Resumo: A alta incidência da dengue no Brasil, causada pela elevada freqüência de seu vetor, o Aedes aegypti, torna importante conhecer a organização de suas populações em termos de diferenciação genética. Esse conhecimento poderá levar a métodos de monitoramento e controle mais eficientes. No presente trabalho, a técnica RAPD-PCR foi utilizada na análise de quatro populações brasileiras de A. aegypti, sendo três classificadas pela SUCEN (Superintendência do Controle de Endemias) como resistentes aos inseticidas utilizados para seu controle (São Luís- SL; São José do Rio Preto- RP; Araçatuba- AR) e uma classificada como portadora de resistência em desenvolvimento (Bauru- BA). Uma quinta população, procedente dos Estados Unidos, suscetível aos mesmos inseticidas (Rockefeller- RO) foi utilizada para comparação. A aplicação dos métodos estatísticos de Nei, (1973, 1978) produziu índices que permitem considerar o conjunto de populações analisadas, no total de primers, como portador de diferenciação genética muito alta conforme a classificação de Wright (1978). Assim indicaram os valores de Gst (0,277), que mede a diferenciação gênica; de Hs (0,129), que mede a heterozigose média e de Ht (0,181), que mede a heterozigose total. Porém, considerando-se as comparações das populações duas a duas, verifica-se que essa diferenciação foi variável, sendo que a comparação entre as populações RP e AR mostrou que estas são as populações menos diferenciadas geneticamente, enquanto as mais diferenciadas foram SL x RO e SL x BA. Os cálculos de similaridade de Nei e Li (1979) confirmaram os dados obtidos com os índices mencionados, reforçando a idéia de maior similaridade entre RP e AR, seguida de RO e BA. De modo geral, pode-se dizer que não é fácil interpretar a estrutura das populações de A. aegypti quanto às causas de sua diferenciação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The high incidence of dengue in Brazil, caused by the high frequency of its vector, Aedes aegypti, makes the organization of their populations in terms of genetic differentiation something important to know. This knowledge could lead to more efficient methods of monitoring and control of the vector. In this study, the RAPD-PCR was used in the analysis of four Brazilian populations of A. aegypti, three of which were classified by SUCEN (Superintencia do Controle de Endemias) as resistant to the insecticides used for its control (San Luis-SL; São Jose do Rio Preto, RP; Araçatuba-AR) and one considered in resistance development (Bauru-BA). A fifth population, from the United States, susceptible to these insecticides (Rockefeller-RO) was used for comparison. The application of the statistical methods of Nei (1973, 1978) produced indices that allowed us to consider the set of populations studied, in the total of primers, as having a very high genetic differentiation, according to the classification of Wright (1978). This is indicated by the values of Gst (0.277), which measure the genetic differentiation, the values of Hs (0.129), which measures the average heterozygosity and of Ht (0.181), that measure the total heterozygosity. However, considering the pair-wise comparisons of populations, this differentiation was variable, being the populations RP and AR the less differentiated genetically, while the more differentiated were SL x RO and BA x SL. The estimation of the similarity of Nei and Li (1979) confirmed the data obtained with the indices mentioned, reinforcing the idea of greater similarity between RP and AR, followed by RO and BA. In general, it is not easy to interpret the structure of A. aegypti populations as to on the causes of their genetic differentiation, since they are under strong interference of the human activity, which includes not only the passive transport... (Complete abstract click electronic access below) / Orientador: Hermione Elly Melara de Campos Bicudo / Coorientador: Lilian Madi-Ravazzi / Banca: Lílian Castiglioni / Banca: Francisco Chiaravalloti Neto / Mestre

Made available in DSpace on 2014-06-11T19:32:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-09-10Bitstream added on 2014-06-13T19:42:40Z : No. of bitstreams: 1 guirado_mm_dr_sjrp.pdf: 243606 bytes, checksum: d763ca85a0e74640c2c01e853c525fde (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Hoje se sabe que as enzimas esterásicas estão relacionadas com o desenvolvimento de resistência a inseticidas, em muitos organismos. Em Aedes aegypti, a dedução desse envolvimento tem resultado mais de testes que permitem a avaliação da atividade das esterases no extrato total dos mosquitos (mostrando valores maiores nas populações resistentes) do que de estudos mais profundos de padrões e bandas individualizadas e sua relação com a resistência. Com o objetivo básico de contribuir para o conhecimento desse aspecto, no presente trabalho 11 populações geográficas daquele vetor, sendo seis classificadas como resistentes, três como suscetíveis e duas como tendo suscetibilidade diminuída, foram analisadas quanto ao polimorfismo de esterases, por eletroforese em géis de poliacrilamida. O resultado do estudo de cerca de 30 amostras de larvas e adultos de cada população mostrou 24 bandas que foram tentativamente associadas com oito loci genéticos. Considerando também os dados de Lima-Catelani et al. (2004) e de Sousa-Polezzi & Bicudo (2005), temos o total de 25 bandas esterásicas, incluídas em 12 supostos loci, em 15 populações daquele vetor, até a presente data. A população de São José do Rio Preto, analisada em intervalos de cinco anos entre aqueles dois estudos, e sete anos entre Sousa-Polezzi & Bicudo (2005) e o presente trabalho, mostrou modificações no padrão de esterases, que ocorreram ao longo do tempo paralelamente ao surgimento e aumento da resistência aos inseticidas utilizados no controle, nessa população. Essas modificações abrangeram, basicamente, aumento ou diminuição da freqüência de algumas bandas e ausência de bandas previamente detectadas. De modo geral, a busca por padrões esterásicos específicos, relacionados ao desenvolvimento da resistência, indicou algumas bandas ou combinações de bandas para um estudo mais aprofundado. Essas bandas são: EST-1, sozinha, devido à sua alta freqüência em cinco das seis populações classificadas como resistentes, a combinação de EST-1 com EST-4, ambas ocorrendo simultaneamente, de forma predominante nas populações resistentes, e as colinesterases , detectadas nas 11 populações, mas apresentando freqüências mais altas em quatro das seis populações consideradas resistentes. Diante do conhecimento atual sobre as esterases e sua relação com a resistência a inseticidas, em A. aegypti, no presente trabalho é discutida a possibilidade de que a quantidade total de esterases (principalmente das carboxilesterases) produzidas por um grupo de genes possa ser mais importante em gerar resistência do que o grau de expressão de genes individuais que codificam para bandas específicas. Contudo, entendemos que as bandas destacadas neste trabalho devem ser alvo de um estudo mais detalhado, antes que essa hipótese ganhe maior força. / It is presently known that the esterases are involved in the process of resistance to insecticides, in several organisms. In Aedes aegypti, the conclusion about such involvement resulted rather from tests in which the total amount of esterases is computed in extracts of the mosquitoes (showing greater quantities in the resistant ones) than from deeper studies of esterase patterns or particular esterase bands and their relationship with resistance. With the basic aim to contribute to the knowledge of this relationship, in the present study the esterase polymorphism of 11 geographic populations of that vector, being six classified as resistant, three as susceptible and two as presenting decreased susceptibility, was studied by electrophoresis in polyacrylamide gels. The results of the analysis of about 30 individual samples of larvae and adults of each population showed 24 esterase bands which were tentatively associated to eight loci. Considering also the data from Lima-Catelani et al. (2004) and Sousa-Polezzi & Bicudo (2005), a total of 25 bands and 12 loci, in 15 populations, was obtained. The population from São José do Rio Preto, analyzed at intervals of five years between those two studies and seven years between Sousa-Polezzi & Bicudo (2005) and the present study, showed changes in the esterase pattern, which occurred along time concomitant to the increase of insecticide resistance in that population, including frequency increase or decrease of some bands and absence of bands previously detected. The search for specific esterase patterns related to the resistance development indicated some bands and combinations of bands as deserving a deeper study. They are EST-1 alone, due to high frequency in five of the six resistant populations, or the combination of EST-1 with EST-4, both occurring simultaneously, with high frequency, mainly in the resistant populations, and the cholinesterases, which although present in the 11 populations, showed higher frequencies in four of the six resistant ones. In front of the present knowledge on esterases related with resistance, in A. aegypti, we discuss the possibility that the total amount of esterases (mainly carboxilesterases) produced by a group of genes might be more important in the generation of resistance than the degree of expression of genes codifying particular bands. However, we understand that the bands stood out in the present study must be the target of a more detailed analysis, before this hypothesis gains a greater consideration. / FAPESP: 05/59219-5

The insecticide resistance mechanisms present in the aphids Myzus persicae and Aphis gossypii have been characterised and sensitive biochemical assays have been developed to monitor their presence in individual aphids. It was found that enhanced esterase activity is present in both aphid species, and that this enhanced activity results from the presence of larger amounts of the same enzyme rather than the presence of a more efficient enzyme. In Myzus persicae this mechanism alone is sufficient to confer high levels of insecticide resistance. In Aphis gossypii, it appears that the presence of insensitive acetylcholinesterase (AChE) is necessary for measurable levels of resistance to occur. During the course of this work, insensitive AChE was detected in Myzus persicae for the first time. This additional resistance mechanism, when combined with the enhanced esterase activity, was found to confer extremely high levels of tolerance against specific insecticides. This additional mechanism is rare in the UK at present but the use of sensitive assays to monitor its existence is of increasing importance. When the AChE mechanism becomes more prevalent in the UK, as it almost certainly will, new strategies for aphid control will be needed. Further examples of insensitive AChE conferring insensitivity not only to carbamates, but also to organophosphates, have also been detected in Aphis gossypii. The inter-relationships of the two mechanisms in this species have been resolved and new monitoring methods made available.

Master of Science / Department of Entomology / Thomas W. Phillips / Resistance of stored-grain insects to the fumigant gas phosphine is becoming common, due to genetic-based resistance. Using proper resistance management, phosphine can continue to be effective with efficient monitoring methods. This thesis focuses on assessing the levels of phosphine resistance across North America in a common stored-product pest, the red flour beetle, Tribolium castaneum (Herbst), and on refining a rapid bioassay method so that resistance can be easily and accurately detected. Previous work found that phosphine resistance was present in two regions of the USA, the Southeast and Midwest. In this study a discriminating-dose bioassay was used with adult beetles to determine the number of resistant and susceptible individuals in a test population. Adult T. castaneum from 25 locations across the United States and Canada were collected, and 25-60 adults from each population were assessed for the percentage of resistant individuals. Thirteen populations were deemed susceptible with no resistant insects in the samples, while eight populations had 52% or fewer individuals scored as resistant, and four populations had between 88 and 100% resistant individuals. Dose-mortality experiments were conducted to characterize the “strength” of resistance. One population with 41% resistant beetles in the discriminating dose assay was 4.5-fold resistant relative to the susceptible laboratory strain, compared to 127-fold resistant for a population with all 100% scored as resistant. Adult beetles from twelve populations were used to determine if a “knockdown” test of insects exposed to a high concentration of phosphine (3000 ppm) could assess resistance as well as the discriminating-dose mortality assay. The time required for five out of ten beetles to be knocked down, called the KT[subscript]50 for the time to knockdown 50% of the sample, was useful to characterize resistance. Phosphine susceptible beetles had KT[subscript]50 values less than 15 minutes, while samples from resistant populations had KT[subscript]50’s between 15 and 52 minutes. The refined quick test and knowledge of current levels of phosphine resistance in the United States and Canada reported in this thesis point to the importance of such information in developing phosphine resistance management programs for grain insects.

O percevejo bronzeado, Thaumastocoris peregrinus Carpintero & Dellapé (Hemiptera: Thaumastocoridae), é um inseto-praga de origem australiana, que ataca espécies do gênero Eucalyptus em vários países. No Brasil, sua ocorrência foi relatada em 2008 do Rio Grande do Sul e em junho de 2012 foi registrada ocorrência na região sudoeste do Paraná. Também foram encontrados insetos possivelmente sendo atacados pelo fungo entomopatogênico Beauveria bassiana em campo. Após procedimentos de isolamento e identificação, o fungo foi armazenado e denominado UTFPR 01. Com a verificação do potencial de controle de B. bassiana sobre T. peregrinus , realizou-se estudo sobre a patogenicidade de isolados não comerciais, oriundos do Instituto Biológico de Campinas (IBCB 75, IBCB 210, IBCB 254) e a possibilidade de uso do fungo Isaria sp. (IBCB 367), comparando-os com o UTFPR 01. Soluções com 1,0 x 108 conídios.mL-1 foram aplicada sobre folhas de Eucalyptus camaldulensis e mantidas em frascos de vidro vedados com filme plástico recebendo 13 insetos adultos. As avaliações ocorreram até o quinto dia retirando os insetos mortos que foram colocados em câmara úmida para extrusão do patógeno. Também foram testados os produtos: Orobor®, Topneem, Rotenat, Rotenat CE, Baicao, Compostonat, Pironat, Assist, Extrato de Alho e Calda Bordalesa sobre a mortalidade de T. peregrinus . Folhas de E. camaldulensis foram mergulhadas em solução diluída dos produtos, nas doses recomendadas pelos fabricantes. Após secagem o substrato foi transferido para tubos de vidro contendo 10 insetos adultos de T. peregrinus e mantidos durante cinco dias à temperatura de 26 ± 2°C, U.R. de 70 ± 10% e fotofase de 14 horas. A avaliação foi feita diariamente retirando-se os insetos mortos. Os melhores resultados foram obtidos com os produtos Topneem, Rotenat, Rotenat CE e Compostonat. Estes produtos foram avaliados quanto a sua provável ação na indução de resistência nas plantas de Eucalyptus. Utilizou- se cotilédones de soja como planta indicadora e o indutor padrão quitosana a 1% como testemunha “branca”. Avaliou-se o teor de fitoalexina gliceolina, proteínas e a atividade da FAL (fenilalanina amônia-liase). Como resultados induziram a produção de fitoalexinas e atividade da FAL os produtos Topneem e o Rotenat CE. Em relação ao teor de proteínas não correu diferença estatística entre os tratamentos. Apresentaram efeito sobre a mortalidade de T. peregrinus os fungos B. bassiana e Isaria sp. bem como os produtos Topneem e Rotenat CE, os quais também apresentaram potencial na indução de resistência em plantas. / The bronzed bug Thaumastocoris peregrinus Carpintero & Dellapé (Hemiptera: Thaumastocoridae), is an insect pest of Australian origin, attacking Eucalyptus species in several countries. In Brazil, its occurrence was reported in 2008 in Rio Grande do Sul and in June 2012 was recorded occurrence in the southwest region of Paraná. Also found were possibly being attacked by insects entomopathogenic fungus Beauveria bassiana in the field. After isolation and identification procedures, the fungus was stored and called UTFPR 01. With verification of the potential control B. bassiana against T. peregrinus , a study was conducted on the pathogenicity of isolates non-commercial, from the Biological Institute of Campinas (IBCB 75, IBCB 210 and IBCB 254) and the possibility of using the fungus Isaria sp. (IBCB 367), comparing them with UTFPR 01. Solutions with 1.0 x 108 conidia mL-1 were applied to leaves of Eucalyptus camaldulensis and maintained in glass bottles closed with plastic film 13 receiving adult insects. Assessments occurred until the fifth day removing dead insects were placed in a moist chamber for extrusion of the pathogen. We also tested products: Orobor ®, Topneem, Rotenat, Rotenat CE Baicao, Compostonat, Pironat, Assist Extract, Garlic and Lime Bordeaux on mortality of T. peregrinus . Sheets E. camaldulensis leaves were dipped in dilute solution products, in doses recommended by the manufacturers. After drying, the substrate was transferred to glass tubes containing 10 adult insects of T. peregrinus and maintained for 5 days at 26 ± 2 ° C, RH 70 ± 10% and photoperiod of 14 hours. The evaluation was done daily by removing the dead insects. The best results were obtained with the products Topneem, Rotenat, Rotenat CE and Compostonat. The best results were obtained with the products Topneem, Rotenat, Rotenat CE and Compostonat. These products have been assessed for their likely action in the induction of resistance in Eucalyptus. It was used as an indicator of soybean cotyledons of induced resistance and the inductor pattern 1% chitosan as witness "white". We evaluated the phytoalexin glyceollin content, protein and activity of PAL (phenylalanine ammonia lyase). As results induced phytoalexin and activity of PAL the products Topneem and Rotenat CE. Regarding protein content did not run statistical difference between treatments. Had an effect on mortality of T. peregrinus fungi B. bassiana and Isaria sp. and products Topneem and Rotenat CE, which also showed potential to induce resistance in plants.

O percevejo bronzeado, Thaumastocoris peregrinus Carpintero & Dellapé (Hemiptera: Thaumastocoridae), é um inseto-praga de origem australiana, que ataca espécies do gênero Eucalyptus em vários países. No Brasil, sua ocorrência foi relatada em 2008 do Rio Grande do Sul e em junho de 2012 foi registrada ocorrência na região sudoeste do Paraná. Também foram encontrados insetos possivelmente sendo atacados pelo fungo entomopatogênico Beauveria bassiana em campo. Após procedimentos de isolamento e identificação, o fungo foi armazenado e denominado UTFPR 01. Com a verificação do potencial de controle de B. bassiana sobre T. peregrinus , realizou-se estudo sobre a patogenicidade de isolados não comerciais, oriundos do Instituto Biológico de Campinas (IBCB 75, IBCB 210, IBCB 254) e a possibilidade de uso do fungo Isaria sp. (IBCB 367), comparando-os com o UTFPR 01. Soluções com 1,0 x 108 conídios.mL-1 foram aplicada sobre folhas de Eucalyptus camaldulensis e mantidas em frascos de vidro vedados com filme plástico recebendo 13 insetos adultos. As avaliações ocorreram até o quinto dia retirando os insetos mortos que foram colocados em câmara úmida para extrusão do patógeno. Também foram testados os produtos: Orobor®, Topneem, Rotenat, Rotenat CE, Baicao, Compostonat, Pironat, Assist, Extrato de Alho e Calda Bordalesa sobre a mortalidade de T. peregrinus . Folhas de E. camaldulensis foram mergulhadas em solução diluída dos produtos, nas doses recomendadas pelos fabricantes. Após secagem o substrato foi transferido para tubos de vidro contendo 10 insetos adultos de T. peregrinus e mantidos durante cinco dias à temperatura de 26 ± 2°C, U.R. de 70 ± 10% e fotofase de 14 horas. A avaliação foi feita diariamente retirando-se os insetos mortos. Os melhores resultados foram obtidos com os produtos Topneem, Rotenat, Rotenat CE e Compostonat. Estes produtos foram avaliados quanto a sua provável ação na indução de resistência nas plantas de Eucalyptus. Utilizou- se cotilédones de soja como planta indicadora e o indutor padrão quitosana a 1% como testemunha “branca”. Avaliou-se o teor de fitoalexina gliceolina, proteínas e a atividade da FAL (fenilalanina amônia-liase). Como resultados induziram a produção de fitoalexinas e atividade da FAL os produtos Topneem e o Rotenat CE. Em relação ao teor de proteínas não correu diferença estatística entre os tratamentos. Apresentaram efeito sobre a mortalidade de T. peregrinus os fungos B. bassiana e Isaria sp. bem como os produtos Topneem e Rotenat CE, os quais também apresentaram potencial na indução de resistência em plantas. / The bronzed bug Thaumastocoris peregrinus Carpintero & Dellapé (Hemiptera: Thaumastocoridae), is an insect pest of Australian origin, attacking Eucalyptus species in several countries. In Brazil, its occurrence was reported in 2008 in Rio Grande do Sul and in June 2012 was recorded occurrence in the southwest region of Paraná. Also found were possibly being attacked by insects entomopathogenic fungus Beauveria bassiana in the field. After isolation and identification procedures, the fungus was stored and called UTFPR 01. With verification of the potential control B. bassiana against T. peregrinus , a study was conducted on the pathogenicity of isolates non-commercial, from the Biological Institute of Campinas (IBCB 75, IBCB 210 and IBCB 254) and the possibility of using the fungus Isaria sp. (IBCB 367), comparing them with UTFPR 01. Solutions with 1.0 x 108 conidia mL-1 were applied to leaves of Eucalyptus camaldulensis and maintained in glass bottles closed with plastic film 13 receiving adult insects. Assessments occurred until the fifth day removing dead insects were placed in a moist chamber for extrusion of the pathogen. We also tested products: Orobor ®, Topneem, Rotenat, Rotenat CE Baicao, Compostonat, Pironat, Assist Extract, Garlic and Lime Bordeaux on mortality of T. peregrinus . Sheets E. camaldulensis leaves were dipped in dilute solution products, in doses recommended by the manufacturers. After drying, the substrate was transferred to glass tubes containing 10 adult insects of T. peregrinus and maintained for 5 days at 26 ± 2 ° C, RH 70 ± 10% and photoperiod of 14 hours. The evaluation was done daily by removing the dead insects. The best results were obtained with the products Topneem, Rotenat, Rotenat CE and Compostonat. The best results were obtained with the products Topneem, Rotenat, Rotenat CE and Compostonat. These products have been assessed for their likely action in the induction of resistance in Eucalyptus. It was used as an indicator of soybean cotyledons of induced resistance and the inductor pattern 1% chitosan as witness "white". We evaluated the phytoalexin glyceollin content, protein and activity of PAL (phenylalanine ammonia lyase). As results induced phytoalexin and activity of PAL the products Topneem and Rotenat CE. Regarding protein content did not run statistical difference between treatments. Had an effect on mortality of T. peregrinus fungi B. bassiana and Isaria sp. and products Topneem and Rotenat CE, which also showed potential to induce resistance in plants.

Com a crescente expansão de cultivos agrícolas no Brasil, tem sido bastante comum o sistema de produção de algodão e milho em uma mesma região. Como uma possível conseqüência deste sistema de cultivo, os problemas com Spodoptera frugiperda (J. E. Smith) têm aumentado nestas duas culturas nos últimos anos. Assim, para o estabelecimento de um manejo mais efetivo desta praga, foi levantada a hipótese de que as mesmas populações de S. frugiperda atacam as culturas do algodão e milho em uma determinada região. Para testar esta hipótese, foram realizados os seguintes estudos: 1) a avaliação a suscetibilidade ao piretróide deltametrina em populações de S. frugiperda, e 2) a estimativa da similaridade e da estrutura genética em populações de S. frugiperda com o uso de marcadores moleculares RAPD e AFLP. A avaliação da suscetibilidade a deltametrina das populações de S. frugiperda foi realizada mediante bioensaio de aplicação tópica. Além disso, foi avaliada a resposta à seleção com deltametrina em uma população de S. frugiperda em condições de laboratório. As populações de S. frugiperda coletadas na cultura do algodão foram significativamente menos suscetíveis a deltametrina do que as populações coletadas no milho. Estes resultados poderiam ser entendidos como uma conseqüência da pré-seleção de indivíduos resistentes a deltametrina A população de S. frugiperda selecionada em laboratório apresentou uma razão de resistência a deltametrina de ≈14 vezes. Pela técnica de RAPD, os dendrogramas (Simple Matching e Jaccard) classificaram as populações da praga em grupos proximamente relacionados com a região geográfica de coleta dos insetos. Não foi identificado nenhum ramo capaz de separar e associar as populações de S. frugiperda a nenhuma das duas plantas hospedeiras avaliadas. Estes resultados sugeriram que as populações da praga em algodão e milho em uma determinada região do Brasil apresentam um nível significativo de fluxo gênico. Os resultados da técnica AFLP foram organizados em um dendrograma UPGMA (índice de Jaccard), o qual também não classificou as populações da praga em grupos relacionados às plantas nas quais os insetos foram coletados. Não foi detectada correlação significativa entre a dissimilaridade genética e distância geográfica nas populações testadas. Foi detectada variação molecular entre as populações da praga atribuída à origem geográfica dos insetos. A análise molecular de variância indicou que 7% da variação molecular total poderiam ser atribuídos à divisão das populações de S. frugiperda em grupos de insetos coletados no Brasil e na Argentina. Além disso, foi detectado 0% de variação genética, e um valor de fluxo gênico Nm=1,32 entre os grupos de populações da praga coletadas nas culturas do algodão e do milho. Assim, as infestações de S. frugiperda que ocorrem em campos de milho e algodão podem ser consideradas como subunidades potencialmente intercruzantes de uma mesma população. Portanto, conclui-se que há necessidade de um planejamento bastante estratégico nos plantios de algodão e de milho, no delineamento de programas de manejo de S. frugiperda no Brasil. / Due to the expansion of the cultivated areas in Brazil, it has been very common to find the cultivation of cotton and maize in the same region. As a potential consequence to this cultivation system, the problems with Spodoptera frugiperda (J.E. Smith) have increased for the last years at both crops. In order to provide elements to the establishment of a more effective management of this pest it was hypothesized that the same populations of S. frugiperda attack the cotton and maize crops in Brazil. To test this hypothesis the following studies were conducted: 1) the evaluation the susceptibility to the pyrethroid deltamethrin in S. frugiperda populations and 2) the assessment of the molecular variability and genetic structure in S. frugiperda populations by using RAPD and AFLP molecular markers. The evaluation of the susceptibility to deltamethrin in S. frugiperda populations was conducted by using topical application bioassays. Furthermore, the response of this pest to the selection pressure with the insecticide was evaluated under laboratory conditions. The insect populations collected in the cotton crop were significantly less susceptible to deltamethrin than the ones collected in the maize crop. These results might be consequence of a pre-selection of deltamethrin-resistant individuals. The deltamethrin-resistant population selected under laboratory conditions had the resistance ratio of ≈14 fold. The dendrograms obtained by using RAPD markers (Simple Matching and Jaccard) classified the populations into clusters related to the geographical origin of the samples. Any branch of the dendrograms underpinned a molecular association of S. frugiperda with neither of the two host plants. These results suggested the existence of considerable gene flow between cotton and maize populations of S. frugiperda collected at the same region in Brazil. The AFLP results were organized in a UPGMA dendrogram (Jaccard index) which also did not classify the populations of S. frugiperda into clusters related to the host plant in which the insects were collected. It was not found a significant correlation between genetic dissimilarity and geographical distances. It was detected genetic variation attributable to the geographical origin of the populations. The analysis of molecular variance highlighted 7% of the variation due to the division of the S. frugiperda populations into Brazilian and Argentine groups. Also, no molecular variation (0%) and a gene flow rate equal to Nm=1.32 were estimated between fall armyworm group of populations collected at maize and cotton fields in Brazil. The same populations of S. frugiperda infest cotton and maize crops in Brazil and could be considered as interbreeding subunits of the same population. Therefore, there is a need of strategic action plans to the planting of cotton and maize crops for designing of management programs of S. frugiperda in Brazil.

<p>The German cockroach (<em>Blattella germanica</em>) is one of the most critical urban pests globally due to the health risks, such as asthma, it imposes on people. Insecticides are known to manage their large population sizes, but the rapid rate at which cockroaches develop resistance is a continuing problem. This can be expensive and time-consuming for both the consumer and the pest management professional (PMP) applying the treatment. Each cockroach population is unique because different strains have different resistance profiles, so resistance profiles must be considered. This thesis addressed this little-studied issue in a controlled laboratory setting. Cockroach strains from Indianapolis, Indiana, Danville, Illinois, and Baltimore, Maryland, were used. Fifteen insecticide active ingredients most used by consumers and PMPs were selected for testing in vial bioassays to establish resistance profiles. No choice and choice feeding assays with four currently registered bait products were performed to assess the impacts of competing food and circadian rhythms on bait resistance levels. Selected population growth characteristics were compared in virgin females and nymphs in each cockroach strain to determine if certain population traits were associated with insecticide resistance. The results indicate that emamectin benzoate is the most effective active ingredient in causing the highest mortality in all strains in vial bioassays. No choice assays confirmed vial assay results the best, with Optigard (emamectin benzoate) being the most effective bait in all strains. The time a female carries its egg case and takes for a nymph to become an adult was significantly different across all strains, suggesting possible fitness costs for higher-level multi-resistance. The results acquired from these studies can help develop rapid tests to use in the field based on the no choice feeding assay while also adding more information supporting current resistance and cross-resistance evolution theories.</p>

The tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois), has been a devastating insect pest in cotton agroecosystems in mid-southern cotton for several decades. Similar to related Heteropteran insect pests, L. lineolaris uses piercing-sucking mouthparts to penetrate harvestable fruiting structures on the cotton plant (i.e., squares, flowers, small bolls) leading to significant reductions in lint yield when infestations are above economic injury levels. Economically damaging infestations of L. lineolaris have occurred in Virginia and North Carolina cotton since 2013. In response, cotton area sprayed with broad-spectrum insecticides for L. lineolaris has increased in these states. As such, this dissertation research sought to answer a variety of questions to address this issue including 1) mapping the spatiotemporal abundance of L. lineolaris across Virginia as well as creating models to predict landscape and climate factors increasing infestation risk, 2) using a systems approach to provide growers with cost-effective and sustainable integrated pest management (IPM) solutions including economic spray thresholds, 3) investigating the incidence and transmission of fungal pathogens by L. lineolaris increasing Fusarium hardlock disease, further impacting yield loss at harvest, and 4) conducting insecticide resistance monitoring of L. lineolaris across the Southeast including biochemical lab assays to determine possible mechanisms of insecticide resistance. These findings will help form compressive IPM and insect resistant management (IRM) plans to equip southeastern cotton growers with practical management tools as well as useful information on "high-risk" areas to invest management resources, increasing economic returns while minimizing environmental impacts of over-spraying foliar insecticides. / Doctor of Philosophy / The tarnished plant bug (Lygus lineolaris) is an important pest in cotton from July through September that causes reduced yields and lower quality of lint and seed. Tarnished plant bugs cost the cotton industry hundreds of millions of dollars in losses annually. However, tarnished plant bug infestations were rare and sporadic in Virginia and North Carolina before 2013. In recent years, tarnished plant bug infestations have nearly doubled in these states, and research is needed to better understand how to manage recent pest outbreaks to avoid substantial economic losses. To address this issue, this dissertation research investigated a variety of questions including 1) the distribution of tarnished plant bugs in this region and the effects of geography and climate on infestation risk, 2) best practices for managing this pest in cotton fields, 3) possible associations between tarnished plant bugs and cotton boll diseases further impacting yield, and 4) whether tarnished plant bugs in this region are resistant to frequently used broad-spectrum insecticides as well as potential mechanisms driving resistance levels. Findings from this research will equip southeastern cotton growers with regionally specific recommendations for managing and monitoring tarnished plant bugs that minimize management costs and increase the quality and quantity of cotton yields.

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a serious pest of crucifer vegetables (Brassica sp.) worldwide because of a lack of effective natural enemies in certain regions and because of insecticide resistance. In 2003, laboratory and field studies were initiated in Virginia to better understand P. xylostella, its primary natural enemies, and their susceptibilities to insecticides in order to develop an economically and environmentally sound integrated pest management program for collards in the state. Ecological life table studies of P. xylostella immature stages on collards located on the Eastern Shore and on Kentland Farm, near Blacksburg at the New River Valley, VA revealed that most (98 to 99%) of P. xylostella died from natural causes. Mortality factors varied between the two regions. Neonates, small larvae, and large larvae disappearing were major mortality factors. Rainfall, predation, and dispersal probably contributed the most to this mortality. Egg mortality played a bigger role at the New River Valley compared with the Eastern Shore. Three parasitoid species were found that contributed to the mortality of P. xylostella: Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae); Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae); and Microplitis plutellae (Muesebeck) (Hymenoptera: Braconidae). Additional studies conducted in the laboratory using leaf-dip bioassays revealed that P. xylostella collected from the Eastern Shore of Virginia, showed significant tolerance levels to esfenvalerate, acetamiprid, methomyl, methoxyfenozide, indoxacarb, and acephate compared with a susceptible strain of P. xylostella. The highest tolerance ratio (1,876 fold) was to esfenvalerate, a commonly-used pyrethroid. All of the insecticides tested in this study were quite toxic to the adult stage of the parasitoids, D. insulare and O. sokolowskii. The insect growth regulator, methoxyfenozide was considerably less toxic than other insecticides such as esfenvalerate, methomyl, acephate, spinosad, indoxacarb, and emamectin benzoate at field-rate and 1% of field-rate concentrations. The aforementioned insecticides as well as some other insecticides were evaluated several times in the field for efficacy against P. xylostella as well as other pests of collards. The most efficacious insecticides over five field experiments included acephate, emamectin benzoate, esfenvalerate, methomyl, methoxyfenozide, novaluron, indoxacarb, and spinosad. These insecticides were followed in relative efficacy by Bt kurstaki, acetamiprid, and azadirachtin, which provided relatively inconsistent control of lepidopteran larvae over the experiments. Effective insecticide options in collards that are less toxic to natural enemies and that can fit well into integrated pest management programs include indoxacarb, spinosad, novaluron, emamectin benzoate, methoxyfenozide, and Bacillus thuringiensis subsp. kurstaki. / Ph. D.