O uso de inseticidas em um agroecossistema pode interferir na densidade e ação dos inimigos naturais e comprometer a eficácia do controle biológico dentro de um programa de manejo integrado de pragas. Dessa forma, objetivou-se avaliar, em laboratório, os efeitos letal e subletais de inseticidas reguladores de crescimento sobre larvas e adultos com até 24 h de idade do predador Ceraeochrysa cubana (Hagen, 1861). Para isso, larvas recém-eclodidas foram submetidas à pulverização de 2 mL de calda, do respectivo tratamento, em torre de Potter ajustada para deposição de 1,8 ± 0,1 mg cm-2. Os inseticidas e doses (g i.a. L-1) avaliados foram: piriproxifem 0,2 (Tiger 100 EC), buprofezina 0,5 (Applaud 250), tebufenozida 0,22 (Mimic 240 SC), metoxifenozida 0,75 (Intrepid 240 SC), diflubenzurom 0,12 (Micromite 240 SC), lufenurom 0,05 (Match EC). Água destilada foi utilizada como tratamento controle. A mortalidade de larvas, pupas e adultos e o número de ovos depositados pelas fêmeas foram avaliados a cada 24 h. A viabilidade de ovos foi determinada a partir da terceira oviposição das fêmeas utilizando 100 ovos de cada indivíduo. Os efeitos letais foram observados em larvas tratadas com diflubenzurom, lufenurom e piriproxifem. Os inseticidas piriproxifem, tebufenozida, metoxifenozida e buprofezina causaram redução na fecundidade de 20 a 40% e na fertilidade de no máximo 10%, sendo considerados levemente nocivos (30<E<=79 de redução), enquanto que, diflubenzurom e lufenurom causaram 100% de mortalidade de larvas de C. cubana e foram considerados nocivos ao predador (E>99%). Não houve diferenças significativas entre os tratamentos quanto aos parâmetros taxa líquida de reprodução (Ro), taxa intrínseca de crescimento (rm) e taxa finita de aumento (?). No entanto, diferenças significativas foram constatadas no tempo médio entre gerações (T), sendo que os menores valores foram constatados nos insetos expostos aos inseticidas tebufenozida e metoxifenozida. No bioensaio com adultos, lufenurom, diflubenzurom reduziram significativamente a fecundidade e fertilidade, enquanto que, tebufenozida, metoxifenozida e buprofezina não diferiram do controle. Piriproxifem reduziu significativamente a fecundidade total, porém, não afetou a fertilidade e a longevidade. Embora inseticidas reguladores de crescimento sejam comumente considerados como seletivos, afetaram a sobrevivência e reprodução de C. cubana em condições de laboratório. Todos os inseticidas testados devem ser submetidos a ensaios de semi-campo o para confirmação dos resultados, entretanto, tebufenozida, metoxifenozida, buprofezina e piriproxifem foram considerados levemente nocivos e, consequentemente, mais indicados para utilização dentro de programas de manejo integrado de pragas envolvendo C. cubana ou outras espécies de crisopídeos. / The use of pesticides within an agricultural system can interfere with the density and functionality of natural enemies, thus endangering the efficacy of biological control in the Integrated Pest Management program. Hence, this study evaluated the lethal and sublethal effects of six Insect Growth Regulators (IGR) insecticides over the larvae and adults of Green Lacewing Ceraeochrysa cubana (Hagen, 1861) under laboratory conditions. Neonate larvae and newly-emerged adults were sprayed with the respective treatments with the aid of a Potter Tower (2 mL of spray solution, 1.8 ± 0.1 mg cm-2 of deposition). The insecticides and rates (g a.i. L-1) evaluated were: pyriproxyfen 0.2 (Tiger 100 EC), buprofezin 0.5 (Applaud 250), tebufenozide 0.22 (Mimic 240 SC), methoxyfenozide 0.75 (Intrepid 240 SC), diflubenzuron 0.12 (Micromite 240 SC), lufenuron 0.05 (Match EC) and for control, distilled water. The mortality of larvae, pupa and adults and the number of eggs laid were registered daily. The viability was assessed by observing the percentage of eclosion from 100 eggs. Lethal effects were observed in larvae treated with diflubenzurom, lufenuron and pyriproxyfen. The insecticides pyriproxyfen, tebufenozide, methoxyfenozide and buprofezin reduced fecundity from 20 to 40% and fertility at highest 10%, being considered slightly harmful (30%<E<79%), whereas diflubenzuron and lufenuron caused 100% of larvae mortality and were considered harmful (E>99%). No significant differences were found among treatments for net reproduction rate (Ro), intrinsic growth rate (rm) and finite rate of increase (?). However, significant differences were found in mean generation time (T) for methoxyfenozide and tebufenozide. For adult bioassay, lufenuron and diflubenzuron reduced significantly the fecundity and fertility, whereas tebufenozide, methoxyfenozide and buprofezin did not differ from control. Pyriproxyfen significantly reduced the fecundity, but, did not affect fertility and longevity. Although IGRs are commonly taken as selective insecticides, they reduced the survivorship and reproduction of C. cubana in laboratory conditions. All products must be directed for semi-field studies for confirmation of results, however, tebufenozide, methoxyfenozide and buprofezin were considered slightly harmful for larvae and, consequently more appropriate to use in Integrated Pest Management programs whenever C. cubana as well as other lacewing species are present.

Lufenuron é um novo inseticida do grupo dos inibidores da biossíntese de quitina utilizado para o controle de Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae) na cultura do milho. O uso deste inseticida para o controle de S. frugiperda tem aumentado muito nos últimos anos. Este incremento pode ser atribuído à sua alta eficiência e devido ao desenvolvimento da resistência desta praga aos produtos tradicionalmente recomendados para o seu controle (por exemplo, fosforados e piretróides). Neste trabalho, a linha básica de suscetibilidade de S. frugiperda foi obtida com o intuito de implementar um programa proativo de manejo da resistência. Para a caracterização da suscetibilidade de populações de S. frugiperda ao lufenuron, utilizou-se o bioensaio que consistiu no tratamento superficial de dieta artificial. Lagartas de 2° e 3° instar foram expostas à dieta tratada por um período de até 5 dias (120 h). A partir deste estudo concluiu-se que a utilização de lagartas de 3° instar expostas por um período de 4 dias (96 h) foi o procedimento de bioensaio mais adequado. Baseado na curva de concentração-resposta da população suscetível de referência, as concentrações de 3,2 e 10,0 mg de lufenuron / mL de água destilada foram escolhidas para o monitoramento da suscetibilidade. Resultados do monitoramento da suscetibilidade de populações de S. frugiperda provenientes dos principais Estados produtores de milho do Brasil (Rio Grande do Sul, Paraná, São Paulo, Goiás e Minas Gerais) mostraram diferenças significativas quanto à suscetibilidade ao lufenuron. Esses resultados sugerem a necessidade da implementação de estratégias de manejo da resistência para preservar a vida útil do lufenuron no controle de S. frugiperda no Brasil. / Lufenuron is a newly benzoylphenyl urea chitin synthesis inhibitor insecticide. The use of this compound to control Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae) has increased significantly in the past years. This increase can be attributed to its high activity against S. frugiperda and to the reduction of efficacy due to resistance to some traditional insecticides (such as phosphates, carbamates and pyrethroids) recommended for controlling this pest. In this study, a baseline susceptibility data of S. frugiperda populations to lufenuron were obtained for implementing a proactive resistance management program. An artificial diet treatment surface bioassay was used to characterize the response to lufenuron in a susceptible strain. Second and third instar larvae were exposed to the treated diet up to 5 days (120 h). A period of 4 days (96 h) and third instar larvae were defined as standard procedures for bioassays. After the characterization of the susceptible population, diagnostic concentrations of 3.2 and 10.0 mg of lufenuron / mL of distilled water were chosen for monitoring the susceptibility. A survey of susceptibility to lufenuron was conducted in field populations of S. frugiperda collected from major corn-growing regio ns located in the States of Rio Grande do Sul, Paraná, São Paulo, Goiás and Minas Gerais. Significant differences in susceptibility to lufenuron were detected among S. frugiperda populations. These results suggest the need to implement resistance management strategies to preserve the lifetime of lufenuron for controlling S. frugiperda in Brazil.

Gong Jun. / "March 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 254-294) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-12-22T14:20:57Z No. of bitstreams: 1 Wevertton Marllon Anselmo.pdf: 2083454 bytes, checksum: 55af889b8cc4630b6dfacc2da84c662b (MD5) / Made available in DSpace on 2016-12-22T14:20:57Z (GMT). No. of bitstreams: 1 Wevertton Marllon Anselmo.pdf: 2083454 bytes, checksum: 55af889b8cc4630b6dfacc2da84c662b (MD5) Previous issue date: 2013-02-26 / The tomato (Lycopersicon esculent) is a vegetable subject to the occurrence of many disease problems. The need to develop less toxic insecticides has been placed as an alternative found in insecticide plants. Alternative methods of control, such as the use of plant extracts with insecticidal activity have shown promising results. Among the spontaneous species of the caatinga biome silk flower (Calatropis procera) and endemic species of the caatinga biome such as juazeiro (Ziziphus joazeiro) have been studied through their extracts as insecticides. Thi way, the objective of this work was to evaluate the efficiency of plant extracts of the spontaneous species and endemic of the Caatinga biome in the management of pests and diseases in tomato. The experiment was conducted in the experimental area of UAST in two stages, the first being in greenhouse and second in field. In the first stage trays in greenhouse were used and it was verified the action of aqueous extracts of plant on the primary pests which are the transmitters of viruses in tomato Caline Ipa 7. In the second stage, in field it was verified the effect of the use of these aqueous extracts of plants on the main pests and virus using tomato seedlings from the first step. The extracts were produced by grinding leaves of silk flower (C. Procera) and juazeiro (Z. Joazeiro) in a proportion of 10% strained and then filtered through cheesecloth fabric plus 1% detergent. Sprays were made every two days and assessments made every seven days. The design in the first step was completely randomized with three treatments and two replications; in the second, the design was randomized in block with three treatments and six replications. Among the major pests associated with the cultivation of tomato in this study occurred more frequently in the White Fly Bemisia tabaci (Hemiptera: Aleyrodidae); Minadora to fly Liriomyza sp. (Diptera: Agromyzidae) and Thrips Frankliniella schultzei (Thysanoptera: Thripidae). Extracts of Silk Flower and Juazeiro reduced the infestation of fly B. White Thrips tabaci and F. schultzei compared to the control and the infestation of leaf miner Liriomyza sp. was lower in plants treated with silk flower extract against those not treated with plant extracts. The populational fluctuation of the Fly B. White Thrips tabaci and F. schultzei showed that these pests are present throughout the crop cycle, already Minadora fly Liriomyza sp. only appeared in the first two weeks. There was no difference between treatments in the proportion of plants with virus and production. The percentage of plants with virus symptoms was 49.8% in control and 35.36% and 47.38% for plants treated with extracts of Silk Flower and Juazeiro respectively. Tomato production was 61.03 kg in the control and 65.3 and 74.14 kg in plants treated with extracts of Silk Flower and Juazeiro, respectively, there was no difference in tomato production between treatments. So, Silk Flower and Juazeiro extracts reduced the infestation of fly B. White tabaci, Mosca Minadora Liriomyza sp. Thrips and F. schultzei compared to the control during the production of seedlings, Fly Minadora Liriomyza sp. is considered a pest and requires initial monitoring at the beginning of cultivation. Despite the decrease extracts and Silk Flower Juazeiro had not an effective control against the population of Thrips F. schultzei field. / O tomate Lycopersicon esculentum é um vegetal sujeito à ocorrência diversos problemas fitossanitários. A necessidade do desenvolvimento de inseticidas menos tóxicos tem-se colocado como alternativa encontrada em plantas inseticidas. Métodos alternativos de controle, como o uso de extratos vegetais com atividade inseticida têm revelado resultados promissores. Dentre as espécies espontâneas do bioma caatinga a flor de seda Calatropis procera e espécies endêmicas do bioma caatinga como o juazeiro Ziziphus joazeiro vem sendo estudadas através de seus extratos como inseticidas. Nesse sentido este trabalho teve como objetivo avaliar a eficiência de extratos vegetais das espécies espontânea e endêmica do bioma caatinga no manejo de pragas e doenças na cultura do tomateiro. O experimento foi conduzido na área experimental da UAST em duas etapas, sendo a primeira em telado e a segunda em campo. Na primeira etapa foi utilizado bandejas em telado, foi verificado a ação de extratos aquosos de vegetais sobre as pragas primárias transmissoras de viroses em tomate Caline Ipa 7. Na segunda etapa, em campo verificou o efeito da utilização desses mesmos extratos aquoso de vegetais sobre as principais pragas e virose do tomateiro usando as mudas provenientes da primeira etapa. Os extratos foram produzidos triturando folhas de flor de seda C. procera e juazeiro Z. joazeiro numa proporção de 10% depois coados e filtrados em tecido voil acrescido de 1% de detergente neutro. As pulverizações foram feitas a cada dois dias e a avaliações feitas a cada sete dias. O delineamento na primeira etapa foi inteiramente ao acaso com três tratamentos e duas repetições, na segunda o delineamento foi em blocos ao acaso sendo três tratamentos e seis repetições. Dentre as principais pragas associadas ao cultivo do tomateiro, no presente trabalho, ocorreram em maior frequência a Mosca Branca Bemisia tabaci (Hemiptera: Aleyrodidae); a Mosca Minadora Liriomyza sp. (Diptera: Agromyzidae) e o Tripes Frankliniella schultzei (Thysanoptera: Thripidae). Os extratos de Flor de Seda e Juazeiro reduziu a infestação da Mosca Branca B. tabaci e do Tripes F. schultzei em relação à testemunha e a infestação da Mosca Minadora Liriomyza sp. foi menor em plantas tratadas com extrato de flor de seda em relação aquelas não tratadas com extratos vegetais. A flutuação populacional da Mosca Branca B. tabaci e Tripes F. schultzei mostra que essas pragas estão presente durante todo o ciclo da cultura, já a Mosca Minadora Liriomyza sp. só apareceu nas duas primeiras semanas. Não houve diferença entre os tratamentos em relação à proporção de plantas com virose e a produção. A porcentagem de plantas com sintomas de virose foi de 49,8% no controle e 35,36% e 47,38% para plantas tratadas com extrato de Flor de Seda e Juazeiro, respectivamente. A produção de tomate foi de 61,03kg no controle e de 65,3 e 74,14 kg em plantas tratadas com extratos de Flor de Seda e Juazeiro, respectivamente, não houve diferença na produção de tomate entre os tratamentos. Assim, os extratos de Flor de Seda e Juazeiro reduziram à infestação da Mosca Branca B. tabaci, Mosca Minadora Liriomyza sp. e do Tripes F. schultzei em relação à testemunha durante a produção das mudas, A Mosca Minadora Liriomyza sp. é considerada uma praga inicial e requer monitoramento no inicio do cultivo. Apesar da diminuição os extratos de Flor de Seda e Juazeiro não apresentou um controle eficaz contra a população de Tripes F. schultzei em campo.

Orientador: Lilian Madi-Ravazzi / Banca: Carlos Roberto Ceron / Banca: Alba Regina De Abreu Lima / Resumo: D. melanogaster e D. simulans são espécies irmãs nativas da África tropical que divergiram de um ancestral comum a cerca de dois Myr. Estas espécies têm sido comparadas em vários traços, incluindo a morfologia, fisiologia, comportamento sexual, aloenzimas e outras proteínas, inversões cromossômicas, DNA nuclear e mitocondrial, elementos transponíveis, infecção por Wolbachia entre outros. Entretanto, estudos em populações da América do Sul, inclusive do Brasil, são escassos. O objetivo principal do trabalho foi comparar linhagens geográficas de D. melanogaster e D. simulans do Brasil, África e França, quanto à suscetibilidade ao inseticida DDT, ao padrão de beta e alfa esterases, principalmente em relação à frequência do polimorfismo da esterase- 6 em indivíduos fenotipados como resistentes e suscetíveis, e a atividade da glutationa S-transferase. Ambas as espécies mostraram uma ampla variabilidade nos valores da CL50 obtidos. Os maiores valores foram observados nas linhagens africanas de D. melanogaster e D. simulans, TANA (447,89 μg/mL), e TANA-4 (920 μg/mL). A linhagem Canton-S de D. melanogaster foi a que apresentou o menor valor de CL50 = 2,99 μg/mL. Comparando as populações de mesma localidade de ambas as espécies verifica-se que as linhagens de D. melanogaster mostraram valores de CL50 maiores que os de D. simulans, com exceção da linhagem FLO onde D. simulans apresentou um valor de CL50 (94,60) ligeiramente superior ao de D. melanogaster (81,82). Foram analisadas duas bandas α-esterásicas, denominadas de α-1 e α-2, sendo que a banda α-2 foi observada em 100% de todos os indivíduos analisados de ambas as espécies. Os dados mostram maior variabilidade genética para D. melanogaster em relação à resistência ao DDT, alta resistência para as linhagens africanas de ambas as espécies, indicando que estas populações continuam sendo selecionadas por este... / Abstract: D. melanogaster and D. simulans are sister species native to tropical Africa which diverged from a common ancestor about two Myr. These species have been compared in several traits, including morphology, physiology, sexual behavior, allozymes and other proteins, chromosomal inversions, nuclear and mitochondrial DNA, transposable elements, Wolbachia infection among others. However, studies in populations of South America, including Brazil, are scarce. The main objective of the study was to compare geographic strains of D. melanogaster and D. simulans from Brazil, Africa and France, for susceptibility to the insecticide DDT, the pattern of α and β esterases, especially in relation to the frequency of the polymorphism of esterase-6 in individuals phenotyped as resistant and susceptible, and the activity of glutathione-S-transferase . Both species showed a wide variability in LC50 values obtained. The highest values were observed in African strains of D. melanogaster and D. simulans, TANA (447.89 mg / mL), and TANA-4 (920 / mL). The Canton-S strain of D. melanogaster was the one with the lowest LC50 = 2.99 mg / mL. Comparing populations from the same location of both species the strains of D. melanogaster showed LC50 values larger than D. simulans, except FLO D. simulans strain had a LC50 (94.60) slightly higher than D. melanogaster (81.82). We analyzed two bands α-esterases, which we call α-1 and α-2, and the band α-2 was observed in 100% of all individuals analyzed in both species. The data show greater genetic variability for D. melanogaster for resistance to DDT, high resistance to African strains of both species, indicating that these populations continue to be selected by this or another insecticide, the lack of a cline for the F and S alleles in strains of both species, suggest that treatment with DDT may have selected individuals heterozygous for some strains, which may have masked the... / Mestre

Made available in DSpace on 2017-07-10T17:37:38Z (GMT). No. of bitstreams: 1 Lilian_Bortoluzzi.pdf: 601021 bytes, checksum: 32fb8cf95dc69539e950c2ecdd8f63ad (MD5) Previous issue date: 2009-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The black weevil (Cosmopolites sordidus) is the main pest of banana crops in several regions of the world, causing significant losses in productivity of the culture. The larvae build galleries in the rhizome or pseudostem base, affecting the development of the plant and the fruits, beside favoring the installation of pathogenic microrganisms. The use of nematodes to control of the pest can be an alternative, mainly because the insect's habits make them a potential target of entomopathogenic nematodes. So, this study had the objectives to evaluate isolates of entomopathogenic nematodes in laboratory conditions to their use in controlling the borer. Sixteen isolates Sterinernematidae and Heterorhabditidae were tested, applied on pseudostem (100JIs/cm2). The evaluation was performed 7 days after application. After, the most virulent isolates were compared with each other for production of nematodes in cadavers of wax moth (Galleria mellonella) and also about his compatibility with the insecticide carbofuran. All isolates were pathogenic to the adults of C. sordidus, except the isolate SC (Steinernema carpocapsae). The most virulent isolates were CB24 and CB40 (both of the Heterorhabditidae), which caused respectively 33,3% and 36,7% of mortality. The two isolates showed high production of JIs. The insecticide was compatible with isolated CB40 and incompatible with CB24, nevertheless, CB24 showed better performance in combination with carbofuran / A broca-da-bananeira (Cosmopolites sordidus) é a principal praga dos cultivos de banana em várias regiões do mundo, acarretando perdas significativas na produtividade da cultura. As larvas constroem galerias no rizoma ou base do pseudocaule, afetando o desenvolvimento da planta e dos frutos, além de favorecer a instalação de microrganismos patogênicos. O uso de nematóides para o controle da praga pode ser uma alternativa, principalmente devido aos hábitos do inseto que os tornam um potencial alvo dos nematóides entomopatogênicos. Assim, este trabalho teve como objetivos avaliar isolados de nematóides entomopatogênicos em condições de laboratório visando sua utilização no controle da broca. Foram testados 16 isolados pertencentes às famílias Sterinernematidae e Heterorhabditidae, aplicados sobre pseudocaule (100JIs/cm2). A avaliação foi realizada 7 dias após a aplicação. Os isolados mais eficientes foram comparados entre si quanto à produção de nematóides em cadáveres da traça dos favos (Galleria mellonella) e também quanto a sua compatibilidade com o inseticida carbofurano. Todos os experimentos foram realizados em delineamento inteiramente casualizado. Verificou-se que exceto o isolado SC (Steinernema carpocapsae), todos os demais foram patogênicos aos adultos de C. sordidus. Os isolados mais virulentos foram o CB24 e CB40, os quais provocaram respectivamente 33,3% e 36,7% de mortalidade, ambos da família Heterorhabditidae. Os dois isolados apresentaram alta produção de JIs, não diferindo estatisticamente entre si. O inseticida foi compatível com o isolado CB40 e incompatível com CB24, mesmo assim, CB24 apresentou melhor desempenho em associação com carbofurano

Bibliography: leaves 177-191.

1,1,1-trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) residues (DDTr) are widespread and persistent environmental contaminants, and have been classed as priority pollutants by the United Nations Environment Programme (UNEP). DDTr are potent endocrine disrupting molecules, and have been associated with reproductive abnormalities in juvenile alligators and rats. Microorganisms that metabolise DDTr both aerobically and anaerobically have been isolated and characterised. Bacteria that degrade DDTr aerobically typically utilise a dioxygenase to initiate degradative reactions through ring-hydroxylation, and convert DDTr to 4-chlorobenzoate without further degradation. Terrabacter sp. strain DDE-1 was isolated from DDTr-contaminated soil from Canterbury, New Zealand, and aerobically degrades 1,1-dichloro-2,2-bis-(4-chlorophenyl)-ethylene (DDE) to 4-chlorobenzoate, when grown in the presence of biphenyl (BP). The intermediates of degradation were inferred to be the end products of dioxygenase activity. Sequencing of a large linear plasmid, pBPH-1, from strain DDE-1 identified a cluster of genes with high levels of sequence similarity to BP-degradation genes from Rhodococcus spp. and Pseudomonas spp. This plasmid is lost at high frequency producing the plasmid-cured strain MJ-2, which has lost the ability to degrade BP or DDE. The aim of this study was to confirm that DDE-degradation in strain DDE-1 is encoded by the bph operon located on pBPH-1. No genetic systems to study gene function in either DDE-1 or MJ-2 could be developed using an array of broad-host range vectors. However, heterologous expression of the bph genes in Rhodococcus erythropolis strain TA422 was successful, with the recombinant strain TA425, obtaining the ability to utilise BP and DDE as a sole source of carbon and energy. DDE-1 was shown to convert indole to indigo, but MJ-2 could not, indicating that the biphenyl dioxygenase located on pBPH-1 is responsible for this activity. The bph genes from strain DDE-1 also conferred the ability to produce indigo from indole on strain TA425, confirming successful expression of the functional biphenyl dioxygenase in this strain. Despite several attempts to show quantitative degradation in strain TA425 using gas chromatography, the results were inconclusive Further analysis is needed to provide unequivocal evidence of DDE-degradation by strain TA425. Attempts to express the bph genes in rhizosphere-colonising bacteria, such a Rhizobium spp. or Pseudomonas spp., were unsuccessful, as evidenced by the inability to produce indigo, hence the lack of a functional biphenyl dioxygenase. However, RT-PCR did indeed indicate that P. aeruginosa strain Fin1 produced a bphA1 transcript, indicating that an error is occurring post-transcriptionally in these strains, to prevent production of the functional enzyme. New Zealand has recently been shown to contain hotspots of DDTr-contamination. The second aim of this study was to determine the prevalence of DDTr-degrading bacteria and to gain insight into the types of bacteria that inhabit sites contaminated with DDTr. To investigate this, culture-dependent and culture-independent techniques were employed. Enrichment for DDTr-degrading bacteria yielded species of Rhodococcus and Ralstonia using DDTr-overlayer plate assays. The polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) were used to amplify and analyse the 16S rDNA and 16S rRNA for the identification of dominant and active bacteria in soil samples. The results of this analysis identified bacteria such as Williamsia spp. and Gordonia spp. that degrade other types of pollutants. This analysis did not identify a predominance of Rhodococcus or Ralstonia spp., or other bacteria that have been shown to degrade DDTr. To identify ecologically relevant members of the bacterial communities in DDTr-contaminated soils, and potentially important metabolic pathways, identification of ring-hydroxylating dioxygenase (RHD) genes was performed. PCR and restriction fragment length polymorphism (RFLP) analysis were employed together with phylogenetic analyses. The results showed that the RHD genes identified, clustered separately to those genes previously characterised from cultivated bacteria. Among these genes, one phylogenetic group was most closely related to the dioxygenase genes from Ralstonia eutropha H850, which is potent PCB-degrading bacterium that possesses a dioxygenase with a wide substrate range for many types of heavily chlorinated, PCB congeners. The identification of a predominance of genes with similarity to phenyl-propionate dioxygenases has been not been recognised previously in soil studies.

Bibliography: leaves 177-191. / xxi, 191 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, Dept. of Soil and Water, 2001

Present in almost all living organisms, cytochrome P450s form one of the biggest enzyme superfamilies. They are versatile biocatalysts, capable of performing a range of biochemical reactions and are involved in a wide spectrum of biological functions. The vinegar fly, Drosophila melanogaster, has 85 P450s in its sequenced genome. Six of these have been found to catalyse the synthesis of the important insect molting hormone, 20-hydroxyecdysone and a handful have been implicated in insecticide resistance. The other P450s remained largely uncharacterised. / In the first half of this thesis, the expression patterns of P450s in the D. melanogaster genome were characterised by in situ hybridisation at the third instar larval stage. Most P450s have defined expression patterns at this stage of development. A majority of P450s are expressed in the midgut, Malpighian tubules and fat body, tissues that are involved in the metabolism of xenobiotics. Other P450s are expressed in specific tissues, such as the prothoracic glands, the salivary glands and the gonads, where they might have roles in development or reproduction. In particular, Cyp6g2 is expressed in the corpus allatum (CA), where it could play a role in juvenile hormone synthesis. An RNAi lethality screen using lines that were available from the Vienna Drosophila RNAi Centre identified a number of P450s which are essential for development and viability. / In the second half of the thesis, the transcriptional regulation of a P450 involved in insecticide resistance, Cyp6g1, was investigated. Cyp6g1 was regulated by two discrete cis-regulatory modules/enhancers, one controlling expression in the Malpighian tubules and one controlling expression in the midgut and fat body. Phenobarbital induction of Cyp6g1 is tissue-specific and is mediated by a fragment in the 5’ regulatory region that interacts with both enhancers. Characterisation of the long terminal repeat (LTR) of the Accord transposable element in the 5’ region of Cyp6g1, present in insecticide resistant populations, shows that the Accord LTR contains cis-regulatory elements which increase expression of Cyp6g1 in the fat body, midgut and Malpighian tubules, and contribute to insecticide resistance in these populations. / This study shows that the diverse tissue distribution of different P450s in D. melanogaster is related to the diverse biological functions of the enzymes encoded. This is exemplified by the detailed examination of the regulation of the insecticide resistance-conferring P450, Cyp6g1. Its expression pattern reflects its detoxification function in the fly. The role of transposable element insertions in changing gene expression patterns and contributing to selectable variation in genomes is also demonstrated through the Cyp6g1 study.