Os objetivos deste trabalho com Mahanarva fimbriolata foram estudar a influência de fatores abióticos (temperatura, umidade e fotoperíodo) sobre sua biologia, avaliar a flutuação populacional, sistema de amostragem de ninfas e adultos e os métodos de controle, biológico com o fungo Metarhizium anisopliae, químico com thiamethoxam (Actara® 250WG) e por resistência varietal. As condições térmicas influem na duração das fases do ciclo, não havendo desenvolvimento embrionário a 32°C. As temperaturas constantes de 30 e 32°C são letais para ninfas, sendo 25°C a temperatura ideal. Os limites térmicos inferiores de desenvolvimento e as constantes térmicas são 11,2°C e 318,2 graus-dias para a fase de ovo e 11,8°C e 468,0 graus-dias para a fase de ninfa. Condições térmicas flutuantes influem na duração das fases do inseto, mas não são letais a nenhuma delas. A umidade influi na duração e viabilidade do período embrionário. O menor período ocorre na umidade de contato, seguido pela UR de 100%. Nas UR de 80, 60 e 40%, não há desenvolvimento embrionário. Ovos expostos a essas umidades por 120 dias e, então, submetidos à umidade de contato, continuam inviáveis ou com baixas viabilidades (9,6; 6,3 e 0%, respectivamente). Indivíduos expostos à fotofase de 10 horas colocam ovos inférteis ou em aparente diapausa. Para sugarem a seiva, as ninfas inserem os estiletes na epiderme da raiz, atravessam todo o córtex e atingem o cilindro vascular, alimentando-se no xilema e no tubo crivado do floema primário. Na lâmina foliar, os adultos introduzem os estiletes, preferencialmente, pelos estômatos, atravessam as células do parênquima clorofiliano e atingem o metaxilema nos feixes vasculares. O aparecimento da cigarrinha está condicionado ao excedente hídrico e à temperatura. É possível se amostrarem adultos, com armadilhas adesivas amarelas e determinar o momento para controlar ninfas de mesma geração. Não há diferença em relação ao número de conídios depositados por ninfa em concentrações que variam de 1,6 a 5,3; 2,9 a 4,9 e 0,7 a 3,6 conídios/ninfa, respectivamente. As maiores mortalidades acumuladas, total e confirmada, de M. fimbriolata pulverizada com M. anisopliae, oito dias após a inoculação, são constatadas na dosagem de 5,0 x 108 conídios.ml-1, sendo de 57,5 e 62,3% (total) e 42,7 e 45,2% (confirmada) com pulverização sobre ninfa e espuma, respectivamente. M. anisopliae apresenta maior potencial para controle da cigarrinha quando pulverizado sobre a ninfa ou a espuma e sem a lavagem de conídios após a aplicação. Dentre as variedades estudadas, SP81-3250 é a mais suscetível à cigarrinha, possibilitando maior longevidade de machos e fêmeas, maior período de oviposição e elevada fecundidade. A variedade RB72454 reduz em 50% a população de ninfas nas raízes. A aplicação de thiamethoxam, a 1,0 kg p.c./ha, na base das plantas, proporciona controle superior a 90% até 60 DAA e residual de 105 dias (0,02 mg.kg-1) nas raízes. A eficiência de controle na pulverização foliar diminui para 34%, 15 DAA, com resíduos de 2,61 mg.kg-1 nas raízes. Pulverizações dirigidas ao colmo apresentam resíduos inferiores a 0,02 mg.kg-1 nas raízes, sem controle da praga. / The objectives of this work were to study the influence of abiotic factors (temperature, moisture, and photoperiod) on Mahanarva fimbriolata biology, and to evaluate population fluctuation, sampling system for nymphs and adults, and biological control with the fungus Metarhizium anisopliae, chemical control with thiamethoxam (Actara® 250 WG), and control by varietal resistance. The temperature conditions influence life cycle stage duration; no embryonic development is observed at 32°C. Constant temperatures of 30 and 32°C are lethal to nymphs, whereas 25°C is the ideal temperature. The lower temperature development thresholds and thermal constants are 11.2°C and 318.2 degree-days for the egg stage and 11.8°C and 468.0 degree-days for the nymphal stage. Fluctuating temperature conditions influence stage duration but are not lethal to any of the stages. Humidity influences the duration and viability of the embryonic period. The shortest period occurs at contact humidity, followed by 100% RH No embryonic development occurs at RH values of 80, 60, and 40%. Eggs exposed to these humidity values for 120 days and then submitted to contact humidity remain unviable or present low viability (9.6; 6.3, and 0%, respectively). Individuals exposed to a 10-hour photophase lay infertile or apparently-diapausing eggs. In order to suck sap, the nymphs insert their stylets into the root epidermis, passing through the entire cortex and reaching the vascular cylinder, feeding on the xylem and on the sieve tube of the primary phloem. On the leaf blade, the adults introduce their stylets preferentially through the stomata, passing through the chlorophyll-bearing parenchyma cells and reaching the metaxylem on the vascular bundles. Spittlebug occurrence is conditioned to water surplus and temperature. Adults can be sampled by means of yellow sticky traps, allowing the control of same-generation nymphs to be synchronized. There are no differences with regard to the number of conidia deposited per nymph at concentrations ranging from 1.6 to 5.3; 2.9 to 4.9; and 0.7 to 3.6 conidia/nymph, respectively. The highest cumulative, total, and confirmed mortalities of M. fimbriolata sprayed with M. anisopliae eight days after inoculation are verified at a dose of 5.0 × 108 conidia.ml-1, with values of 57.5 and 62.3% (total), and 42.7 and 45.2% (confirmed) when sprayed on the nymphs and on the spittle, respectively. M. anisopliae has a greater potential to control spittlebugs when sprayed on nymphs or on the spittle without washing off the conidia after application. Among the varieties studied, SP81-3250 is the most susceptible to the spittlebug, allowing greater longevity of males and females, a longer oviposition period, and high fecundity. Variety RB72454 reduces the nymphal population on roots by 50%. The application of thiamethoxam at 1.0 kg c.p./ha at the base of plants provides control rates higher than 90% until 60 DAA and a residual control of 105 days (0.02 mg.kg-1) on the roots. Leaf spray control effectiveness decreases to 34% at 15 DAA, with residues of 2.61 mg.kg-1 in roots. Sprays directed at the stalk show residues lower than 0.02 mg.kg-1 in roots, without controlling the pest.

A pústula bacteriana é uma das principais doenças que afetam o pimentão em todo o mundo. Seu agente causal pode ser disseminado por sementes, e é capaz de diminuir a produção e depreciar os frutos para comercialização. A bactéria Xanthomonas spp., o agente causal da doença, apresenta alta variabilidade. Três espécies estão associadas à doença: Xanthomonas axonopodis pv. vesicatoria, X. vesicatoria e X. gardneri. Enquanto alguns isolados infectam somente o pimentão, outros infectam pimentão e tomate. Xanthomonas axonopodis pv. vesicatoria é considerada a espécie mais comum em pimentão, e era anteriormente conhecida como o grupo A de Xanthomonas campestris pv. vesicatoria (A1 não amidolítico, A2 amidolítico); e o grupo B era representado por Xanthomonas vesicatoria (fortemente amidolítico). Até agora, 11 raças do patógeno foram relatadas, sendo as raças 1, 2 e 3 as mais comuns. A resistência genética tem sido a mais importante forma de controle e pode ser obtida pelo emprego de 4 genes dominantes (Bs1, Bs2, Bs3, Bs4). Estes genes estão associados à reação de hipersensibilidade e representam a forma mais promissora de resistência atualmente. Mesmo assim, o gene de resistência a ser utilizado depende da correta identificação das raças no campo. Este trabalho teve como objetivo a identificação de raças de Xanthomonas spp. isoladas em áreas de produção no Estado de São Paulo, visando o desenvolvimento e/ ou recomendação de cultivares resistentes. A identificação de raças do patógeno foi realizada através da observação da reação de hipersensibilidade em linhas quase isogênicas de pimentão Early California Wonder - ECW, ECW-10R, ECW-20R, ECW-30R; e na pimenta PI-235047. Os resultados obtidos entre os 41 isolados avaliados, indicaram a ocorrência das seguintes raças por região: raça 0 (Lins); raça 1 (Bacuriti); raça 2 (Bragança Paulista, Bacuriti, Lins, Ibiúna, Piacatu e Guaíra); raça 3 (Piedade); raça 7 (Mogi das Cruzes) e raça 8 (Piedade, Bragança Paulista, Bacuriti, Lins e Mogi das Cruzes). Pelos resultados, sugere-se o desenvolvimento e a recomendação de cultivares com o gene Bs2 para as regiões estudadas, pois este gene confere resistência às raças 0, 1, 2, 3, 7 e 8 do patógeno. / Bacterial spot is one of the main diseases that affects the pepper worldwide. Its causal agent can be spreaded by seeds, and it is able to decrease the production and to depreciate fruits for commercialization. The bacteria Xanthomonas spp. the causal agent of bacterial spot is highly variable. Three species are associated to the disease: Xanthomonas axonopodis pv. vesicatoria, X. vesicatoria and X. gardneri. Some isolates infect only pepper and other infect pepper and tomato. Xanthomonas axonopodis pv. vesicatoria has been considered the most common species in pepper, and was formerly known as group A of Xanthomonas campestris pv. vesicatoria (A1 non amylolitic, A2 amylolitic) and group B represented by Xanthomonas vesicatoria (strongly amylolitic). Up to now 11 races of the pathogen have been reported and the races 1, 2 and 3 are the most common. The genetic resistance has been the most important control method, through 4 dominant genes (Bs1, Bs2, Bs3, Bs4). These genes are associated to the hipersensitivity reaction and represent the most promising form of resistance nowadays. Even so, the resistance gene to be used depends on the correct identification of the races in the field. This work aimed the identification of the Xanthomonas spp. races in the São Paulo State from production areas, for the development and/ or recommendation of resistant cultivars. The identification of races of the pathogen was accomplished through the observation of the hypersensitivity reaction on near isogenic lines of Early California Wonder pepper - ECW, ECW-10R, ECW-20R, ECW-30R; and in the PI-235047 hot-pepper. Obtained results from 41 isolates, indicated the occurrence of the next races per region: race 0 (Lins); race 1 (Bacuriti); race 2 (Bragança Paulista, Bacuriti, Lins, Ibiúna, Piacatu and Guaíra); race 3 (Piedade); race 7 (Mogi das Cruzes); and race 8 (Piedade, Bragança Paulista, Bacuriti, Lins, Mogi das Cruzes). The results suggest the development and/ or recomendation of cultivars carring the Bs2 gene for studied regions, which confers resistance to 0, 1, 2, 3, 7, and 8 races of the pathogen.

Citrus tristeza virus (CTV) ocorre em quase todas as áreas produtoras de citros do mundo. O controle da doença se baseia, principalmente, no uso de porta-enxertos tolerantes e na premunização das copas. A obtenção de copas de laranjas doces ou de porta-enxerto de laranja azeda transgênicos resistentes ao CTV permitiria retornar a um uso mais intensivo deste excelente porta-enxerto. Com isso, esse trabalho buscou avaliar linhagens transgênicas de laranja doce (Citrus sinensis) e obter plantas transgênicas de laranja azeda (Citrus aurantium) para a resistência ao CTV, a fim de oferecer uma outra alternativa para o controle desta doença em citros. Foram avaliadas plantas transgênicas de laranja doce cv. Valência e cv. Hamlin contendo três diferentes construções gênicas. Uma contendo uma sequência sense (684 pb) do gene da capa protéica do CTV (pCTV-CP), outra contendo uma sequência conservada (559 pb) do CTV (pCTV-SC) e uma do tipo hairpin, contendo sequências sense e antisense do gene da capa protéica separadas por um íntron (pCTV-dsCP). Dez linhagens transgênicas de cada construção gênica e de cada cultivar foram previamente confirmadas por análises de Southern blot e RT-PCR, totalizando 60 linhagens transgênicas. Tais linhagens foram clonadas e enxertadas sobre limão Cravo (C. limonia) e laranja azeda (C. aurantium), totalizando 360 plantas. Essas plantas, juntamente com plantas não transgênicas utilizadas como controle, foram inoculadas com o CTV por meio de Toxoptera citricida virulífero. As técnicas de ELISA indireto utilizando anticorpo monoclonal contra a capa protéica do CTV ou de Real-time PCR utilizando primers amplificadores dos genes p20 e p23 do genoma do CTV foram utilizadas para detectar o vírus nas plantas avaliadas, 4 semanas após as inoculações. Ocorreu variação na resistência ao vírus nas diferentes construções transgênicas utilizadas e entre clones de uma mesma planta. Alguns clones não foram infectados com o vírus mesmo após a quarta inoculação, indicando uma possível resistência ao patógeno. Um total de 30 experimentos de transformação genética de laranja azeda foram realizados, utilizando como explantes segmentos internodal, de epicótilo e de cotilédone associado ao hipocótilo. O teste de GUS permitiu a identificação de duas gemas com reação positiva (0,13% de eficiência de transformação). Tais gemas foram enxertadas in vitro sobre citrange Carrizo, mas apenas uma gema se desenvolveu. A planta obtida foi aclimatizada em casa-de-vegetação. / Citrus tristeza virus (CTV) occurs in almost all citrus-growing areas of the world. Control of citrus tristeza relies mainly on the use of tolerant rootstocks and scion cross protection. Obtaining transgenic sweet oranges cultivars or sour orange resistant to CTV would allow a better use of this excellent rootstock. This way, the aim of this work was to evaluate transgenic sweet orange (Citrus sinensis) lines and to obtain transgenic sour orange (Citrus aurantium) for the resistance to CTV, in order to offer another alternative for the control of the disease in citrus. Transgenic sweet orange cv. Valencia and cv. Hamlin containing three different genetic constructs were evaluated. One gene construct contains a sense sequence (684 pb) of the coat protein gene of CTV (pCTV-CP), another contains a conserved sequence (559 pb) of CTV (pCTV-SC), and the last one a hairpin type, containing the sense and antisense sequences of the coat protein gene separated by an intron (pCTV-dsCP). Ten transgenic lines of each gene construct and each cultivar were previously confirmed by Southern blot and RT-PCR analysis, totalizing 60 transgenic lines. These lines were cloned and grafted into C. limonia and into C. aurantium, totaling 360 plants. The plants, along with non-transgenic plants used as control, were challenged four times with the CTV by means of viruliferous Toxoptera citricida. Indirect ELISA using monoclonal antibody against the CTV coat protein or the Real-time PCR using primers to amplify the CTV genes p20 and p23 were used to detect the virus in the tested plants, 4 weeks after inoculation. Variation in the virus resistance was observed among different transgenic constructs and different clones of the same plant. Some clones were not infected with the virus even after the fourth inoculation, indicating a possible resistance to the pathogen. A total of 30 genetic transformation experiments of sour orange were performed, using as explants internodal segments, epicotyl segments and cotyledon fragment with hypocotyl attached. GUS reaction detected two shoots positive (transformation efficiency of 0,13%). These shoots were in vitro grafted in Carrizo citrange, but only one shoot developed. The plant obtained was acclimatized in greenhouse.

O maracujá-doce (Passiflora alata Curtis) é uma espécie nativa no Brasil. Seu cultivo tem crescido nos últimos anos devido a sua valorização no mercado in natura e seus usos na fitoterapia. Entretanto, os cultivos comerciais enfrentam problemas devido a ocorrência da bacteriose (Xanthomonas axonopodis pv. passiflorae). O patógeno é endêmico no país, apresentando considerável variabilidade genética em suas populações naturais. Este trabalho teve como objetivo identificar QTL relacionados à resistência de P. alata à bacteriose em uma população F1 segregante oriunda do cruzamento entre acessos não endogâmicos. Foram avaliados os caracteres: área total da folha (TA), idade de queda da folha inoculada (IK), área total da lesão foliar (LA), área de clorose foliar (CA) e área da necrose foliar (NEA). Apenas um dos isolados apresentou diferenças de severidade em relação aos demais, sendo o menos agressivo (PA8-2). A inoculação do isolado M-129 mostrou que há variação significativa na resposta da população ao patógeno, sendo possível a identificação de genótipos transgressivos. A herdabilidade dos caracteres variou de 45% a 71%%. Foi construído um mapa de ligação integrado com 1.786 cM e uma densidade média de 4,5 cM. A análise de marcas individuais indicou a associação de 51 marcas aos fenótipos avaliados. O mapeamento de QTL, realizado por intervalo composto e utilizando uma estratégia diferenciada para populações F1 segregantes, identificou regiões associadas a 26 QTL para os cinco caracteres avaliados, sendo 16 deles referentes à LA, CA e NEA. A variação fenotípica explicada individualmente pelos marcadores variou de 0,8% a 16,7%. Sugere-se que a resistência à bacteriose é quantitativa, com predominância de efeitos genéticos aditivos. / The sweet passion fruit (Passiflora alata Curtis) is a specie native to Brazil. Its cultivation has increased in recent years due to its market valuation in natura and their uses in herbal medicine. However, crops are facing problems due to the occurrence of bacterial blight (Xanthomonas axonopodis pv. passiflorae). The pathogen is endemic in the country, with considerable genetic variability in their natural populations. This study aimed to identify QTL related to resistance of P. alata to bacterial blight in an F1 segregant population from the cross between outbred accessions. Five traits were evaluated: total area of the leaf (TA), age of inoculated leaf fall (IK), area of the leaf´s lesion (LA), area of the leaf´s chlorosis (CA) and area of the leaf´s necrosis (NEA). Only one of the isolates showed differences in severity in relation to others, being the least aggressive (PA8-2). The inoculation of the isolate M-129 showed significant variation in population response to the pathogen, making it possible to identify transgressive genotypes. The heritability of characters ranged from 45% to 71%. An integrated linkage map was constructed, with a length of 1,786 cM and an average density of 4.5 cM. The analysis of individual marks indicated the association of 51 markers to phenotypes. The QTL mapping was performed using composite interval and a special strategy for segregating F1 populations, identified 26 regions associated with QTL for the five traits, 16 of them related to LA, CA and NEA. The phenotypic variation explained by individual markers ranged from 0,8% to 16,7%. It is suggested that the resistance to bacterial blight is quantitative, with a predominance of additive genetic effects.

Neste trabalho teve-se por objetivo estimar parâmetros genéticos e avaliar o potencial agronômico em gerações F2 e F3:2 de cruzamentos do tipo adaptado x exótico em soja, quanto ao potencial de gerar descendentes agronomicamente superiores e com resistência à ferrugem asiática. Ademais, procurou-se estudar a resistência a doenças de final de ciclo (DFC). Os experimentos nas gerações F2 e F3:2 foram conduzidos em 2007 e 2007/08, respectivamente, em áreas experimentais do Departamento de Genética, ESALQ/USP, Piracicaba, SP, Brasil. Foram utilizados como genitores exóticos resistentes: 1) PI 200487 (Kinoshita), 2) PI 471904 (Orba), 3) PI 459025 (Bing nan) e 4) PI 200526 (Shira Nuhi); e, como genitores adaptados, mas suscetíveis à ferrugem, foram utilizados os genótipos: 1) IAC-100, 2) MGBR 46 (Conquista), 3) BRSMT (Pintado), 4) BRS-154 e 5) BRS-232. Foram avaliados 27 cruzamentos em F2, sendo dez com recíprocos e sete sem recíprocos, e mais os nove genitores. Na geração F3:2 foram avaliados dois cruzamentos: Conquista x Orba e IAC-100 x Kinoshita; cada cruzamento foi avaliado em dois experimentos principais. Um destes experimentos foi protegido com aplicações dos fungicidas Impact Duo & Opera para controle da ferrugem e das DFC, enquanto que o outro recebeu apenas o fungicida Derosal para controle das DFC. Foram avaliadas 40 progênies F3:2 por recíproco de cada cruzamento. Além dos experimentos principais, foram instalados três experimentos auxiliares com 12 genótipos: quatro genitores exóticos, cinco genitores adaptados e três genótipos adicionais (BR-16, IAS-5 e OC-4). Cada experimento auxiliar recebeu um tratamento diferenciado de fungicida: Impact Duo & Opera, Derosal e Controle (sem aplicação de fungicida); o contraste do Impact Duo & Opera vs Derosal forneceu uma estimativa do efeito da ferrugem, enquanto que o contraste entre Derosal e Controle estimou o efeito das DFC. Os resultados levaram às seguintes conclusões: a) a estratégia de se usar diferentes tipos de fungicidas mostrou-se eficiente para estimar a reação das plantas à ferrugem e a DFC, em termos de produtividade de grãos; b) em relação às notas de severidade da ferrugem, a discriminação genotípica foi melhor observada a partir de 97 dias (S2) e 104 dias (S3) após a semeadura, respectivamente para genitores nos experimentos auxiliares e cruzamentos; c) no cultivo de outono (geração F2 e genitores), o hábito de crescimento indeterminado foi um caráter importante para o desempenho favorável dos genótipos; d) foram identificadas fontes de resistência/tolerância à ferrugem e a DFC entre os genitores exóticos e também, adaptados e adicionais; e) em F2, os cruzamentos envolvendo o genitor Orba foram os mais promissores e os cruzamentos com o genitor Shira Nuhi foram os menos promissores; o caráter valor agronômico mostrou-se eficiente na seleção de cruzamentos, pelos altos coeficientes de herdabilidade, observados no sentido amplo; f) em F3:2, o cruzamento IAC-100 x Kinoshita mostrou-se mais promissor do que o cruzamento Conquista x Orba, para o desenvolvimento de linhagens com níveis apropriados de resistência à ferrugem e produtividade de grãos; g) nas duas gerações as diferenças entre recíprocos ocorreram apenas em situações pontuais. / This work aimed to estimate genetic parameters and evaluate the agronomic potential in F2 and F3:2 generations of adapted x exotic soybean crosses, concerning the potential to generate progenies with higher agronomic offspring and with resistance to Asian soybean rust. Moreover, the resistance to late season leaf diseases (LSLD) was studied. The experiments in F2 and F3:2 generations were carried out during 2007 and 2007/08, respectively, in the Department of Genetics, ESALQ/USP, Piracicaba, SP, Brazil. As resistant exotic parents were used: 1) PI 200487 (Kinoshita), 2) PI 471904 (Orba), 3) PI 459025 (Bing nan) and 4) PI 200526 (Shira Nuhi); and as adapted parents, but susceptible to soybean rust, were used: 1) IAC-100, 2) MGBR 46 (Conquista), 3) BRSMT (Pintado), 4) BRS-154 and 5) BRS-232. Twenty seven crosses in generation F2, ten with reciprocals and seven without reciprocals were evaluated, plus the nine parents. In F3:2 generation, two crosses were evaluated: Conquista x Orba and IAC-100 x Kinoshita. Each cross was evaluated in two main experiments, one of them was protected with applications of the Impact Duo & Opera fungicides, to control soybean rust and LSLD, while the other experiment was spraied with Derosal to control only the LSLD. For each reciprocal cross, were evaluated 40 progenies in F3:2. Besides the main experiments, three auxiliary experiments were installed, with twelve genotypes: four exotic parents, five adapted parents and three additional parents (BR-16, IAS-5 and OC-4). Each experiment received one differential treatment of fungicide: Impact Duo & Opera, Derosal and Control (no applications of fungicide); the contrast Impact Duo & Operal vs. Derosal gave an estimate of the Asian soybean rust effect, while the contrast between Derosal and Control estimated the LSLD effect. The results led to the following results: a) the strategy of using different types of fungicides were effective in estimating the response of plants to rust and LSLD, in terms of grain yield; b) in relation to the notes of severity of rust, genetic discrimination was better observed from 97 days (S2) and 104 days (S3) after sowing, respectively for parents in the auxiliary experiments and crosses; c) in the cultivation of autumn (parents and F2 generation), the indeterminate growth habit was an important character to the favorable performance of the genotypes; d) sources of resistance/tolerance to rust and LSLD were identified among exotic, adapted and additional parents; e) In F2 generation, crosses having Orba as parent were the most promising and crosses involving Shira Nuhi were the less promising; agronomic value (VA) showed to be efficient for cross selection, by the high magnitude of the heritability coefficient, observed in broad sense; f) In F3:2 generation, the cross IAC-100 x Kinoshita showed more promising than Conquista x Orba cross, for the development of lines with appropriate levels of resistance to soybean rust and high grain yield; g) in the two generations, the differences between reciprocals occurred only in specific situations.

O sul de Minas Gerais é a principal região produtora de morangos (Fragaria x ananassa Duch.) no Brasil. O ácaro-rajado, Tetranychus urticae Koch (Acari: Tetranychidae), é considerado uma das principais pragas do morangueiro no Brasil e em vários países. Uma prática importante na cultura do morango refere-se à cobertura de solo, usualmente realizada com filme de polietileno, porém além de ser caro gera resíduos muito persistentes no ambiente. Objetivou-se com este trabalho comparar a resistência de oito genótipos de morango (\'Albion\', \'IAC Guarani\', \'IAC Princesa Isabel\', \'Oso Grande\', IAC T-0104, IAC 12, IAC 4 e IAC 1.13) ao ácaro-rajado; determinar o efeito da cobertura de solo (com a polpa de café desidratada, conhecida como palha de café) nas pragas/ patógenos e ácaros predadores desta cultura; comparar a ocorrência de pragas, patógenos e inimigos naturais entre um cultivo orgânico e outro convencional de morango. Os resultados obtidos indicaram que \'IAC Princesa Isabel\', IAC T-0104 e IAC 12 são resistentes, IAC 1.13 e IAC 4 apresentam resistência moderada e \'IAC Guarani\', \'Oso Grande\' e \'Albion\' são suscetíveis ao ácaro-rajado. \'Oso Grande\' e \'Albion\' são bastante utilizadas pelos produtores do sul de Minas Gerais. O uso de palha de café aumentou o número de predadores edáficos, tanto no solo dos canteiros (campo) e em vasos (laboratório) como em folíolos de morangueiro. O Gamasina Proctolaelaps pygmaeus (Müller) (Melicharidae) foi visto sobre morangueiros, principalmente no período noturno. Maior número de ácaro-rajado e maior severidade de doenças foram observados em plantas cultivadas em solo coberto com polietileno. Além disso, foi maior o nível de infecção de ácaro-rajado pelo fungo Neozygites floridana (Weiser e Muma) em plantas cultivadas em solo coberto com palha de café. Não foi observada diferença significativa entre a produtividade da cultura em solo coberto com polietileno e em solo coberto com palha seca de café. Os resultados da comparação da ocorrência de ártropodes e patógenos entre sistema orgânico e convencional mostraram menor ocorrência de ácaro-rajado e predadores em cultivo de morangueiro convencional, porém ocorrência considerável de tripes, mosca-branca e mofo cinzento. A incidência de dendrofoma e mancha de pestalotia foi a mesma nos dois sistemas de cultivos. Os resultados sugerem a conveniência de se continuar o processo de desenvolvimento dos genótipos que se mostraram menos afetados pelo ácaro-rajado, para que estes possam no futuro ser utilizados pelos produtores, e a condução de estudos complementares, que avaliem o desempenho de cultivos em sistema orgânico que incorporem o uso da palha de café para a cobertura do solo. / The southern of Minas Gerais is the main region producing strawberries (Fragaria x ananassa Duch.) in Brazil. The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is considered one of the main strawberry pests in Brazil and in several countries. An important practice in strawberry cultivation refers to soil cover, which is usually made with polyethylene film, but it is expensive and generates very persistent residues in the environment. The objective of this study was to compare the resistance of eight strawberry genotypes (\'Albion\', \'IAC Guarani\', \'IAC Princesa Isabel\', \'Oso Grande\', IAC T-0104, IAC 12, IAC 4 and IAC 1.13); to determine the effect of soil cover (with dehydrated coffee pulp, known as coffee straw) on the pests mites/ pathogens and predatory mites of this crop; to compare the occurrence of pests, pathogens and natural enemies between an organic and a conventional strawberry crop. The results indicated that \'IAC Princesa Isabel\', IAC T-0104 and IAC 12 are resistant, IAC 4 and IAC 1.13 are moderately resistant, and \'IAC Guarani\', \'Oso Grande\' and \'Albion\' are susceptible to the two-spotted spider mite. \'Oso Grande\' and \'Albion\' are widely used by producers in the southern of Minas Gerais. The use of coffee straw increased the number of edaphic predators, both in the soil beds (field) and in pots (laboratory) as well as in strawberry leaflets. The Gamasina Proctolaelaps pygmaeus (Müller) (Melicharidae) was seen on strawberry leaftlets, mainly in the nocturnal period. Higher numbers of the two-spotted spider mites and disease severity were observed in plants grown on soil covered with polyethylene. In addition, the level of the two-spotted spider mite infected by the fungi Neozygites floridana (Weiser and Muma) was higher in plants cultivated in soil covered with coffee straw. No significant difference was observed between yield in soil covered with polyethylene and in soil covered with dry coffee straw. The results of the comparison of the occurrence of arthropods and pathogens between the organic and conventional systems showed fewer occurrences of the two-spotted spider mites and predators in conventional strawberry cultivation, but considerable occurrence of thrips, whitefly and gray mold. The incidence of dendrophoma and leaf spots caused by pestalotia was the same in both cropping systems. The results suggest the convenience to continue the development process of the genotypes that were less affected by the two-spotted spider mite, which could be used in the future by producers, and the conduction of complementary studies to evaluate the performance of crops in organic system that incorporate the use of coffee straw as soil coverage.

Master of Science / Department of Entomology / John C. Reese / The soybean aphid, Aphis glycines Matsumura, is a pest of soybean, Glycine max (L.) Merr. Studies to find control methods were initiated in 2000 when it was first detected in the United States. Aphis glycines can reduce yields by as much as 50%, and vectors several viral diseases. Plant resistance to A. glycines is one important component of integrated control. In the first study, reproduction of A. glycines was compared on 240 soybean entries. Eleven had fewer nymphs produced compared with two susceptible checks (KS4202 and Pioneer® 95B15). Antibiosis and antixenosis were assessed in no-choice and choice tests, respectively. Nine entries showed moderate antibiosis and the other two (K1639 and Pioneer® 95B97) showed strong antibiosis and antixenosis as categories of resistance to A. glycines. In the second study, chlorophyll loss was estimated in no-choice tests on infested and uninfested leaves of KS4202. The minimum combined number to detect significant chlorophyll loss was 30 aphids confined for 10 days. Using this number, seven resistant entries found in the first study were evaluated. There was no significant chlorophyll reduction between infested and uninfested leaves of five of the resistant entries (K1621, K1639, 95B97, Dowling and Jackson). Jackson and Dowling had a significantly lower percentage loss than the susceptible checks. In the third study, assessment of feeding behavior of A. glycines was compared and recorded for 9 h on four resistant entries and KS4202. The average time needed to reach the first sieve element phase by A. glycines was 3.5 h in KS4202 while in the resistant entries it was 7.5 h, and the total duration in this phase was longer than an hour in KS4202, and only two to seven minutes in the resistant entries. These data suggest that phloem tissues in the resistant plants change feeding behavior. However, aphids first reached the xylem phase and then the sieve element phase, and the time that aphids spent ingesting xylem sap was not different among all entries; therefore, it is possible that xylem sap in the resistant entries may contain toxic substances that alter aphid behavior and restrain further activities on the sieve element phase.

No description available.

Disease resistance is critical in soft red winter wheat (Triticum aestivum L.) cultivars. Leaf rust caused by Puccinia triticina Eriks and stripe rust caused by Puccinia striiformis Westend. f.sp. tritici Eriks. are destructive pathogens of wheat. From 2014 to 2015 phenotypic data was collected at diverse locations for resistance to leaf rust (North Carolina, Texas, and Virginia) and stripe rust (Arkansas, North Carolina, Georgia, Texas, and Virginia) in a Pioneer ‘25R47’ /‘Jamestown’ (P47/JT) population composed of 186 F5:9 recombinant inbred lines (RILs). Analysis of the P47/JT population identified two quantitative trait loci (QTL) for leaf rust resistance on chromosome 5B and two QTL for stripe rust resistance on chromosomes 3B and 6A. Phenotypic variation (%) explained by the putative leaf rust resistance QTL of Jamestown on 5B was as high as 22.1%. Variation explained by the putative stripe rust resistance QTL of Jamestown on 3B and 6A was as high as 11.1 and 14.3%, respectively. Jamestown is postulated to contain gene Lr18. Seedlings of 186 F5:9 recombinant inbred lines from the P47/JT population and 200 F2 seedlings from eight other crosses including Jamestown and/or the Lr18 host differential line RL6009 (Thatcher*6/Africa 43) were screened with P. triticina race TNRJJ. Genetic analysis of the populations was conducted to validate the presence of Lr18 in Jamestown. Results of linkage analysis identified SNP maker IWB41960 linked within 5 cM of gene Lr18 in all three populations. From 2016 to 2017 phenotypic data was collected at diverse locations for resistance to leaf rust (Illinois, North Carolina, and Virginia) in a ‘2013412’ (PI 667644) / VA10W-21 (PI 676295) population (412/21) composed of 157 doubled haploid (DH) lines. The 412/21 DH lines were genotyped via genotyping by sequence (GBS). Analysis of the 412/21 population identified one quantitative trait loci (QTL) region associated with adult plant resistance to leaf rust on chromosome 1B. Phenotypic variation (%) explained by the putative leaf rust resistance QTL of 2013412 on 1B was as high as 40.1%. Kompetitive allele-specific (KASP) markers KASP_S1B_8414614 and KASP_S1B_8566239 were developed as markers for use in marker assisted selection. / Ph. D. / Disease resistance to leaf rust and stripe rust is important when growing soft red winter wheat. Genetic resistance can have a benefit to cost ratio of up to 27:1, considerably better than that of fungicide treatments. From 2013 to 2017 disease data was collected across multiple locations spanning the eastern United States (Arkansas, Georgia, Illinois, North Carolina, Texas, and Virginia). DNA molecular markers were used to identify specific chromosome regions containing genes associated with leaf and stripe rust resistance. DNA markers associated with genes conferring resistance to leaf rust resistance were identified in three chromosome regions, and genes in two regions were associated with stripe rust resistance. These genes and molecular markers associated with them can be used by scientists to further enhance resistance in wheat cultivars. Another study was conducted to determine if Lr18, a gene for leaf rust resistance that has a large effect, is present in the Virginia Tech soft red winter wheat breeding material. This gene (Lr18) is known to have been introduced from an ancestral species highly related to wheat. Wheat seedlings derived from crosses between lines postulated to carry Lr18 with susceptible lines were tested for resistance to a specific strain of leaf rust lacking virulence to Lr18. Genetic analysis of the ratio of resistant versus susceptible seedlings and association between DNA molecular markers and resistant seedlings were conducted to validate the presence of gene Lr18. A molecular marker linked tightly to gene Lr18 was identified in the study. This gene was found to be widely distributed in soft red winter wheat breeding materials and the molecular marker associated with gene Lr18 will be useful for scientists to further improve resistance in wheat cultivars.

Plusieurs recherches sont effectuées sur la laitue commercialisée (Lactuca sativa L.), afin d’améliorer sa résistance aux ravageurs. L’objectif de cette étude est d’examiner les impacts de la résistance de la laitue sur le puceron de la laitue, Nasonovia ribisnigri (Mosley) (Hemiptera : Aphididae) et son parasitoïde, Aphidius ervi Haliday (Hymenoptera: Braconidae). La résistance de la laitue affecte négativement la valeur adaptative du puceron en augmentant sa mortalité et son temps de développement et en diminuant sa fécondité, sa taille et son poids. Cet impact sur la valeur adaptative du puceron affecte aussi négativement le parasitoïde qui s'y développe en diminuant le pourcentage d’émergence, la taille et le poids des adultes, et en diminuant la fécondité des femelles. La femelle parasitoïde estime de manière absolue la qualité de ses hôtes puisqu’elle peut discriminer entre des hôtes de bonne et de faible qualité, sans expérience préalable. L’acceptation des hôtes de bonne qualité est similaire lorsqu’ils sont présentés successivement à la femelle; l’estimation de la valeur des hôtes est donc adéquate dès la première rencontre. Cependant, cet estimé absolu est modifié par l'expérience, puisque la femelle peut changer son exploitation selon la qualité des agrégats rencontrés. Lorsque des hôtes de basse qualité sont présentés successivement, l’acceptation de la femelle augmente. Accepter des hôtes de mauvaise qualité pour l’oviposition peut être préférable que de risquer de ne pas pondre tous ses œufs. L’utilisation d’une estimation absolue et relative par A. ervi peut mener à une exploitation optimale des agrégats. / New cultivars of commercialized lettuce (Lactuca sativa L.) with an improved resistance to pests are now available. The objective of this study was to examine the impacts of lettuce resistance on the lettuce aphid, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) and one of its parasitoids, Aphidius ervi Haliday (Hymenoptera: Braconidae). Lettuce resistance negatively affects aphid fitness by: increasing its mortality and developmental time and decreasing its fecundity, size and mass. This impact on aphid fitness also negatively impacts the parasitoid by decreasing its proportion of emergence, the size and mass of adults and decreasing fecundity of females. Female parasitoids estimate hosts quality in an absolute way as they can discriminate between high and low quality hosts, without previous experience. High quality host acceptation remains constant when hosts are successively offered to a female, indicating that the female can adequately estimate host value without experience. However, this absolute estimate of host quality is modified through experience as the female changes her patch exploitation according to the quality of the patches she encounters. When low quality hosts are successively offered, female acceptation increases. Accepting low quality hosts for oviposition can be preferable to the risk of not using all her eggs. The two strategies combined, using an absolute and a relative estimation, could lead to optimal patch exploitation by A. ervi.