Productive, resilient and sustainable agricultural systems are required to meet the immediate needs of a burgeoning human population, while avoiding ecosystem collapse. Agriculture provides food, fiber, fuels and other products for our current population of 7 billion and is still the major livelihood for 40% of people worldwide. By replacing natural habitat and employing chemical inputs, agriculture also negatively impacts biodiversity and impairs the provision of ecosystem services. This poses a challenge for agriculture as these impacted services are often those required for high yielding and high-quality crop production. Evidence is accumulating that agricultural management can safeguard biodiversity and ecosystem services while maintaining production, but critical questions remain concerning how management actions are shaped by broader landscape pattern and how these actions influence service-providing organisms across space and time. Through a combination of observational, experimental and modeling approaches, my dissertation examines relationships between management actions, landscape pattern and service-providing organisms using crop pollination by wild bees as a model system. First, I investigate how local management and landscape pattern interact to affect pollination services and the abundance and diversity of native bees in Vermont, USA. I then use two established models of pollinator foraging to investigate whether one popular intervention, enhancing floral resources, improves crop visitation, and whether pollinator traits and landscape pattern influence this effect. Next, I use a national data set of native bee diversity to test whether habitat enhancements increase taxonomic and functional diversity of native bee communities. Finally, I investigate whether resource continuity provided by consecutively blooming crops benefits wild bee communities. These four chapters contribute ecological knowledge of plant-animal interactions in anthropogenic landscapes. My findings also provide land managers with clear information about the effects of landscape conservation and farm management on crop pollinators.

Native bees are only recently gaining attention for the extent to which they aid in pollination and ecosystem services. These services are threatened by predictions of warming temperatures if bees are not able to respond. Voltinism - the number of generations produced annually- can strongly influence thermal conditions experienced by both developing and adult bees based on emergence strategies for each voltinism type. Differences in experienced thermal conditions brought on by climate change could therefore affect upper thermal limits (UTL) in bees. This study observes UTLs across a foraging season within and among native bee species vi to elucidate the potential response by bees to a warming climate. Bees were collected across the field season in Central Virginia and subjected to dynamic ramping trials to determine the fatal knockdown point (FKP). Results show in both univoltine and multivoltine bees an increase in upper thermal tolerance as the foraging season progresses (in quadratic and linear fashions respectively). Within multivoltine bees, FKP was related to nest type; with stem-nesting bees having the highest FKP. All average FKPs were higher than historic air temperatures of the study region, but within several degrees of the highest recorded maximum temperature. The diversity of responses in native bees provides evidence for both genetic and plastic responses to extreme temperature. While bees still face a potential myriad of other issues brought on by climate change, the observed increases in FKP across warming temperatures offer tentatively hopeful predictions for limited physiological responses in native bees to a warming climate

Bibliography: leaves 256-323.

Bee declines have been reported globally and habitat loss and degradation due to urbanization and agricultural intensification are two of the primary drivers. Native bees play a critical role in plant reproduction, and declines in abundance and diversity of bees are expected to impact flowering plant biodiversity and productivity of insect pollinated agricultural crops. Habitat restoration can help mitigate declines by increasing the amount and quality of available bee habitat. However, outside of agroecosystems bees are rarely specified in restoration targets and little is known about how they respond to habitat restoration. My thesis addresses this knowledge gap by: (1) documenting the structure and function of the native bee community at a restored wet meadow to establish a baseline for future monitoring activities, (2) comparing the influence of two restoration approaches on the established bee community, and (3) exploring changes in functional groups and pollination function with time since restoration. I sampled bees at degraded, restored, and (semi)natural habitats at 12 sites in four locations in southern Ontario. I used a combination of structural (abundance, richness, and evenness) and functional (guilds based on social and nesting habits and plant-pollinator interaction networks) characteristics to describe and compare bee communities. I collected a total of 10,446 bees from 30 genera and six families representing a range of phenologies, social behaviours, and nesting habits. At Dunnville Marsh, a restored wet meadow, I collected 5,010 bee specimens from 27 genera and six families. The bee community at Dunnville Marsh was diverse and well connected within 4-6 years of restoration, emphasizing the importance of wet meadows as native bee habitat. However, wood nesters and cleptoparasites were relatively uncommon suggesting that the community may be less stable compared to older habitats. Between 2005 and 2008, individual fields at Dunnville Marsh were dug with pits and mounds before planting and seeding or were seeded into weedy ground. Digging pits and mounds did not convey a clear advantage to the establishing bee community, but genus richness was greater in pit and mound sites (p=0.04). As well, the restoration approach used influenced the relative representation of guilds within the community. Ground nesters and wood nesters were significantly more abundant in pit and mound treated sites (p<0.001), perhaps reflecting the larger amounts of bare ground (p<0.001) and the greater potential for sapling survival on mound tops. Stem nesters were more abundant in planted sites (p<0.001), and floral richness and abundance did not differ between the two restoration approaches. Finally, diversity and evenness of guilds based on social and nesting habits increased with age since restoration, indicating that communities in (semi)natural habitats are more functionally diverse than those in restored habitats, but that communities in restored habitats are more functionally diverse than those in degraded habitats. Relative abundance of guilds changed with age since restoration in ways that reflected structural habitat changes associated with succession. Degraded sites had the highest relative abundance of ground nesters, while (semi)natural sites had the highest relative abundance of wood nesters. Plant-pollinator interaction networks did not demonstrate clear trends with respect to age since restoration, but indicated that communities that establish in response to non-targeted restorations can be diverse, robust to extinction, and well connected.

Understanding changes in materials properties as a function of size is crucial for both fundamental science development and technological applications. Size restriction results in quantum confinement effects that modify both energy level structures and electron dynamics of solid materials. This study investigates individual quantum states in a single nanocrystal. Single electron charging effects in gold and semiconductor nanocrystals are observed. Charging effects are found to be dominant in samples, where the nanocrystals are weakly coupled to the substrate. For nanocrystals strongly coupled to the substrate, nanocrystal-substrate tunneling rate is larger than tip-nanocrystal tunneling rate. Therefore, the resulting peaks in the dI/dV spectrum are attributed to tunneling through the energy levels of the nanocrystal. A newly developed nanocrystals BEES technique is used successfully to further explore quantized energy levels and electron dynamics in single gold nanocrystals. BEES samples were grown successfully by depositing $unit[10]{nm}$ thick gold on silicon substrates. Nanocrystals are chemically attached to the gold substrate using a self assembled monolayer (SAM) of xyelendithiol molecules. Immobile and single isolated nanocrystals were imaged at low temperature. A BEES turn-on voltage of $unit[0.84]{V}$ was found on nanocrystal-free region of the substrate. The BEES spectrum acquired on a single gold nanocrystal is found to be attenuated by a factor of 10 when compared with BEES acquired on the substrate. The attenuation is attributed to electron relaxation to lower energy states before tunneling out of the nanocrystal. The measured hot electron lifetimes from experimental data were found to be on the order of $unit[16]{picoseconds}$, which is a long time compared to lifetimes in bulk metals or large nanocrystals. The long measured lifetimes result from the molecular-like energy level structures of these small nanocrystals.

In this dissertation, we explore the properties of correlation structure for spatio-temporal point processes and a quantitative spatial process. Spatio-temporal point processes are often assumed to be separable; we propose a formal approach for testing whether a particular data set is indeed separable. Because of the resampling methodology, the approach requires minimal conditions on the underlying spatio-temporal process to perform the hypothesis test, and thus is appropriate for a wide class of models. Africanized Honey Bees (AHBs, Apis mellifera scutellata) abscond more frequently and defend more quickly than colonies of European origin. That they also utilize smaller cavities for building colonies expands their range of suitable hive locations to common objects in urban environments. The aim of the AHB study is to create a model of this quantitative spatial process to predict where AHBs were more likely to build a colony, and to explore what variables might be related to the occurrences of colonies. We constructed two generalized linear models to predict the habitation of water meter boxes, based on surrounding landscape classifications, whether there were colonies in surrounding areas, and other variables. The presence of colonies in the area was a strong predictor of whether AHBs occupied a water meter box, suggesting that AHBs tend to form aggregations, and that the removal of a colony from a water meter box may make other nearby boxes less attractive to the bees.

Environmental issues have gained importance due to global environmental threat, such as depletion of energy resources and the impacts of climate change. The building sector is responsible for almost half of the impacts on the environment. Hence, this study focuses on the importance of environmental impacts of building materials. In this regard, firstly, sustainability indicators for building materials were determined and the environmental impacts of selected building materials were studied. Then, the evaluation system BREEAM and the evaluation software BEES were selected and used to evaluate one block of bachelor flats and one of housing units in ODTUKENT, which is located in the Middle East Technical University campus in Ankara, Turkey. Building materials used for the construction of walls, floors and roofs were evaluated according to the indicators accepted by BREEAM and BEES. The results for both units were compared and it was seen that the block of bachelor flats takes lower ratings than the triplex unit for BREEAM and also lower values for BEES. Therefore, the block of bachelor flats has less environmental impact than the triplex unit. While evaluating the materials an exact match for all the materials used in the case buildings could not be found in these tools. Hence, it was not possible to exact results for these materials. In this regard, countries should determine their own evaluation indicators and develop their evaluation systems.

During spring, it has been observed that several thousand bees leave their hive, and settle on some object such as a tree branch. Some of the scout bees search for a suitable place where a new hive can be set up, while the rest collect together to form a swarm. Heinrich (J. of Exp. Biology 91 (1981) 25; Science 212 (1981) 565; Scientific American 244:6 (1981) 147) has done some experiments with free and captive swarms. His observations are as follows. (1)The core (centre) temperature is around 35°C irrespective of the ambient temperature. (2)The mantle (outer surface) temperature exceeds the ambient temperature by 2- 3°C, provided the ambient temperature is greater than 20°C. Otherwise the mantle temperature is maintained around 17°C. (3) The temperature gradient vanishes just before take-off of the swarm. The present work attempts to predict temperature profiles in swarms and compare them with the data of Heinrich. A continuum model involving unsteady heat conduction and heat generation within the swarm is used. Heat loss from the outer surface of the swarm by free convection and radiation is accounted for approximately. To simplify the analysis, internal convection within the swarm is neglected. The energy balance equation is solved using the finite element method. The effective thermal conductivity (k) is determined by comparing model predictions with data for a swarm of dead bees. The estimated value of k is 0.20 W/m-K. Both spherical and a non-spherical axisymmetric shapes are considered. Considering axisymmetric swarms of live bees, temperature profiles are obtained using various heat generation functions which are available in literature. The effective thermal conductivity is assumed to be the same as that for the swarm of dead bees. Results based on a modified version of Southwick's heat generation function (The Behavior and Physiology of Bees, pp. 28-47, 1991) are qualitatively in accord with the data. The predicted maximum temperature within the swarm and the temperature at the lower surface of the swarm at the ambient temperature of 5°C are 34°C and 17-20°C, respectively. These are comparable to the measured values of 36°C and 19°C. The predicted maximum temperature within the swarm and the temperature at the lower surface of the swarm at the ambient temperature of 9°C are 36.5°C and 17-22°C, respectively. These are comparable to the measured values of 35°C and 19°C. The predicted oxygen consumption rates are 2.55 ml/g/hr for a swarm of 5284 bees at an ambient temperature Ta = 5°C and 1.15 ml/g/hr for 16,600 bees at Ta = 9°C. These are of the same order as the measured values (2 ml/g/hr for 5284 bees at Ta = 4.4DC and 0.45-0.55 ml/g/hr for 5284 bees at Ta = 10°C). Omholt and Lanvik (J. of Theoretical Biology, 120 (1986) 447) assumed a non-uniform steady state profile and used it to estimate the heat generation function. Using this function in the transient energy balance, it is found that their steady state profile is unstable.

Thesis (M.S.)--Mississippi State University. Department of Entomology and Plant Pathology. / Title from title screen. Includes bibliographical references.

Cooperation is pervasive in nature but paradoxically also provides opportunity to cheaters. My dissertation involves the study of both cooperation and conflict in two species of Megalopta bees. Megalopta is a Neotropical genus of halictid bees whose biology is characterized by complex life cycles that can range from solitary to eusocial. These bees nest in dead wood and forage under dim light conditions. Megalopta’s nests are inhabited by an extensive array of organisms and each nest therefore constitutes a miniature ecosystem providing opportunities for cooperation and conflict, both within and between species. I first delineate the social structure of M. genalis and M. ecuadoria nests in several Panamanian populations and integrate the factors that play a role in the behavioral decisions of females when joining a social group or not. Within a kin-selection framework, I discuss how genetic relatedness plays a role in the formation of social nests. Second, I investigate the conflict between host bees and a congener social parasite, and I elucidate reproductive structures that are relevant for understanding the evolution of parasitism. Finally, I describe a cleaning mutualism between Megalopta bees and their mite associates. Bee-mite associations encompass a broad spectrum of interspecific interactions. Some bee-mites are thought to perform cleaning services for their hosts in exchange for suitable environments for reproduction and dispersal. Field observations and experimental manipulation reveal a significant correlation between the presence of mites and the absence of fungi inside the brood cells, as well as between the absence of mites and increased bee mortality. This study therefore provides evidence of the sanitary effect of mites in nests of Megalopta bees. This bee-mite association constitutes one of the few examples of terrestrial cleaning mutualisms. / text