Resumo: A couve comum (Brassica oleracea L. var. acephala DC) pertence à família Brassicaceae e de provável origem a região mediterrânea, atualmente têm ampla distribuição nos cinco continentes, desenvolvendo-se bem em temperaturas amenas, entretanto resiste bem ao frio e a geadas leves. No Brasil, a produção está localizada predominantemente em pequenas áreas do centro-sul do Brasil. O consumo das brássicas está associado ao seu alto valor nutricional, como fonte de vitaminas, minerais e fibras, bem como na prevenção de certos tipos de câncer, além de suas folhas apresentarem altos teores de fibras, imprescindíveis para boa digestão. Dentre os fatores que podem comprometer a produção encontram-se o inseto-praga Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae), conhecida no Brasil como traça-dascrucíferas que ataca cultivares de couve, repolho, brócolis, cenoura e aipo. Seus danos são graves ao limbo foliar, chegando a comprometer economicamente a cultura, ocorrendo em todas as regiões produtoras de brássicas do país apresentando maiores populações em períodos quentes e secos. Nesse contexto, o trabalho teve por objetivos identificar genótipos de couve com fonte de resistência a P. xylostella determinando-se os tipos não-preferência para oviposição, alimentação e antibiose. Os testes de nãopreferência para alimentação foram realizados com os genótipos: Manteiga de Ribeirão Pires I-2620, Roxa I-919, Manteiga I-1811, Manteiga de São Roque I-1912, Gigante I- 915, Manteiga I-916, Crespa I-918, Manteiga de Ribeirão Pires I-2446, Crespa de Capão Bonito, Manteiga de Tupi, Manteiga de Jundiaí, Manteiga de Mococa, Manteiga de São José, Manteiga de Monte Alegre, Pires 2 de Campinas, Comum, Couve de Arthur Nogueira 2, Couve de Arthur Nogueira 1. Nestes experimentos realizaram-se testes com e sem chance de escolha ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The cabbage (Brassica oleracea L. var. acephala DC) belong to Brassicaceae family and probable origin the Mediterranean region and actually have large distribution in the five continents, developing in moderate temperatures, however it resists good the cold and the low frosts. In Brazil, the production is located predominantly in small areas of the center-south of Brazil. The consumption of the brássicas is associated with its high nutricional value, as vitamin, minerals and staple fibres, and can prevent certain types of cancer, beyond of high fibre value, necessary for good digestion. Amongst the factors that can compromise the production, have the pest Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae), recognized in Brazil how traçadas- crucíferas, attacking borecole, cabbage, broccolis, carrot and celery. Your damages are serious in the leaves, arriving to compromise the culture economically, occurring in all the producing regions of brássicas of the country presenting major population in hot and dry periods. In this context, the aim of this work to identify genotypes with resistance of the type antibiosis and no-preference to P. xylostella, and to determine the involved types of resistance. The tests of no-preference for feeding was realized with the genotypes: Manteiga of Ribeirão Pires I-2620, Roxa I-919, Manteiga I-1811, Manteiga of São Roque I-1912, Gigante I-915, Manteiga I-916, Crespa I-918, Manteiga de Ribeirão Pires I-2446, Crespa of Capão Bonito, Manteiga of Tupi, Manteiga de Jundiaí, Manteiga of Mococa, Manteiga of São José, Manteiga of Monte Alegre, Pires 2 of Campinas, Comum, Couve of Arthur Nogueira 2, Couve of Arthur Nogueira 1. Free-choice and nochoice tests possibility had been carried through, with larvae of first and fourth ínstar evaluates for 24 hours. It demonstrated less attractive and to be consumed by the feeding...(Complete abstract, click electronic access below) / Orientador: Arlindo Leal Boiça Junior / Coorientadora: Leila Trevizan Braz / Banca: João Carlos de Oliveira / Banca: José Roberto Sacarpellini / Mestre

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-22T18:12:21Z No. of bitstreams: 2 Tese - Walter Santos de Araújo.pdf: 2149997 bytes, checksum: 6ada687150a99d08e94670136a570e65 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-23T10:19:17Z (GMT) No. of bitstreams: 2 Tese - Walter Santos de Araújo.pdf: 2149997 bytes, checksum: 6ada687150a99d08e94670136a570e65 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-23T10:19:17Z (GMT). No. of bitstreams: 2 Tese - Walter Santos de Araújo.pdf: 2149997 bytes, checksum: 6ada687150a99d08e94670136a570e65 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The intensification of land use due to human activities in natural environments has led to various consequences to biodiversity, ranging from local extinction of native species and colonization of by exotic and invasive ones to the complete conversion of ecosystems in to anthropic landscapes. Among the different biodiversity components that can be influenced by human habitat modification are the ecological interactions between insect herbivores and their host plants, which together represent 75% of the known diversity of terrestrial species. In this context, the objective of my thesis was to investigate global patterns in the structure and fragility of plant-herbivore networks. Specifically, I sought to answer as the intensification of land use and the dominance of exotic host plant species influence the structure and fragility of interaction networks of insect herbivores and host plants, and also I investigate whether there latitudinal gradient in the structuration of these interactions. I compiled 90 local plant-herbivore networks distributed worldwide, spanning different taxonomic groups of plants and insects and several feed guilds of herbivores. The main results of my analyses show that land use intensification and the dominance of exotic host plant species influence different aspects of plant-herbivore networks, such as species richness and taxonomic distinctness (a proxy to phylogenetic diversity) of herbivore species and the structure and fragility of interactions. Another recurrent result was that, when networks composed exclusively of endophagous herbivores were analyzed separately from those composed exclusively by exophages, only the networks of endophages had consistent effects of the land use intensity and proportion of exotic host plant species. Altogether, land use intensification surprisingly increases network specialization by decreasing connectance and nestedness, and increases modularity; while the increase in the proportion of exotic hosts had opposite effects. Possibly these changes in the network structure are due to loss proportionally higher of species with many interactions (i.e., generalists) in relation to species with few interactions (i.e., specialists). As a consequence of these changes in the network connectivity, land use intensification decreases the robustness of plant-herbivore networks, while the proportion of exotic host plant species increases. Therefore, networks located in habitats with higher land use intensity tend to be less robust that networks in more pristine habitats, which is a very intriguing result that goes in the opposite direction of most of the literature on ecological networks. Controling the antropic effects that can act on the networks, my results show that plant–herbivore networks are structured independently of latitude, suggesting that the factors that influence the interactions between host plants and insect herbivores are latitudinally invariant. The results and patterns found emphasize the important contribution of this thesis to the understanding of plant-herbivore networks in the context of human disturbances in natural habitats. / A intensificação do uso do solo devido às atividades humanas nos ambientes naturais tem promovido uma série de consequências à biodiversidade, que vão desde a extinção local de espécies nativas, passando pela colonização de espécies exóticas e invasoras, até a completa conversão de ecossistemas em paisagens antropizadas. Dentre os vários componentes da biodiversidade que podem ser influenciados pela alteração antrópica dos habitats estão às interações ecológicas entre insetos herbívoros e suas plantas hospedeiras, que juntos representam quase dois terços da diversidade de espécies terrestres conhecidas. Nesse contexto, o objetivo da minha tese foi avaliar padrões globais na estrutura e fragilidade das redes planta-herbívoro. Especificamente avaliei como a intensificação do uso do solo e a dominância de plantas hospedeiras exóticas influenciam a estrutura e fragilidade de redes de interação envolvendo insetos herbívoros e plantas hospedeiras, e também avaliei se existe gradiente latitudinal na estruturação dessas interações. Para isso eu compilei 90 redes locais, mundialmente distribuídas, constituídas por diferentes grupos taxonômicos de insetos e plantas e por várias guildas alimentares de herbívoros. Os meus principais resultados mostram que a intensificação do uso do solo e a dominância de plantas hospedeiras exóticas influenciam diferentes aspectos das redes planta-herbívoro, tais como, riqueza de espécies e distinção taxonômica (um substituto para diversidade filogenética) de herbívoros e estrutura e fragilidade das interações. Outro resultado constante no meu estudo foi que quando as redes compostas exclusivamente por herbívoros endófagos foram analisadas separadamente daquelas compostas exclusivamente por herbívoros exófagos, foi encontrado que apenas as redes de endófagos mostraram uma mudança consistente em resposta à intensidade de uso do solo e à proporção de plantas hospedeiras exóticas. De modo geral, a intensificação do uso do solo surpreendentemente aumenta a especialização das redes, por diminuir a conectância e o aninhamento, e aumentar a modularidade; enquanto que o aumento na proporção de hospedeiras exóticas tem efeitos opostos. Possivelmente essas mudanças na estrutura das redes se devem à perda proporcionalmente maior de espécies com muitas interações (i.e., generalistas) em relação às com poucas interações (i.e., especialistas). Como consequência dessas mudanças na conectividade das redes, a intensificação do uso do solo diminui a robustez das redes plantaherbívoro, enquanto o incremento na proporção de plantas hospedeiras exóticas aumenta. Portanto, redes localizadas em habitats com maior intensificação do uso do solo foram menos robustas do que as redes de habitats que tendem a naturais, o que é um resultado contrário à maioria da literatura de redes ecológicas. Controlando os efeitos antrópicos que podem atuar sobre as redes, meus resultados mostram que as redes planta-herbívoro são estruturadas independentemente da latitude, sugerindo que os fatores que influenciam as interações entre plantas e insetos são latitudinalmente invariantes. Os resultados e padrões encontrados enfatizam a contribuição importante da tese para a compreensão das redes planta-herbívoro em um contexto de modificações antrópicas.

As rizobactérias promotoras de crescimento (PGPR) são microrganismos que ocorrem naturalmente no solo, são conhecidas por proporcionar melhorias no desenvolvimento das plantas atuando de diversas formas. Bacillus subtilis (cepa GB03) é uma PGPR disponível para comercialização como fungicida biológico concentrado, utilizada no tratamento de sementes de diversas culturas como algodão, soja, amendoim, trigo e cevada. Destaca-se pela capacidade de promover o crescimento de plantas por meio da emissão de voláteis. Vários estudos com Arabidopsis thaliana já comprovaram que B. subtilis (GB03) é capaz de auxiliar no desenvolvimento da planta por meio da promoção de crescimento e pela supressão de patógenos habitantes de solo. No entanto, o seu papel na proteção de plantas contra a herbivoria de insetos ainda não é bem caracterizado. Deste modo, buscou-se avaliar os efeitos da interação de B. subtilis (GB03) com plantas de rúcula (Eruca sativa) e Plutella xylostella (traça-das-crucíferas). Este inseto pertence à ordem Lepidoptera, considerado praga de maior importância no cultivo de Brassicaceae ao redor do mundo. Devido à sua alta prolificidade e capacidade de adaptação e ao seu curto ciclo de vida, tornou-se uma das pragas mais resistentes e de difícil controle da agricultura. Atualmente, os custos em escala mundial com o controle da praga anualmente chegam em torno de US $ 4 a 5 bilhões. Foram utilizados dois tratamentos, plantas inoculadas com B. subtilis (GB03) e controle (plantas não inoculadas). Avaliou-se o crescimento de plantas de rúcula e o peso seco de parte aérea. Para avaliar o desempenho e dano de P. xylostella em ambos tratamentos, previamente foram pesados grupos de quinze lagartas e submetidas a alimentação de plantas de rúcula durante 24 horas. Posteriormente, as lagartas foram retiradas e pesadas novamente e a área foliar consumida foi calculada por meio do software editor de imagens ImageJ®. A preferência de oviposição do inseto foi testada por meio de olfatometria, composta apenas de pistas olfativas e em arenas contendo tanto pistas olfativas quanto visuais. A emissão de voláteis foi caracterizada quantitativamente e qualitativamente por cromatografia gasosa e analisada por espectrometria de massas. A inoculação com GB03 em plantas de rúcula promoveu melhor crescimento das plantas em relação ao tratamento controle, ao mesmo tempo em que diminuiu os danos pelo consumo alimentar do inseto na planta. P. xylostella não apresentou distinção entre os odores das plantas nos testes de olfatometria. Entretanto, observou-se menor número de ovos em plantas com GB03 nos bioensaios de arena. Não foram constatadas diferenças significativas na emissão total de voláteis entre os tratamentos com e sem GB03, no entanto, foram encontradas concentrações diferentes dos compostos (Z)-3-hexenol e 2-ethyl-1-decanol. Outros testes devem ser realizados com a finalidade de estabelecer o papel desempenhado por GB03 na indução de defesas de plantas contra insetos. / The plant growth promoting rhizobateria (PGPR) are microorganisms that naturaly live in the soil, known by improving the plants\' development in many ways. Bacillus subtilis (strain GB03) is a comercial available PGPR, sold as a concentrated biological fungicide, applied in seed treatment of different cultures as cotton, soybean, peanut, wheat and barley. Moreover, it stands out by its capacity of plant growth promoting via volatiles emission. Several studies with Arabidopsis thaliana showed that B. subtilis (GB03) can help the plant development via growth promotion and by soil pathogens supression. However, its role in plant protection against insect herbivory has not been characterized yet. Thus, it aimed to evaluate the interaction effects among B. subtilis (GB03), arugula plants (Eruca sativa) and Plutella xylostella (Diamondback moth). This insect belongs to the order Lepidoptera and have been considered the main pest in Brassicaceae fields around the world. Due to its high prolificacy and plasticity in field survival, and its short life cycle, it has become one of the most resistant and hard control pest in agriculture. Currently, the annualy world costs with this pest control is about US $ 4-5 bilions. Here, it was used two treatments, innoculated plants with B. subtilis (GB03) and control (non-innoculated plants). The arugula plants growth and dry mass of shoots were evaluated. To analyze the performance and damage by P. xylostella in both treatments, it was previously weighed groups with fifteen caterpillars and submitted to feeding on arugula plants during 24 hours. After that, the caterpillars were removed and weighed again and the consumed leaf area was calculated by the image editor software ImageJ®. The insect oviposition preference was tested by olfactometry, with only olfactory cues and in arenas containing both, olfactory and visual cues. Volatiles emission was quantitatively and qualitatively characterized by gas chromatography and analyzed by mass spectrometry. GB03 innoculation in arugula plants promoted a better growth when compared to control, and, at the same time, there was an increasing in the plant damage by insect food consumption. P. xylostella did not show distinction between odors of the plants in olfactometry tests. Although, it was observed less number of eggs in plants with GB03 in arena bioassays. It was not found significant differences in total volatile emission between the treatments with and without GB03, even though different concentrations of (Z)-3-hexenol and 2-ethyl-1-decanol were observed. Other tests must be performed in order to estabilish the role played by GB03 in plant induction defense against insects.

The recognition of ecological speciation and hybridisation as key components of speciation has led to a major shift in evolutionary biology over the last decade. The mimetic Heliconius butterflies of the Neotropics have served as a prominent example of both, although the vast majority of studies have focused exclusively on very recent divergences and on colour pattern adaptation, neglecting deeper timescales and patterns across the rich diversity of the adaptive radiation. The relative importance across adaptive radiations of allopatry, changing ecological pressures, adaptive morphology and introgression promoted by natural and sexual selection remains unknown. I combine phylogenetics, genomics and comparative approaches to elucidate the patterns and identify the key drivers of diversification in the continental-scale radiation of Heliconius and nine related genera. I present the first comprehensive, multilocus and time-calibrated phylogeny of the group and find that shifts in diversification rate cannot be unequivocally attributed to a single environmental factor. The potential role of coevolution with the obligatory host plants Passiflora is examined with the aid of a new phylogeny of the passion vines. Evidence is found for diffuse coevolution, as the diet of most Heliconiini is not predicted by their phylogeny and varies at short timescales. Although passion vine butterflies are the leading example of speciation by hybridisation, this process has been described in only one subgenus. I utilise whole exome data to examine the morphologically suggestive case of a putative hybrid from another clade and find no evidence of introgression. The data is further used to answer long-standing questions about the origins of the most phenotypically diverse species. In the final chapter whole genome data are applied to characterise the patterns of divergence and gene flow across the entire genera Heliconius and Eueides, characterising the patterns of conflicting signal and comparing the performance of philosophically distinct approaches to reflect the heterogeneity across the genome. I find that the phylogeny is unstable due to a combination if incomplete lineage sorting and introgression and may never be fully resolved, perhaps necessitating a network representation. Genomic admixture is a unique property of just one clade comprising a quarter of all species, and involves primarily the adaptive wing pattern loci. Surprisingly, the sex-linked Z chromosome shows a different order of speciation events. Altogether my results show unexpectedly limited role of allopatry, geoclimatic variables and host plant adaptation in the diversification of a major insect radiation, thus confirming the importance of ecological speciation driven by selection on wing patterns. However, I also demonstrate that introgression may be less important in this group than previously thought.

This study represents the first comprehensive analysis of gene regulation underlying the distinct categories of resistance afforded to wheat (Triticum aestivum, L.) by different Dn genes. Russian wheat aphid (Diuraphis noxia, Mordv.) feeding on susceptible wheat cultivars causes leaf rolling, chlorosis and the eventual death of the plant. Plants expressing Dn genes are resistant to D. noxia infestation, but different Dn genes afford phenotypically distinct modes of resistance: the Dn1 gene confers an antibiotic effect to lower aphid fecundity; Dn2 confers tolerance to high aphid pressure; and Dn5 confers antixenosis, and aphids do not prefer such plants as hosts. Little is known about the components involved in establishing a successful defence response against D. noxia attack and how these differ between the distinct resistance categories. It is assumed that the Dn genes function as classic R genes in plant defence, being receptors for elicitors in aphid saliva. Upon recognition, defence response signalling is initiated, but the exact mechanics of subsequent cellular events in aphid resistance have only recently come under investigation. Evidence from cDNA microarray and subtractive hybridization experiments indicated the involvement of kinase signalling cascades and photosynthetic proteins in the response against D. noxia. However, expression analysis describing how these processes differ between plants carrying different Dn genes and how these differences account for antibiosis, antixenosis or tolerance had not been conducted. We consequently investigated the downstream components involved in or affected by the generation of these resistance mechanisms by comparing the responses in transcript regulation of Tugela near-isogenic lines with different Dn genes to D. noxia infestation. cDNA-AFLP analysis was selected as an appropriate functional genomics tool, since it is semi-quantitative, does not require prior sequence information and allows for the discovery of novel genes. cDNA-AFLP analysis yielded 121 differentially regulated transcript-derived fragments (TDFs) grouped into eight expression clusters. We cloned and sequenced 49 representative TDFs, which were further classified into five broad functional categories based on inferred similarity to database sequences. Transcripts involved in such diverse processes as stress, signal transduction, photosynthesis, metabolism and gene regulation were found to be differentially regulated during D. noxia feeding. Many TDFs demonstrated homology to proteins with unknown function and several novel transcripts with no similarity to previously published sequences were also discovered. Detailed expression analysis using quantitative RT-PCR and RNA hybridization provided evidence that the time and intensity of induction of specific pathways is critical for the development of a particular mode of resistance. This includes: the generation of kinase signalling cascades and the induction of several ancillary processes such as ubiquitination, leading to a sustained oxidative burst and the hypersensitive response during antibiosis; tolerance as a passive resistance mechanism countering aphid-induced symptoms through the repair or de novo synthesis of photosystem proteins; and the possible involvement of ethylene-mediated wounding pathways in generating volatile organic compounds during antixenosis. This is the first report on the involvement of KCO1, a vacuolar K+ channel, in assisting cytosolic Ca2+-influx and preventing leaf rolling, as well as on the role of iron homeostasis as a gene regulatory mechanism for sustaining the oxidative burst during the antibiotic defence response. This study opens up several areas of investigation heretofore unexplored in cereal-aphid interaction research. Of particular interest is the induction of genes involved in photosynthetic compensation during Dn2 tolerance responses, since these constitute a novel, passive resistance mechanism exclusive to aphid defence as opposed to the active resistance triggered in the presence of the Dn1 gene in the form of a general hypersensitive response. / Dissertation (MSc)--University of Pretoria, 2008. / Genetics / unrestricted

Les forêts fournissent de nombreux services écosystémiques qui peuvent être compromis par les insectes. Le maintien de la santé des forêts est un enjeu majeur de la gestion forestière qui nécessite l’acquisition de connaissances sur les interactions arbres-ravageurs. Dans ce contexte, nous nous sommes focalisés sur la question de la résistance des chênes à un ravageur, la chenille processionnaire du chêne (CPC).La CPC est un herbivore spécialiste des chênes décidus en Europe. Elle est responsable de fortes défoliations, en plus de graves urtications chez les usagers de la forêt. Au travers d’une série d’observations et d’expériences menées à plusieurs niveaux d’intégration (de l’arbre jusqu’à la forêt), nous nous sommes intéressés à la réponse de la CPC à différents facteurs écologiques intervenant dans la résistance des arbres : la composition du peuplement, le voisinage et les traits foliaires liés à la défense.La résistance des arbres aux herbivores est influencée par la composition des forêts. Pour une espèce donnée, les arbres subissent en général moins d’attaques dans les mélanges que dans les peuplements purs (résistance par association). Nous avons testé l’effet des associations entre espèces d’arbres sur la résistance des chênes à la CPC, en comparant l’abondance des adultes et les dégâts des larves sur le chêne pédonculé (Quercus robur) et le chêne sessile (Q.petraea) dans des peuplements purs ou mélangés. Nous avons exploré les mécanismes sous-jacents, en recherchant les traits foliaires des chênes impliqués dans la variabilité des performances de la CPC. Enfin, nous nous sommes interrogés sur les causes génétiques et environnementales de la variabilité interindividuelle dans l’expression de ces traits.Premièrement, nous avons mis en évidence une plus grande susceptibilité de Q.petraea, caractérisée par une plus grande attractivité de Q.petraea pour les papillons de CPC, un niveau de défoliation plus élevé et une plus grande survie et prise de poids des larves sur cette essence. Nous avons aussi mis en évidence une plus grande susceptibilité des chênes dans les peuplements purs par rapport aux peuplements mélangés, en particulier ceux associant un chêne à une autre essence non hôte. Ensuite, nous avons étudié les mécanismes conférant une plus grande résistance à Q.robur et aux peuplements mélangés, en mesurant les traits foliaires (les défenses chimiques et la phénologie). La synchronisation entre le développement des feuilles et celui des larves est apparue comme un facteur clé déterminant les performances de la CPC. La concentration des défenses chimiques dans les feuilles était positivement corrélée au taux de consommation des feuilles par les chenilles, suggérant une compensation alimentaire pour maintenir la croissance sur les feuilles les plus défendues. Nous avons montré que l’expression de ces traits était influencée par l’identité des voisins. Enfin, chez Q.robur, nous avons montré l’existence d’un contrôle génétique de l’arbre sur les performances des chenilles.L’ensemble des résultats permet de mieux comprendre les processus impliqués dans l’effet du mélange d’essences sur les dégâts d’insectes et apporte des éléments permettant d’orienter la gestion des peuplements de chênes pour une meilleure résistance à la CPC. Au vu de ces résultats, il semblerait préférable de favoriser Q.robur pour sa moindre attractivité et sa plus grande résistance à la CPC. Cette proposition va toutefois à l’encontre des préconisations d’utilisation de Q.petraea pour adapter les chênaies au risque de déficit hydrique et ne fait que rajouter un élément de complexité à la gestion de la résistance des forêts face à des perturbations multiples en interaction. A l’aune de la mise en évidence de l’effet du génotype de l’arbre et de ses traits foliaires dans le développement de la CPC, la caractérisation des gènes et des molécules de défenses impliquées reste un champ de recherche quasi inexplorée, qu’il conviendra de défricher. / Forest ecosystems provide a series of ecosystem services that can be threatened by pest insects. Maintaining forest health is therefore a major challenge of forest management that requires a sound understanding of tree-pest interactions. In this context, we investigated oak resistance (and its drivers) to a pest insect, the oak processionary moth (OPM), Thaumetopoea processionea.The OPM is a specialist herbivore feeding on oaks in Europe. It is responsible for significant defoliation, in addition to serious urtication in forest users and practitioners. Through a series of observations and experiments carried out at several levels of integration (from tree to forest stand levels), we investigated the response of this insect to various ecological factors involved in oak resistance: forest stand species composition, tree neighbourhood effects and leaf traits potentially associated with defence.Forest species composition has well documented effects on tree resistance to herbivores. For a given species, trees are generally less attacked in mixtures than in pure stands (i.e. associational resistance). But the opposite - associational susceptibility - also exists. We tested whether tree species diversity generated associational resistance to OPM, by comparing abundance and damage on the pedunculate (Quercus robur) and sessile oaks (Q. petraea) in pure and mixed stands. We also investigated the underlying mechanisms, by characterizing the leaf traits involved in the variability of OPM performance. Finally, we focused on the genetic and environmental causes of inter-individual variability in the expression of these traits.First, we found that Q. petraea was generally more susceptible to the OPM than Q. robur. Stands dominated by Q. petraea attracted more OPM moths, Q. petraea suffered more defoliation, and OPM larvae had greater survival and weight gain on this species. We also found greater susceptibility of both oak species in pure stands as compared to mixed stands, particularly those associating an oak with another non-host species. Second, we investigated the mechanisms conferring greater resistance to Q. robur and to mixed stands by quantifying leaf chemical and developmental traits involved in oak-OPM interactions. The synchronization between leaf development and larval development also appeared to be a key factor determining the OPM performance. The concentration of leaf chemical defences was positively correlated with OPM consumption rate, suggesting a compensatory feeding response to maintain OPM growth rate on well-defended leaves. Leaf traits involved in oak-OPM interactions were partially determined by the identity of oak neighbours. Third, we found evidence that OPM performance was partially under the genetic control of their host trees in Q. robur.Overall, these results built toward a better understanding of the processes involved in the effect of tree species mixture on the damage caused by pest insects and provide new avenues to guide oak stand management for improved resistance to OPM. Based on the results of this study, it would seem preferable to favour Q. robur in oak stands because it is less attractive and more resistant to OPM attacks, both in the field and in the laboratory. However, this statement goes against current recommendations to use Q. petraea to adapt the oak to the increased risk of water deficit and therefore adds to complexity of managing forests for resistance to multiple-interacting stresses.

We consider a population dynamics model in investigating data from controlled experiments with aphids in broccoli patches surrounded by different margin types (bare or weedy ground) and three levels of insecticide spray (no, light, or heavy spray). The experimental data is clearly aggregate in nature. In previous efforts [1], the aggregate nature of the data was ignored. In this paper, we embrace this aspect of the experiment and correctly model the data as aggregate data, comparing the results to the previous approach. We discuss cases in which the approach may provide similar results as well as cases in which there is a clear difference in the resulting fit to the data.

No description available.

Master of Science / Department of Entomology / C. Michael Smith / The Russian wheat aphid Diuraphis noxia (Kurdjumov) is a serious pest of world cereal grain crops, primarily barley and wheat. A phenotypic characteristic of D. noxia feeding, leaf rolling, creates a leaf pseudo gall which protects aphids, making it difficult to treat infested plants with insecticides or biological control agents. Therefore, the use of D. noxia-resistant crops is a desirable aphid management tactic. Because of the development of virulent D. noxia biotypes, the identification of new sources of barley and wheat resistance is necessary. Virus-induced gene silencing (VIGS) utilizes the plant defense system to silence viruses in inoculated plants. The accumulation of virus RNA in plants triggers the defense system to silence sequences homologous to the introduced virus and sequences of interest from a plant are inserted into the virus and silenced along with the virus. The VIGS method was tested to determine the ability of barley stripe mosaic virus (BSMV) to serve as a VIGS vector in wheat plants containing the Dnx gene for resistance to D. noxia. Dnx leaves with silenced BSMV virus yielded D. noxia populations that were significantly no different from populations produced on healthy Dnx leaves. Thus, BSMV silencing does not interfere with Dnx resistance. Several different methods were examined to determine how best to confine aphids to the silenced leaf, and a modified plastic straw cage was chosen as the optimum cage type. Microarray and gene expression data were analyzed to select two NBS-LRR type disease resistance protein genes - TaAffx.104814.1.S1_at and TaAffx.28897.1.S1 - (NBS-LRR1 and NBSLRR2), in order to assess their role in Dnx resistance. NBS-LRR1 and NBSLRR2 were silenced by inoculating leaves of Dnx plants with barley stripe mosaic virus (BSMV) containing sequences of each gene. Controls included Dnx and Dn0 plants inoculated with BSMV and non-BSMV inoculated plants. Aphids were allowed to feed on control and treatment plants to assess aphid population and mean weight of aphids surviving at the end of the experiment. There were no differences among treatments based on aphid population, but there were significant differences the mean weights of aphids reared on several different treatments.

Os inibidores inibidores de serino proteinases do tipo Bowman-Birk (BBI) possuem dois sítios ativos e são encontrados em plantas das famílias Fabaceae e Poaceae. Neste trabalho foi apresentada a estrutura primária e o padrão de expressão de 14 seqüências expressas (EST, expressed sequence tags) de BBI putativos encontradas no banco de dados do "Projeto Transcriptoma da Cana-de-açúcar" (SUCEST). Estas quatorze seqüências foram utilizadas em conjunto com outras 87 seqüências de BBI previamente descritas e depositadas no banco de dados "GenBank" para a construção de árvores filogenéticas da família BBI. A análise filogenética mostrou que os BBI de monocotiledôneas e dicotiledôneas podem ser claramente separados em diferentes grupos e a topologia das árvores filogenéticas sugere um padrão evolutivo diferente das famílias de BBI em plantas. Os inibidores de dicotiledôneas são bem conservados e acumularam diferenças sutis durante a evolução. Em contrapartida, os inibidores de monocotiledôneas são altamente variáveis, indicando a ocorrência de um processo evolutivo interessante, baseado em eventos de duplicação intragênica e mutação. Dois inibidores de serino proteinases, um de tripsina e outro de quimotripsina, derivados do gene que codifica o inibidor Bowman-Birk de soja, foram expressos na superfície do fago filamentoso M13 e utilizados para a construção de bibliotecas de variantes. Para tal foram feitas mutações em quatro aminoácidos do sítio ativo destes inibidores e duas bibliotecas de expressão na superfície de fagos filamentosos foram construídas. Posteriormente, estas bibliotecas foram utilizadas para a seleção de variantes que melhor interagiam com a tripsina bovina e de Diatraea saccharalis e com as enzimas digestivas presentes no extrato intestinal desta praga. Os variantes selecionados foram seqüenciados, analisados e caracterizados. Os resultados mostraram que a técnica de expressão na superfície de fagos filamentosos foi eficiente para selecionar novos inibidores. Além disto, com as mutações realizadas, foi possível transformar a alça de inibição de quimotripsina em uma alça de inibição de tripsina. / The Bowman-Birk inhibitors (BBIs) are double headed inhibitors of serine proteinase found in plants from Fabaceae and Poaceae families. We describe the primary structure and the gene expression profile of 14 putative BBIs from the sugarcane expressed sequence tag (SUCEST) database and show how we used these newly discovered sequences together with 87 previously described BBI sequences from the "GenBank" database to construct phylogenetic trees for the BBI family. Phylogenetic analysis revealed that BBI-type inhibitors from monocotyledonous and dicotyledonous plants could be clearly separated into different groups, while the overall topology of the BBI tree suggests a different pattern of evolution for BBI families in flowering plants. We also found that BBI proteinase inhibitors from dicotyledonous plants were well conserved, accumulating only slight differences during their evolution. In addition, we found that BBIs from monocotyledonous plants were highly variable, indicating an interesting process of evolution based on internal gene duplications and mutation events. Two serine-type proteinase inhibitors, a trypsin and a chymotrypsin, both derived from the soybean Bowman-Birk inhibitor, were expressed on the surface of a filamentous phage. Site mutations were made in four positions of the reactive sites of these inhibitors and two phage-display libraries were constructed. Later, these libraries were used to select better ligands to the bovine and Diatraea saccharalis trypsin and to the midgut enzymes of this insect pest. The selected variants were sequenced, analyzed and characterized. The results showed that the phage-display technique is efficient to select new proteinase inhibitors. Furthermore, it was possible to modify the chymotrypsin loop into a trypsin loop using the library constructed by the insertion of a degenerated primer.