Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 83-85.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 104-112).

Several insect species can use the amino acid proline as a major energy substrate, a unique characteristic of these animals. Although initially thought to be limited to blood feeding dipterans, studies revealed this capability may be more widespread. Recent work showed that the bumblebee Bombus impatiens can oxidize proline at a high rate, as measured using isolated flight muscle. However, its role as a metabolic fuel to power flight is unclear. To elucidate the extent to which proline is oxidized to power flight and how its contribution changes during flight, metabolites of central carbon and proline metabolism were profiled at key time points in hemolymph and flight muscle tissue. Analysis using UPLC-MS-QTOF has revealed trends in fuel use and changes in pathway metabolites. Of 29 targeted metabolites, 18 were detected in flight muscle tissue. Two flight experiments were conducted and concentrations of metabolites at the end of prolonged flight are similar to those at rest, or have decreased significantly. In total, 14 of 19 metabolites significantly changed in concentration. The results correspond to a model of fuel use during flight, which states that proline is oxidized at the onset of flight, then carbohydrates take over as the main fuel, accompanied by a decrease in glycogen. By 8 minutes of flight, metabolite concentrations stabilize and flight performance does not change. Patterns in metabolite fluctuations suggest proline is used to supplement the Krebs cycle, and carbohydrates are the main fuel, maintained by glycogen stores. This indicates homeostatic regulation of intermediates and replenishment of fuels, or depletion of fuels due to their recruitment for ATP generation. This targeted metabolomics approach will clarify the role of proline and carbohydrate metabolism and pathway regulation during flight in B. impatiens.

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This two-part study addressed the foraging flight performance of bumble bees (Bombus spp.) burdened with artificially induced wing wear between fireweed flowers (Chameriion angustifolium). The first part of the study examiend the effects of wing wear and interflower distance on travel time. The second part of the study addressed the effect of mean wing clipping and wing asymmetry on flight biomechanics (flight distance, velocity, acceleration, and deceleration) and flight biomechanics (flight distance, velocity, acceleration, and deceleration) and flight path (displacement from a bee-line). Bees with wing wear flew faster between flowers spaced more sparsely, possibly compromising accuracy in choosing rewarding flowers. Flight biomechanics were relatively unchanged by wing wear. Bees with low wing loss and little asymmetry increased slightly in acceleration and deceleration. Bees with high mean wing loss and high asymmetry flew further and higher between flowers compared to control bees. When the high mean wing loss was symmetrical, bees flew as far and as high as control bees. The results of these studies suggest the resilience of bumble bees to induced wing wear, with little change in flight performance. / 64 leaves ; 29 cm.

The consequences to wildlife of living in contaminated areas with chronic low-dose rates of radiation are still relatively unknown. Laboratory studies using acute radiation have demonstrated that invertebrates are relatively radioresistant compared to other taxa. However, there is little scientific evidence to show how chronic low dose rates affect invertebrates. This is problematic for understanding the consequences to wildlife living in highly contaminated areas and also testing assumptions made for invertebrates by the International Commission on Radiological Protection (ICRP). This thesis was designed to address a number of recommendations have been suggested to improve radioecological studies and help reduce the uncertainty as to effects at low dose rates. These include environmentally relevant laboratory studies (Chapters 2 and 4), improved dosimetry and dose assessments (Chapter 3), investgating confounding factors (Chapter 4) and continuity between laboratory experiments and field work conducted in the Chernobyl Exclusion Zone (CEZ) (Chapter4). Chapter 2 presents an environmentally-relevant experiment testing how bumblebee reproduction and life history is affected by chronic low-dose rates. Unexpectedly, at dose rates equivalent to the CEZ, queen production declined and reproductive timing was altered. The estimation of dose rates to establish a dose-effect relationship for wild animals is difficult and a common criticism of radioecological studies, therefore, Chapter 3 tests whether the common approach to measuring only external ambient dose rates is suitable and whether the inclusion of life-history traits significantly alters the dose rate. The findings from this chapter reiterate the necessity to use dose-assessment tools to test different parameters to estimate dose rate in different scenarios to account for unknown variation. Chapter 4 demonstrates that in areas of elevated dose rates in the CEZ parasite burden was higher and bumblebees did not live as long. These results were reinforced by a laboratory study, which determined bumblebees exposed to increased radiation doses had high parasite burdens and were infected quicker, resulting in reduced longevity. The data in this thesis detected effects below the current dose bands used in international radioprotection and therefore advocate these dose bands be re-evaluated. However, the data do not support studies which have measured adverse effects at dose rates similar to background and suggest that confounding factors such as habitat quality and co-stressors need to be included in field and laboratory studies.

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My study was designed to answer two main questions: 1. ) Do the bees, through their foraging behavior, alter the rates of salmonberry nectar productivity? 2. ) Do the plants, through their rates of nectar secretion, alter the foraging behavior of the bees? Since there are well-documented examples of morphological coadaptations between plants and their pollinators, it was reasonable to suppose that physiological/behavioral coadaptations exist as well. Thus I hypothesized that the above questions would be answered in the affirmative. Though the two questions have been individually studied by several biologists, I felt it important to examine the possible reciprocal responses of plants and pollinators as they occur in a natural community context. Nectar productivity of salmonberry flowers (Rubus spectabilis, Pursh) was investigated using flowers isolated for various lengths of time from insect visitors. Nectar volumes were extracted using micropipettes and sugar concentrations were determined with a hand refractometer. Volumes and sugar concentrations were then used to calculate calories/hour. Nectar standing crop (calories/flower) was similarly derived using untagged flowers. During the study I monitored temperature, sunshine levels, relative humidity, date of sampling, time of sampling, and the androecium diameters of all flowers sampled. It was found that an increase in experimental extraction rate brought about a corresponding decrease in productivity. This result is opposite to that reported by other authors, yet it was found that this result was not due to flower damage or to artificial fertilization of flowers. This flower response to simulated visitation frequency may be of competitive advantage to flowers not being used by pollinators present in the area, Productivity and nectar standing crop decreased as the salmonberry flowering season progressed, and decreased throughout the course of each day as relative humidity fell and air temperatures increased. This decline in productivity reflected decreases in volumes of nectar secreted, though sugar concentrations increased with increasing sunshine levels. Younger flowers apparently secreted calories/hour at higher rates than older flowers, this again reflecting trends in volumes of nectar secreted. In each sample of ten flowers, there were four which secreted at rates significantly higher than the remaining six. Further, the four most productive flowers secreted at more predictable rates in trends of the environmental variables monitored during the study. Throughout the season there was a dramatic increase of .bumblebees (Bombus sitkensis, Nylander) observed at patches of salmonberry flowers. Throughout each day, the bees increased in density as sunshine levels and temperatures increased and relative humidity fell. The bees foraged from the more productive younger flowers more frequently than older flowers, and increasingly foraged from older flowers as nectar abundance in all flowers declined through the day and season. In addition, they may also have been avoiding increasing numbers of flowers they approached, though this conclusion must remain tentative. Bumblebee behavior was more predictable during the early morning hours of each day as opposed to hours in the afternoon. It is postulated that, this was because bumblebees experience more uniform energy conditions in the morning. Based on the distribution curves of nectar resources and bee density, it is postulated that plants compete for pollinators early in the day and early in the season, while bees compete for nectar later in the day and later in the season. This hypothesis is further supported by observations on the shifts in bee foraging behaviors. / Science, Faculty of / Zoology, Department of / Graduate

Many bumblebee species have experienced severe population declines in response to the use of intensive land management practices throughout the UK and western Europe during the latter half of the twentieth century. The loss of wildflower-rich unimproved lowland grasslands has been particularly detrimental and, as a result, in the UK two bumblebee species are now extinct, seven are listed on the UK Biodiversity Action Plan (BAP), and only six extant species remain common and ubiquitous. Populations of the rarer species are often fragmented and restricted to isolated areas, such as the crofting regions of northwest Scotland, in which the use of intensive farming practices has remained relatively limited. Consequently, in this study I primarily focus on the conservation of B. distinguendus and B. muscorum, two of the UK’s rarest species which have strongholds in the Outer Hebrides. In this region crofting is the dominant form of agriculture, and is traditionally typified by small-scale mixed livestock production accompanied by rotational cropping activities. With the use of very few artificial inputs, traditional crofting activities are environmentally sensitive and promote the diverse wildflower assemblages characteristic of the machair which provide suitable forage for bumblebees. However, the changing demographic structure of the islands, in conjunction with a range of other socio-economic factors, is resulting in the adoption of more intensive land management practices by crofters and changing the nature of the crofted landscape. These changes are likely to have a detrimental impact on the rare bumblebee populations that rely on crofting to provide suitable foraging habitats. Neglecting to examine the socio-economic issues behind the decline in crofting activities, and failure to develop a means of making the system economically viable and sustainable, is likely to reduce the effectiveness of any bumblebee conservation measures introduced in the region. Through my research I address this socio-ecological problem by taking an interdisciplinary approach, and combine the two disciplines of ecology and economics to find a way to ensure crofting is sustainable whilst promoting sympathetic land management practices to aid bumblebee conservation. The results of my research demonstrate that current croft land management practices do not support high abundances of foraging bumblebees in the Outer Hebrides, and that sheep grazing during the summer has a particularly negative impact on bumblebee abundance on croft land. My research also highlights the importance of non-agricultural habitats for foraging long-tongued bumblebee species in agricultural landscapes. Grazing management can promote bumblebee abundance, with cattle grazing providing a valuable foraging habitat for short-tongued bumblebees in southwest England. Therefore, to conserve bumblebees in agricultural landscapes the type of farming system needs to be taken into account in developing grazing management regimes, whilst non-agricultural habitats need to be integrated into local land management plans to ensure the provision of forage for bumblebees throughout the flight period. The outputs of the ecological-economic models show that compensation payments are not always required to encourage beneficial land management practices to enhance bumblebee populations in crofted areas. However, crofting is a marginal farming system that is heavily influenced by socio-economic factors, and this should be taken into consideration in the development of future agricultural policy for the region.