This research was an attempt to use a dicot transformation vector to transform a monocot. The initial purpose of this thesis was to transform orchids with the sense and antisense coat protein genes from the Odontoglossum ringspot virus (ORSV) in an effort to mitigate viral symptoms in transgenic plants using the transformation vector, Agrobacterium tumefaciens. However, it soon became apparent that much time would be needed to develop a transformation protocol. The transformation vectors used included the Agrobacterium tumefaciens disarmed strain LBA4404 with the binary plasmid pB1121, the disarmed strain At699 with the binary plasmid pCNL65, and the wild-type strain Chry5. The marker gene on the binary plasmids of both disarmed strains was p-glucuronidase (GUS).Several transformation protocols were used in an effort to determine if this transformation system would work on orchids. Transformation was not achieved even though a number of experimental conditions were varied. These included using two different types of orchid tissue, callus and protocorms; using two different species of orchids, Cattleya Chocolate Drop x Cattleytonia Kieth Roth and Cymbidium maudidum; varying the time the plant tissue was exposed to the bacteria from 1 hour to 96 hours; performing experiments with and without the wound signal molecule acetosyringone; and exposing the tissue to the virulent strains of A. tumefaciens mentioned previously.This research also developed GUS assay conditions necessary to decrease the number of false positives due to bacterial contamination. These conditions included chloramphenicol in the GUS assay buffer. / Department of Biology

Thesis (MSc (Genetics))--Stellenbosch University, 2008. / The vine mealybug, Planococcus ficus (Signoret), is a severe pest of grapevine in many grape and wine producing countries around the world. It is renowned not only for the considerable damage it infers to grapevine of its own accord, but in particular for its role in transmitting deleterious viral diseases such as grapevine leafroll disease, Kober stem grooving, Shiraz disease and corky bark. Incidentally, it is an exceptionally tenacious antagonist of grapevine, being resistant to both chemical and biological control mechanisms. As a result, finding an effective strategy for P. ficus control has become a main priority of viticultural industries worldwide. Possible implementation of biotechnological approaches to pest management has resulted in a need for P. ficus genetic data - of which there are currently very little available. The transcribed genes of an organism can be captured in a cDNA library, and the sequences of the various transcripts can then be characterized. In this study altogether five cDNA libraries were constructed from the transcribed sequences of Planococcus ficus (Signoret). Instrumental to their construction was the identification of an RNA extraction protocol that provided large quantities of high quality RNA from mealybugs. The five cDNA libraries were the result of a set of modifications to the Creator™ SMART™ cDNA Library Construction Kit (used for Primary Library construction), and differed mainly with regards to range of insert sizes they contain. Whereas an abundance of short fragments were found in the Primary Library (42% of screened inserts 60.5 kb, and 20% >1 kb), the Fractionated Libraries contained inserts of specific size ranges that were more-or-less equally represented. The broadest size range was found in Fractionated Library 4, for which a uniform distribution over the range 0.25 kb - 4 kb was observed. Average insert sizes of Fractionated Libraries 1 to 4 were estimated at 0.25 kb, 0.5 kb, 1 kb and 2 kb respectively. These results demonstrated the importance of using a protocol designed to circumvent the bias towards incorporation of shorter transcripts in cDNA libraries. Although the libraries were not exhaustively analyzed, the outcome of a pilot investigation indicated that 41% of the submitted sequences had matches in the non-redundant database of the National Center for Biotechnology Information (NCBI, E-value 6 10-5), and that approximately 82% of these were of insect origin. Moreover, two potential targets for an RNAi-mediated approach to P. ficus pest control were identified. With one exception, these sequences seemed to be unique to arthropods. Future research needs to investigate the efficiency by which these sequences are able to constrain P. ficus proliferation, and their suitability for grapevine transformation.

Made available in DSpace on 2015-03-26T12:42:06Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1359880 bytes, checksum: 75e8020a52662b6da6545e57d6103547 (MD5) Previous issue date: 2014-02-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Coffee is the most traded commodity in the world and Brazil is the largest producer. Coffee leaf rust, caused by the biotrophic fungus Hemileia vastatrix is the most important coffee disease reducing coffee yield by 35 to 50%. Too little is known about this pathosystem as well as the pathogen impacts on plant photosynthesis, defense enzymes activities, concentration of plant pigments and chlorophyll a fluorescence parameters under different fungicides sprayed treatments. To contribute with new knowledge generation, this study aimed: 1) to evaluate the Fv/Fm (Maximal photosystem II quantum yield) chlorophyll a fluorescence imaging parameter as tool to differentiate pre-symptomatic coffee leaf rust infections in plants sprayed with pyraclostrobin and epoxiconazole and 2) to investigate the relationships between photosynthetic pigments, defense enzymes activities and some chlorophyll a fluorescence parameters on leaves of coffee plants sprayed with epoxiconazole and pyraclostrobin and inoculated or non-inoculated with Hemileia vastatrix. Experiments in a completely randomized design were performed in greenhouse and coffee plants were inoculated with urediniospores. Epoxiconazole and pyraclostrobin were sprayed in coffee plants in order to study the Fv/Fm chlorophyll a fluorescence parameter, coffee leaf rust severity, defense enzymes activities, photosynthetic pigments concentration and other chlorophyll a fluorescence parameters. Results from the present study showed that the different fungicides application on soil and/or leaves of triazoles and strobilurins were efficient to control coffee leaf rust. There was a significant linear relationship between the areas of real severity and visual severity and for each additional unit in the visual severity there was an increase of 53% on the real severity. For the epoxiconazole and pyraclostrobin treatments, the coffee leaf rust symptoms decreased based on both visual and Fv/Fm images. Pustules on leaves sprayed with epoxiconazole were smaller in size than the ones on leaves of plants from the control treatment, but bigger than pyraclostrobin. Reduction on Fv/Fm values at the pustules epicenter on leaves of plants sprayed with epoxiconazole and pyraclostrobin were lower than those of the control treatment. Coffee leaf rust severity decreased until 40 days after inoculation on plants sprayed with epoxiconazole and pyraclostrobin. Catalase, peroxidases, β-1,3-glucanases and chitinases activities were different among treatments with inoculated and non-inoculated plants. There was a significant reduction in pigments concentration between non-inoculated and inoculated treatments but not, in plants sprayed with epoxiconazole and pyraclostrobin. Chlorophyll a fluorescence parameters were different between non-inoculated and inoculated plants and non- sprayed and fungicides sprayed plants. Hemileia vastatrix affected the photosynthetic capacity of Coffea arabica and the Fv/Fm parameter was able to show this effect before the appearance of visual symptoms. Changes on photosynthesis were detected in non- inoculated and inoculated plants sprayed with epoxiconazole and pyraclostrobin. Also, the effect of fungicides on photosynthesis should be studied to provide more opportunities to understanding the impacts on plant defense mechanisms that lead to reduced coffee leaf rust symptoms. / O café é a commodity mais negociada no mundo sendo o Brasil seu maior produtor. A ferrugem do cafeeiro, causada pelo fungo biotrófico Hemileia vastatrix é a doença mais importante do cafeeiro e pode causar redução em sua produtividade entre 35 a 50%. Muito pouco se sabe sobre este patossistema, bem como os impactos do patógeno sobre a fotossíntese da planta, a atividade de enzimas de defesa, a concentração de pigmentos vegetais e os parâmetros de fluorescência clorofila a sob diferentes tratamentos com fungicidas. Para contribuir com a geração de novos conhecimentos, este estudo teve como objetivos: 1) avaliar a variável Fv/Fm (Rendimento quântico máximo do fotossistema II) obtida através da imagem da fluorescência da clorofila a como ferramenta para diferenciar infecções pré-sintomáticas em plantas pulverizadas com epoxiconazol e piraclostrobina e 2) investigar as relações entre pigmentos fotossintéticos, atividade de enzimas de defesa e alguns parâmetros de fluorescência da clorofila a em folhas de café pulverizadas com epoxiconazol e piraclostrobina e inoculadas ou não-inoculadas com Hemileia vastatrix. Os experimentos seguiram delineamento inteiramente casualizado e foram conduzidos em casa de vegetação. As plantas de café foram cultivadas em estufa e inoculadas com urediniósporos. Epoxiconazol e piraclostrobina foram pulverizadas sobre as plantas, a fim de estudar o parâmetro Fv/Fm de fluorescência da clorofila a, a severidade da ferrugem do cafeeiro, a atividade de enzimas de defesa, a concentração de pigmentos fotossintéticos e outros parâmetros de fluorescência da clorofila a. Houve uma relação linear significativa entre severidade real e visual das áreas foliares estimadas pelo parâmetro Fv/Fm e para cada unidade adicional na severidade visual, houve um aumento de 53% na severidade real. Para os tratamentos com epoxiconazol e piraclostrobina, os sintomas da ferrugem do cafeeiro diminuíram tomando como base as imagens visual e as geradas a partir do parâmetro Fv/Fm da fluorescência da clorofila a. Pústulas nas folhas pulverizadas com epoxiconazol foram menores nas folhas do tratamento controle mas, maiores do que piraclostrobina. A redução nos valores do parâmetro Fv/Fm no epicentro das pústulas das folhas pulverizadas com epoxiconazol e piraclostrobina foram menores do que os do tratamento controle. A severidade da ferrugem do cafeeiro diminuiu até 40 dias após a inoculação nas plantas pulverizadas com epoxiconazol e piraclostrobina. As atividades de catalase, peroxidases, β-1,3-glucanases e quitinases foram diferentes entre os tratamentos com plantas inoculadas e não-inoculadas. Houve redução significativa na concentração de pigmentos entre as plantas não-inoculadas e inoculadas mas, não entre as plantas pulverizadas com epoxiconazol e piraclostrobina. Os parâmetros de fluorescência da clorofila a foram diferentes entre plantas não-inoculadas e inoculadas e não-pulverizadas e pulverizadas com fungicidas. Hemileia vastatrix afetou a capacidade fotossintética de Coffea arabica e o parâmetro Fv/Fm de fluorescência da clorofila a foi capaz de mostrar esse efeito antes do aparecimento dos sintomas visuais. Alterações na fotossíntese foram detectadas em plantas não-inoculadas e inoculadas pulverizadas com epoxiconazol e piraclostrobina. Além disso, o efeito dos fungicidas sobre a fotossíntese deve ser estudado, para proporcionar mais oportunidades para a compreensão dos impactos sobre os mecanismos de defesa da planta, que levam à redução de sintomas da ferrugem do cafeeiro.

Three sampling methods for estimating abundance of alfalfa weevil (AW) larvae (Hypera postica Gyllenhal) were evaluated for both accuracy and precision. Calibration equations were developed to convert intensity estimates of AW larvae among sampling methods. Greenhouse experiments evaluating the interaction of moisture stress and defoliation by AW larvae indicated that yield response of alfalfa to AW feeding is dependent on moisture stress levels. Field studies on the influence of AW feeding on alfalfa confirmed the importance of moisture stress in alfalfa tolerance to weevil feeding. Quadratic regression models are presented to predict yield loss and changes in stem density as a function of weevil intensity. A sequential sampling plan was developed and validated for use in pest management decision making. Validation of the plan indicated an average error rate of 1.8%, with the number of samples needed reduced by 55% in 1980, 53% in 1981, and 28% in 1982. A net benefit analysis the Virginia Alfalfa IPM program indicated that growers participating in the program during 1981-84 realized an estimated average increase in net revenue of $8.80 per hectare from the alfalfa weevil scouting program, and $28.13 per hectare from the potato leafhopper scouting program. / Ph. D. / incomplete_metadata

Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) (obscure mealybug), is a common and serious pest of apples and pears in South Africa. Consumer and regulatory pressure to produce commodities under sustainable and ecologically compatible conditions has rendered chemical control options increasingly limited. Information on the seasonal occurrence of pests is but one of the vital components of an effective and sustainable integrated pest management system needed for planning the initiation of monitoring and determining when damage can be expected. It is also important to identify which orchards are at risk of developing mealybug infestations while development of effective and early monitoring tools for mealybug populations will help growers in making decisions with regards to pest management and crop suitability for various markets. It is also essential to determine the presence and efficacy of naturally occurring biological control agents in orchards so as to ascertain the potential of biological control as a viable alternative in orchards. However, under the current integrated pest management protocol, it has been difficult to determine this, due to the sporadic and relatively low incidence of mealybug infestations in some orchards, or by simply relying on naturally occurring field populations of biocontrol agents. Knowledge of the environmental conditions under which P. viburni population levels may become destructive is also essential for timing the release of insectary reared natural enemies as well as understanding the population ecology of this pest and its natural enemies. Information was gathered regarding the seasonal phenology of P. viburni and its natural enemies in pome fruit orchards in the Western Cape Province during the 2007/08 and 2008/09 growing seasons. Seasonal population studies showed that P. viburni has multiple overlapping generations with all life stages present throughout the year. The highest orchard infestations occurred during the summer period until early winter (January to early June). This was followed by a decrease in population from late June to November, before another increase in December. Presence-absence sampling of mealybugs on the host plant revealed that woody parts of the tree, such as the trunk and old stems were the most preferred sites for mealybug habitation, due to the availability of protected refuge sites. Migration of mealybug populations to newer growth and the upper sections of the tree crown, such as the new stems, leaves and eventually the fruit, was observed from December throughout the summer period until the early winter in June. Fruit colonization in both apples and pears commenced in January, when the fruit had developed a size sufficient for P. viburni to penetrate and occupy spaces such as the fruit core, calyx and stem end. There was no evidence of P. viburni occurring beneath the soil surface or on the roots of host trees. Two natural enemies of mealybugs, namely Pseudaphycus maculipennis (Mercet) and Coccidoxenoides perminutus (Girault), were found to be active in apple and pear orchards in the Western Cape. However, the status of C. perminutus as a parasite of P. viburni still needs to be verified despite evidence of emergence from P. viburni mummies, which was not sufficient enough to suggest that it is a useful biological control agent. Seasonal abundance trends of the two natural enemies revealed that their lifecycle is synchronized with that of the host. However, there was no evidence of P. maculipennis activity in Ceres. No predators were found during the course of this study. The rate of P. viburni parasitism at harvest was 46.52%, with P. maculipennis and C. perminutus constituting 98.966% and 1.034% of the parasitoids recovered from mealybug mummies, respectively. Studies on the use of pheromone traps as early monitoring tools for P. viburni showed that there was a positive and significant relationship between the fruit infestation and number of P. viburni adult males caught in pheromone-baited traps (r2 = 0.454). The action threshold level was estimated to be 2.5 male P. viburni caught per trap per fortnight at an economic threshold of 2% fruit infestation. / AFRIKAANSE OPSOMMING: Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) (ligrooswitluis), is ‘n algemene en ernstige plaag van appels en pere in Suid-Afrika. Druk deur verbruikers en regulasies om kommoditeite onder volhoubare en ekologies verenigbare toestande te produseer het chemiese beheeropsies toenemend beperk. Inligting oor die seisoenale voorkoms van plae is een van die essensiële komponente van ‘n effektiewe en volhoubare geïntegreerde plaagbestuurprogram. Dit is in die aanvanklike beplanning van monitering en om te bepaal wanneer skade verwag kan word. Dit is ook belangrik om boorde vroegtydig te identifiseer wat die risiko het om witluisbesmettings te ontwikkel. Die ontwikkeling van effektiewe en vroeë moniteringstegnieke vir witluisbevolkings sal produsente help met besluitneming rakende plaagbestuur en die geskiktheid van gewasse vir verskeie markte. Dit is ook noodsaaklik om die teenwoordigheid en effektiwiteit van biologiese beheer agente wat natuurlik in boorde voorkom te bepaal ten einde die potensiaal van biologiese beheer as ‘n lewensvatbare alternatief vas te stel. Onder die huidige geïntegreerde plaagbestuurprotokol was dit egter moeilik om laasgenoemde te bepaal weens die sporadiese en relatiewe lae voorkoms van witluisbesmettings in sommige boorde of deur bloot staat te maak op die veldpopulasies van biologiese beheer agente wat natuurlik voorkom. Kennis van die omgewingstoestande waaronder P. viburni bevolkingsvlakke skadelik raak is ook noodsaaklik vir die beplanning van vrylating van biologiese beheer agente, asook om die bevolkingsekologie van hierdie plaag en sy natuurlike vyande te verstaan. Inligting oor die seisoenale fenologie van P. viburni en sy natuurlike vyande in sagtevrugte boorde in die Westelike Kaapprovinsie is gedurende die 2007/08 en 2008/09 groeiseisoene versamel. Seisoenale bevolkingstudies het getoon dat P. viburni verskeie oorvleuelende generasies het met alle stadia teenwoordig regdeur die jaar.

The phytopathogen Phytophthora ramorum (Werres, DeCock & Man in't Veld), causal agent of Sudden Oak Death (SOD) of oaks (Quercus spp.) and tanoaks (Notholithocarpus densiflorus syn. Lithocarpus densiflorus), is established in coastal forests of the western United States. Since the discovery of SOD in the Douglas-fir / tanoak forests of southwest Oregon in 2001, a multiagency effort has ensued with the goal of fully eliminating P. ramorum from this originally small and isolated area. In this study we investigated the epidemiology of SOD in Oregon, particularly as it affects the success of the eradication program. Two approaches were taken to discern the mechanism of long distance dispersal: first, a landscape analysis of the spatial relationship between SOD sites and roads or streams, features associated with movement of infested soils, and, second, a local analysis to discern if understory infection is originating from soil or stream-borne inoculum. Using a restricted randomization test we concluded that SOD sites were no closer to roads than expected by chance, which is inconsistent with soil dispersal by people. While we found evidence that SOD sites were preferentially closer to waterways, inoculum had not moved away from streams into adjacent understory foliage. The local distribution of understory infection around SOD positive trees indicated that primary inoculum is infecting overstory canopies first, suggesting that P. ramorum is dispersing in air currents. Regression modeling indicated that weather conditions two years before detection could explain variation in the maximum distance inoculum moved each year of the epidemic between 2001 and 2010. This two year delay between infection and detection has allowed ample time for infested sites to contribute to further spread. Model results were consistent with observations made the summer of 2011, when trees likely infected by secondary inoculum at non-eradicated sites developed symptoms but were still undetectable by aerial surveys. Due to the prevalence of infection on tanoak, opportunities for sporulation and infection occur more often in Oregon than in California. These data can explain the failure to eliminate P. ramorum. Nevertheless, we did find evidence that the eradication program has significantly reduced the potential size of the SOD epidemic in Oregon. / Graduation date: 2012

The objectives of this study were to establish the effectiveness of chlorpyrifos in suppressing H. armigera population in oranges and to determine the effect chlorpyrifos had on the health of farm pesticide operators. Experiments showed that by applying chlorpyrifos on orange trees, H. armigera larvae population was suppressed significantly. High fruit yields were realized from trees that were sprayed with chlorpyrifos. Visual observation of personnel involved in pesticide related duties, revealed that judicious use of pesticides was not practiced by farm workers in all three farms. Data analysis from questionnaires, health records and interviews proved that farm workers suffered from illnesses that were pesticide related. It was mainly those farm workers in the age group of 31 to 35 years who suffered the most from pesticide related illnesses. / Agriculture and Life Sciences / M. Sc. (Agriculture)

Thesis (PhD (Agric) (Conservation Ecology and Entomology))--University of Stellenbosch, 2006. / A study was performed to develop a generic pest monitoring system for sampling the main table grape pests in vineyards in the Hex River Valley, Western Cape Province of South Africa. The presence of phytophagous and predatory mites on cover crop plants was also investigated as this may contribute to biological control of the phytophagous mites in vines. Life table studies for Epichoristodes acerbella (Walker), an important phytosanitary pest, were conducted to determine whether or not this pest was sensitive to high temperatures. Information gained from the latter can also be used for breeding purposes in the possible future development of a sterile insect technique (SIT) programme to control this pest. The sampling system consisted of inspecting 20 plots of five vines per plot per one to two hectares. The top fork of each of the five vines per plot was examined for Planococcus ficus (Signoret) to a distance of within 30 cm of the stem, as well as the distal 15 cm of one cane per vine for the presence of P. ficus and damage caused by Phlyctinus callosus Boh. One bunch per vine was examined for insect damage or presence, and one leaf per vine for the presence of leaf infesting arthropods, such as Tetranychus urticae Koch, P. ficus and Frankliniella occidentalis (Pergande). Corrugated cardboard bands, tied around the stem of one vine per plot, were used to monitor activity of P. callosus. Blue sticky traps, at a density of four to five traps per one to two hectares, were used to monitor activity of F. occidentalis. Pheromone traps, at a density of one trap per one to two hectares, were used to monitor activity of P. ficus, E. acerbella and Helicoverpa armigera (Hübner). All the above-mentioned inspections were done at two-weekly intervals, except traps for E. acerbella and H. armigera, which were inspected weekly. In each of the rows in which the sample plots were situated, one leaf of each of the cover crop plant species was examined for the presence of phytophagous mites and their predators. The abundance and distribution of cover crop plants were determined using a co-ordinate sampling system. Cover crop sampling was done at monthly intervals. The current threshold for P. ficus is 2% stem infestation, which is reached when more than 65 males per pheromone trap are recorded. Counting mealybugs on the sticky pads in the pheromone traps is time consuming. However, the number of grid blocks on the sticky pad with males present can be counted. When P. ficus males are found in 27 blocks on the sticky pad, stem inspections should commence. Due to the spatial association between P. ficus bunch and stem infestation, stem infestation could give an indication of where bunch infestation could be expected. The use of blue sticky traps for predicting halo spot damage, caused by F. occidentalis, is not recommended. The presence of thrips on the vine leaves could not give an indication of where to expect bunch damage, since thrips on the leaves and halo spot damage were not spatially associated. A suitable sampling method for F. occidentalis still needs to be developed. The monitoring system described here can only provide information on the infestation status of the vineyard. For E. acerbella, H. armigera and P. callosus, the traps and cardboard bands could be used to identify vineyards where these pests are present and therefore, where phytosanitary problems may arise. The presence of P. callosus under the bands was spatially associated with P. callosus damage and could be used as an indicator of the latter. The presence of drosophilid flies in the bunches could not be used as an indicator of the presence of E. acerbella in the bunches. If 5% bunch damage is used as an economic threshold for E. acerbella and P. callosus, there will be a good chance of not under spraying if control measures are applied at 1% bunch damage. Epichoristodes acerbella favoured more moderate constant temperatures, with constant temperatures of 28°C and above being unfavourable for development. The economic threshold for Tetranychus urticae Koch is six mites per leaf, or if presence-absence sampling is used, 11 to 29% leaf infestation. Three important predatory mites, that kept T. urticae under control, were found in the Hex River Valley, namely Euseius addoensis (Van der Merwe & Ryke), Neoseiulus californicus (McGregor) and an undescribed phytoseiid in the genus Typhlodromus. Various cover crop plants served as hosts for T. urticae and predatory mites. The presence of these plants created suitable conditions for the survival of these mites and may have influenced their presence on the vine leaves. In the case of phytosanitary pests, both field and pack shed inspections can be used to conclude with a 99% degree of certainty that infestation levels in the pack shed will be 10% or less, since similar results for both methods were obtained. However, more than 20 plots will have to be inspected.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2005. / The South African table grape industry exports approximately 60% of the table grapes produced. A major threat to the export of these grapes is the phytosanitary risk that insect pests pose. This study was conducted in the Hex River Valley, South Africa’s main table grape producing area. The aim of this study was to reduce the number of phytosanitary rejections from insects on table grapes from the Hex River Valley. Thus the main objectives of the study were to identify the most important phytosanitary pests in the Hex River Valley; the determination of their presence in the vineyards with possible means to control them; and to assess the possibility of using postharvest quarantine treatments in the Western Cape. Further aims were to determine the effect of different colour harvesting crates on the phytosanitary pests and whether the phytosanitary pests infested the grapes via packhouses. The most important phytosanitary pests of table grapes of the Hex River Valley are in order of importance: Phlyctinus callosus (Schonherr) (Coleoptera: Curculionidae), Epichoristodes acerbella Walker (Lepidoptera: Tortricidae), Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), Gonocephalum simplex Fabricius (Coleoptera: Tenebrionidae) and Dysdercus fasciatus Signoret (Hemiptera: Pyrrhocoridae). 12.71% of rejections were from species that were not identified, while a further 33% of the rejections were possibly identified incorrectly. Phytosanitary control of P. callosus appeared to be far more effective using Plantex® than pesticides. Weather conditions appeared to affect the abundance of P. callosus, especially warm weather, while bunches harboured less P. callosus later in the day. Control of E. acerbella with DiPel® (Bacillus thuringiensis var. kurstaki) appeared to at least reduce the population within the vineyards, and so its use is recommended. P. ficus is a non-actionable species for the USA market and is not listed as a phytosanitary pest for the Israeli market and so should not be causing any phytosanitary rejections. C. capitata appeared to be successfully controlled by the fruit fly sterile release program and the cold sterilisation it currently undergoes. G. simplex caused few rejections. It is still unclear where this pest infests the grapes, as it was found in both the field and in the packhouses. D. fasciatus occurrence on grapes was probably accidental. It was shown that picking during the early and late parts of the day, when this species was less active, reduced its occurrence in bunches. Gryllus bimaculatus (De Geer) (Orthoptera: Gryllidae), although not reported as a reason for rejections in table grapes for the past two years, was an actionable species that was present in large numbers in the Hex River Valley. There was a strong correlation between increasing quantities of pesticides and higher abundances of G. bimaculatus. It appeared to be an indicator of the overuse of pesticides. Results of this study showed that infestation by the phytosanitary pests came from neighbouring vineyards. The creation of barriers to prevent the movement of these pests between vineyards is suggested. Methyl bromide is the most commonly used postharvest quarantine treatment. Owing to the ozone-depleting properties of methyl bromide, it is scheduled to be outlawed in many countries from 2005. Alternative postharvest treatments are irradiation, extreme temperatures, forced air, vapour-heat treatments and the use of controlled atmospheres. Irradiation treatments appeared to control the pests at doses that do not damage the grapes. Controlled atmosphere treatments also have a high probability of success, although more research is required on this treatment. Low temperature treatments are relatively cheap as most exported fruit already undergoes cold storage, and appears to control species in the families Pseudococcidae and Tephritidae, although further research is required for the other pest. Colour or location of the harvesting crates in the vineyards appeared not to influence the number of phytosanitary pests collected, as they were not attracted to these crates.

"August 2003." / Includes bibliographical references (leaves 294-333) / 2 v. (xxxi, 333 leaves) ; ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2005