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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Host plant resistance to Whiteflies, Bemisia tabaci (Gennadius), Biotype B, (Homoptera: Aleyrodidae) in cotton race stocks for breeding improved cotton cultivars

Ripple, Brandon Wayne 30 September 2004 (has links)
Whiteflies (Bemisia tabaci, Biotype B, Homoptera: Aleyrodidae) are pests of cotton crops, affecting the yield of the crop both indirectly and directly. These pests feed on the leaves of cotton plants and produce "honeydew," a sticky liquid excretion which covers the lint of the open cotton boll creating problems during the processing of the lint. High densities of these pests also can decrease the productivity of the cotton plant by stripping it of vital nutrients. The primary objective of this research was to screen 116 converted cotton race stocks for resistance to sweetpotato whiteflies. Responses of converted race stocks to whiteflies are compared to that of known susceptible commercial cultivars PSC 355 and Delta Pearl. Screens for antibiosis resistance to whitefly were established using excised leaves placed in a nutrient solution (¼ strength Hoagland's). Cohort populations of whiteflies were established on these leaves and followed daily to determine differences in developmental time as well as percent survival. Resistant candidates were determined using a chi-squared test comparing the ranked sums of leaf averages for the two selection criteria, whitefly developmental time and percent whitefly survival, of each cotton race stock to that of the putative known susceptibles (KS). These tests showed 6 converted race stocks to be significantly different (P ≤ 0.1) from the KS for at least one of the two selection criteria. Of these converted race stocks, M-9044-0154 and M-9044-0156 showed to have lower whitefly survival than the KS, while M-9644-0188, M-9644-0195, M-0044-0221, and M-9644-0242 showed whitefly to have an increased developmental time. Retesting of these six converted race stocks along with several others identified another race stock line, M-0044-0171, which was significantly different from the KS. Retesting also indicated that M-9644-0188 was different for survival in addition to developmental time which was determined in the original screening. Additional tests were conducted in the greenhouse and field to examine these race stock lines. Greenhouse screenings indicated that M-9044-0156 and M-9644-0188 contained possible non-preference resistance characteristics. Field screenings conducted in Weslaco and College Station, TX in 2002 and 2003 failed to provide useful data due to low densities of insects.
22

Efeito de éster de sacarose sobre Bemisia tabaci biótipo B, sobre seu predador Chrysoperla externa e sobre o desenvolvimento de plantas de tomateiro e melão

Bernardes, Maria Aparecida [UNESP] 07 March 2006 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:25:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-07Bitstream added on 2014-06-13T20:53:01Z : No. of bitstreams: 1 bernardes_ma_me_jabo.pdf: 986376 bytes, checksum: 42280e4eceff4f2087b647d8dd861daa (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os ésteres de sacarose são uma classe de compostos produzidos através da reação de ácidos gordurosos e açúcares e que podem possuir ação inseticida. Com isso trata-se de um método alternativo de fonte renovável e de baixo custo. Assim, estudou-se o efeito de éster de sacarose sobre ovos, ninfas e adultos de Bemisia tabaci biótipo B; sobre ovos, larvas e adultos do predador Chrysoperla externa; e sobre o desenvolvimento de tomateiro e melão. Utilizou-se concentrações de 0, 1, 2, 3, 5 e 10 g/L do éster de sacarose. Os testes com ovos e ninfas de mosca-branca foram realizados sobre plantas de tomate e melão, enquanto o teste com adultos foi realizado em gaiolas de tela antiafídeo. O éster de sacarose causou mortalidade em ovos, ninfas e adultos de mosca branca. Para se avaliar o efeito do éster de sacarose sobre as diversas fases de C. externa utilizou-se o método do filme seco, método de imersão e aplicação tópica. No método do filme seco, o éster de sacarose foi inócuo para ovos e adultos de C. externa e levemente nocivo para larvas de 3o ínstar. Todavia, no método de imersão, a concentração de 10 g/L causou mortalidade média de 73,3% dos ovos, enquanto a pulverização sobre larvas e adultos causou 80,0% e 16,6 % de mortalidade, respectivamente. Sementes de tomate e melão foram imersas em soluções de éster de sacarose enquanto as plantas foram pulverizadas semanalmente A germinação e desenvolvimento das plântulas ou plantas não foram afetados. / Sucroesters are a class of compounds produced through the reaction between fat acids and sugars that can have insecticide properties. Thus, as they can be made using renewable sources and are inexpensive, they can be an alternative pest control method. The effect of sucroester on Bemisia tabaci B biotype eggs, nymphs and adults; Chrysoperla externa eggs, larvae and adults; tomato and melon plants development was studied. Concentrations from 0 to 10 g/L of the sucroester were tested. The essays on whitefly eggs and nymphs were carried out on tomato and melon plants, whereas the essay on adults was carried out using screened cages. The sucroester caused mortality of whitefly eggs, nymphs and adults. Both dry film and dip methods were used to evaluate the effect of sucroester on C. externa. In the dry film method, the sucroester did not cause any effect on eggs and adults of C. externa, and was considered innocuous. However, it was slightly noxious to the third instar larvae. On the other hand, in the dip method, the mortality of C. externa eggs caused by the concentration of 10 g/L was 73.3 %, whereas topic application on larvae and adults caused mortality of 80% and 16%, respectively. Tomato and melon seeds were dipped into sucroester solutions while the plants were sprayed weekly. The germination and development of seedlings and plants were not affected.
23

Efeito de éster de sacarose sobre Bemisia tabaci biótipo B, sobre seu predador Chrysoperla externa e sobre o desenvolvimento de plantas de tomateiro e melão /

Bernardes, Maria Aparecida. January 2006 (has links)
Resumo: Os ésteres de sacarose são uma classe de compostos produzidos através da reação de ácidos gordurosos e açúcares e que podem possuir ação inseticida. Com isso trata-se de um método alternativo de fonte renovável e de baixo custo. Assim, estudou-se o efeito de éster de sacarose sobre ovos, ninfas e adultos de Bemisia tabaci biótipo B; sobre ovos, larvas e adultos do predador Chrysoperla externa; e sobre o desenvolvimento de tomateiro e melão. Utilizou-se concentrações de 0, 1, 2, 3, 5 e 10 g/L do éster de sacarose. Os testes com ovos e ninfas de mosca-branca foram realizados sobre plantas de tomate e melão, enquanto o teste com adultos foi realizado em gaiolas de tela antiafídeo. O éster de sacarose causou mortalidade em ovos, ninfas e adultos de mosca branca. Para se avaliar o efeito do éster de sacarose sobre as diversas fases de C. externa utilizou-se o método do filme seco, método de imersão e aplicação tópica. No método do filme seco, o éster de sacarose foi inócuo para ovos e adultos de C. externa e levemente nocivo para larvas de 3o ínstar. Todavia, no método de imersão, a concentração de 10 g/L causou mortalidade média de 73,3% dos ovos, enquanto a pulverização sobre larvas e adultos causou 80,0% e 16,6 % de mortalidade, respectivamente. Sementes de tomate e melão foram imersas em soluções de éster de sacarose enquanto as plantas foram pulverizadas semanalmente A germinação e desenvolvimento das plântulas ou plantas não foram afetados. / Abstract: Sucroesters are a class of compounds produced through the reaction between fat acids and sugars that can have insecticide properties. Thus, as they can be made using renewable sources and are inexpensive, they can be an alternative pest control method. The effect of sucroester on Bemisia tabaci B biotype eggs, nymphs and adults; Chrysoperla externa eggs, larvae and adults; tomato and melon plants development was studied. Concentrations from 0 to 10 g/L of the sucroester were tested. The essays on whitefly eggs and nymphs were carried out on tomato and melon plants, whereas the essay on adults was carried out using screened cages. The sucroester caused mortality of whitefly eggs, nymphs and adults. Both dry film and dip methods were used to evaluate the effect of sucroester on C. externa. In the dry film method, the sucroester did not cause any effect on eggs and adults of C. externa, and was considered innocuous. However, it was slightly noxious to the third instar larvae. On the other hand, in the dip method, the mortality of C. externa eggs caused by the concentration of 10 g/L was 73.3 %, whereas topic application on larvae and adults caused mortality of 80% and 16%, respectively. Tomato and melon seeds were dipped into sucroester solutions while the plants were sprayed weekly. The germination and development of seedlings and plants were not affected. / Orientador: Odair Aparecido Fernandes / Coorientador: Maurício Boscolo / Banca: André Luiz Lourenção / Banca: Antonio Carlos Busoli / Mestre
24

Atividade do inseticida chlorantraniliprole + tiametoxam, aplicados em diferentes modalidades, no manejo de pragas do tomateiro

Storti, Danilo de Carvalho [UNESP] 29 September 2000 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:29:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2000-09-29Bitstream added on 2014-06-13T21:00:03Z : No. of bitstreams: 1 storti_dc_me_ilha.pdf: 438021 bytes, checksum: dc88c1c130d9f83ab5b30b6b17a83b51 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Entre os fatores que limitam o potencial produtivo da cultura do tomate (Lycopersicon esculentum Mill.) estão às pragas. A mosca-branca, Bemisia tabaci biótipo B, a traça-do- tomateiro, Tuta absoluta e a broca-pequena-do-fruto, Neoleucinodes elegantalis causam danos consideráveis à cultura, requerendo pulverizações sequenciais de inseticidas durante todo o ciclo da cultura, podendo alcançar 20 ou mais pulverizações. Na busca por alternativas que possibilitem a redução dessas pulverizações, avaliou-se a atividade de nova molécula química de perfil toxicológico favorável (chlorantraniliprole), associado ao tiametoxam, no manejo de pragas do tomateiro. O experimento foi instalado em delineamento inteiramente casualizado, com quatro repetições. Cada parcela foi constituída de uma linha, com dez plantas do híbrido Débora Plus, espaçadas em 0,5 m. Os tratamentos e doses (g i.a. ha−1) foram: testemunha, chlorantraniliprole + tiametoxam a 40 + 80, 60 + 120 e 80 + 160 aplicados sobre a bandeja de mudas um dia antes do transplante (DAT), chlorantraniliprole + tiametoxam a 40 + 80 aplicados sobre a bandeja 1 DAT e em esguicho na planta e no solo (drench) 14 dias pós-transplante (DPT), chlorantraniliprole + tiametoxam a 60 + 120 aplicados sobre a bandeja de mudas 1 DAT e a 40 + 80 em drench 14 DPT, chlorantraniliprole + tiametoxam a 80 + 160 aplicados sobre a bandeja de mudas 1 DAT e a 40 + 80 em drench 14 DPT, chlorantraniliprole a 80 aplicado sobre a bandeja de mudas 1 DAT e tiametoxam a 160 em drench 14 DPT, imidacloprid a 210 aplicado sobre a bandeja de mudas 1 DAT e imidacloprid a 90 aplicado em três pulverizações foliares sequenciais aos 7, 14 e 21 dias pós-transplante, utilizando-se um pulverizador costal, propelido por CO2 comprimido. Semanalmente foram contados o número de ninfas de mosca-branca em 10 folíolos por parcela, número de folíolos com sintomas... / Among the factors limiting the yield potential of tomato crop (Lycopersicon esculentum Mill.) are the pests. The whitefly, Bemisia tabaci biotype B, the tomato pinworm, Tuta absoluta, and the fruit small borer, Neoleucinodes elegantalis cause considerable damage to crop, mainly due to sequential spraying of insecticides during the growing cycle and it can reach 20 or more sprays. Searching for alternatives that enable the reduction of these sprays, it was evaluated the activity of new molecule chemistry of favorable toxicological profile (chlorantraniliprole), associated with thiamethoxam and applied in different modes, on the pest management of tomato crop. The experiment was conducted in completely randomized design with four replications. Each plot consisted of one row with ten plants of the Debora Plus hybrid, spaced at 0,5 m. The treatments and doses (g a.i. ha−1) were: control, chlorantraniliprole + thiamethoxam at 40 + 80, 60 + 120 e 80 + 160, applied on the tray of seedlings one day before transplant (DBT), chlorantraniliprole + thiamethoxam at 40 + 80, applied on the tray of seedlings 1 DBT and in squirt on the plant and on the soil (drench) 14 days post transplant (DPT), chlorantraniliprole + thiamethoxam at 60 + 120 applied on the tray of seedlings 1 DBT and chlorantraniliprole + thiamethoxam at 40 + 80 in drench 14 DPT; chlorantraniliprole + thiamethoxam at 80 + 160 applied under the tray of seedlings 1 DBT and chlorantraniliprole + thiamethoxam at 40 + 80 in drench 14 DPT, chlorantraniliprole at 80 applied on the tray of seedlings 1 DBT and thiamenthoxam at 160 in drench 14 DPT, imidacloprid at 210 applied on the tray of seedlings 1 DBT and imidacloprid at 90 applied in three sequential foliar sprays at 7, 14 and 21 days post-transplant, using a backpack sprayer, propelled by CO2. Weekly were counted the number of whitefly nymphs on 10 leaves per plot, number of leaves,,, (Complete abstract click electronic access below)
25

Využití entomopatogenních hub v biologické ochraně proti molici skleníkové Trialeurodes vaporariorum a bavlníkové Bemisia tabaci / Use of entomopathogenic fungi in biological control against greenhouse whitefly Trialeurodes vaporariorum and sweetpotato whitefly Bemisia tabaci

NAVRÁTILOVÁ, Dana January 2007 (has links)
Diploma Thesis concerns with usage of entomopathogenic fungi in system of biological control against greenhouse whitefly Trialeurodoes vaporariorum and sweetpotato whitefly Bemisia tabaci. The Aim of diploma thesis was through in vivo and in vitro experiments determinated the basic evolutional and vegetative characteristics of selected entomopathogenic fungi and compare their effectivity in completed system {\clqq}plant - pest - pathogenic``. All experiments and results are demonstrated in the tables and the graphs. The photo-documentation of the method used during founding and interpretation of experiments is the part of the thesis.
26

Begomovirus disease complex: emerging threat to vegetable production systems of West and Central Africa

Leke, Walter N., Mignouna, Djana B., Brown, Judith K., Kvarnheden, Anders January 2015 (has links)
Vegetables play a major role in the livelihoods of the rural poor in Africa. Among major constraints to vegetable production worldwide are diseases caused by a group of viruses belonging to the genus Begomovirus, family Geminiviridae. Begomoviruses are plant-infecting viruses, which are transmitted by the whitefly vector Bemisia tabaci and have been known to cause extreme yield reduction in a number of economically important vegetables around the world. Several begomoviruses have been detected infecting vegetable crops in West and Central Africa (WCA). Small single stranded circular molecules, alphasatellites and betasatellites, which are about half the size of their helper begomovirus genome, have also been detected in plants infected by begomoviruses. In WCA, B. tabaci has been associated with suspected begomovirus infections in many vegetable crops and weed species. Sequencing of viral genomes from crops such as okra resulted in the identification of two previously known begomovirus species (Cotton leaf curl Gezira virus and Okra yellow crinkle virus) as well as a new recombinant begomovirus species (Okra leaf curl Cameroon virus), a betasatellite (Cotton leaf curl Gezira betasatellite) and new alphasatellites. Tomato and pepper plants with leaf curling were shown to contain isolates of new begomoviruses, collectively referred to as West African tomato-infecting begomoviruses (WATIBs), new alphasatellites and betasatellites. To study the potential of weeds serving as begomovirus reservoirs, begomoviruses and satellites in the weed Ageratum conyzoides were characterized. Sequence analyses showed that they were infected by isolates of a new begomovirus (Ageratum leaf curl Cameroon virus) that belong to the WATIBs group, a new betasatellite (Ageratum leaf curl Cameroon betasatellite), an alphasatellite and two types of defective recombinants between a begomovirus and an alphasatellite. Putative recombinations were detected in begomovirus genomes for all four plant species studied, indicating that recombination is an important mechanism for their evolution. A close relationship between the begomoviruses infecting pepper and tomato and A. conyzoides and the detection of the same alphasatellite in them support the idea that weeds are important reservoirs for begomoviruses and their satellites. With this high diversity, recombination potential and transmission by B. tabaci, begomoviruses and ssDNA satellites pose a serious threat to crop production in West and Central Africa.
27

THE EFFECT OF PHOTOPERIOD AND TEMPERATURE UPON ADULT ECLOSION OF THE SWEETPOTATO WHITEFLY, BEMISIA TABACI (GENNADIUS).

Hoffman, Christopher John. January 1985 (has links)
No description available.
28

Molecular mechanisms of insecticide resistance in the glasshouse whitefly, Trialeurodes vaporariorum

Karatolos, Nikolaos January 2011 (has links)
The whitefly Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) is a serious pest of protected vegetable and ornamental crops in most temperate regions of the world. Neonicotinoids, pymetrozine (a feeding blocker), spiromesifen (a tetronic acid derivative), bifenthrin (a pyrethroid), and pyriproxyfen (a juvenile hormone mimic) are among the most important insecticides used to control this species. Bioassays were used to quantify responses of recently-collected strains of T. vaporariorum to three neonicotinoids (imidacloprid, thiamethoxam, and acetamiprid), pymetrozine, spiromesifen, bifenthrin, and pyriproxyfen. 454 pyrosequencing was exploited to generate the first transcriptome for this species. PCR-sequencing was used to identify mutations in the target proteins of spiromesifen and bifenthrin potentially associated with resistance to these compounds. Microarray sequencing technology was employed to investigate differences in gene expression associated with pyriproxyfen resistance. Resistance to neonicotinoids was age-specific in expression and consistently associated with resistance to pymetrozine, supporting a hypothesis of metabolic resistance analogous to that in the tobacco whitefly, Bemisia tabaci. Bioassays also showed moderate to high level resistance to spiromesifen, bifenthrin and pyriproxyfen in some strains. Analysis of the transcriptome identified genes encoding enzymes involved in the detoxification of xenobiotics (cytochrome P450s, carboxyl/cholinesterases, and glutathione-s transferases) and ones encoding insecticide targets: acetyl-coA carboxylase (ACCase), the target of spiromesifen and the voltage-gated sodium channel protein targeted by pyrethroids. PCR-sequencing revealed a single nucleotide polymorphism in the ACCase gene, which was consistently associated with spiromesifen resistance. Three amino-acid substitutions in the sodium channel of pyrethroid-resistant T. vaporariorum were found in positions previously implicated in pyrethroid resistance in B. tabaci. Microarray sequencing disclosed that a cytochrome P450 gene (CYP4G61) was overexpressed in a strain selected for increased pyriproxyfen resistance. The implications of these results and opportunities for further work are discussed.
29

Seleção de linhagem de Amblyseius tamatavensis (Acari: Phytoseiidae) mais eficiente no controle de Bemisia tabaci Biotipo B / Selection of strain of Amblyseius tamatavensis (Acari: Phytoseiidae) more efficient in the control of Bemisia tabaci Biotype B

Silva, Marcela Massaro Ribeiro da 04 April 2019 (has links)
Alimentos produzidos de forma mais sustentável têm ganhado espaço e o controle biológico vem assumindo importância cada vez maior em programas de manejo integrado de pragas. Dentre os principais agentes de controle biológico estão os ácaros predadores pertencentes a família Phytoseiidae. Amblyseius tamatavensis Blommers é um ácaro predador pertencente a esta família, amplamente distribuído no Brasil e no mundo. Este predador apresentou resultados promissores em relação ao possível uso para o controle de Bemisia tabaci (Gennadius). Alguns estudos mostraram diferenças biológicas marcantes entre as populações de fitoseídeos. Portanto, espera-se que tais diferenças também possam ocorrer entre as populações brasileiras de A. tamatavensis. Por isso, 14 populações de diferentes regiões do Brasil (dos estados de Alagoas, Goiás, Minas Gerais e São Paulo) foram comparadas em relação ao potencial de predação e oviposição quando alimentadas com ovos de B. tabaci biótipo B. A população coletada em Olhos d\'Água das Flores (Alagoas) apresentou as maiores taxas de predação diária (7,9 ovos / fêmea) e oviposição (1,2 ovo / fêmea) e uma variabilidade entre os indivíduos da população que possibilitou um processo de seleção. O objetivo deste trabalho foi selecionar em laboratório uma linhagem de A. tamatavensis com maior potencial de predação e oviposição, sendo assim mais favorável para uso prático no controle de B. tabaci. Na seleção para predação, após seis gerações, foi observado um ganho genético de 1,1 ovo/fêmea/dia (aproximadamente 15% de aumento em relação à população) na taxa de predação, demonstrando resultado promissor para o melhoramento. Entretanto, o ganho genético foi praticamente nulo quando a população selecionada para predação foi submetida ao processo de seleção para oviposição, e também foi observado um baixo diferencial de seleção, mostrando um baixo potencial para a seleção das melhores fêmeas em relação a este parâmetro. Em função dos resultados promissores em relação ao aumento da eficiência da população de A. tamatavensis no controle de B. tabaci e das tabelas de vida de fertilidade não mostrarem custos adaptativos importantes, testes em plantas de pimentão mantidas em um telado foram realizados para avaliar a real eficiência desta linhagem. Foram comparadas diferentes populações, selecionadas e não selecionadas em laboratório. Os melhores resultados foram observados com a população que passou pelo processo de seleção, que teve uma eficiência maior quando comparada com as outras populações. Essa população apresentou uma redução nos imaturos de B. tabaci que variou de 82% a 90% após 14 dias da liberação dos predadores. Os resultados obtidos nas plantas de pimentão sugerem que, assim como observado nas tabelas de vida realizadas no capítulo anterior, não houve um custo adaptativo significativo na população que passou pelo processo de seleção. Estudos complementares devem ser realizados, para avaliar se essas populações estudadas mantém o mesmo comportamento em cultivos no campo. / More attention has been given recently to sustainable food production, and biological control has become increasingly important in integrated pest management programs. Predatory mites of the family Phytoseiidae are among the main biological control agents. Amblyseius tamatavensis Blommers is a predatory mite belonging to this family, widely distributed in Brazil and worldwide. This predator presented promising results regarding the possible use for the control of Bemisia tabaci (Gennadius). Some studies have shown marked biological differences among phytoseiid populations. It is expected that such differences may also occur among Brazilian populations of A. tamatavensis. Therefore, 14 populations of different regions of Brazil (from the states of Alagoas, Goiás, Minas Gerais and São Paulo) were compared in relation to predation and oviposition potential when fed with B. tabaci biotype B. The population collected in Olhos d\'Água das Flores (Alagoas) presented the highest rates of daily predation (7.9 eggs / female) and oviposition (1.2 egg / female) and sufficient variability among individuals of the population to enable a selection process. The objective of this work was to select in the laboratory a strain of A. tamatavensis with higher predation and oviposition potential, being thus more favorable for practical use in the control of B. tabaci. In the selection for predation, after six generations, a genetic gain of 1.1 eggs / female / day (approximately 15% increase in relation to the population) in predation rate was observed, showing promising result for breeding. However, the genetic gain was practically null when the population selected for predation was submitted to the selection process for oviposition, and a low selection differential was also observed, showing a low potential for the selection of the best females in relation to this parameter. As a result of the promising results in increasing the efficiency of the A. tamatavensis population in the control of B. tabaci and because the fertility life tables did not show important adaptive costs, tests on pepper plants were carried in a screen-house to evaluate the real efficiency of this strain. Different populations were compared, selected and not selected in the laboratory. The best results were observed with the population that passed by the selection process, which had a greater efficiency when compared with the other populations. This population showed a reduction in the immatures of B. tabaci that ranged from 82% to 90% after 14 days of predator release. The results obtained on the pepper plants suggest that, as observed in the life tables performed previously, there was no significant adaptive cost in the population that passed by selection process. Complementary studies should be carried out to evaluate whether these studied populations maintain the same behavior in field crops.
30

Identificação de isolados do Sida mottle virus e Sida micrantha mosaic virus não transmissíveis por Bemisia tabaci biótipo B que infectam maracujazeiros (Passiflora edulis f. flavicarpa) / Identification of Sida mottle virus and Sida micrantha mosaic virus isolates non transmissible by Bemisia tabaci biotype B infecting passionflower (Passiflora edulis f. flavicarpa)

Alves, Ana Carolina Christino de Negreiros 14 September 2012 (has links)
Doenças causadas por virus do gênero Begomovirus (família Geminiviridae) são incomuns em espécies de passifloras. Nos últimos dez anos, entretanto, foram encontrados no Brasil begomovirus infectando passifloras em pomares nos municipios de São Fidelis (RJ), Paragominas (PA), Patos de Minas (MG) e Araguari (MG). Estes isolados foram transmitidos mecanicamente para plantas de Nicotiana benthamiana, que apresentaram sintomas de mosaico e deformação foliar. Também foi possível a transmissão para plantas de Sida rhombifolia através de inoculação por biobalística com o DNA amplificado do isolado de São Fidelis. Estas plantas demonstraram sintomas de mosaico amarelo e deformação foliar. O DNA total extraído de plantas infectadas foi amplificado por RCA, sendo que o componente A (DNA-A) dos isolados de Paragominas e Patos de Minas foram sequenciados diretamente por \"primer walking\". O DNA-A dos isolados de São Fidelis e Araguari foram clonados e sequenciados. As sequências de nucleotideos dos isolados de Paragominas e de São Fidelis apresentaram 90% de similaridade ao Sida mottle virus (SiMoV), enquanto a sequência de nucleotídeos do isolado de Araguari apresentou 96% de similaridade ao Sida micrantha mosaic virus (SimMV). Assim esses isolados encontrados em maracujazeiro podem ser considerados estirpes do SiMoV e SimMV, respectivamente. Não foi possivel a transmissão desses isolados através de Bemisia tabaci biótipo B, no entanto, os insetos foram capazes de adquirir o vírus. O isolado de São Fidelis foi detectado separadamente na região onde se encontra a glandula salivar (cabeça e protórax) e na região posterior do inseto, indicando que o vírus transpos a barreira do mesenteron e circulou pela hemolinfa do inseto. Alves (2008) obteve uma forma atenuada do isolado de São Fidelis através de inoculações mecanicas em plantas de N. benthamiana. O DNA-A desta forma atenuada foi sequênciado e apresentou 90% de identidade ao isolado do qual se originou. A forma atenuada do begomovirus foi capaz de proteger plantas de maracujazeiro contra a estirpe severa do vírus. / Diseases caused by begomoviruses (family Geminiviridae) are hardly found in Passiflora species. In the last years, however, begomovirus infected passionflowers were found in orchards in the counties of São Fidelis (state of Rio de Janeiro), Paragominas (Pará), Araguari and Patos de Minas (Minas Gerais). These isolates were mechanically transmitted to Nicotiana benthamiana plants, which showed variable symptoms of mosaic and leaf distortion. Another susceptible host is Sida rhombifolia, which was biolistic inoculated with amplified DNA of São Fidelis isolate, and showed symptoms of yellow mosaic and leaf distortion. Total DNA extracted from field infected passiflora was amplified by RCA, and the DNA-A of Paragominas and Patos de Minas isolates were directly sequenced by primer walking. The A component of São Fidelis and Araguari isolates were cloned and also completely sequenced. The complete nucleotide sequence of DNA-A of Araguari isolate shared 96% identity with that of Sida micrantha mosaic virus (SimMV), whereas the DNA-A of Paragominas and São Fidelis isolates shared 90% identity with that of Sida mottle virus (SiMoV). These viruses may be consider as strains of SiMoV and SimMV, respectively. It was not possible to transmit these isolates by Bemisia tabaci biótipo B, although the insects were able to acquire the virus. São Fidelis isolate could be detected separately at salivary gland region and posterior region of the insect, indicating that the virus could cross the digestive tract and circulate in the hemolymph. Alves (2008) obtained a mild strain of São Fidelis isolate by mechanical inoculation in N. benthamiana plants. The mild isolate was able to protect passionflower against the severe isoalte of this begomovirus.

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