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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Pollinator behaviour and the evolutionary genetics of petal surface texture in the Solanaceae

Alcorn, Katrina Leanjka January 2013 (has links)
No description available.
12

ASSESSING AND MITIGATING LAWN INSECTICIDE HAZARDS TO BEES AND OTHER BENEFICIAL INVERTEBRATES

Larson, Jonathan Lane 01 January 2014 (has links)
Turfgrass settings, including lawns, golf courses, and sports fields, support many beneficial invertebrates that provide important ecosystem services. These non-target organisms and their associated predation, decomposition, and pollination services can be disrupted by the use of certain insecticides. I compared the ecotoxicity of representatives from three major turf insecticide groups, the neonicotinoids, premix formulations, and the anthranilic diamides, in lab and field realistic settings in order to inform industry initiatives towards environmental sustainability. In lab and field bioassays clothianidin, a neonicotinoid, and a premix clothianidin/pyrethroid spray were acutely toxic to beneficial insects. Populations of predators, springtails, and earthworms, as well as parasitism, predation, and decomposition rates were all reduced. In contrast, chlorantraniliprole, a novel anthranilic diamide with a similar spectrum of pests controlled, had no apparent impact on natural enemies, decomposers, or ecosystem services. This newer class is a good fit for industry initiatives to use relatively less toxic pesticides, with the caveat that golf course superintendents may see secondary pest outbreaks of ants and earthworms. Bumble bee colonies exposed to clothianidin-treated white clover for two weeks suffered acute effects including increased mortality of workers and decreases in the number of honeypots constructed in the hive. When hives were exposed to clothianidin treated clover for six days and then allowed to develop naturally over six weeks they exhibited delayed weight gain and produced no new queens. Colonies exposed to chlorantraniliprole-treated flowers suffered no observable adverse effects. When treated blooms were mowed, colonies exposed to newly-formed blooms exhibited no ill effects. After a single mowing neonicotinoid residues in clover nectar were reduced from > 2000 ng/g, to < 10 ng/g. Residues of imidacloprid were also short-lived in guttation water. Some 50 species of bees and other pollinators were collected from flowering white clover and dandelions in lawns across an urbanization gradient. Such weeds, an underappreciated resource for urban bees, could play a role in pollinator conservation if tolerated and not over-sprayed with broad-spectrum insecticides. Informing the public about the potential benefits these weeds could have for pollinators may help lead to more environmentally conscious management decisions.
13

Worth a thousand words: the impact of images on the perception of pollinator habitat

Jackman, Sarah M. January 1900 (has links)
Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Blake Belanger / The pollinator crisis - a catastrophic decline in domestic and feral pollinator populations across the world - has grown in severity over the last decade, and recent rise in the publicity of pollinator decline has brought it to the forefront of conservation work. The decline in pollinator populations is due to many human and environmental factors – one of the most prominent being the decline in natural pollinator habitat as urban and agricultural areas expand. Designed urban pollinator habitat can fill the need for foraging and shelter, however gaining public support for these ecological spaces can be a difficult endeavor. Pollinator gardens and urban ecological habitats are typically viewed as messy or unattractive to users, and landscape architects and designers are often met with resistance when proposing such landscapes for public spaces. What visual elements can be used as communication tools by professionals in landscape architecture and ecological design to increase the understanding and appeal of pollinator spaces to the public? This knowledge could provide insight into the ways designers and landscape architects present their work to improve the chances of public approval, and thus implementation. A visual preference survey was implemented and became a vital strategy to find the relationship between key visual elements in images, and the visual appeal and the quality of habitat they communicate. Previous studies in the field of semiotics show that images contain visual elements of language that imply meaning through the use of signs and visual cues. Participants evaluated images showing naturalistic sites during the growing season, and showing subjects like flowers and pollinators, especially up-close images. The survey revealed various levels of understanding of ecological function in different demographics, and a proportional level of appeal. The relationships revealed from the survey were used to create a set of representation guidelines for landscape architects and designers to use when proposing urban pollinator habitat, and other urban ecological spaces. These tools will help to communicate the functionality and need of these spaces, while portraying their intrinsic beauty and potential for enjoyment. A conceptual design was produced from the literature to illustrate how the guidelines can be used in the context of an urban setting.
14

Nesting aggregation as a Determinant of Brood Parasitism in Mason Bees (Osmia spp.)

Groulx, Adam January 2016 (has links)
Identifying forces that affect population dynamics can allow us to better understand the distribution and abundance of animals. Both top-down and bottom-up factors can significantly influence animal populations. Mason bees (members of the genus Osmia; Hymenoptera: Megachilidae) are important pollinators for agricultural systems and are vulnerable to exploitation by brood parasites, such as kleptoparasitic wasps. High levels of nesting density have the potential to increase rates of brood parasitism by attracting larger numbers of parasites to areas with aggregations of nests. I conducted a field study in subalpine meadows at the Rocky Mountain Biological Laboratory in Colorado, USA, to assess whether mason bees suffer increased brood parasitism as the size of nesting aggregations increases. Mason bees were allowed to nest in artificial nest boxes and establish natural variations in numbers of nesting individuals within nest boxes. Nest cells constructed by bees were then checked for the presence of kleptoparasite larvae shortly after they were completed. Overall, nest cells constructed in blocks containing multiple active bees were significantly more likely to be oviposited in by brood parasites compared to cells constructed in blocks with fewer active nesting bees. This suggests that gathering in large aggregations for nesting can negatively affect populations of mason bees, given the high levels of brood parasitism observed in areas of high nesting density. In addition, the last nest cell in mason bee nests was significantly more likely to be parasitized than inner cells, suggesting bees may be abandoning nests that are parasitized, representing a potential defensive response of bees to brood parasitism. These results have implications for the management of mason bees as agricultural pollinators, as cultivating them in large groups could reduce their survival.
15

Impacts of the Naturalized Bee Centris nitida on a Specialized Native Mutualism in Southern Florida

Downing, Jason L 30 March 2011 (has links)
This study assesses the impacts of the invasive oil-collecting bee Centris nitida on the established endemic mutualism between Byrsonima lucida and Centris errans its sole native pollinator. In natural pine rocklands and urban areas, I examined the breeding system of B. lucida, assessed the degree of its pollen limitations, and compared the key processes of pollination for the Centris bees. Breeding system results showed that B. lucida was self incompatible and pollinator dependent. Pollen limitation treatments suggested that B. lucida is pollen limited, regardless of the contributions of the invasive bee. The native bee had significantly higher visitation rates to B. lucida plants, but had a lower foraging rate and was the less efficient pollinator. The invasive bee appears to be more common in urban environments. Further understanding the nature of these novel relationships is vital for the conservation of B. lucida and integrity of pine rocklands.
16

Diel Nectar Secretion Rhythm in Squash (Cucurbita pepo) and Its Relation With Pollinator Activity

Edge, Andrea A., Van Nest, Byron N., Johnson, Jennifer N., Miller, Samara N., Naeger, Nick, Boyd, Sam D., Moore, Darrell 01 January 2012 (has links)
Most studies of foraging behavior in bees have been performed under artificial conditions. One highly neglected area is the daily nectar secretion rhythm in flowers including how nectar properties may vary with time of day. As a first step in understanding the connections between forager behavior and nectar presentation under more natural conditions, we examined nectar secretion patterns in flowers of the squash Cucurbita pepo. Under greenhouse conditions, squash flowers exhibit consistent diel changes in nectar volume and concentration through anthesis. These temporal patterns are robust, persisting under field conditions as well as simulated drought conditions in the greenhouse. In the presence of active pollinators, diel patterns are evident but with highly variable, severely reduced volumes. The potential consequences of these factors for pollinator behavior are discussed.
17

The Effects of Impervious Surface Area, Tree Canopy Cover, and Floral Richness on Bee Abundance, Richness, and Diversity Across an Urban Landscape

Gerner, Eden 14 October 2020 (has links)
As urbanization increases globally, habitat loss is increasing at an unprecedented rate, eroding the suitability of many landscapes for most forms of wildlife, including bees. At least some of this habitat loss is through the ongoing expansion of urban areas, a process termed ‘urbanization’. Studies of the effects of urbanization and urban land use on bees have reported a mixture of results, including some instances where at least some species appear to do better in urban areas than they do in lands surrounding urban areas. While the impacts of urbanization on bee communities has been investigated, tree canopy cover has been largely overlooked as a contributor to urban bee distributions, despite their potential importance as a predictor of bee activity. I investigated the impacts of urban land use and tree canopy cover on bee communities across a variety of neighbourhoods in a medium-sized Canadian city (Ottawa, Ontario). In total, I surveyed bee communities in 27 residential yards that varied in terms of the degree of urban land use (measured as percent impervious surface area) and tree canopy cover (percent deciduous canopy cover) across a range of spatial scales. Using linear regression and model selection, I determined that bee abundance was negatively correlated with the degree of urban land use surrounding a yard, and positively correlated with the richness of the local (i.e., yard) flowering plant community. Yard floral richness, but not urban land use or tree cover, was also a predictor of the diversity of the bee community visiting the yard. In fact, tree canopy cover did not factor in any of the top models predicting either bee abundance, richness, or diversity. My results support the idea that urban land use could negatively impact bee communities, but also suggest that landscaping and urban planning decisions that maximize local floral richness could counteract some of the negative impacts of urbanization on bee populations.
18

The Effects of Flower Patch Density on Pollinator Visitation

Barley, Tristan Alexander 20 November 2020 (has links)
No description available.
19

Quantification of pollinating insects of the superfamily Apoidea in three ecological niches of three communities in the municipality of Coroico-Nor Yungas, department of La Paz

Claros Sossa, Óscar Jaime 01 January 2008 (has links) (PDF)
The superfamily Apoidea (commonly referred to as bees), are insects whose diet consists of the nectar and pollen from flowering plants. Therefore, they are essential pollinators of many species, both wild and cultivated. Bees are similar to other Hymenoptera in appearance, size, and color variety. The superfamily Apoidea contains 17,000 known species and could possibly contain up to 30,000. Bees perform many tasks that benefit humanity such as pollinating the flowers of both wild and cultivated plants. Without this work, fruits and seeds necessary for the survival of different species, for our own food supply, and for industry would not be able to be produced. The study was done in three communities in the Yungas (Carmen Pampa, San Pablo, and San Juan de la Miel). In each community, three Malaise traps were introduced in three ecological ni ches (Forest, Forest Edge, and Crop Area). Each collection was done every 14 days throughout the six months of winter and spring. The quantification and identification of the Apoidea was conducted in a laboratory through identification keys for families, genera, and species. In total, 83 different morphospecies were identified. In the three communities, a total of 1117 individuals were recorded during the six months of field work. With regard to the niche factor, Partamona sp. (sp2) and Apis mellifera (sp1) were those species that contributed most to the abundance of individuals. In addition, both species contributed to the similarity and dissimilarity seen in the three ecological niches of the three communities. This indicates that they are the most abundant groups within the Yungas forests. They nest primarily in wood, are highly general, are highly social, and are present throughout the year. It is also worth mentioning that the community and station factors do not contribute to the differences in species diversity. Based on the results of this research, a new phase was initiated to identify the species contained within the 83 morphospecies found in the Yungas of La Paz.
20

Ornamental Plants Impact Insect Pollinator Abundance and Diversity in Gardens

Palmersheim, Michala Christine 02 February 2022 (has links)
As pollinator populations decline globally, public interest in creating pollinator gardens to help sustain bee abundance and diversity is rising, and there are many lists of recommended pollinator plantings and suggestions for bee-friendly flowers. However, these suggestions often lack grounding in empirical data. While anecdotal and expert suggestions are not without merit, it is crucial that we have clear, replicable, evidence-based planting recommendations to help boost the abundance and diversity of pollinators that will visit the plants. To fill this gap, we created a pollinator garden containing 25 pollinator plantings, some on previous recommendation lists, some not, and that were either native or non-native and perennial or annual. We surveyed the number and taxonomy of pollinator visitors to these plants through non-destructive methods. These data were analyzed to determine which plants are most effective at attracting abundant and diverse flower-visiting insects. We analyzed preference between native and non-native plants, perennials and annuals, and among different plant species. Our data revealed significant variation in the total abundance and diversity of flower-visiting attracted insects among plant species. Brown-eyed Susans attracted the highest abundance of insect visitors (average number of visitors per day = 53) and were 26-fold more attractive than Begonias, which attracted the lowest abundance of insect visitors (average number of visitors per day = 2). Lavender attracted the highest diversity of insect visitors (Simpson's Reciprocal Diversity Score: 3.5) compared to Pineapple Sage (Simpson's Reciprocal Diversity Score: 1.6), which attracted the lowest diversity of insect visitors. Additionally, we found that native perennials significantly attracted the greatest abundance of visitors compared to either non-native annuals or non-native perennials (p < 0.001). We conclude that ornamental landscape plants can support an abundance and diversity of pollinator visitors, and planting schemes should take into consideration the effects of plant species, plant lifespan, and plant origin. We can use these data to better inform the regional community how to attract and support abundant and diverse pollinator populations within urban and sub-urban ornamental landscape gardens. / Master of Science in Life Sciences / Many people want to build gardens with flowers that are attractive to pollinators, which can be bees, flies, butterflies, moths, and other insects. How, though, do we know what should be planted in that garden? Anyone with access to a computer can find lists of recommended plants for a pollinator garden, and they are provided by a variety of sources. However, the plants included on these lists are often not the same. Some lists may claim a handful of plants are the most attractive to pollinators, while another list will suggest different plants as the most attractive. In addition, these lists often are not based on scientific evidence. Our goal was to use these recommendations to build a pollinator garden so that we can collect data on the plants and determine which plants are best in our garden at attracting insect pollinators. We created a pollinator garden that includes 25 of popular landscape plants, many of which are found on lists of current plant recommendation lists. Then we let the plants grow and bloom, and during the summer, we counted and identified the different species of insects found on each plant. We then ranked plants, from best to worst, at their ability to attract insects and pollinators in numbers and in diversity. Additionally, we found that insects are generally more likely to visit plants that are native to the region. Using this information, we can share our results with the public so that anyone can build their own pollinator garden that will be the most attractive to pollinators.

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