Brachycaudus helichrysi est un puceron ravageur des cultures qui inflige de sérieux dégâts à ses hôtes primaires (arbres fruitiers du genre Prunus) ainsi qu'à plusieurs herbacées cultivées correspondant à ses hôtes secondaires (par exemple les tournesols et les chrysanthèmes).L'étude phylogéographique de l'espèce basée sur un échantillonnage mondial, montre que B. helichrysi rassemble deux taxa appelés B. helichrysi H1 et H2. Cette étude, basée sur plusieurs marqueurs génétiques (mitochondriaux, nucléaire et bactériens), révèle une divergence génétique de l'ordre de celle observée entre espèce du genre Brachycaudus. Ceci suggère que B. helichrysi H1 et H2 sont deux espèces sœurs. Comme H1 et H2 sont morphologiquement indistinguables, nous avons mis au point un test de discrimination génétique par PCR-RFLP.L'analyse des génotypes (14 loci microsatellites) combinés aux données écologiques suggère que ces deux espèces sœurs ont des histoires évolutives différentes. Le cycle de vie de B. helichrysi H1 correspondrait à la parthénogenèse cyclique, utilisant les pruniers comme hôte primaire. Nous avons montré qu'il existe chez H1 des clusters génétiques structurés géographiquement. Au contraire, B. helichrysi H2 rassemble principalement des lignées clonales polyphages, persistantes et largement distribuées dans le monde (i.e. superclones), ainsi qu'une lignée sexuée, probablement hétéroécique, qui a été trouvée sur pêchers en Inde. Les individus des deux espèces colonisent fréquemment une même plante herbacée, composant ainsi des colonies « mixtes ». Cette étude apportera un éclairage sur comment l'évolution des cycles de vie, en particulier la perte de la reproduction sexuée, a pu jouer un rôle dans les processus de spéciation au sein du complexe B. helichrysi / Brachycaudus helichrysi is a worldwide polyphagous aphid pest that seriously damages its primary hosts (Prunus spp.) and the various cultivated plants among its secondary hosts (e.g. sunflower, chrysanthemums).In a phylogeographic study based on a worldwide sampling, I have shown that this species is actually an amalgamation of two sibling taxa called B. helichrysi H1 and B. helichrysi H2. This study based on mitochondrial, nuclear and Buchnera aphidicola (the primary symbiont of aphids) DNA markers revealed that these two taxa display levels of genetic divergence as great as those generally found between sister species in the Brachycaudus genus, suggesting that they actually correspond to two distinct sibling species. As these two species are morphologically indistinguishable, we developed a PCR-RFLP test to genetically discriminate them.Further investigations, based on microsatellites data combined with ecological information suggest that these two species have two very different evolutionary histories. Brachycaudus helichrysi H1 exhibits a typical signature of cyclical parthenogenesis, using plum trees during the sexual phase, and we demonstrate the existence of distinct geographic genetic clusters within this species. By contrast B. helichrysi H2 comprises two types of lineages. First, it gathers several persistent obligate clonal lineages distributed worldwide (i.e. superclones) and highly polyphagous, and second, we reveal the existence of a cyclical parthenogenetic H2 lineage that uses peach trees as primary hosts and has so far only been found in India. All B. helichrysi lineages of H1 and H2 co-occurred in mixed colonies on herbaceous hosts all around the world.This study will shed light on how life cycle evolution, especially the loss of sexual reproduction, could explain the ongoing speciation process in the B. helichrysi species complex.

Substrate specificity of epiphytic communities of diatoms (Bacillariophyceae) and desmids (Desmidiales) Bc. Petra Mutinová Master's thesis, Prague, 2015 Abstract It has been always assumed, and frequently reported, that host plants, as biologically active substrates, should have a direct influence on associated epiphyton. However, some studies favoured the neutral substrate hypothesis. Thus the relationship between host plant and epiphytic community remained unresolved. This Master's thesis focused on the basal question that numerous previous studies overlooked. Is there any significant influence of host plant on freshwater algal epiphyton in comparison to the influence of other factors, e.g. site and environmental conditions? In addition, substrate specificity of individual algal taxa was investigated. The research concerned several types of natural plant substrates at several water bodies in the Czech Republic, which provided a more accurate and general insight in the ecology of microphytobenthos. The results have demonstrated that site was the main factor affecting epiphytic community structure, followed by mild, but still noticeable, effect of environmental conditions (pH and conductivity). In contrary, host plant had almost no influence and very few algal species were found to be host specific....

La compréhension du processus d’adaptation des populations de parasites à leur plante-hôte est une question fondamentale en écologie évolutive. C’est également un enjeu majeur de recherche finalisée qui a des retombées pour la protection des cultures. L’oomycète Plasmopara viticola, agent causal du mildiou de la vigne, attaque les espèces du genre Vitis. Dans un contexte où l’enjeu principal des programmes d’amélioration est la durabilité des résistances, des connaissances nouvelles sur l’écologie et l’évolution de l'interaction entre le parasite et son hôte sont nécessaires afin d’évaluer le potentiel du mildiou à surmonter ces résistances. Dans ma thèse, je me suis intéressée au rôle de la plante-hôte comme facteur d’évolution des populations de mildiou, en posant cette question à différentes échelles évolutives : (i) dans le bassin d’origine du pathogène (Amérique du Nord), j’ai cherché à évaluer le degré de spécialisation du parasite sur sa gamme d’hôtes sauvages et cultivés; (ii) en Europe, où le mildiou de la vigne a été introduit récemment, j’ai étudié l’évolution des populations de mildiou soumis à la pression de sélection des résistances des nouvelles variétés de vigne. Pour comprendre la spécialisation plante-hôte dans ce pathosystème où plusieurs espèces cryptiques ont été identifiées, nous avons réalisé des tests d’inoculations croisées entre espèces hôtes (Vitis spp.) et agent pathogène (P. viticola). Les données phénotypiques et morphologiques apportent les preuves d’une spécialisation plante-hôte au sein des populations de P. viticola : les espèces A et D de mildiou sont spécialisées sur leur plante-hôte, tandis que le processus de spécialisation est en cours pour les espèces B et C. Même si aucune différenciation génétique n’a été montrée au sein de l’espèce C, il existe deux groupes distincts au sein de l’espèce B. Les isolats du compartiment cultivé sont en moyenne plus agressifs que les isolats issus des vignes sauvages, indiquant une adaptation des isolats cultivés sur leur plante hôte. A partir d’un large échantillonnage, nous avons étudié la distribution des espèces de mildiou sur leurs plantes-hôtes sauvages et cultivées. Ce travail a permis d’identifier une nouvelle espèce cryptique et a confirmé la spécialisation plante-hôte. En Europe, nos résultats montrent que le déploiement limité de variétés à résistantes partielles a conduit à des modifications des populations de mildiou: apparition d’isolats virulents (i.e. contournant un QTL majeur de résistance), et augmentation de l’agressivité sur Vitis vinifera. Dans le but de comprendre les mécanismes à l’origine de la spécialisation et du contournement des résistances, nous nous sommes intéressés au répertoire d’effecteurs du parasite. Une centaine d’effecteurs candidats ont été identifiés en utilisant les données disponibles sur le génome de P. viticola. L’analyse du polymorphisme de 32 candidats sur une sélection d’isolats montre que trois d’entre eux évoluent sous sélection positive. Ces résultats soulignent l’importance de la plante-hôte comme facteur de diversification des populations de l’agent pathogène et révèlent que le mildiou s’adapte rapidement aux résistances de la vigne. Il est désormais nécessaire de mieux appréhender le déploiement des résistances de la vigne afin qu’elles puissent être durables. / Understanding the process of adaptation of parasite populations to their host-plant is a key issue in evolutionary ecology. It is also a major subject in applied research that has implications for crop protection. The oomycete Plasmopara viticola, the causal agent of downy mildew, attacks the species of the Vitis genus. In a context where the main concern of the breeding programs is the durability of resistance, new knowledge about the ecology and evolution of the interaction between parasite and host is needed in order to evaluate the potential of downy mildew to overcome the resistance. In my thesis, I addressed the role of the host-plant as an evolutionary factor for downy mildew populations, by asking this question at two different evolutionary scales: (i) in the pathogen region of origin (North America) I assessed the degree of specialization of the parasite on its wild and cultivated host range (ii) in Europe, where downy mildew has been introduced recently, I studied the evolution of downy mildew populations subject to the selection pressure imposed by resistant grapevine varieties. To understand the host-plant specialization in this pathosystem, where several cryptic species have been identified, we performed cross inoculations between different host (Vitis spp.) and pathogen (P. viticola) species. Morphological and phenotypic data provide evidence of host-plant specialization in P. viticola populations: downy mildew species A and D are specialized on their host-plant, while the specialization process is ongoing for species B and C. Although no genetic differentiation has been shown inside species C, there are two distinct groups within species B. Isolates from the cultivated compartment are on average more aggressive than isolates from wild vines, indicating an adaptation of isolates growing on cultivated host-plants. Finally, a large-scale study of the distribution of downy mildew species on both their wild and cultivated host-plants resulted in the identification of a new cryptic species and confirmed the host-plant specialization. In Europe, our results show that the limited deployment of resistant varieties has led to changes in downy mildew populations: emergence of virulent isolates (i.e. breakdown of a major QTL for resistance), and increased aggressiveness on Vitis vinifera. In order to understand the mechanisms at the origin of specialization and resistance breakdown, we examined the parasite’s effector repertoire. Over one hundred effector candidates were identified using available data on the P. viticola genome. The polymorphism of 32 candidate genes revealed that three of them evolve under positive selection. Our results reveal the strong ability of downy mildew to adapt to its host plant and to plant resistance. They should be taken into account when devising strategies for the deployment of grapevine resistances in order to guarantee their durability.

Esta pesquisa foi conduzida para avaliar os efeitos de interações entre a planta hospedeira e um biofertilizante líquido sobre o ácaro Brevipalpus phoenicis (Geijskes). Primeiramente avaliaram-se os efeitos residual e sistêmico de biofertilizantes aplicados a plantas de Canaialia etlçifbrmis (L.) DC. sobre parâmetros bioecológicos de uma população de B. phoenicis. Para o efeito residual foram testados os seguintes tratamentos: a) Água destilada (Controle); b) Biofert -- biofertilizante produzido em um único bioreactor; e) Biornix - uma mistura com biol@ertilizantes produzidos em quatro bioreatores; e d) Bio+VL - Biofert + Verticillium leca;,iii (Zimm.) Viégas. Para o efeito sistêmico somente dois tratamentos foram avaliados: a) Biofert e b) Água destilada (Controle). A seguida avaliou-se a interação tópica e residual entre concentrações do biofertilízante nas plantas hospedeiras: C. ensíformis e Ligustnim lucindum Aiton. Utilizando-se n-úcroscopia eletrônica de varredura (MEV), caracterizaram-se as manifestações patológicas sobre os cadáveres de 8. phoenicis. Foram observados efeitos adversos do biofertilizante sobre os parânietros de sobrevivência e de oviposição. A taxa líquida de reprodução (Ro)foi de 18,1; 12,9; 12,5 e 10,5 fêmea/fêmea (efeito residual) e 19,4 e 13,0 fêmea/fêrnea (efeito sistêmico), respectivamente para os tratamentos nas ordens supra mencionadas. Tanto na ação residual quanto via sistêmica houve redução significativa do potencial de crescimento populacional de B. phoenicis. Nas duas plantas hospedeiras a sobrevivência e oviposição do ácaro foram significativamente reduzidas com o aw-nento de concentração do biofertilizante, sendo mais severo em C ensijbrmis. Evidenciou-se uma colonização microbiana nos ácaros mortos pela ação do biofertilizante e também verificou-se que um composto coloidal do biofertilizante causou imobilização e obstrução do sistema digestivo do ácaro. A interação entre a planta hospedeira e o biofertilizante, numa relação de equilíbrio trofobiótico, contribui para um melhor manejo desse ácaro. / This study was conducted to evaluate interactions between host plants and the effect of biofertilizers on Brevipalpits phoeiiicis (Geijskes) bioecology. The residual and systemic effects of biofertilizer mjxtures sprayed on Canavalia ensiformis (L.) DC. plants on the bioecology parameters were firstly evaluated. For the residual effect bioassay the following treaúnents were tested: a) Distilled water (Control); b) Biofert biofertilizer produced in a single bioreactor; e) Biomix - a mix of biofertilizers produced in four bioreactors; and d) Bio+VL - Biofei-t, + Verticilliuin lecanii (Zimm.) Viégas. For tbe systemic effect bloassay two stispensions were tested: a) Biofert and b) Distilled water (Control). Thereafter the topical and residual interaction effects between concentrations of the biofertilizer and C. ensiformis and Ligustrum lucidum Aiton. Host plants were evaluated. Were also characterized pathological manifestations in the dead mites by using seanning electronic microscopy images. Adverse effects of biofertilizers on both survival and oviposition parameters were verified. The net reproduction rates (Ro) were 18.09; 12.92; 12.52 and 10.52 female/female (residual effect) and 19.42 and 13.00 female/female (systemic effect), respectively, for the treatments in the above mentioned orders. The results showed that the biofertilizers reduced the potential population growth of B. phoenicis in the residual and in the systemie effect assays. The biofertilizer demonstrated deleterious effect on fertility and survival of R. phoenicis on both host plants, mostly on C ens@formis. The mites dead by biofertilizer action showed evidences of microbial colonization. A colloidal coinpound of biofertilizer induced mite immobilization and obstruction in its digestivo tract. The interaction between host plant and biofertilizer deleterious effects will contribute to enhance mite management based on trophobiotic relationships.

Este trabalho foi conduzido na área abrangida pelo campus Luiz de Queiroz/Universidade de São Paulo, no município de Piracicaba, Estado de São Paulo. Teve como objetivos, determinar a composição do gênero Anastrepha Schiner, sua distribuição e a análise quantitativa da população. Além disso, verificou-se a relação da flutuação populacional com variáveis bióticas e abióticas e a associação das espécies de plantas hospedeiras, estabelecidas na área, com as espécies de Anastrepha.Foram examinadas 23.263 fêmeas de Anastrepha coletadas em armadilhas McPhail e 18 espécies pertencentes a 9 grupos infragenéricos foram assinaladas. A distribuição das fêmeas por armadilha foi fortemente agregada, com 5 armadilhas (6%) capturando 50% do total de fêmeas. Apenas A. fraterculus (Wiedemann) e A. obliqua (Macquart) foram dominantes. A. fraterculus foi a espécie mais freqüente, representando 80,2% do total de fêmeas capturadas no campus e a mais constante ocorrendo em 98,04% das amostras. Em ordem decrescente de freqüência, seguiram-se A. obliqua (12,6%), A. pseudoparallela (Loew) (3,1%) e A. bistrigata Bezzi (2,1%). As demais espécies apresentaram freqüência menor que 1%. O valor elevado do índice de Simpson (0,66) e os valores baixos do índice de Shannon (0,7521) e de eqüitatividade (0,459) resultaram da alta freqüência de A. fraterculus. Um aumento no nível populacional das espécies de Anastrepha ocorreu de agosto a novembro com um pico máximo em setembro. A disponibilidade de frutos hospedeiros foi mais determinante na variação do tamanho da população das espécies mais abundantes de Anastrepha que as variáveis climáticas. Um total de 565 amostras de frutos pertencentes a 11 famílias e, pelo menos, 25 espécies botânicas foi coletado em 47 estações de capturas. Foram identificadas 10.290 fêmeas e das 18 espécies de Anastrepha capturadas em armadilhas somente 6 emergiram das amostras de frutos: A. bistrigata Bezzi, A. fraterculus (Wiedemann), A. obliqua (Macquart), A. pseudoparallela (Loew), A. serpentina (Wiedemann) e A. sororcula Zucchi. A. fraterculus foi a espécie que infestou maior diversidade de frutos. Os hospedeiros preferidos de A. obliqua foram as espécies da família Anacardiaceae. A. pseudoparallela e A. serpentina infestaram exclusivamente Passifloraceae e Sapotaceae, respectivamente. Uma nova associação de mosca-das-frutas com planta hospedeira foi constatada: A. fraterculus em Syagrus romanzoffiana (Cham.) Glassman (coquinho). Foi reportado o primeiro registro da associação de A. fraterculus em Manilkara zapota L. (sapoti) no Brasil. / This study was conducted in the Luiz de Queiroz campus of the Universidade de São Paulo, in Piracicaba, state of São Paulo. The aim of this study was to determine the number of species in the genus Anastrepha Schiner on campus, their distribution and the quantitative analysis of the population. Moreover, this study correlated populational fluctuations with biotic and abiotic factors as well as the association between host plant species and the Anastrepha species in that area. A total of 23,263 females of Anastrepha collected in MacPhail traps was examined, and 18 species belonging to nine infrageneric groups were registered. The distribution of females per trap was strongly clustered, with 5 traps (6%) capturing 50% of the total of females. Only A. fraterculus (Wiedemann) and A. obliqua (Macquart) were considered dominant species. A. fraterculus was by far the most frequent species, representing 80.2% of the total of females captured on campus, and the most constant, occurring in 98.04% of the analyzed samples. In decreasing order of frequency, A. obliqua (12.6%), A. pseudoparallela (Loew) (3.1%), and A. bistrigata Bezzi (2.1%) comprised the other major species. The remaining species showed frequency lower than 1%. The high value of the Simpson’s index (0.66) as wel as the low values of Shannon’s index (0.7521) and the equitability index (0.459) resulted from the high frequency of A. fraterculus. The populational level of Anastrepha increased from August to November with the highest peak in September. The availability of host fruit, more than climatic parameters determined most of the variation of population size in the most abundant species of Anastrepha. A total of 565 fruit samples representing at least 25 plant species from 11 families was collected in 47 capture sites. 10,290 females were identified. Of the 18 Anastrepha species captured in traps, only 6 also emerged from fruit samples: A. bistrigata Bezzi, A. fraterculus (Wiedemann), A. obliqua (Macquart), A. pseudoparallela (Loew), A. serpentina (Wiedemann) e A. sororcula Zucchi. A. fraterculus infested the greatest diversity of hosts. The preferred hosts of A. obliqua were plant species in the family Anacardiaceae. A. pseudoparallela and A. serpentina infested only species in the families Passifloraceae and Sapotaceae, respectively. A new fruit fly and host plant association was registered: A. fraterculus with Syagrus romanzoffiana (Cham.) Glassman (queen palm). The association of A. fraterculus with Manilkara zapota L. (sapodilla) was reported here for the first time in Brazil.

Heliconius butterflies exhibit Müllerian mimicry, in which two or more unpalatable species share a mutual advantage from having a common conspicuous colour pattern. These tropical butterflies have impressive visual signals, which are under conflicting selection pressures, as they are used in choosing potential mates and defending against visual predators through aposematic coloration. As both selection pressures are likely to be strong, different elements of the signal might be adapted for different receivers. Here, I combine sensory ecology with behavioural ecology to explain Heliconius colours signals of different co-mimic pairs. I explore how mimicry in Heliconius is perceived both from the perspective of predators and conspecifics, using visual abilities of both butterflies and birds. The different visual sensitivities of avian predators, H. erato females and males make them to perceive Heliconius coloration in different ways. My work suggests that having the ability to see in the ultra-violet light range enables higher discrimination between co-mimics both for birds and butterflies. Heliconius warning colours transmit a consistent signal across time of the day and habitat in a tropical forest for avian vision. In contrast through Heliconius vision there is evidence that patterns are more conspicuous in their own habitats. All these traits could facilitate communication between co-mimics and reduce the cost of confusion in courtship while still maintaining the advantages of Müllerian mimicry against predation. I conducted a field experiment to show that attack rates on a novel distasteful butterfly reduced over time, suggesting that Heliconius wing colouration can enhance aversion among predators. Finally, I have shown that Heliconius butterflies use leaf shape as a cue to approach their host plants, demonstrating the potential for Heliconius to drive negative frequency dependent selection on the leaf shape of their Passiflora host plants. Overall these results highlight ecological interactions between Heliconius butterflies, their predators and host plants.

Orientador: Edson Luiz Lopes Baldin / Banca: Carlos Frederico Wilcken / Banca: Arlindo Leal Boica Junior / Banca: José Djair Vendramim / Banca: Paulo Marçal Fernandes / Resumo: Desde sua introdução no Brasil, em 2003, o psilídeo-de-concha Glycaspis brimblecombei Moore (Hemiptera: Psyllidae) vem ocasionando sérios danos ao eucalipto, principalmente através de desfolha, desenvolvimento de fumagina e secamento de ponteiros. Como estratégia no controle deste inseto, o uso de genótipos resistentes pode ser uma ferramenta valiosa. Neste trabalho, avaliou-se a resistência das espécies Eucalyptus camaldulensis (VM e IPEF), E. grandis e E. urophylla e dos híbridos de E. grandis x E. camaldulensis - gracam 'HGC' (3025 e 1277), de E. urophylla x E. camaldulensis - urocam 'HUC' (VM-1), de E. urophylla x E. grandis - urograndis 'HUG' (H-13, I-144, C-219 e GG-100) e de E. grandis (EG-01, EG-02 e EG-03) a G. brimblecombei, através de testes de atratividade, preferência para oviposição e preferência para alimentação e/ou antibiose sob condições de laboratório e campo. Foram realizados testes preliminares, a fim de verificar a ocorrência de condicionamento pré-imaginal, além de ajustar a melhor densidade para infestação com adultos para testes de atratividade e a melhor posição nas mudas para avaliações de preferência para oviposição. Em laboratório, verificou-se que os adultos de G. brimblecombei não apresentaram condicionamento pré-imaginal, independentemente do hospedeiro de criação ser o híbrido 3025 ou E. camaldulensis IPEF. As densidades de 10 e 15 adultos de psilídeo-de-concha por muda de eucalipto proporcionaram maior número de ovos. As folhas próximas ao ápice foram preferidas para oviposição, sendo que o número de ovos decresceu do ápice para a base. No teste com chance de escolha, os genótipos E. grandis, E. urophylla, C-219 e H-13 foram menos atrativos ao psilídeo-de-concha, expressando não-preferência. Em teste com chance de escolha, o número de ovos depositados nas folhas dos genótipos H-13, E. grandis... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Since its introduction in Brazil in 2003, the red gum lerp psyllid Glycaspis brimblecombei Moore (Hemiptera: Psyllidae) has been causing serious damages in eucalyptus trees, especially through defoliation, development of sooty mold and dieback. The use of resistant genotypes as a strategy to control this insect may be a valuable tool. In this study, the resistance of species Eucalyptus camaldulensis (VM e IPEF), E. grandis and E. urophylla and hybrids E. grandis x E. camaldulensis - gracam 'HGC' (3025 and 1277), E. urophylla x E. camaldulensis - urocam 'HUC' (VM-1), E. urophylla x E. grandis - urograndis 'HUG' (H-13, I-144, C-219 and GG-100) and E. grandis (EG-01, EG-02 and EG-03) on G. brimblecombei, through attractiveness, oviposition preference and feeding preference and/or antibiosis tests under laboratory and field conditions evaluated. Initially preliminary tests were carried out, using eucalyptus seedlings, in order to verify the occurrence of preimaginal conditioning, and also adjust the best density for adult infestation for attractiveness tests and the best position in the seedlings for the evaluation of oviposition preference. In laboratory conditions, that G. brimblecombei adults did not present preimaginal conditioning, despite the fact that the rearing host was a 3025 hybrid or E. camaldulensis IPEF. The densities of 10 and 15 psyllid adults per eucalyptus seedlings showed a higher number of eggs. The insects showed preference for the leaves close the apex for oviposition, being that the number of eggs decreased from the apex to the basis. In the choice test concerning attractiveness, genotypes E. grandis, E. urophylla, C-219 and H-13 were less attractive to psyllid, showing non-preference. In a choice test, the number of eggs oviposited in leaves of genotypes H-13, E. grandis and E. urophylla were lower when compared... (Complete abstract click electronic access below) / Doutor

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-24T12:10:01Z No. of bitstreams: 2 Bergamini, Leonardo Lima.pdf: 1174414 bytes, checksum: 8ab040a0c96a503f2c2dab35be6be5ea (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-24T15:37:12Z (GMT) No. of bitstreams: 2 Bergamini, Leonardo Lima.pdf: 1174414 bytes, checksum: 8ab040a0c96a503f2c2dab35be6be5ea (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-24T15:37:12Z (GMT). No. of bitstreams: 2 Bergamini, Leonardo Lima.pdf: 1174414 bytes, checksum: 8ab040a0c96a503f2c2dab35be6be5ea (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-06-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The process of host-plant selection is the main interface in the herbivore-plant interactions, with deep consequences for the ecology and evolution of those groups. In this work, we investigate some steps of the host-plant selection in two congeneric species of seed beetles. In the first chapter, we assess the oviposition pattern and larval survival in the seed-beetle G. cavillator to evaluate whether oviposition site choices maximize offspring survival, accounting for the spatially hierarchic structure of the system. In the second chapter, we analyze the fine-scale positioning of G. speculifer eggs, and explore the role of geometric constraints in the egg distribution patterns. Altogether our results exemplify how small differences in key traits of the host-plant selection can lead to significant differences in the interaction between herbivore insects and their host plants. / O processo de seleção de plantas hospedeiras é a principal interface nas interações herbívoro-planta, com profundas consequências para a ecologia e evolução destes grupos. Neste trabalho investigamos algumas etapas da seleção de hospedeiras em duas espécies co-genéricas de besouros bruquíneos. No primeiro capítulo avaliamos o padrão de oviposição e de sobrevivência das larvas de G. cavillatorpara testar se as escolhas das fêmeas estão de acordo com as expectativas da teoria de oviposição ótima, considerando a estrutura espacialmente hierárquica do sistema. No segundo capítulo analisamos a seleção em fina-escala da posição dos ovos nas vagens pelas fêmeas de G. speculifer, e exploramos o papel da restrição geométrica da vagem em definir o padrão de distribuição dos ovos. Tomados em conjunto, os resultados dos dois capítulos exemplificam como pequenas diferenças em atributos-chave do processo de seleção de hospedeiras podem levar a importantes diferenças na interação entre insetos herbívoros e suas plantas hospedeiras.

Many insects form close relationships with microbial symbionts. Insect symbionts can provide novel phenotypes to their hosts, including influencing dietary breadth. In the polyphagous cowpea aphid, Aphis craccivora, the facultative symbiont Arsenophonus improves aphid performance on one host plant (locust), but decreases performance on other plants. The goal of my thesis was to investigate the mechanism by which Arsenophonus facilitates use of locust. First, I assembled an Aphis craccivora-Arsenophonus-Buchnera reference transcriptome to conduct RNAseq analysis, comparing gene expression in aphids feeding on locust and fava, with and without Arsenophonus infection. Overall, few transcripts were differentially expressed. However, genes that were differentially expressed mapped to a variety of processes, including metabolism of glucose, cytoskeleton regulation, cold and drought regulation, and B-vitamin synthesis. These results imply that Arsenophonus is producing B-vitamins, which might be deficient in locust. In a second set of experiments, I used qPCR to test whether symbiont function across host plants might be mediated by bacterial titer. I measured relative Arsenophonus abundance across plants, and found Arsenophonus titer was variable, but generally greater on locust than fava. In summary, my results suggest that Arsenophonus synthesis of B-vitamins should be further investigated and may be mediated by bacterial titer.

Objective – research the pine wood nematodes Bursaphelenchus sp. situation in Lithuania. Goals: 1. Research of native pine wood nematode species composition in Lithuania; 2. Research of preconditions for harmful pine wood nematode species to enter Lithuania; 3. Research of conditions for non-native pine wood nematode species to establish, breed and spread; 4. Research of consequences if harmful species becomes established in Lithuania, anticipate pest management options. Object of the study – coniferous (pine) forests in Lithuania and companies, processing imported wood. Methods. Samples were taken in coniferous clearcuts and wood processing companies from the stained wood or wood with evidence of Monochamus activities. Nematodes were extracted sing Baermann method. Preconditions for nematodes to enter Lithuania, establish and spread were analysed using statistical and literature sources. Strengths, weaknesses, opportunities, threats (SWOT) analysis was applied to the situation of Bursaphelenchus in Lithuania. Results. 27 forest enterprises and 62 wood processing companies were studied. For the first time in Lithuania non-pathogenic species Bursaphelenchus mucronatus was found. Assessement of conditions for wood nematodes in the country (import assortment and volume, countries, host plants and potential vectors), real probability for harmful species, particularly Bursaphelenchus xylophilus, to enter, establish and spread was defined. Existing quarantine system might... [to full text]