoderma Isolates AA4, AA16, Eco-TID and SYN6 were further studied at four different doses (1 X 103, 1 X 104, 5 X 105 or 1 X 106 spores / ml) on rough lemon and trifoliate orange seedlings. Trifoliate oranges responded positively to 1 X 104 and 5 X 105 spores / ml of Eco-TID, but rough lemon responded negatively to all dosages of the Trichoderma isolates applied. This indicates that the inoculum density responses may be host specific. Higher population density of 1 X 106 spores / ml of all tested Trichoderma isolates had a stunting effect on seedling growth of both species. Based on t he positive results 0 f individual applications of some Trichoderma and Bacillus isolates, of the biological control agents on rough lemon seedlings against Phytophthora parasitica in an earlier greenhouse trial, their combined effect in the control of the pathogen was performed. Before carrying out a greenhouse trial, activities of the isolates to be combined were evaluated in vitro. This trial showed that Trichoderma Isolates AA16 and Eco-T®were compatible. Trichoderma isolates AA16 and Eco-T®were also found to be compatible with Bacillus Isolates B77, B81 and PHP. As a result, further in vivo trials were conducted. The tunnel trials were carried out as two separate experiments: In the first experiment, a combination of two Trichoderma Isolates A A 16 and Eco-T®was conducted assayed at 5 X 105 or 1 X 106 spores / ml, on rough lemon seedling, and cuttings and trifoliate orange and sour orange seedlings. A combination of Trichoderma isolate AA16 and Eco-T®at 5 X 105 spore / ml increased significantly the new flush biomass of rough lemon cuttings compared to AA16 alone, but was not different from Eco-TID alone. The combination of AA16 and Eco-T® achieved no change of biomass of rough lemon and trifoliate orange seedlings. The combination of AA16 and Eco-TID did not increase the root biomass of sour orange compared to AA16 or Eco-r® alone. The combination of AA16 and Eco-r® at higher doses (1 x 106 spores / ml) showed significantly better suppression of Phytophthora root rot of rough lemon cuttings but did not show disease suppression in all seedling species verities tested. In a second experiment, individual and combined effects of Trichoderma isolates (drenched at 5 X 105 spores / ml) with Bacillus isolate (drenched at 1 X 106 colony forming units (CFU) / ml) for suppression of Phytophthora root rot on rough lemon and trifoliate orange seedlings was performed. The combination of Trichoderma Isolate AA16 and Bacillus Isolate B81 increased root biomass on rough lemon seedlings compared to the combination of Trichoderma AAI6 or Bacillus PHP but was not significantly different to Trichoderma AA16 alone. Bacillus PHP combined with Trichoderma AA16 or singly had no effect on rough lemon seedlings. Combining Trichoderma Eco--r® and with Bacillus B8I or PHP did not increase biomass of rough lemon seedlings compared to Trichoderma Isolate Eco--r® alone. There was no statistically significant differences in the effects of the combinations of the Trichoderma and Bacillus isolates compared to their individual applications on the biomass of trifoliate oranges. This study established the antagonistic potential of several South African isolates of Trichoderma and Bacillus as a viable alternative to agrochemicals for controlling Phytophthora parasitica. The growth stimulation capabilities of Trichoderma isolates in terms of seedling development was also demonstrated. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

O cultivo da videira no estado do Rio Grande do Sul é de grande importância, sendo responsável pela produção de mais da metade das uvas colhidas no país. A podridão da uva madura, causada pelo agente patogênico Glomerella cingulata (Colletotrichum gloeosporioides), tem provocado sérios prejuízos nos vinhedos da Serra Gaúcha nestes últimos anos. Para o controle desta doença tem-se usado intensivamente e indiscriminadamente agrotóxicos, os quais tem causado diversos danos ao meio ambiente. O objetivo do presente trabalho foi gerar conhecimento básico e aplicado sobre o controle da podridão da uva madura, enfocando aspectos relativos ao controle biológico com Trichoderma spp. e óleo essencial de Cymbopogum citratus. Para isso analisou-se in vitro o efeito antifúngico de diferentes concentrações do óleo essencial de capim-limão (Cymbopogon citratus), de isolados de Trichoderma spp. e de fungicidas, no controle do patógeno Glomerella cingulata (C. gloeosporioides). Com isso estabeleceu-se a concentração de 0,2% do óleo essencial, o isolado T8 de Trichoderma sp. e o fungicida Tebuconazole para serem aplicados nas videiras a fim de controlar a podridão da uva madura. Também avaliou-se, In Vivo, o biofungicida comercial Trichodel®, composto por células do fungo Trichoderma spp em diferentes dosagens. No momento de colheita, avaliou-se as características das uvas tratadas e determinou-se a eficiência dos diferentes tratamentos no controle da doença. No teste no vinhedo de Niágara Branca a produtividade foi menor no tratamento com o óleo essencial de C. citratus, não diferindo estatisticamente com a testemunha, sem aplicação de produtos com ação sobre a doença podridão da uva madura. Os demais tratamentos apresentaram produção entre 28 e 30,5 ton/ha. Em relação ao peso médio dos cachos, também não foram observadas grandes variações, sendo que não houveram diferenças significativas entre os tratamentos, inclusive no tratamento testemunha. O teor de sólidos solúveis totais foi de 14º Brix em todos os tratamentos. Quanto à incidência e a severidade da doença, todos os tratamentos diferiram com a testemunha. O tratamento com fungicida foi o que apresentou os melhores resultados, seguido dos tratamentos alternados entre o fungicida e o óleo essencial de C. citratus e do tratamento com o fungicida e o antaginista Trichoderma sp. O biofungicida Trichodel® testado em diferentes dosagens não demonstrou incremento na ação sobre a doença com o aumento da dosagem. O isolado T8 de Trichoderma sp. não diferiu com a biofungicida. Enquanto que a menor redução foi observada no tratamento com o óleo essencial de C. citratus. Conclue-se que o controle alternado entre o fungicida e o antagonista Trichoderma spp. é a melhor forma para se promover o controle da podridão da uva madura com menor impacto ambiental, ou seja reduzindo o número de aplicações de agrotóxicos. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-01-27T18:02:57Z No. of bitstreams: 1 Dissertacao Rosemeri Ines Conte Rizzotto .pdf: 1834477 bytes, checksum: f5a94773ed9aeaab50798ee28c77a697 (MD5) / Made available in DSpace on 2016-01-27T18:02:57Z (GMT). No. of bitstreams: 1 Dissertacao Rosemeri Ines Conte Rizzotto .pdf: 1834477 bytes, checksum: f5a94773ed9aeaab50798ee28c77a697 (MD5) / The vine cultivation in Rio Grande do Sul state is of great importance, being responsible for producing more than half of the grapes harvested in the country. The rot of ripe grape, caused by the pathogen Glomerella cingulata (Colletotrichum gloeosporioides), has caused serious damage in the vineyards of the Gaucha Saw in recent years. To control this disease has been used intensively and indiscriminately pesticides, which has caused extensive damage to the environment. The objective of this study was to generate basic knowledge and applied on the control of the ripe grape rot, focusing on aspects of biological control using Trichoderma spp. and essential oil Cymbopogum citratus. To this was analyzed In Vitro antifungal effect of different concentrations of essential oil of lemongrass (Cymbopogon citratus), isolates of Trichoderma spp. and fungicides in controlling pathogen Glomerella cingulata (C. gloeosporioides). With this set is the concentration of 0.2% essential oil, isolated T8 Trichoderma sp. Tebuconazole and the fungicide to be applied on the vines to control grape ripe rot. Also it was evaluated in vivo commercial biofungicide Trichodel® consisting of Trichoderma spp cells at different dosages. At the time of harvest, it was evaluated the characteristics of the treated grapes and determined the effectiveness of different treatments in controlling the disease. In the test at the White Niagara vineyard productivity was lower in the treatment with the essential oil of C. citratus, did not differ statistically with the witness without application products acting on the rot of ripe grape disease. The other treatments showed production between 28 and 30,5ton/ha. Compared with the average weight of bunches also large variations were observed, and there were no significant differences between treatments, including the control treatment. The total soluble solids content was 14º Brix in all treatments. The incidence and severity of the disease, all treatments differed with the witness. Treatment with fungicide showed the best results, followed by alternate treatments between the fungicide and the essential oil of C. citratus and treatment with fungicide and antaginista Trichoderma sp. The Trichodel® biofungicide tested in different dosages showed no increase in action on the disease with increasing dosage. The isolated T8 Trichoderma sp. it did not differ with the biofungicide. While the smallest decrease was observed in the treatment with the essential oil of C. citratus. Concludes that the control alternated between the fungicide and the antagonist Trichoderma spp. it is the best way to promote control of the ripe grape rot with less environmental impact, ie reducing the number of pesticide applications.

O cultivo da videira no estado do Rio Grande do Sul é de grande importância, sendo responsável pela produção de mais da metade das uvas colhidas no país. A podridão da uva madura, causada pelo agente patogênico Glomerella cingulata (Colletotrichum gloeosporioides), tem provocado sérios prejuízos nos vinhedos da Serra Gaúcha nestes últimos anos. Para o controle desta doença tem-se usado intensivamente e indiscriminadamente agrotóxicos, os quais tem causado diversos danos ao meio ambiente. O objetivo do presente trabalho foi gerar conhecimento básico e aplicado sobre o controle da podridão da uva madura, enfocando aspectos relativos ao controle biológico com Trichoderma spp. e óleo essencial de Cymbopogum citratus. Para isso analisou-se in vitro o efeito antifúngico de diferentes concentrações do óleo essencial de capim-limão (Cymbopogon citratus), de isolados de Trichoderma spp. e de fungicidas, no controle do patógeno Glomerella cingulata (C. gloeosporioides). Com isso estabeleceu-se a concentração de 0,2% do óleo essencial, o isolado T8 de Trichoderma sp. e o fungicida Tebuconazole para serem aplicados nas videiras a fim de controlar a podridão da uva madura. Também avaliou-se, In Vivo, o biofungicida comercial Trichodel®, composto por células do fungo Trichoderma spp em diferentes dosagens. No momento de colheita, avaliou-se as características das uvas tratadas e determinou-se a eficiência dos diferentes tratamentos no controle da doença. No teste no vinhedo de Niágara Branca a produtividade foi menor no tratamento com o óleo essencial de C. citratus, não diferindo estatisticamente com a testemunha, sem aplicação de produtos com ação sobre a doença podridão da uva madura. Os demais tratamentos apresentaram produção entre 28 e 30,5 ton/ha. Em relação ao peso médio dos cachos, também não foram observadas grandes variações, sendo que não houveram diferenças significativas entre os tratamentos, inclusive no tratamento testemunha. O teor de sólidos solúveis totais foi de 14º Brix em todos os tratamentos. Quanto à incidência e a severidade da doença, todos os tratamentos diferiram com a testemunha. O tratamento com fungicida foi o que apresentou os melhores resultados, seguido dos tratamentos alternados entre o fungicida e o óleo essencial de C. citratus e do tratamento com o fungicida e o antaginista Trichoderma sp. O biofungicida Trichodel® testado em diferentes dosagens não demonstrou incremento na ação sobre a doença com o aumento da dosagem. O isolado T8 de Trichoderma sp. não diferiu com a biofungicida. Enquanto que a menor redução foi observada no tratamento com o óleo essencial de C. citratus. Conclue-se que o controle alternado entre o fungicida e o antagonista Trichoderma spp. é a melhor forma para se promover o controle da podridão da uva madura com menor impacto ambiental, ou seja reduzindo o número de aplicações de agrotóxicos. / The vine cultivation in Rio Grande do Sul state is of great importance, being responsible for producing more than half of the grapes harvested in the country. The rot of ripe grape, caused by the pathogen Glomerella cingulata (Colletotrichum gloeosporioides), has caused serious damage in the vineyards of the Gaucha Saw in recent years. To control this disease has been used intensively and indiscriminately pesticides, which has caused extensive damage to the environment. The objective of this study was to generate basic knowledge and applied on the control of the ripe grape rot, focusing on aspects of biological control using Trichoderma spp. and essential oil Cymbopogum citratus. To this was analyzed In Vitro antifungal effect of different concentrations of essential oil of lemongrass (Cymbopogon citratus), isolates of Trichoderma spp. and fungicides in controlling pathogen Glomerella cingulata (C. gloeosporioides). With this set is the concentration of 0.2% essential oil, isolated T8 Trichoderma sp. Tebuconazole and the fungicide to be applied on the vines to control grape ripe rot. Also it was evaluated in vivo commercial biofungicide Trichodel® consisting of Trichoderma spp cells at different dosages. At the time of harvest, it was evaluated the characteristics of the treated grapes and determined the effectiveness of different treatments in controlling the disease. In the test at the White Niagara vineyard productivity was lower in the treatment with the essential oil of C. citratus, did not differ statistically with the witness without application products acting on the rot of ripe grape disease. The other treatments showed production between 28 and 30,5ton/ha. Compared with the average weight of bunches also large variations were observed, and there were no significant differences between treatments, including the control treatment. The total soluble solids content was 14º Brix in all treatments. The incidence and severity of the disease, all treatments differed with the witness. Treatment with fungicide showed the best results, followed by alternate treatments between the fungicide and the essential oil of C. citratus and treatment with fungicide and antaginista Trichoderma sp. The Trichodel® biofungicide tested in different dosages showed no increase in action on the disease with increasing dosage. The isolated T8 Trichoderma sp. it did not differ with the biofungicide. While the smallest decrease was observed in the treatment with the essential oil of C. citratus. Concludes that the control alternated between the fungicide and the antagonist Trichoderma spp. it is the best way to promote control of the ripe grape rot with less environmental impact, ie reducing the number of pesticide applications.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-11-13T14:16:38Z No. of bitstreams: 2 Dissertação - Elen Regozino Muniz - 2015.pdf: 5452848 bytes, checksum: 01e704bb99491be79de20d410d521a0f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-11-13T14:18:52Z (GMT) No. of bitstreams: 2 Dissertação - Elen Regozino Muniz - 2015.pdf: 5452848 bytes, checksum: 01e704bb99491be79de20d410d521a0f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-11-13T14:18:52Z (GMT). No. of bitstreams: 2 Dissertação - Elen Regozino Muniz - 2015.pdf: 5452848 bytes, checksum: 01e704bb99491be79de20d410d521a0f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-04-01 / Rhipicephalus microplus, known as tick of the cattle, cause great economic losses each year in Brazil. Entomopathogenic fungi stand out as an alternative to the exclusive control and indiscriminate use of the chemical. However, ambient temperature above the threshold considered optimal for these organisms can interfere with your biology, and compromise their development and effectiveness. In the present study evaluated biological parameters seven strains of Metarhizium spp. (IP1, IP34, IP46, IP60, IP119, IP125 and IP146) originated from the Central Brazil, incubated at 32 ± 0.5°C or 27 ± 1°C. In addition, the virulence was assessed for each strain of R. microplus engorged females. IP119, Metarhizium anisopliae s.s., was selected among the other isolates for virulence tests against R. microplus submitted with stressful temperature condition (32 ± 0.5°C) or low relative humidity (RH = 75%) to present considerable heat tolerance and virulence in the screening tests. Tests with conidia formulated in oil-water emulsion (liquid vaseline 5%), carboxymethylcellulose gel or emulgel 5% were conducted to evaluate the conidial thermotolerance when exposed to 45°C for 4 hours or 6 hours, and to test the efficacy of formulated to control engorged female R. microplus the stressful conditions of temperature (32°C) and low humidity (RH = 75%). It was concluded that a constant temperature of 32°C or exposure for a few hours at 45°C is stressful condition for the isolates. The conidia IP119 when bathed in liquid vaseline jelly were more tolerant of exposure to 45°C for 4 hours. IP119 was shown to be virulent for engorged female R. microplus, being the oil-water emulsion 5% of the most effective formulation. / Rhipicephalus microplus, conhecido como carrapato-dos-bovinos, causa grandes percas econômicas por ano no Brasil. Fungos entomopatogênicos se destacam como controle alternativo ao uso exclusivo e indiscriminado do químico. Contudo, a temperatura ambiente acima do limiar considerado ótimo para estes organismos pode interferir na sua biologia, e comprometer seu desenvolvimento e eficácia. No presente estudo foram avaliados parâmetros biológicos de sete linhagens de Metarhizium spp. (IP1, IP34, IP46, IP60, IP119, IP125 e IP146), originados do cerrado do Centro-Oeste brasileiro, incubados a 32±0,5°C ou 27±1°C. Além disso, foi avaliada a virulência de cada linhagem para fêmeas ingurgitadas de R. microplus. Metarhizium anisopliae s.s., IP119, foi selecionado dentre os demais isolados para os testes de virulência contra R. microplus submetidos a com condição de temperatura estressante (32±0,5°C) ou em baixa umidade relativa (UR=75%) por apresentar notável tolerância ao calor e virulência nos testes de triagem. Testes com os conídios formulados em emulsão óleo-água (vaselina líquida 5%), gel carboximetilcelulose ou emulgel 5% foram realizados para avaliar a termotolerância dos conídios quando expostos a 45°C por 4 ou 6 horas, e testar a eficácia dos formulados para o controle de fêmeas ingurgitadas de R. microplus nas condições estressantes de temperatura (32°C) e umidade baixa (UR=75%). Concluiu-se que a constante temperatura de 32°C ou a exposição por poucas horas a 45°C foi condição estressante para os isolados estudados. Os conídios de M. anisopliae s.s. (IP119) quando banhados em emulsão óleo-água 5% foram mais tolerantes em exposição a 45°C por 4 horas. M. anisopliae s.s. (IP119) mostrou ser virulento para fêmeas ingurgitadas de R. microplus, tendo sido a emulsão óleo-água 5% a formulação mais eficaz.

The aims of the project were twofold. The initial objective of the study, based on previous results, was to develop an economically viable methodology for immobilizing yeast cells for the treatment of heavy metal-laden waste water. The non-viable yeast cross-linked by 13% (w/v) formaldehyde/1N HNO₃ exhibited satisfactory mechanical strength and rigidity in a continuous-flow column operation. No apparent disruption of the biomass after repeated use was observed. The cost of immobilizing 1kg dry yeast pellets was estimated at less than US$I. Zn uptake capacity of FA-cross-linked pellets, on batch trials, remained similar to that of raw yeast, reflecting that the immobilizing procedure did not hinder its metal removing capacity. In column studies, cation metals were effectively removed by the yeast pellets from aqueous solution at natural pHs, and then recovered completely by washing the pellets in situ with O.1M HCl. The recovered metals were concentrated in such small volumes that recycling or precipitation of them was facilitated. The metal uptake capacity of the regenerated biomass remained constant in comparison with cycle 1, indicating that reuse of the yeast would be possible. In the case of Cr⁶⁺, a gradual breakthrough curve of Cr in the column profile was noted, with a simultaneous reduction of Cr⁶⁺ to Cr³⁺. However, Cr⁶⁺ in the effluent can be markedly minimised either by accumulation onto the biomass or reduction to its trivalent form. Desorption of bound Cr⁶⁺ with either alkali or salt could not accomplish the regeneration of the biomass. A combination of reduction and desorption with FA/HNO₃ appeared promising in regeneration of the saturated biomass at 4°C. The metal sorption capacities of the yeast pellets, on a batch or a fixed-bed system are relatively lower than that of documented sorbents. Apparently more of the yeast pellets would be required for treating a certain volume of waste effluent, than with other sorbents. Therefore Azolla filiculoides was examined as a suitable sorbent for this purpose. This constitutes the second part of the project. Azolla filiculoides, a naturally-abundant water fern, was screened for its metal sorption and recovering capacities, mechanical stability, flow-permeability and reusability. The azolla biomass appeared to have fulfilled the required mechanical criteria during the repeated sorption-desorption column operations. It is water-insoluble and appears flexible under pressure when rinsed with water. These characters are of crucial importance in a continuous-flow system since a column can be operated at high flow rates without apparent compact of the biomass and pressure loss. Therefore, immobilization of the biomass can be avoided. The sorption isotherm data, obtained from batch removal of Cr⁶⁺, showed that the sorption process was effective, endothermic and highly pH dependent. Considerable amounts of Cr⁶⁺ were accumulated at the optimum pHs of 2-2.5. Column sorption of Cr⁶⁺ at a low flow rate and pH of 2.5 showed optimum performance with a total Cr uptake of 50.4mg/g at 60% saturation of the biomass. Removal of Cr⁶⁺ from an electroplating effluent using an azolla column was deemed reasonably satisfactory, although the uptake declined slightly. Desorption of bound Cr⁶⁺ with various desorbents was incomplete, which resulted in a low regeneration efficiency of about 50%. However, removal and recovery of Cr³⁺ using the azolla column was than that of Cr⁶⁺. Desorption of Cr³⁺ from the spent biomass column was accomplished with the recovery of 80% using O.5N H₂SO₄, The regeneration efficiencies for Cr³⁺ removal were up to 90% and demonstrated that the biomass is reusable. Cation metal uptake capacities of azolla, obtained either from batch or column experiments, are reasonably high in comparison with other sorbents. The uptake of Ni or Zn ions from solution is pH dependent showing the optimum pH of around 6 to 6.5, under the current experimental conditions. The sorption kinetics for cation metals was rapid with about 80% of the bound Ni ions being taken up in the first 10 min. The character of rapid binding is extremely important in a column sorption process, especially on a large scale since it favours an optimum uptake of metals at high flow rates. The Ni or Zn uptakes in column sorption were not markedly affected when the flow rates were increased from 80mllh up to 800ml/h for the 5g biomass used. The cation heavy metals removed from waste effluents were recovered in a concentrated solution of small volume. The desorption of bound Ni and Zn ions from the saturated biomass was accomplished with either O.2N HCl or H₂SO₄ that resulted in recoveries of more than 95%. The metals recovered, in the case of Ni and Zn, are identical to that of plating agents ego nickel sulphate or chloride, so that recycling of the metals is possible. An effluent-free, closed loop of Ni or Zn treatment system was proposed, whereby the Ni or Zn ions can be recycled to the plating bath whilst the purified water is fed back to the rinse tanks. Ca and Mg ions, commonly present in the electroplating effluents, appeared to affect sorption of heavy metals by azolla when metal concentrations were relatively low, presumedly through its competitive binding for the shared sites on surfaces of azolla. The data obtained from column sorption of Ni and Zn follows the BDST model well, enabling the application of the model to predicting design parameters for scale-up of the biosorption column system. It is interesting that the values of metal uptake, expressed in molar quantities, obtained on respective single-metal solutions and the multiple metal system, are similar, implying that the mechanisms involved in the sorption of all metal cations are similar and that the binding sites on surfaces of azolla are probably shared by all cation metals. The surface of the biomass provides sites for metal binding estimated in the range of 0.45-0.57mmol/g, based on the current experiments. The biomass has a surface area of 429 m²/g and water retention of 14.3 ml/g. The functional groups on the surface of azolla were partially identified using chemical modification and metal binding comparison. Among the functional groups examined, carboxyl groups, provided by amino acids and polysaccharides, appeared to play an important role in metal cation binding. The infrared spectra of the samples support this conclusion.

Sphaeropsis sapinea and Diaporthe ambigua are important pathogens of forest and orchard tree species, respectively. Some isolates of S. sapinea are co-infected with two dsRNA viruses, SsRVl and SsRV2. Isolates of D. perjuncta (formerly thought to be D. ambigua) are infected with a positive-stranded RNA virus known as DaRV. While S. sapinea is. infected with a heterogeneous mixture of dsRNA elements of different sizes, D. perjuncta is infected with a single virus. This presents excellent opportunity for biocontrol of Diaporthe. The aim of this study was to assess these three viruses for possible application as biological control agents of S. sapinea and D. ambigua. This was' done by transfecting these with in vitro-produced RNA from the cloned viral genomes and assessing the pathogenicity of the transfected isolates on apples and apple trees. Attempts to transfect S. sapinea spheroplasts with SsRVl and SsRV2 failed. Co¬transfection of S. sapinea spheroplasts with both viruses also failed. Three isolates of D. ambigua and a single isolate of a Phomopsis sp. were successfully transfected with DaRV. Attempts to transfect the same fungi with a mutant of DaRV, bearing six codons for histidine immediately downsteam of an AUG thought to be a start codon for the translation of ORFl, failed. DaRV was originally thought to be isolated from D. ambigua. The fungal isolates transfected with DaRV were thought to be D. ambigua. The transfectants did not resemble the naturally-infected isolate. The ITS regions from the ribosomal DNA operon of these isolates were amplified using ITS 1 and ITS4 primer pair. The blast search revealed that the ITS sequence of the naturally-infected isolates are identical to D. perjuncta. One virus-free isolate was identified as a Phomopsis sp. while three other virus-free isolates were identified as D. ambigua. A PCR-based RFLP was developed to differentiate the naturally-infected D. perjuncta isolates from the virus¬free Phomopsis sp. and D. ambigua isolates. In the growth and pathogenicity studies, a DaRV-transfected, wild-type and negative control isolate of one Phomopsis and three D. ambigua isolates, were used. The DaR V -transfected Phomopsis sp. had a higher growth rate than the wild-type isolate. This DaRV-transfected Phomopsis sp. was more virulent on apples than the wild-type isolate. The wild-type isolate was slightly more virulent than the DaR V -transfected Phomopsis sp. on apple trees. There were no significant differences in growth rates between the DaRV-transfected and wild-type isolates of D. ambigua CMW5587 and D. ambigua CMW5287. There were no significant differences in virulence on apples between the DaRV-transfected and wild-type isolates of these fungi. The DaRV-transfected D. ambigua CMW5287 was more virulent than the wild-type isolate on apple trees. The DaRV-transfected D. ambigua CMW5587 had the same virulence as the wild-type isolate on both apples and apple trees. The DaRV-transfected D. ambigua CMW5288 had a slower growth rate than the wild-type isolate. There were no significant differences in virulence on apples between these isolates. The wild-type isolate of this isolate was significantly more virulent on apple trees than the DaRV-infected isolate. Although transfection was successfully done, the effects of DaRV on the Phomopsis sp. and D. ambigua isolates are not conclusive. In order to obtain conclusive results, virus-free isolates of D. perjuncta must be transfected. During the course of this study, there were no available virus-free isolates of this fungus. / Dissertation (PhD)--University of Pretoria, 2006. / Genetics / Unrestricted

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, March 2017. / Water hyacinth (Eichhornia crassipes) is an example of an alien invasive plant, threatening ecosystems around the world. Taking into consideration all the negative impacts caused by the proliferation of water hyacinth, many control measures have been implemented to manage this weed. These include mechanical control, chemical control and biological control. But in recent years, the focus has shifted towards natural enemies for control (biological control) of water hyacinth because they have many advantages for environmental safety. However, in South Africa, success is limited in most parts of the country. Factors affecting the success of biological control of water hyacinth in South Africa have been attributed in part to weather conditions. Therefore, further studies and other strategies are needed to reinforce the biological control of water hyacinth. This is why this research investigated the influences of temperature on Neochetina eichhorniae larvae feeding and development on water hyacinth, to contribute to the future management of water hyacinth biological control. To measure the effect of temperature on the feeding and development of Neochetina eichhorniae larva, experiments were conducted at four fixed temperatures (15 °C, 20 °C, 25 °C, and 30 °C). Larval feeding is expected to be greater and the development faster at warm temperatures compared with cold temperatures. The results of this study confirmed that, both feeding and larval development increased with an increase in temperature. The highest larval feeding damage was recorded at 30°C and the lowest at 15°C. Similar to the feeding of larvae, warmer temperatures were more favourable to the growth of larvae than cold temperatures; all larvae found at 30°C were in their third instars (with 0.72 mm being the biggest headwidth found) while all larvae at 15°C were in the first instars (with 0.28 mm being the smallest headwidth found). Even if the optimal temperature for larval performance took place at 30 °C (with a high amount of biomass removal), it was at 25 °C that the larvae had a larger effect on the growth of water hyacinth. Larval feeding damage reduced the growth of water hyacinth by 30 % at 25 °C and only affected 24 % of water hyacinth growth at iv 30 °C. Therefore, for the biocontrol of water hyacinth, the ideal temperature to slow the progression of the weed will be recommended at between 25- 30 °C. / LG2017

No description available.

No description available.

The potential impact of generalist predators on armyworm mortality was evaluated in the field, through a predator removal study, and in the laboratory, through controlled feeding trials. The most common potential armyworm predators removed from the field included ground beetles (Carabidae), rove beetles (Staphylinidae), ants (Formicidae), and spiders (Araneae). Armyworm damage to corn plants was significantly greater where generalist predator populations were reduced, through the use of pitfall traps and exclusion arenas, than in the control where predator populations were unaltered. The differences in the proportion of damaged plants and the degree of damage between the predator removal treatment and the control were statistically significant. Generalist predator consumption rates of live armyworm larvae in the laboratory were variable, however most predators did feed on the larvae. Large carabid beetles, including Pterostichus chalcites Say, Pterostichus lucublandus Say, and Scarites subterraneus F., exhibited the highest consumption rates. Generalist predators were sampled in four reduced-tillage corn systems which differed in the degree of soil disturbance and quantity and structure of the surface mulch due to tillage and cover crop management practices. The two sampling methods which were used, pitfall trapping and vacuum sampling, showed similar trends in predator abundance. The treatment with the highest degree of mulch ground cover had the highest overall predator abundance while the treatment which was disked and had no surface mulch had the lowest. Although several species tended to prefer the system with the least amount of ground cover, most of the common species preferred the treatment with the most groundcover. Pitfall trap catches over a three-day period indicated that predator activity was significantly higher during the day than night in all treatments. However, a laboratory study provided evidence that night activity in the field may have been reduced due to unusually low temperatures. Catch data from pitfall traps, unbaited and baited with live armyworm larvae, indicated that long-distance chemical detection is not an important cue for generalist predators in finding armyworm as prey. A removal sampling technique was used and evaluated for estimating the absolute densities of ground beetles (Carabidae). Removal sampling is a method of absolute density estimation based on the decline in successive catch numbers as individuals are removed from a population. Field arenas were used to isolate sampling areas in a no-till corn field and barrier pitfall traps were installed within the arenas to remove the carabids. Three three-week sampling trials were conducted in 1991 providing data for estimates on 5 June, 26 June, and 17 July. A single six-week sampling period was conducted in 1992 providing data for estimates on 2 June based on three, four, five, and six weeks of sampling. A linear regression method was used for calculating the estimate from the removal sampling data. The technique's practicality and agreement with the assumptions of removal sampling are discussed. / Master of Science