The work carried out in this thesis involves the investigation of some reactions of heterocyclic compounds by a wide range of spectroscopic and kinetic techniques. Chapter 1 describes several methods, including stopped-flow spectrophotometry, high pressure kinetics and MNDO calculations, which are used to analyse the mechanism of the reaction of imidazole with diazonium ions. Chapter 2 describes the use of the temperature-jump technique to follow the extremely fast protonation of pyrroles. Diazonium ions are further investigated in Chapter 3 which examines the structure of p-nitrobenzenediazonium tetrafluoroborate by X-ray crystallography. The nature of other benzenediazonium ions and some of their complexes is also investigated by solid state 15N nmr spectroscopy. Chapter 4 switches the emphasis to nmr spectroscopy. The reactive intermediates of reactions of benzil with nitrogen heterocycles are investigated using 13c nmr spectroscopy in a kinetic application. Chapters 5 and 6 continue the use of nmr spectroscopy in the structural assignment of bilirubin and the determination of the nature of bilirubin inclusion complexes. Chapter 6 also examines by spectrophotometry the reaction used in the clinical analysis of bilirubin and the effect on this reaction of binding agents such as albumin and α-cyclodextrin.

The work of this thesis is concerned with the investigation of the propagation of waves in a magnetized plasma containing various parameter gradients, and with the stability of ion acoustic waves in a weakly collisional plasma with a strong temperature gradient. The thesis is divided into three sections. In the first section the intention is to derive in a compact and unambiguous tensor form the dispersion relation describing the propagation of waves in a magnetized plasma containing three-dimensional density and temperature gradients, an E̲⏜ B̲ drift, and differing temperatures parallel and perpendicular to the magnetic field. This is achieved by introducing and extending the polarized co-ordinate system first proposed by Buneman in 1961, and then carrying through the standard procedure of integration along unperturbed trajectories. The "local" approximation of Krall and Rosenbluth is used in order that an analytic result may be derived. The dispersion relation obtained includes certain moment tensors whose elements may be evaluated independently of the gradients involved in the problem. These elements may then be listed and the list referred to in order to obtain the elements required for a specific problem. The second section is concerned with the use of the theory and results of J.P. Dougherty to show that in the high-frequency regime the introduction of a small amount of collisions into a plasma is sufficient to disrupt the gyro-resonances which allow the existence of Bernstein waves at multiples of the gyro-frequencies perpendicular and near- perpendicular to the magnetic field. It is shown that a collision frequency v such that (k ρ) ⁻² ≲ v/Ω < (k ρ) ⁻¹ where k ρ >> 1 is sufficient to do this; k is the wave-number, ρ the Larmor radius, and the gyro-frequency. It is also shown that in this case the ion-acoustic dispersion relation is valid even for propagation perpendicular to the magnetic field. In the final section the result of the second section is used to derive a dispersion relation for high-frequency wave propagation in a weakly-collisional plasma containing an electron temperature gradient. The dispersion relation is solved numerically for various electron-ion temperature ratios and electron temperature gradient drift velocities. Earlier predictions, based on analytic calculations for small temperature ratios and drift velocities, are confirmed and some new results presented. In particular, it is shown that a temperature gradient is a more effective destabilizing agent then a simple drift between ions and electrons. Dispersion plots are given, along with analytic and physical explanations of their form; finally neutral stability curves are presented. The thesis concludes with a summary of the results obtained.

No description available.

I use field observations, experiments and molecular techniques to describe the social biology of the sweat bee Lasioglossum calceatum, and to investigate the mechanisms underlying social polymorphism and body size in this species. I also investigate environmental constraints on sociality, and the impact that workers have on productivity, in the obligate social species L. malachurum. Chapter 1 introduces sweat bees as a study system, and reviews social behaviour within the group. I then provide concise introductions to the study species. In Chapter 2 I show that L. calceatum exhibits latitudinal social polymorphism in the UK, with only bees in the south expressing primitive eusociality. I then describe the social life cycle from continuous field observations, with reference to genetic data. In Chapter 3 in I examine environmental and genetic components of social phenotype in L. calceatum by conducting a field transplant of bees from the north of the UK to the south. Social phenotype is likely to be predominantly determined by fixed genetic differences between social and solitary populations. Chapter 4 examines whether the transition between social and solitary nesting results in saw-tooth size clines in L. calceatum and Halictus rubicundus. Overall, both species exhibit converse-Bergmann clines but not saw-tooth clines. In Chapter 5 I transplant the obligate social sweat bee L. malachurum to the north of the UK, to test whether sociality is constrained by season length. Phenology was considerably delayed such that the life cycle could not be completed. In Chapter 6 I investigate queen quality, productivity and costs of worker production in L. malachurum, by manipulating the number of workers per nest. I show that queens probably incurs costs from producing more workers, and that a possible mechanism is that workers from larger groups may be of lower quality. In Chapter 7 I bring together key findings of the thesis, and comment on future directions.

The honey bee, Apis mellifera, is important both ecologically and economically. Pests and diseases are arguably the greatest current challenge faced by honey bees and beekeeping. This PhD thesis is focused on honey bee disease control including natural resistance by means of hygienic behaviour. It contains eleven independent experiments, ten on honey bee pests and diseases and their control and resistance, and one on stingless bees. Each is written as a separate chapter, Chapters 4 and 14 of this thesis. Chapter 4: How effective is Apistan® at killing varroa? This shows that Apistan is not very effective at killing varroa, presumably because of resistance. It also shows that a single Apistan treatment resulted in the next treatment being significantly less effective, indicating strong selection for resistance. Chapter 5: Towards integrated control of varroa: comparing application methods and doses of oxalic acid on the mortality of phoretic Varroa destructor mites and their honey bee hosts. This shows that oxalic acid can be highly effective at killing varroa mites under beekeeping conditions in broodless hives in winter. However, varroa mortality is affected by application method and dose. In addition, bee and colony mortality and colony performance are also affected by application method and dose. The results of this chapter shows that sublimation is the best method, in that it gives greater varroa mortality at lower doses, and results in no harm to the colonies. In fact, colonies treated via sublimation had significantly more brood in spring that controls, and lower winter mortality, although this difference was not significant. Chapter 6: Towards integrated control of varroa: varroa mortality from treating broodless winter colonies twice with oxalic acid via sublimation. This shows that two treatments of 2.25 g oxalic acid via sublimation at an interval of 2 weeks in broodless honey bee colonies in winter result in greater varroa mortality than a single treatment, 99.6% vs. 97%. Making a second oxalic acid treatment was not harmful as the performance (frames of brood, queen and colony survival) of the twice-treated colonies over the next 4 months was not significantly different to the once-treated control colonies. Chapter 7: Towards integrated control of varroa: Efficacy of early spring trapping in drone brood. This indicates that trapping in drone brood in spring is probably not sufficiently effective to be able to control varroa populations on its own. It shows that trapping varroa in capped drone cells in early spring is not highly effective at controlling varroa. The first and second test frames of drone foundation removed 44% and 48% of the varroa, respectively. Chapter 8: Towards integrated control of varroa: Monitoring honey bee brood rearing in winter and the proportion of varroa in small patches of sealed cells. This shows that December is the month with the least brood. However, winter reduction in brood rearing varied among years and even in December some colonies still had sealed brood. Although the amounts of sealed brood were low, even a small patch of c. 500-600 sealed cells could contain 14% of the varroa in a colony. This will halve the duration of control provided by an oxalic acid treatment. Chapter 9: Towards integrated control of varroa: effect of variation in hygienic behaviour among honey bee colonies on mite population increase and deformed wing virus incidence. This shows clearly that hygienic behaviour reduces the one-year population growth of varroa in honey bee colonies by more than 50% and reduces the levels of deformed wing virus by more than 1000 times. Chapter 10: Hygienic behaviour saves the lives of honey bee colonies. This shows that hygienic behaviour saves the lives of honey bee colonies with shrivelled wings, a visible symptom of deformed wing virus that is considered a predictor of colony death. Over one year, only 2 of 11 colonies requeened with a non-hygienic queen survived, versus 13 of 15 requeened with a hygienic queen. Chapter 11: Hygienic behaviour by non-hygienic honey bee colonies: all colonies remove dead brood from open cells. This shows that all honey bee colonies are highly hygienic in response to dead or diseased brood in open cells. All larvae killed by freezing with liquid nitrogen and larvae with chalkbrood disease were removed. This was true even for colonies with low levels of removal of dead brood from sealed cells, which would be considered as non-hygienic colonies. Chapter 12: Removal of larvae infected by different strains of chalk brood and other fungi by hygienic and non-hygienic bee colonies. This shows that hygienic and non-hygienic honey bee colonies are highly hygienic in response to diseased larvae killed with different strains of fungus in open cells. Chapter 13: Hygienic behaviour in Brazilian stingless bees. This shows that the three stingless bee species studied (Melipona scutellaris, Scaptotrigona depilis, Tetragonisca angustula) all have high levels of hygienic behaviour, quantified as the removal of freeze-killed brood, in comparison to the honey bee Apis mellifera. In S. depilis there was considerable variation in hygienic behaviour among colonies, and hygienic colonies removed more brood affected by a naturally-occurring disease which we discovered and for which the causative agent remains to be identified. Chapter 14: First record of small hive beetle, Aethina tumida Murray, in South America. This reports the discovery of adult small hive beetles, Aethina tumida, in honey bee, Apis mellifera, hives in an apiary in Brazil, in March 2015. This is the first record for South America of this honey bee pest.

This thesis focuses on hygienic behaviour in honey bees. In beekeeping, brood diseases incur heavy economical and biological costs and are no longer effectively treated with chemicals. Previous research has shown how hygienic behaviour, a trait expressed by c. 10% of unselected colonies, can be effective in reducing the impact and presence of such diseases. Hygienic behaviour is experimentally measured using the freeze-killed brood (FKB) bioassay and can be increased by selective breeding, generating lines of hygienic colonies. Chapter 4 demonstrates that the relative rarity of hygienic behaviour in unselected colonies is not because it incurs a cost via the removal of healthy brood. Chapter 5 - 6 focus on the impact of external factors on hygienic behaviour. Specifically, we demonstrate that the presence of brood, amount of food, and strength of the colony affect hygienic levels (Chapter 5). Chapter 6 shows that hygienic behaviour does not correlate with agressiviness or agitated behaviour. When breeding honey bees, it is possible to exploit instrumental insemination to have complete control over the genetic composition of the resulting progeny. This technique is however laborious and requires particular equipment and training. In Chapter 7 we show that it is possible to obtain acceptable levels of hygienic behaviour without artificial insemination. Chapter 8 illustrates how we obtained the first breeing line of hygienic honey bees through a selective breeding program that saw its first milestone in autumn 2013 when we detected high levels of hygienic behaviour. The results obtained represent the foundation for future research projects. Chapter 9 presents a valid, minimal methodology to keep virgin queens. We tested a variety of methods and factors to determine the best, mos cost-effective way to maintain queens for the week prior their introduction into a queenless hive. The results obtained provide some insights on both basic and applied aspects of honey bee breeding for hygienic behaviour and represent the foundation of what will be an ongoing selection programme towards a disease-resistant honey bee.

As is much of the world's biodiversity, bees and other flower-visiting insects are in global decline, largely due to human activities. The impacts of humans on wildlife can be ameliorated, at least to an extent, by wildlife-friendly management practices in both rural and urban areas. This thesis comprises two introductory chapters (Part 1), followed by a series of ten research chapters (Parts 2 - 5) aimed at informing management practices that encourage bees and other flower-visiting insects in urban areas, and ends with a concluding chapter (Part 6). The projects are grouped in four parts making contributions to four broad areas of research. Part 2 is concerned with evaluating the attractiveness of ornamental garden plants to insect flower-visitors. Individual projects examine the advice currently available to gardeners via recommended plant lists, and describe surveys of plant varieties grown in a public garden (Southover Grange garden, Lewes), a Plant Heritage national collection of asters (Picton Garden, Malvern), and the experimental gardens planted on campus of the University of Sussex, Brighton, as well as in towns of Plumpton and Magham Down. Part 3 evaluates the attractiveness to insects of urban wild flowers, including those growing in amenity grass areas in parks, and the effects on their abundance and diversity of the various mowing regimes, as well as the attractiveness of the common autumn flowering ivy. Part 4 uses waggle dance decoding to investigate honey bee foraging in the urban landscape of Brighton, with an additional particular focus on foraging on spring-blooming oilseed rape in the surrounding agricultural land. Part 5 examines an aspect of good practice in urban apiary set up, the use of lattice fence or hedge barriers, which should facilitate beekeeping in urban areas, including in private gardens and allotments.

Bumblebees are important pollinators of crops and wildflowers and are currently in global decline. The main drivers of decline include agricultural intensification, climate change, invasive species, pesticides, parasites and pathogens and it is thought that these multiple stressors act together to impact populations. However, their relative importance is unknown and there are wide knowledge gaps in relation to the current status of species populations and their response to environmental variables such as climate, habitat and land use change. Citizen science offers a potential method of collecting data at a broad enough scale to measure species population responses to environmental stressors and it has successfully been applied to other taxa, particularly UK birds and butterflies. This thesis investigates the use of citizen science to address the current knowledge gaps in the status of UK bumblebee populations by analysing volunteer-collected data on current distribution and abundance trends in relation to habitat and climate change. Results are compared to previous studies to infer long-term changes in population dynamics. The value of applying citizen science methods to bumblebee monitoring is highlighted, revealing evidence for decline of some common species and the recent retraction of rare species to their climatic optima. The main findings reveal a potential impact of climate on the distribution of winter-active bumblebees. They also indicate that, while urban parks and gardens provide refuge for bumblebees in an otherwise impoverished landscape, urbanisation may favour short-tongued generalist species over long-term specialists. The outcomes of this thesis have important management implications for UK bumblebee populations including the need for reassessment of the conservation status of B. soroeensis and the sympathetic management of urban parks and gardens for longtongued specialists through the provision of suitable forage material.

[by] A. Ross Johnson. / Based on the author's thesis, Columbia. / Bibliography: p. [245]-264.

Cette thèse vise à démontrer l’importance de la PI 3-kinase dans la régulation hormonale de la réabsorption rénale du sodium. Ce contrôle extrêmement précis, notamment par l’aldostérone, s’effectue au niveau du néphron distal. Nous avons utilisé comme modèle l’épithélium de cellules A6, dérivées du tubule distal de Xenopus Laevis. Le transport unidirectionnel de sodium s’effectue en deux étapes: depuis, l’entrée à partir du milieu luminal par des canaux sodiques épithéliaux (ENaCs) insérés dans la membrane apicale, jusqu’à la sortie vers le liquide extracellulaire par des pompes Na+/K+-ATPases, situées dans la membrane basolatérale. L’insuline augmente ce transport de sodium et la PI 3-kinase semble assurer un rôle-clef. Nous avons étudié l’importance de chacun des 3-phosphoinositides produits par la PI 3-kinase, sur le transport du sodium en ajoutant au milieu cellulaire des formes «perméantes» de ces phospholipides. Parmi ceux-ci, le PIP3 et dans une moindre intensité le PI(3,4)P2 augmentent ce transport. En revanche, le PI3P, le PI(3,5)P2, ainsi que le PI(4,5)P2 n’ont pas d’effet sur lui. Nous avons démontré par la technique du Western blot que la 3-phosphatase PTEN est exprimée dans les cellules A6. Cette phosphatase déphosphoryle le PIP3 en PI(4,5)P2. Nous avons surexprimé PTEN dans les cellules A6. Ceci réduit l’augmentation du transport du sodium induite par l’insuline, ainsi que celle induite par addition de la forme «perméante» de PIP3. Nous avons ensuite vérifié si d’autres agents qui activent la PI 3-kinase, stimulent également le transport de sodium à travers cet épithélium. A cette fin, nous avons d’abord vérifié que l’EGF et le peroxyde d’hydrogène, connus pour stimuler la PI 3-kinase dans d’autres systèmes, activent également cette enzyme dans les cellules A6. Tous deux augmentent ce transport. L’importance de l’augmentation induite par H2O2 est comparable à celle de l’insuline, tandis que l’effet de l’EGF est plus transitoire. Un dosage d’activité de la PI 3-kinase, nous a permis de démontrer que l’intensité de l’activation de la PI 3-kinase est corrélée avec l’amplitude de l’augmentation du transport du sodium. Par comparaison avec l’effet de l’insuline et de l’H2O2, l’EGF augmente faiblement l’activité de la PI 3-kinase et induit une faible augmentation du transport. Nous avons également examiné si la voie des MAPK influence la stimulation du transport du sodium par ces différents agents. Cette voie ne semble pas impliquée dans l’effet de l’insuline ou du peroxyde d’hydrogène. Par contre, elle diminue la stimulation du transport de sodium par l’EGF. L’effet de l’EGF sur le transport semble résulter d’un compromis entre l’activation de la voie de la PI 3-kinase qui l’augmente et l’activation de la voie des MAPK qui le diminue. En conclusion, une augmentation de PIP3, soit par addition de PIP3 exogène, soit par augmentation endogène sous l’effet de l’insuline ou d’autres agents stimulant la PI 3-kinase, augmente le transport du sodium tandis qu’une diminution de PIP3 endogène (par surexpression de PTEN) le diminue. L’importance de l’activation de la PI 3-kinase est quantitativement corrélée avec l’importance de l’augmentation du transport du sodium. La PI 3-kinase est donc un médiateur-clef de la régulation rénale de ce transport.