Overbrowsing by ungulates decimates plant populations and reduces diversity in a variety of ecosystems, but the mechanisms by which changes to plant community composition influence other trophic levels are poorly understood. In addition to removal of avian nesting habitat, browsing is hypothesized to reduce bird density and diversity through reduction of insect prey on browse-tolerant hosts left behind by deer. In this study, we excluded birds from branches of six tree species to quantify differences in songbird prey removal across trees that vary in deer browse preference. Early in the breeding season, birds preyed on caterpillars at levels proportional to their abundance on each host. Combining these data with tree species composition data from stands exposed to experimentally controlled deer densities over 30 years ago, we tested whether overbrowsing by white-tailed deer reduces prey biomass long after deer densities are reduced. Our analysis predicts total prey availability in the canopy of regenerating forests is fairly robust to historic exposure to high deer densities, though distribution of prey available from host species changes dramatically. This predicted compensatory effect was unexpected and is driven by high prey abundance on a single host tree species avoided by browsing deer, Prunus serotina. Thus, while we confirm that prey abundance on host trees can act as a reliable predictor for relative prey availability, this study shows that quantifying prey abundance across host trees is essential to understanding how changes in tree species composition interact with ungulate browse preference to determine prey availability for songbirds.

Please read the abstract in the section 00front of this document / Thesis (PhD (Entomology))--University of Pretoria, 2005. / Zoology and Entomology / unrestricted

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Tetraviruses are a family of small non-enveloped positive sense RNA viruses that exclusively infect members of the order Lepidoptera. Their replication biology is poorly studied because, with the exception of Providence virus (PrV), tetraviruses are unable to replicate in tissue culture cells. The overall aim of the research described in this thesis was to develop a fundamental understanding of the replication of tetraviruses, focussing on the site of replication within host cells and in particular, the subcellular localisation of the viral replicase. Helicoverpa armigera stunt virus (HaSV, Genus: Omegatetravirus) was chosen for this study because it is the only tetravirus for which the cDNAs have been shown to be infectious. In the absence of tissue culture cell lines susceptible to HaSV infection, the approach was to use confocal fluorescence microscopy to examine the subcellular localisation of the HaSV replicase fused to enhanced green fluorescent protein (EGFP) in mammalian and insect tissue culture cells. The replicase (with EGFP fused at its C-terminus) localised to punctate structures throughout the cytoplasm of transfected HeLa and Sf9 cells. These structures were then shown – using live cell imaging and time lapse photography – to behave similarly to cellular endocytic organelles and fluorescence partially overlapped with membranes containing the late endosomal marker protein CD63. Biochemical fractionation of Sf9 cells expressing the replicase via a recombinant baculovirus (as well as transfected HeLa and Sf9 cells expressing EGFP-replicase fusion proteins) demonstrated that the replicase was strongly associated with detergentresistant membranes (DRMs) in these cells. Deletion analysis of the replicase coding sequence revealed two regions involved in the generation of the punctuate structures. Firstly, the C-terminal half of the replicase RNAdependant RNA polymerase domain was found to be essential for targeting and the tight association with DRMs while the second region, within the Nterminal 44 amino acids, enhanced localisation through a combination of secondary structural elements and sequence-specific functions. A comparative immunofluorescence study on PrV, which replicates as a persistent infection in an insect midgut cell line, showed that the PrV replicase also localised to punctate structures in the cytoplasm. Biochemical fractionation showed that the replicase was also strongly associated with DRMs. This thesis describes the development of new experimental systems for the study of tetravirus replication biology and the data lead to the conclusion that the HaSV replicase associates with DRMs derived from alternate endocytic pathway organelles.

Since 1968 UK macro-moths have declined by 28%, with the most notable trends revealed for the south of England; the dual influences of climate change and intensive land use are thought to be the main drivers for this trend. This study aimed to determine the landscape and local-scale factors influencing moth abundance and species richness in intensive Northamptonshire farmland. The research consisted of four parts: 1. the analysis of historic county moth records using landscape-analysis, 2. Moth trapping in areas of intensive lowland farmland and subsequent local and fine-scale landscape-scale analysis of trap yields, 3. Moth movement studies along farmland hedgerows and 4. Moth visitation surveys of hedgerow flora. The results of the analysis of county moth records revealed that land-use statistics had a highly significant relationship with the abundance of moths across Northamptonshire. Woodland cover was found as having a positive relationship with the abundance of moths, but that urban cover was negatively associated. The farmland moth trapping study recorded a total of 121 species, the majority of which were generalist (98%) and none of which have Biodiversity Action Plans. For this trapping, hedgerow length, width and cross-sectional area, vegetative diversity and the numbers of hedgerow gaps all had an influence on the abundance of some of the species trapped, but no hedgerow or margin variables had a significant influence on overall abundance or species richness. Moth movement surveys found that a significant proportion of moths were travelling parallel along hedgerows (69% of moths observed at 1m from the hedgerow) in farmland and that moth activity was higher close to hedgerows. Nocturnal visitation surveys of hedgerow flora found that 53% of visitors were Lepidoptera and that the most visited species was Bramble (Rubus fruticosus agg.). The results of the combined studies suggest that land use influences moth abundance at a range of spatial scales and that hedgerows may be providing sheltered dispersal routes and nectar resources for these species.

Rising temperatures associated with climate change will alter the fundamental physiological processes of most ectothermic species. Drastic changes in catabolic and anabolic reaction rates exert strong effects on growth, reproduction, and consumption rates that cascade up through all levels of the biological hierarchy. This dissertation determined how climate warming might alter the important relationship between plants and insect herbivores, as mediated through changes in herbivore physiology. Consumption and fitness increased with temperature for almost all consumers. However, all consumers also exhibited a critical temperature, beyond which consumption declined rapidly through metabolism continued to increase. This mismatch in metabolic demands and energy intake reduced consumer fitness at high temperatures. Furthermore, increased metabolic nitrogen demand can induce nitrogen limitation in insect herbivores at high temperatures. These basic physiological changes can modify the way herbivores interact with plants in a number of ways. For example, the Japanese beetle, Popillia japonica, altered its feeding behavior on numerous host plant species, depending on host plant quality. Unfortunately, the effects of temperature on plant-herbivore interactions will be difficult to predict, as there was no predictable relationship between consumption and temperature across numerous plant-herbivore pairs. Finally, rising temperatures disrupt insect herbivore control of plant fitness, thereby altering one of the most important components of plant-herbivore interactions. Thus, climate change will fundamentally change the nature of plant-herbivore interactions in the future.

Aricoris Westwood, 1851 é um gênero Neotropical cujas larvas são mirmecófilas e que até o presente momento é constituído por 27 espécies. Dentro do gênero, o grupo constantius é representado por borboletas de médio a pequeno porte, de coloração marrom e facilmente confundidas com Satyrinae (Nymphalidae). Por formarem um complexo de espécies crípticas, apresentam uma história taxonômica confusa e tortuosa. Dessa maneira, aqui é proposta uma revisão taxonômica com abordagem integrativa, utilizando-se um gene mitocondrial (citocromo c oxidase subunidade I -COI) aliado a análise morfológica. O complexo constantius é recuperado como uma linhagem monofilética constituída de seis espécies: A. constantius (Fabricius, 1793), A. monotona (Stichel, 1910), A. tutana (Godart, [1824]), A. sp. 1 sp. nov. (Brasil: Distrito Federal, Goiás, Minas Gerais, São Paulo), A. sp. 2 sp. nov. (Brasil: Distrito Federal, Mato Grosso do Sul e Paraná) e A. sp. 3 sp. nov. (Brasil: Bahia e Minas Gerais). As espécies novas aqui descritas eram tratadas até então como A. tutana.Os resultados moleculares corroboram com os caracteres morfológicos. Neótipos são designados para Papilio constantius Fabricius, 1793 e Erycina tutana Godart, [1824], cujos tipos foram perdidos. Todas as espécies podem ser identificadas através de uma combinação de características de padrão alar e genitálias. Para auxiliar na identificação destas espécies, foram elaboradas diagnoses, ilustrações dos caracteres diagnósticos e uma chave de identificação. Os indivíduos adultos apresentam óleo em suas asas, indicando hábitos afitófagos no estágio larval. Além disso, A. constantius foi observada na natureza se alimentando de honeydew de hemípteros atendentes de formigas. Esse trabalho contribui com o conhecimento de Riodinidae, uma das famílias de borboletas menos estudadas, e ilustra a necessidade de uma abordagem integrativa na taxonomia deste grupo. / Aricoris Westwood, 1851 is a Neotropical genus whose larvae are myrmecophilous and, until the present moment, is constituted of 27 species. Within the genus, the group constantius is represented by medium to small butterflies of brown color and easily confused with Satyrinae (Nymphalidae). Because these butterflies form a complex of cryptic species, they present a confusing and tortuous taxonomic history. Thus, a taxonomic revision with an integrative approach is proposed herein, using a mitochondrial gene (cytochrome c oxidase subunit I – COI) allied to the morphological analysis. The complex constantius is recovered as a monophyletic lineage consisting of six species: A. constantius (Fabricius, 1793), A. monotona (Stichel, 1910), A. tutana (Godart, [1824]), A. sp. 1 sp. nov. (Brazil: Distrito Federal, Goiás, Minas Gerais and São Paulo), A. sp. 2 sp. nov. (Brazil: Distrito Federal, Mato Grosso do Sul and Paraná) e A. sp. 3 sp. nov. (Brazil: Bahia and Minas Gerais). The new species described herin were previously treated as A. tutana. The molecular results corroborate with the morphological characters. Neotypes are assigned to Papilio constantius Fabricius, 1793and Erycina tutana Godart, [1824], whose types were lost. All species can be identified through a combination of characteristics in the wing pattern and of genitalia. To assist in the identification of these species, diagnoses, illustrations of the diagnostic characters and an identification key were elaborated. Adult individuals have greasy in their wings, indicating aphytophagy in the larval stage. Furthermore, A. constantius was observed in nature feeding on honeydew produced by ant-tended Hemiptera. This work contributes to the knowledge of Riodinidae, one of the less studied butterfly families, and illustrates the need for an integrative approach in the taxonomy of this group.

The tropics are host to incredible insect diversity. One of the most charismatic groups that exhibit this diversity are the butterflies. Despite the tropical butterfly fauna being heavily researched, there remains much hidden diversity in the form of undescribed life histories and cryptic species. This is especially true among the species rich Nymphalidae, the brush-footed butterflies. Species in the genus Adelpha are known to be “the most trying taxonomically of all nymphalids” DeVries (1987), and as such are fruitful ground for uncovering unknown diversity. About half of the species within Adelpha have undescribed life histories, while A. serpa stands out within the genus in having remarkably wide host breadth, and thus potentially harbors cryptic diversity. Here we describe the life histories of two species of Adelpha from Costa Rica, and use an integrative approach to clarify species level boundaries within the Adelpha serpa-group. We conclude that A. serpa does not show significant evidence of harboring cryptic species, and appears to be a geographically widespread species and a hostplant generalist. Three additional species within the serpa-group show strong evidence of harboring cryptic species, and further research should be done to clarify these species relationships.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20954号 / 理博第4406号 / 新制||理||1633(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 沼田 英治, 准教授 森 哲, 教授 中川 尚史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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