Academic literature on the topic 'Bemisia argentifolii'

Populations of Bemisia argentifolii Bellows and Perring in the Charleston, SC area declined sharply during December and remained low through March and April in a two-year study (1991–92). Populations of this whitefly increased slowly during spring with highest populations on collard (Brassica) and potato. Infestations of B. argentifolii were present in 13 of 14 greenhouses at 10 commercial nurseries that were monitored. Eggs were more cold-tolerant than adults and nymphs, respectively, at temperatures of −2°, − 6°, and −10°C.

A survey was conducted to identify which native parasitoids of Bemisia argentifolii Bellows and Perring (sweetpotato whitefly strain-B = silverleaf whitefly) are present in coastal South Carolina and to monitor their seasonal abundance. South Carolina is the northern geographic limit of year-round field populations of B. argentifolii in the eastern U.S. Yellow sticky cards were used to monitor the parasitoids. Parasitoid abundance varied over time and among five coastal South Carolina sweetpotato field locations where pesticide was not used. Five species of parasitoids were found (Encarsia pergandiella, E. nigricephala, E. strenua, E. quaintancei, and Eretmocerus sp.). The most abundant species were E. nigricephala and E. pergandiella (89% in 1993; 70% in 1994). No parasitoid fauna of B. argentifolii had heretofore been reported from fields in South Carolina. This background information will aid in developing a biological control component in a management strategy for B. argentifolii.

Bacteria called ‘Fritschea’ are endosymbionts of the plant-feeding whitefly Bemisia tabaci and scale insect Eriococcus spurius. In the gut of B. tabaci, these bacteria live within bacteriocyte cells that are transmitted directly from the parent to oocytes. Whiteflies cause serious economic damage to many agricultural crops; B. tabaci fecundity and host range are less than those of Bemisia argentifolii, possibly due to the presence of this endosymbiont. The B. tabaci endosymbiont has been characterized using electron microscopy and DNA analysis but has not been isolated or propagated outside of insects. The present study compared sequences for 11 endosymbiont genes to genomic data for chlamydial families Parachlamydiaceae, Chlamydiaceae and Simkaniaceae and to 16S rRNA gene signature sequences from 330 chlamydiae. We concluded that it was appropriate to propose ‘Candidatus Fritschea bemisiae’ strain Falk and ‘Candidatus Fritschea eriococci’ strain Elm as members of the family Simkaniaceae in the Chlamydiales.

AbstractThe effectiveness of inundative releases of the parasitoid Eretmocerus eremicus n. sp. Rose & Zolnerowich for control of Bemisia argentifolii Bellows & Perring on poinsettia in replicated experimental greenhouses was determined. We evaluated two release rates of E. eremicus: a low release rate (one female per plant per week, released in two greenhouses, in spring 1995) and a high release rate (three females per plant per week, released in two greenhouses, in spring 1994), each over a 14 week growing season. Each release trial had either one (1995) or two (1994) control greenhouses in which B. argentifolii developed on poinsettia in the absence of E. eremicus. Life-tables were constructed for B. argentifolii in the presence and absence of E. eremicus by using a photographic technique to follow cohorts of whiteflies on poinsettia leaves. Weekly population counts of whiteflies were also made. In the absence of E. eremicus, egg to adult survivorship of B. argentifolii on poinsettia was 75–81%. At the low release rate, egg to adult survivorship of B. argentifolii was 12% and parasitism was 34%. At the high release rate, egg to adult survivorship of B. argentifolii was 0.9% and parasitism was 10%. The average net reproductive rates (Ro) for populations of B. argentifolii in the absence of E. eremicus ranged from 20.5 to 26.1, indicating a rapidly increasing population density. Net reproductive rates for whitefly populations subject to parasitoid releases were 3.7 in the low release rate greenhouses, and 0.25 in the high release rate greenhouses, indicating substantially reduced B. argentifolii population growth. At week 14 of the trial, densities of immature whiteflies were lower in greenhouses at the low release rate when compared to the high release rate greenhouses. This was attributed to high levels of in-house reproduction by parasitoids at the low release rate.

In crosses of bifenthrin-resistant and susceptible populations of the silverleaf whitefly, Bemisia argentifolii Bellows & Perring or b-strain Bemisia tabaci Gennadius, we found that net reproduction (Ro) was significantly different between the parental populations and “F1, male” backcrossed populations with approximately a two-fold increase in Ro occurring in the backcrosses. Also, the level of adult emergence was positively related to the changes of Ro in B. argentifolii. The average longevity of adults, number of eggs adults oviposited, and percentage female in the progenies changed across populations, with some factors enhancing reproduction in the bifenthrin resistant backcross. These results confirm that, not only does increased vigor occur in bifenthrin-resistant whitefly backcrosses, but also that males of cross-mated females differ from males of the parent population in their ability to induce increased vigor in the backcross. This is the first evidence that whitefly males from mated and unmated females could be genetically distinct.

Occurrence ofBemisia Argentifoliion Chrysanthemums in Northern TanzaniaSamples of whiteflies were collected fromDendranthemaspp. in major growing areas of Tanzania. The insects were transferred onto test plants to confirm host specificity. Infested with insects, test plants were then protected with polyethylene bags. Samples of whiteflies from infested plants were taken at 10 day intervals post-infestation (dpi), 28 dpi and 35 dpi, for behavioural studies. At 10 dpi eggs were seen as oval bodies while at 28 dpi crawling bodies and newly emerged adults were observed, leaving behind characteristic shiny hollow cases. At 35 dpi, all the stages of development were seen. The features observed are typical ofBemisia argentifoliiand the area is endangered by the occurrence and spread of viruses transmitted by this species. This identification, which is an integral part of pest surveillance, initiates a study of the viruses and will lead to pest records for regulatory purposes. The international scientific and trading community is assured that the report reflects the real situation. The pest is thought to be present in the reported areas only and the pest status is actionable and under surveillance.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes)/MEC
Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG)
Funda??o Diamantinense de Apoio ao Ensino, Pesquisa e Extens?o (FUNDAEPE)
O trabalho teve os objetivos de comparar a efetividade de linhagens melhoradas de tomateiro, ricas em acila??cares (AA), zingibereno (ZGB) ou 2-tridecanona (2-TD), quanto aos n?veis de resist?ncia ? mosca-branca (Bemisia argentifolii) e verificar se a sele??o de linhagens com base em sua densidade de tricomas glandulares ? efetiva no sentido de promover n?veis satisfat?rios de resist?ncia a esse inseto. Essas linhagens foram obtidas atrav?s de sucessivos retrocruzamentos em tomateiro Solanum lycopersicum, a partir do cruzamento interespec?fico S. lycopersicum x S. habrochaites var. glabratum 'PI 1344171'. Linhagens ricas em AA (TOM-687), ZGB (ZGB-703) e 2-TD (TOM-622) foram testadas para os n?veis de resist?ncia ? Bemisia argentifolii. Duas linhagens de tomateiro (TOM-584 e TOM-679), com n?vel normal dos tr?s aleloqu?micos, e o acesso selvagem (PI 134417), alto teor de 2-TD, foram utilizados como testemunhas. TOM-687, ZGB-703 e TOM-622 mostraram diminui??es significativas na ovoposi??o e na contagem de ninfas depois de 23 dias ap?s infesta??o, quando comparadas com os controles TOM-584 e TOM-679. Todas as tr?s linhagens ricas nos aleloqu?micos mostraram n?veis de resist?ncia ? praga, relativamente aos controles, e n?o deferiram significativamente entre si nos n?veis de resist?ncia. Os resultados mostram que linhagens de tomateiro ricas em AA, ZGB e 2-TD s?o eficazes alternativas de sele??o indireta para cria??o de resist?ncia ? Bemisia argentifolii. Todas as linhagens selecionadas para maior densidade de tricomas, exceto BPX-365F-751-05-01-03, apresentaram n?meros m?dios de ninfas inferiores aos das testemunhas suscet?veis (TOM-584, TOM-679), indicando que a sele??o para maior n?mero de tricomas glandulares foi efetiva no sentido de promover algum aumento dos n?veis de resist?ncia ? mosca-branca
Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2011.
ABSTRACT The study had two objectives compare the levels of whitefly resistance of improved tomato lines rich in acylsugars (AS), zingiberene (ZGB) or 2-tridecanona (2-TD), and check whether the selection of strains based on their density of glandular trichomes is effective in promoting satisfactory levels of resistance to whitefly. These strains were obtained by successive backcrossing to tomato Solanum lycopersicum from the interspecific cross S. lycopersicum x S. habrochaites var. glabratum 'PI 1344171'. Lines rich in AS (TOM-687), ZGB (ZGB-703) or 2-TD (TOM-622) were tested for levels of resistance to Bemisia argentifolii. Two lines (TOM-584 and TOM-679) with normal levels of all three allelochemicals, and the wild accession PI 134417 (AS-rich), were used as checks. TOM-622, ZGB-703 and TOM-622 showed decreased ovopositioning and lower number of nymphs 23 days after infestation, when compared to the checks TOM-584 and TOM-679. All three strains rich in allelochemicals showed higher levels of pest resistance, than the cheches, but did not differ significanthy from each, and either reject significantly among themselves in resistance other in their levels of resistance. The results show that strains of tomato rich in AA, ZGB or 2-TD are effective alternatives to direct selection for resistance to Bemisia argentifolii. All the strains selected for greater trichome density except BPX-365F-751-05-01-03, showed number of nymphs lover than the susceptible checks (TOM-584, TOM-679), indicating that selection towards higher glandular trichome densites was effective in promoting increased in levels of resistance to the whitefly.

A soja é uma das culturas mais antigas e praticadas no mundo, tendo sua importância pelo elevado teor de proteínas, sendo utilizada na alimentação humana e animal, além de ser o principal produto de exportação brasileira. Apesar da alta produção nacional, a cultura possui perdas de produtividade pelos ataques de insetos-pragas, dentre eles, a mosca-branca Bemisia tabaci Biótipo B (Hemiptera: Aleyrodidae). Seu controle tradicional é realizado com inseticidas, mas atualmente métodos alternativos estão sendo avaliados, considerando a não contaminação do ambiente e a saúde humana. O presente trabalho teve como objetivo avaliar o potencial de indutores de resistência no processo de defesa vegetal contra a mosca-branca em plantas de soja. Foram realizados dois experimentos na Universidade Tecnológica Federal do Paraná, Campus Dois Vizinhos-PR, no ano de 2017. Sementes de soja da cultivar BRS 284 foram semeadas em vasos de polietileno com capacidade para 10 litros, contendo solo proveniente de lavoura. O cultivo ocorreu em casa de vegetação, sendo que os vasos ficaram dispostos nas bancadas até a fase fenológica V6, onde foram aplicados os indutores conforme os tratamentos. Os tratamentos foram aplicados por microasperção sendo: ASM (0,005%), AS (2Mm), fertilizante foliar composto por fosfito de potássio (0,004%); quitosana (1%) , silício (0,25%) e testemunha (água destilada). O primeiro experimento buscou avaliar o potencial dos indutores quanto a capacidade de ativar mecanismos de defesa vegetal, considerando a presença e a ausência da mosca branca. Para tanto, aplicou- se os indutores, sendo que para a condição de ausência de insetos, os vasos permaneceram em gaiola individual com tela anti-afídica, para evitar o contato com o inseto praga. Então, realizou-se a coleta do material vegetal em intervalos de 0, 24, 48, 96 e 168 horas após a aplicação dos indutores de resistência. Avaliaram-se proteínas totais, açúcares totais e redutores, compostos fenólicos, taninos e a atividade das enzimas peroxidases, fenilalanina amônia-liase (FAL) e quitinase. O segundo experimento buscou avaliar a preferência de oviposição em função da aplicação dos indutores. Após 24 horas da aplicação dos indutores, 500 adultos coletados não sexados de mosca-branca foram liberados no centro dos vasos sobre a bancada, tendo chance de escolha entre os tratamentos. Após 48 horas da infestação inicial, coletaram-se dois folíolos do terço mediano das plantas, de cada tratamento. Os folíolos foram avaliados em microscópio estereoscópio para a quantificação do número de ovos. A área foliar total dos folíolos também foi calculada, utilizando-se o software Image J. Os indutores de resistência possuem capacidade de ativar o metabolismo primário através da síntese de proteínas totais, bem como demonstram potencial na ativação de mecanismos de defesa entre eles, a rota dos fenilpropanóides com a ativação da enzima FAL e a formação de compostos fenólicos. Ainda demonstram ativar enzimas relacionadas a patogenicidade como as peroxidases e quitinase, tais ativações possuem especificidade quanto ao indutor e o tempo de ativação. O uso dos indutores quando desafiados com insetos demonstraram maior efetividade de ativação da enzima FAL, peroxidade e quitinase, enzimas estas relacionadas ao processo de defesa vegetal a insetos. Os indutores ASM, silício e quitosana possuem potencial de redução da oviposição da mosca-branca, o que pode estar relacionado a ativação de mecanismos de defesa vegetal.
Soybean is one of the oldest and most practiced crops in the world,and its importance is due to its high protein content,its use in food for humans and animals, as well as being the main Brazilian export product. Despite the high national production, the crop has productivity losses due to attacks of insect pests, among them, the whitefly Bemisia tabaci Botype B (Hemiptera: Aleyrodidae). Its traditional control is carried out with insecticides, but currently alternative methods are being evaluated considering the noncontamination of the environment and human health. The present work had as objective to evaluate the potential of resistance elicitors in the process of vegetal defense against the whitefly in soybean plants. Two experiments were carried out at the Federal University of Technology - Paraná, Campus Dois Vizinhos-PR, in 2017. Soybean seeds of cultivar BRS 284 were sown in polyethylene pots with capacity of 10 liters, containing soil gathered from crops at UTFPR. Cultivation occurred in a greenhouse, and the vessels were placed on benches until the V6 phenological phase, when the elicitors were applied by microaspersion according to the treatments: ASM (0.005%), SA (2 Mm), foliar fertilizer composed of potassium phosphite (0.004%); chitosan (1%), silicon (0.25%) and control (distilled water). The first experiment aimed to evaluate the potential of the elicitors to activate plant defense mechanisms, considering the presence and absence of the whitefly. For this, the elicitors were applied, and for the condition of absence of insects, the vases remained in individual cages with anti-aphid screen, to avoid contact with the insect pest. Then, the plant material was collected at intervals of 0, 24, 48, 96 and 168 hours after the application of resistance elicitors. Total proteins, total and reducing sugars, phenolic compounds, tannins and the activity of the enzymes peroxidases, phenylalanine ammonia-lyase (FAL) and chitinase were evaluated. The second experiment sought to evaluate the oviposition preference due to the application of the elicitors. After 24 hours of application, 500 not sexed whitefly adults were released in the center of the vases on the bench, having a choice among treatments. After 48 hours of the initial infestation, two leaflets of the median third of the plants were collected from each treatment. The leaflets were evaluated under stereomicroscope for the quantification of the number of eggs. The total leaf area of the leaflets was also calculated using Image J. The resistance elicitors have the capacity to activate the primary metabolism through the synthesis of total proteins, as well as demonstrate the potential in the activation of defense mechanisms among them, the route of the phenylpropanoids with the activation of the enzyme FAL and the formation of phenolic compounds. They also activated pathogenic enzymes such as peroxidases and chitinase, such activations have specificity for the elicitor and the activation time. The use of elicitors when challenged with insects demonstrated greater effectiveness of activation of the enzyme FAL, peroxidase and chitinase, these enzymes related to the process of plant defense against insects. ASM, silicon and chitosan elicitors have the potential to reduce oviposition of the whitefly, which may be related to the activation of plant defense mechanisms.

SANTOS, C. D. G. Caracterização molecular e biológica de um begomovírus isolado de tomateiro, Lycopersicon esculentum Mill., no estado de Goiás e sua interação com o vetor Bemisia argentifolii Bellows & Perring. 2001. 174 f. Tese (Doutorado em Agronomia/Fitotecnia) - Centro de Ciências Agrárias, Universidade Federal do Ceará, Fortaleza, 2001.
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The whitefly-transmitted viruses from the family Geminiviridae, genus Begomovirus, have been reported as an economically important pathogen group that affect important crops in tropical and subtropical countries. Since the beginning of the 1980 decade, the occurrence of the whitefly associated to Begomovirus infection has drastically increased worldwide. In Brazil, these pathogens have been responsable for severe economical losses in tomato (Lycopersicon esculentum) orchards and the production has hampered since 1994. In this work, infected tomato plants showing symptoms, such as mosaic, intervein clearing, leaf curling and growth reduction were collected in tomato orchards in Anápolis, State of Goiás. The virus was identified as a member of the genus Begomovirus by PCR reaction, using specific primers to amplify fragments of A and B components of the virus DNA genome. The Chapter I of this thesis presents the results of the molecular characterization of the virus and the Chapter II shows the determination of its host range and the relationship with its natural vector Bemisia argentifolii. The virus isolate denoted GO-ANPL was cloned and partially sequenced. Part of the sequenced genome (2.180 nucleotides long) corresponded to the coat protein and Rep genes and comprised the entire intergenic region. Sequence comparison revealed that the GO-ANPL isolate is distantly related to the begomoviruses found in Asia, Europe and Africa, and it is related to other begomoviruses reported in Brazil. The virus isolate showed to be more closely related to viruses found in the State of Minas Gerais (TRMV isolate) and in the Federal District (isolate DF-Br2). The highest homology was observed with the isolate DF-Br2 and it may represent a new specie of the genus Begomovirus. In order to determine the virus host range, 46 plant species from nine different botanical families were mechanically and using the virus vector inoculated. The GO-ANPL isolate preferentially infected plants of the family Solanaceae as Nicotiana benthamiana, Datura stramonium and Nicandra physalodes. The number of infected plants was higher when they were inoculated by the virus vector, and the results were distinct from those obtained for other begomoviruses reported in Brazil. Viruses infections were all confirmed by dot blot hybridization using specific molecular probes to the virus. 4 To study virus/vector interaction, the acquisition access period (AAP), inoculation access period (IAP), and the latent period were determined transfering five whiteflies per plant and using tomato cv. Santa Clara as the host. For the AAP and IAP, nine different time periods were tested: 0.25, 0.5, 1, 2, 4, 8, 16, 20 and 24 h. The minimal AAP determined was 0.25 h, after which, 6% of the tested plants became infected. The number of infected plants increased to 65% with an AAP of24h.Afteran IAP of 0.5 h, 18% of the plants were infected and their number increased to 67% after an IAP of 24 hours. The latent period was considered to be 16 h, after which, 3% of the inoculated plants became infected. The results of AAP, IAP and latent period seem to indicate an early interaction between virus and vector starting at early stages of vector development. The presence of the GOANPL was determined in all stages of the vector (eggs, 1st to 4th instar and adults) in infected plants, in adults under different AAPs, in the progenies of viruliferous females, and in adults originated from nymphs developed from infected plants. More than 2.500 insects were tested by PCR to detect the GO-ANPL isolate. The virus was detected in nymphs from the 1st to 4th instar that had fed in infected plants and no virus was found in eggs from aviruliferous female that had been laid in infected plants. Transmission to the progenies was observed, since the virus was detected in all stages of insect development from eggs to adults. High level transmission was also observed in newly emerged adults that had acess to virus-infected plants as immatures. This fact, in addition to the transmission to the progenies, suggests that virus retention is an important part of virus/vector interaction. No transmission was observed from adults originated from viruliferous females. However, 33% of virus transmission was obtained when adults that retained virus from their early larval stages were employed. 2001.
Os begomovírus, vírus da família Geminiviridae transmitidos por mosca branca, têm emergido como sérios patógenos de culturas agronômicas e hortícolas em regiões tropicais e subtropicais de muitos países em todo o mundo. A partir da década de 80, têm aumentado os relatos da disseminação da mosca branca, Bemisia argentifolii, e de begomovírus provocando impacto devastador nas regiões em que ocorrem. No Brasil, estes patógenos têm sido limitantes para a produção de tomate (Lycopersicon esculentum) em várias áreas de cultivo com incidência crescente desde 1994. No presente trabalho, plantas de tomate exibindo sintomas de infecção provocada por vírus como mosaico, clorose internerval, enrolamento do limbo foliar e redução do crescimento, foram coletadas em lavouras de tomate indústria em Anápolis-GO. O vírus foi identificado como pertencente ao gênero Begomovirus mediante técnica de PCR usando oligonucleotídeos específicos que amplificaram fragmentos dos componentes A e B do genoma viral. No capítulo I são apresentados os resultados da caracterização molecular e no capítulo II, os dados da determinação do círculo de hospedeiros e da investigação da relação do begomovírus com o vetor Bemisia argentifolii. O isolado denominado GOANPL, foi clonado e parcialmente seqüenciado tendo sido obtidas as seqüências nucleotídicas dos genes da capa proteica, Rep e de toda a região intergênica, em um total de 2.130 nucleotídeos. A análise comparativa das seqüências revelou que, em geral, o GOANPL possui relacionamento genético distante com begomovírus da Ásia, Europa e África sendo mais próximo das espécies do Brasil, particularmente, com os begomovírus identificados em Minas Gerais (TRMV) e no Distrito Federal (DF-BR2). Com este último, apresentou alta homologia em todo o genoma podendo vir a constituir, com o mesmo, uma nova espécie. A determinação do círculo de hospedeiros do GO-ANPL foi realizada inoculando-se 46 espécies vegetais pertencentes a nove famílias botânicas, sob duas modalidades de inoculação: mecânica e com a mosca branca. Constatou-se que o GO-ANPL infecta, preferencialmente, plantas da família Solanaceae como Nicotiana benthamiana, Datura stramonium e Nicandra physalodes. O número de espécies infectadas com o inseto vetor foi superior ao obtido pela inoculação mecânica e diferiu dos resultados obtidos para outros isolados de begomovírus de tomate no Brasil. Os testes foram todos confirmados com hibridização com sondas moleculares, em \"dot blot\"No estudo da relação vírus-vetor, foram investigados o período de acesso de aquisição do vírus (PAA), o período de acesso de inoculação do vírus (PAI), e o período de latência do vírus na fase adulta do vetor, empregando-se cinco moscas/planta de tomate \'Santa Clara\' em todos os tratamentos. Para a definição do PAA e do PAI, foram testados nove diferentes períodos de tempo: 0,25, 0,5, 1, 2, 4, 8, 16, 20 e 24 horas. Nos testes para determinação do PAA, após cada um desses períodos seguiu-se uma inoculação de 48 horas e para definição do PAI, antes de cada período antecedeu-se um período de acesso de aquisição fixo de 72 horas. Constatou-se que o PAA mínimo da mosca branca foi de apenas 0,25 hora, com o qual foram obtidas 6% de plantas infectadas. O percentual de plantas aumentou de 6 para 65% com a extensão do PAA de 0,25 para 24 horas. Com relação ao período de acesso de inoculação do vírus, foram registrados 18% de plantas infectadas com o PAI de 0,5 hora. O percentual elevou-se para 67% quando 24 horas de PAI foram concedidos. Valores isolados de 90 e 100% na transmissão viral, também foram observados. O término do período latente do vírus no vetor ocorreu 16h após a aquisição do mesmo em planta infectada, considerando os 3% de infecção observados nas plantas inoculadas. Os dados obtidos indicam que a interação vírus-vetor é estabelecida desde a fase inicial de desenvolvimento do inseto. Como parte do estudo dessa interação, avaliou-se a presença do begomovírus GO-ANPL em todas as fases de desenvolvimento do inseto vetor (ovo, 1º ao 4º ínstar e adulto) na planta infectada, em adultos com diferentes PAA, na progênie de fêmeas virulíferas e em adultos cujos estágios ninfais desenvolveram-se em tomateiro infectado. A técnica PCR foi empregada para a detecção do GO-ANPL em mais de 2.500 espécimens testados. O vírus foi detectado em ninfas do 1º ao 4º ínstar que se alimentaram em plantas de tomate infectada, contudo, em ovos provenientes de avirulíferas, os quais foram ovipositados em planta infectada e coletados após sete dias, o vírus não foi detectado. A transmissão à progênie foi constatada pela detecção do vírus em ovos, ninfas e adultos que se desenvolveram em planta não hospedeira do vírus. A transmissão transestadial ocorreu com índice elevado e, ao lado da transmissão à progênie, indica que a retenção do vírus é uma etapa importante da interação vírus–vetor. A transmissão do vírus para mudas de tomate, a partir de adultos da progênie de fêmeas virulíferas, não foi constatada. Contudo, transmissão para tomateiro em um percentual de 33% foi verificado nos casos em que a inoculação das plantas foi realizada pelos adultos que retiveram o vírus da sua fase imatura (transestadial).

碩士
國立中興大學
昆蟲學系
84
The sliverleaf whitefly, Bemisia argentifolii Bellows & Perring, is a serious pest of many crops throught the tropics and subtropics. It can damage plants directly by its feeding and indirectly by the transmission of several important virus. B. argentifolii transmitted tomato leaf curl geminivirus (TLCV) which DNA fragments from an viruliferous female whitefly and tomato leaves could be amplified by polymerase chain reaction. Squash-blot hybridization could detect TLCV DNA 5-7 days post- inoculation by whitefly of 48 h in tomato tissues, such as leaves, stem, root, flower, and fruits. It also could detect the presence of TLCV DNA in one female adult of B. argentifolii after 2 h acquistion-access period and nymphs collecting from TLCV-infected tomato plants. Transmission of TLCV by female whiteflies were more efficient than the males. A viruliferous female whitefly resulted in 29% transmission, while 10 whiteflies/per plant gave 100% transmission. B. argentifolii transmitted TLCV after a minimum acquistion-access period of 15 min. Transmission rate increased to a maximum after a 24 h acquisition-access period. B. argentifolii transmitted TLCV after a minimum inoculation-access period of 15 min. Transmission rate increased to a maximum after an 48 h acquisition-access period. After a 24 h acquisition-access period, B. argentifolii was immediately able to transmit TLCV. Nucleotide sequencing of TLCV genome reveals that it contains 2739 nucleotides and encodes two open reading frames in the virus sense strand and four in the complementary sense strand (V1, nt 291-1061; V2, nt 131-478; C1, nt 2601-1516; C2, nt 1613-1209; C3, nt 1465-1064; C4, nt 2444-2154). TLCV has a narrow host range confined to members of Solanaceae, such as Datura stramonium, Lycopersicum esculenyum, Nicotiana benthamiana, and N. tabacum.

碩士
國立臺灣大學
昆蟲學研究所
89
The silverleaf whitefly, Bemisia argentifolii Bellows & Perring, was reared on three tomato varieties under various constant temperatures. The nymphal body length and developmental period from egg to adult decreased with the increase of temperature from 20℃ to 32℃. The male at 3rd and 4th instars, were significantly shorter than that of the female. The highest mortality from egg to adult were obsered at 20℃. The developmental time from egg to adult decreased with the increase of temperature from 20℃ to 32℃. The low temperature thresholds for the development of egg, 1st, 2nd, 3rd, and 4th and instar nymphs on Asveg #6 tomato were12.7, 10.1, 4.4, 7.4, and 10.8℃, respectively. Also on Asveg #6 tomato, the effective accumulated temperatures of egg, 1st, 2nd, 3rd, and 4th instar nymphs were 94.2, 72.7, 52.0, 49.5, and 102.3 day-degrees, respectively. With a total of 360.6 day-dgrees required for the development from egg to adult. The low temperature thresholds for the development of egg, 1st, 2nd, 3rd, and 4th and instar nymphs on Santa tomato were12.3, 9.9, 6.8, 11.7, and 12.0℃, respectively. Also on Santa tomato, the effective accumulated temperatures of egg, 1st, 2nd, 3rd, and 4th instar nymphs were 95.0, 72.6, 48.5, 37.2, and 99.0 day-degrees, respectively. With a total of 384.0 day-dgrees required for the development from egg to adult. The low temperature thresholds for the development of egg, 1st, 2nd, 3rd, and 4th and instar nymphs on Chiquita tomato were13.1, 10.6, 12.1, 13.7, and 11.8℃, respectively. Also on Chiquita tomato, the effective accumulated temperatures of egg, 1st, 2nd, 3rd, and 4th instar nymphs were 92.2, 69.0, 34.2, 32.8, and 93.1 day-degrees, respectively. With a total of 323.0 day-dgrees required for the development from egg to adult. The hight longevity reared at 20℃ on Asveg #6, Santa, and Chiquita tomatoes was 9.4, 11.1, and 11.3 days, respectively. The population parameters of intrinsic rate of natural increase( rm), net reproductive rate(), and finite rate of increase(λ) reared on Asveg #6 and Santa tomatoes were increased with the increase of temperatures from 20℃ to 32℃. When reared on Asveg #6 and Santa tomatoes as 32℃, the highest intrinsic rate of natural increase was 0.0946 and 0.0906, the R0 was 9.17 and 9.56, and λ was 1.10 and 1.09, respectively. The mean generation time (T) was 24.8 and 25.4 days, and doubling time was 7.33 days and 7.65 days, respectively. The highest of natural increase was 0.0593, the R0 was 8.76, λ was 1.06, the mean generation time was 27.1 days, and doubling time was 8.37 days when reared on Chiquita tomato at 28℃. The population densities of B. argentifolii , when reared on Asveg #6, Santa, and Chiquita potted tomatoes in an open space at National Taiwan University from July to September, 2000, were no significantly different. The different population densities of B. argentifolii, when reared on potted Asveg #6 tomatoes in an open space at National Taiwan University from September to October 2000, the the yield loss of harvested fruit was positively correlated with the population densities.

碩士
國立臺灣大學
植物醫學碩士學位學程
105
The silverleaf whitefly (Bemisia argentifolii Bellows & Perring) is a serious pest and a virus vector of various crops, especially in agricultural facilities. Exploration of non-chemical methods to control this pest is necessary because whiteflies rapidly develop resistance to many classes of insecticides. Physical control techniques such as color traps are used frequently to reduce whitefly populations. Color traps utilize the attractiveness of specific wavelength ranges to insects. However, other factors that affect insect visual attraction behavior should also be discussed. This study focuses on how shapes, background colors, light wavelengths, light intensities and addictional light sources affect visual attraction to whiteflies, and also how modified traps contribute to whitefly management in agricultural facilities. Results show that among the four shapes of our multi-choice experiment, whiteflies preferred circles and squares. Black background enhanced the proportion of whiteflies trapped in laboratory and greenhouse experiments, but may reduce light intensity and result in lower attractiveness when used in a field setting. Yellow-green light (500-600 nm) was found to attract whiteflies. Blue-violet light (400-490 nm) was shunned by whiteflies and suppressed the attractiveness of yellow-green lights when combined, suggesting there is a wavelength range in blue-violet light that is repulsive to whiteflies, although this range is still unknown. Green light emitting diodes (LEDs) with wavelength peak at 516 nm combined with clear sticky cards significantly increased attractiveness to whiteflies. But attractiveness of yellow sticky trap with LEDs showed no difference to traps without LEDs.

碩士
國立臺灣師範大學
生命科學研究所
95
The whitefly, Bemisia argentifolii, has a host rang of wide plants and tends to expand gradually. They are a phloem-sap feeder. The nutritional composition of host plants lacks essential amino acids that they need. The nutrient deficiency of their diet is supplemented by endosymbionts that are mutually symbiotic for their survivals. Therefore, the relationship between B. argentifolii and its primary endosymbionts are obligate relationship. The endosymbionts live in the cytoplasm of a specialized cell, called mycetocyte. Due to a wide host range of B. argentifolii, the nutritional composition supplied by different host plants may be varied that makes endosymbionts to play a more important role on nutrient supplementation. In my study, we examined and localized the mycetocyte first and then to reveal the structure of mycetocyte by light and electron microscopies, and amplified 16S rDNA with a specific primer set, 28F and 1695R, for FISH (fluorescence in situ hybridization) probe preparation to examine the distribution of primary endosymbiots. The phylogenetic tree was constructed based on primary endosymbiont’s 16S rDNA sequences to find the relationship of our whitefly with the species of the suborder Sternorrhyncha. Finally, we tried to purify the primary endsymbiont’s genomic DNA from whitefly and to estimate their genome size. Mycetocytes of the B. argentifolii are giant cells that disperse in the hemocoelum at the posterior part of abdomen. The cells possess a nucleus contained homogenously distributed heterochromatin and are filled with pleomorphic primary endosymbiont in cytoplasm, some of primary endosymbiont showed a pseudonucleus in section. An obvious electron-lucent space between primary endosymbionts and cytoplasm was found and led to the perforate cytoplasm of mycetocyte, no obvious membrane bound primary endosymbionts to separate the cytoplasm of mycetocyte. Primary endosymbionts in the cytoplasm of mycetocytes and a mycetocyte in developing oocyte of the female adult of B. argentifolii could be clearly observed by paraffin serial sections and FISH. In addition, the FISH-positive reaction was also found in the tissue of oogonium. The genome size of primary endosymbionts is about 1,020 k.b.p. which is larger than that of other species of the suborder Sternorrhyncha. This also was confirmed by the phylogenetic analysis with the species of the suborder Sternorrhyncha and also suggested that this insect needs more genes for their wide and expanding host range.

碩士
國立中興大學
昆蟲學系
91
Delphastus catalinae is an imported predator for controlling of B. argentifolii, an economically important pest in Taiwan. The functional response and fecundity of D. catalinae feeding on eggs of B. argentifolii were assessed under 28℃, 7 0∼80％RH, 14L:10D. The daily predation rate of 1st to 4th instar larvae, female and male adults of D. catalinae increased with increasing density of B. argentifolii eggs. At five different temperature regimes, the predation rate of female D. catalinae also increased with increasing density of B. argentifolii eggs. Results of the functional response experiments showed that the relationships between the predation of both larval and adult stages of D. catalinae and the egg density of B. argentifolii under different laboratory conditions fit the disc and sigmoid equation model. Non-linear regression model was used to fit the sigmoid equation model to determine the theoretical attack rate (a) and handling time (Th) under various laboratory conditions. At 28℃, 1st instar D. catalinae exhibited higher attack rate (0.0126) than female adults (0.0063), and the theoretical maximum predation rate of 1st instar (79 B. argentifolii eggs/day) is less than that of female adults (159 B. argentifolii eggs/day). Among five different temperatures, attack rate of mated female D. catalinae increased with increase of temperature (0.0229, 0.0230, 0.0243, 0.0276 and 0.0287). In addition, results of the fecundity experiments revealed that mated female D. catalinae laid eggs only when reared on eggs of B. argentifolii. The numbers of eggs laid by mated female D. catalinae increased with the increase of the number of B. argentifolii eggs provided. Since the third day, when the density of B. argentifolii eggs is between 200 and 300, the numbers of eggs laid by mated female D. catalinae were between 1.1∼2.4/day. However obtain the number of B. argentifolii eggs offered reached 500, the number of eggs laid by mated female D. catalinae decreased with the increase of the density of D. catalinae. On the 3rd to 7th day of the experiment, the number of eggs laid by individual mated female D. catalinae reached its maximal, stable amount.

Three aphelinid parasitoids were evaluated for the biological control of silverleaf whitefly, Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae) on poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) in replicated experimental greenhouses at Cornell University, Ithaca NY. Life-tables for B. argentifolii in the presence and absence of parasitoids were constructed from bi-weekly photographs of whitefly nymphs on poinsettia leaves. Concurrent with photography, weekly population counts of whitefly lifestages on poinsettia plants were made in experimental greenhouses. A release rate of one Encarsia formosa Beltsville strain/plant/week produced 23% parasitism and 96% mortality of photographed nymphs. Releasing three E. formosa Beltsville strain/plant/week caused parasitism to decrease to 12% and whitefly mortality to increase to 99%. Releasing one Eretmocerus sp. nr. californicus (AZ)/plant/week produced 34% parasitism and 88% whitefly mortality. Releasing three E. sp. nr. californicus (AZ)/plant/week caused observed parasitism to decline to 10% and overall mortality of photographed nymphs to increase to 99.1%. The efficacy of these two parasitoids was compared to the commercially available strain of Encarsia formosa Gahan. The commercial strain of E. formosa achieved 23% parasitism and 92% whitefly mortality at a release rate of three females/plant/week. Releasing one female E. formosa/plant/week caused 13% parasitism and 95% whitefly mortality. In a commercial greenhouse, an average weekly release rate of six E. formosa/plant/week resulted in 39% parasitism and 86% mortality. Increasing levels of parasitism and decreasing mortality levels as release rates of commercial E. formosa increase may be due to mutual interference between searching females. Whitefly mortality on greenhouse grown poinsettia in the absence of parasitoids at Cornell University was 19%-25%. To suppress B. argentifolii population growth with inundative parasitoid releases, whitefly net reproductive rates $\rm(R\sb{o})$ have to be less than one. This was achieved when mortality of photographed nymphs exceeded 96%. Discovery and utilization of whitefly nymphs on single leaf poinsettia plants placed within the canopies of commercially grown poinsettia crops indicated that E. sp. nr. californicus (AZ) had a Type I functional response, while E. formosa Beltsville strain exhibited a Type II functional response. E. sp. nr. californicus (AZ) located a greater number of whitefly patches more quickly, and caused higher levels of whitefly mortality than E. formosa Beltsville strain. The observed results may have been affected by the density of whitefly nymphs on non-experimental plants and crop canopy size which differed between greenhouses; both of which were greater in E. formosa Beltsville strain greenhouses.

碩士
國立臺灣大學
昆蟲學研究所
88
The silverleaf whitefly, Bemisia argentifolii Bellows & Perring, after being properly identified, was reared on balsam pear under various constant temperatures to study its life history traits and construct its life-tables on seven different hosts. Results showed that the silverleaf whitefly could not complete its development under 15℃ and 35℃. The highest survival rate from egg to adult was 68.6﹪at 28℃. The duration for each of the developmental stages decreased with the increase of the temperature from 20℃ to 28℃. By linear regression analysis, the lower temperature threshold for the development from egg to adult was 14.21℃ with an effective thermal summation of 307.27 day-degrees to complete its development. At 20℃ the adult longevity was the longest, being 27.4 days for female and 9.0 days for male. The highest fecundity was observed at 25℃ and 28℃ with an average of 13.1 eggs per female. The population parameters were significantly different at 20℃-30℃. At 20℃-28℃, the intrinsic rate of natural increase ( rm), finite rate of increase (λ) and net reproductive rate (R0) increased with the raise of temperature, the highest being 0.0587, 1.0588 and 5.41, respectively at 28℃. The mean generation time and the doubling time were the shortest at 28℃ with 28.41 days and 11.81 days, respectively. The life history and the life tables of B. argentifolii on seven different host plants were also studied in the laboratory at 28℃, RH 80 ± 5﹪. Results showed that B. argentifolii developed fast from egg to adult on three host plants of Solanaceae, namely black nightshade, eggplant and tomato, being 16.7, 17.7 and 17.6 days, respectively. The slowest development was 25.2 days on balsam pear. The highest survival rate was 93﹪on bottle gourd and the lowest was 54﹪on balsam pear. The longest lifespan of female and male was 32.1 and 15.7 days respectively on eggplant. The fecundity was the highest on eggplant with 179.9 eggs per female and then followed by tomato with 124.6 eggs per female. The fecundity was the lowest with 12.8 eggs per female on balsam pear. The population parameters on seven host plants were significantly different. The highest rm, λ, and R0 were 0.1497, 1.1587, and 62.97, respectively on eggplant, and the lowest 0.0520, 1.0555, and 4.68, respectively on balsam pear. Whereas, the shortest mean generation time was 23.78 days on black nightshade, and the longest 29.25 days on balsam pear. Furthermore, the shortest doubling time was 4.63 days on eggplant and the longest on balsam pear 13.33 days. The three whiteflies of economic importance, including Trialeurodes vaporariorum, Aleurodicus dispersus, and B. argentifolii, could be easily discriminated by using four primers (F2, F12, H9, H16) with the RAPD-PCR (randomly amplified polymorphic-DNA-polymerase chain reaction) method developed by De Barro and Driver in 1997. Analysis of the different developmental stages and both sexes of B. argentifolii showed that the electrophoretic patterns were the same. And using just one silverleaf whitefly specimen was sufficient for analysis by RAPD-PCR. Analysis of the specimens collected from different locations and plants by using RAPD-PCR indicated that they were not different from that of the laboratory colony. However, much more work is needed to confirm whether or not there are any other biotypes existed in Taiwan.