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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.
41

Effects of the availability of floral resources on plant-pollinator interactions and the implications for the long-term survival of plant populations

Evans, Tracie Marie January 2018 (has links)
1. Insect pollinators have been shown to alter their foraging patterns in response to habitat and landscape composition, particularly in relation to changes in the availability of floral resources which provide essential pollen and nectar provisions. Changes to pollinator behaviour and community composition, may alter the distance, directness and frequency of pollen movement and thus, the compatibility and genetic relatedness of pollen transferred between plants. We still lack good understanding of how variation in the spatial and temporal availability of floral resources drives pollinator responses and in turn, affects the fitness of outcrossing plants. Knowledge in this area could contribute to improved management interventions to enhance pollination services for plant conservation. 2. Through a combination of habitat and landscape scale field experiments, I explored how the availability of floral resources at different spatial scales affected plant-pollinator interactions, pollen transfer and mating success in plant populations, particularly those isolated from conspecifics. This involved introducing different species of plants in experimental arrays across a range of study systems that varied in structure and floral availability. Over the course of the thesis, I measured the community composition and behaviour of pollinators visiting experimental arrays; focusing on traits considered important for pollen transfer (e.g. Inter-tegular ('IT') span). Pollen movement was quantified within and between populations (5-150m) and the resulting plant outcrossing rates were measured using different methods including paternity analysis and the use of a dominance inheritance system. In addition, the implications of variations in pollinator foraging and pollination services can be attributed to pollen and gene flow and subsequently the reproduction and fitness of plants were assessed as a means of predicting the impacts on longer-term plant survival. 3. Findings from this thesis demonstrate reductions in the activity density (the abundance of actively foraging pollinators) and richness of pollinators and thus, the potential for plant visitation in response to a high abundance of floral resources within a habitat. This led to disruptions in pollen transfer, illustrated through a lower incidence of intra and inter-population pollen movement, and ultimately, reduced plant outcrossing rates. In parallel, plant seed set and germination rates were also reduced in habitats with high resource availability. Changes to pollinator communities and pollination services varied with the spatial scale at which floral resources were measured. Pollinator communities (activity density, richness and IT span) were most affected by floral resource abundance at a local scale (1-50m), particularly within a 20m radius of a plant population. Intra-population pollen movement was similarly affected by floral resources at a local spatial scale (within a 1m radius of a plant population). In contrast, no effect was observed on pollinator communities, intra-population pollen movement or plant reproduction when floral resources were measured at a landscape scale (within a 100-1500m radius of a plant population). However, findings were variable across different experiments at the same scale of measurement. For instance, the availability of floral resources at a local scale did not always elicit an effect on plant reproduction. This reflects differences in plant species identity and the effects of breeding system and floral traits, illustrated through variations in visitation rates between plant species. Inconsistencies were further observed with pollinator activity density and richness, which were not related to floral resources at a habitat scale in one chapter. 4. This thesis highlights the importance of the availability of floral resources at a local scale on plant-pollinator interactions and pollination services to plants. Co-flowering plants within florally rich habitats compete for pollinators and subsequently, visitation and pollen transfer between individuals of low density plant populations is diluted rather than facilitated. This suggests that although pollinator abundance and diversity may be enhanced through florally rich habitats (e.g. habitats implemented under the agri-environment scheme), pollination services are not automatically improved for plants which are present at low frequency in the landscape. This needs to be considered when designing and implementing management for threatened or isolated plants where plants may instead benefit from focused interventions. For instance, pollination services may be increased by efforts to maximise the facilitative effect of surrounding habitats, while increasing the ability of threatened or isolated plants to withstand competition from co-flowering plants.
42

Ecologia da polinização e análise da composição química do óleo floral de duas espécies de Mouriri (Melastomataceae) e sua importância na atração dos visitantes florais / Ecology of pollination and analysis of the chemical composition of the floral oil of two species of Mouriri (Melastomataceae) and their importance in attracting floral visitors

OLIVEIRA, Fabiana dos Santos 28 June 2016 (has links)
Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-21T18:09:20Z No. of bitstreams: 1 FabianaOliveira.pdf: 3452408 bytes, checksum: e7dc44478824674e852eefdbd9fb1140 (MD5) / Made available in DSpace on 2017-06-21T18:09:20Z (GMT). No. of bitstreams: 1 FabianaOliveira.pdf: 3452408 bytes, checksum: e7dc44478824674e852eefdbd9fb1140 (MD5) Previous issue date: 2016-06-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Mouriri (Melastomataceae, Memecyloideae) is a Neotropical genus with 85 species with "Buzz pollination". Although, to be its main attractive pollen floral, concave and elliptical glands located in the back of the anthers and called elaiophor are responsible for the production of oil. The present study aimed to study two species of Mouriri about phenology, floral biology, visitors, and chemical identification systems of floral oils. Fortnigtly (n = 10 individuals) were observed from June/2013 to June/2014 (M. acutiflora) and December/2013 to March/2015 (M. guianensis). The bees were collected in January/2015 and February/2015 (M. guianensis) and in August/2015 (M. acutiflora). Open pollination, self-pollination manual, spontaneous selfpollination cross-pollination and apomixis were applied to the reproductive systems. Floral glands (n = 1800) and legs of bees [(Centris (Centris) caxiensis Ducke (n = 6), Melipona (Melikerria) fasciculata Smith (n = 10) and M. (Melipona) subnitida Ducke (n = 10)] were subjected to extraction with hexane, methyl and analyzed by GC/MS. Mouriri acutiflora flowering from April to September and fruits from June to November and M. guianensis blooms from September to March and fructifies from November to March. The species are selfcompatible, not apomitcs, although still present reliance on pollinators. A total of 141 visitors were observed in M. acutiflora, and M. fasciculata (59.79%), C. caxiensis (12.31%) and Eulaema (Apeulaema) nigrita Lepeletier (9.4%) bees had the highest percentages, representing 81.5% of the total visits. In M. guianensis 86 individuals were recorded, mainly Xylocopa (Neoxylocopa) cearensis Ducke (60%), M. subnitida (21.17%) and Megalopta (Amoena) amoena Spinola (9.41%) representing 98.58% of all visits. The pollen was predominantly resource harvested through the mechanism of vibration (Buzz pollination), although the floral oil also has been available in both species. Melipona subnitida used only the regions of the glands of M. guianensis for seal/protect of the entrance of the colony, indicating a possible use of the glands/oil. Visitors, except Augochlopsis sp., Trigona sp. and wasps (Chalcidoideae) are pollinators of Mouriri. The substances identified by GC/MS in floral oils were mainly palmitic acids, stearic, oleic, lignoceric and palmitoleic, in the form of their methyl esters. The extracts of the legs of the bees had as main substances linoleic acid, stearic, oleic, palmitic acid and alcohol hexacosanol. Methyl hexadecanoate and methyl octadecanoate were common to the floral oils and extracts of the legs of the bees, indicating possible harvest of the lipids. Thus, Mouriri confers a regular supply of resources to the pollinators, floral oil and pollen, this being the primary resource harvested by bees. / Mouriri (Melastomataceae, Memecyloideae) é um gênero Neotropical com 85 espécies com síndrome de “Buzz pollination”. Embora, seja o pólen o seu principal atrativo floral, glândulas côncavas e elípticas localizadas no dorso das anteras e denominadas elaióforo são responsáveis pela produção de óleo. O presente estudo teve como objetivo estudar duas espécies de Mouriri quanto a fenologia, biologia floral, visitantes, sistemas de reprodução e identificação química dos óleos florais. Quinzenalmente (n = 10 indivíduos) foram observados de junho/2013 a junho/2014 (M. acutiflora) e dezembro/2013 a março/2015 (M. guianensis). As abelhas foram coletadas em janeiro e fevereiro/2015 (M. guianensis) e em agosto/2015 (M. acutiflora). Polinização aberta, autopolinização manual, autopolinização espontânea, polinização cruzada e apomixia foram aplicadas para os sistemas reprodutivos. Glândulas florais (n = 1800) e pernas das abelhas [(Centris (Centris) caxiensis Ducke (n = 6), Melipona (Melikerria) fasciculata Smith (n = 10) e M. (Melipona) subnitida Ducke (n = 10)] foram submetidas a extração com hexano, metiladas e analisadas por CG/EM. Mouriri acutiflora floresce de abril a setembro e frutifica de junho a novembro e M. guianensis floresce de setembro a março e frutifica de novembro a março. As espécies são autocompatíveis, não apomíticas, embora ainda apresentem dependência de polinizadores. Um total de 141 visitantes foram observados em M. acutiflora, sendo que M. fasciculata (59,79%), C. caxiensis (12,31%) e Eulaema (Apeulaema) nigrita Lepeletier (9,4%) tiveram as maiores porcentagens, representando 81,5% do total de visitas. Em M. guianensis 86 indivíduos foram registrados, principalmente Xylocopa (Neoxylocopa) cearensis Ducke (60%), M. subnitida (21,17%) e Megalopta (Amoena) amoena Spinola (9,41%) representando 98,58% de todas as visitas. O pólen foi o recurso predominantemente coletado através do mecanismo de vibração (Buzz pollination), embora o óleo floral também tenha sido disponibilizado em ambas as espécies. Melipona subnitida utilizou apenas as regiões das glândulas de M. guianensis para a vedação/proteção da entrada da colônia, indicando um possível uso das glândulas/óleo. Os visitantes, a exceção de Augochlopsis sp., Trigona sp. e vespas (Chalcidoideae) são polinizadores de Mouriri. As substâncias identificadas por CG/EM nos óleos florais foram principalmente os ácidos palmítico, esteárico, oleico, lignocérico e palmitoleico, na forma de seus ésteres metílicos. Os extratos das pernas das abelhas tiveram como principais substâncias o ácido linoleico, esteárico, oleico, palmítico e o álcool hexacosanol. Metil hexadecanoto e metil octadecanoato foram comuns aos óleos florais e pernas das abelhas, indicando possível coleta dos lipídeos. Assim, Mouriri confere uma oferta regular de recursos para os polinizadores, disponibilizando óleo floral e o pólen, sendo este o principal recurso coletado pelas abelhas.
43

Public Participation in Plant-Pollinator Conservation: Key Assessment Areas that Support Networked Restoration and Monitoring

Battle, Kerissa 19 March 2018 (has links)
Environmental problems are growing at a pace and scale that traditional research methods alone can no longer tackle. Innovative research models that utilize contributory, participatory and crowdsourcing methods are rapidly emerging to fill this gap. For these participatory efforts to be effective and sustainable, however, closer attention must be paid to key components that can promote coordinated action and sustainability. Through the lens of public participation in plant-pollinator conservation, I have, with rigorous social-ecological inquiry, offered three foundational assessment areas that can provide scientific support to this nascent field: accuracy, ecological significance and scalability. In the first study (Chapter 2), I explored a common concern about citizen science: that a lack of foundational knowledge, or familiarity with following scientific protocols could lead to inaccurate data collection. I evaluated the accuracy of plant phenology observations collected by citizen scientist volunteers following protocols designed by the USA National Phenology Network (USA-NPN). Phenology observations made by volunteers receiving several hours of formal training were compared to those collected independently by a professional ecologist. Approximately 11,000 observations were recorded by 28 volunteers over the course of one field season. Volunteers consistently identified phenophases correctly (91% overall and 70% during transitions) for the 19 species observed. Accuracy varied significantly by phenophase and species (p<0.0001). Volunteers who submitted fewer observations over the period of study did not exhibit a higher error rate than those who submitted more total observations, suggesting that volunteers with limited training and experience can provide reliable observations when following explicit, standardized protocols. Overall, these findings demonstrate the ii legitimacy of phenology observations collected by volunteers, an important finding for the increasing number of analysts relying on data collected by citizen scientists. In Chapter 3, I explored a common concern that restoration efforts implemented by the public may not have adequate ecological value. I addressed key ecological variables to determine how small-scale patches attracted pollinators and explored which of these variables might be best to prioritize for restoration efforts suited to public initiatives. This study demonstrated that in small-scale plant restoration sites, plant diversity and resource (nectar) availability significantly affects the abundance and diversity of pollinating insects. Specifically, the treatments which contained high-resource (nectar-rich) plant species increased pollinator abundance and diversity the most. Plant diversity increased pollinator diversity and abundance only in the absence of high-resource plants. Pollination facilitation was observed in high resource treatments, but varied among species. Competition for pollinators was observed in high diversity treatments but did not affect seed set for high-resource plants in any of the treatments. Together, these results suggest that managers or landowners who are restoring patches of native plants as habitat for pollinators should prioritize including species with high nectar production, and secondarily, a diverse mix of species if space and resources allow. In Chapter 4, I explored an emergent approach to public participation in regional community science initiatives (and networks) through an exploratory case study of the New York Phenology Project. I demonstrated that local organizations have the opportunity to utilize existing data aggregation platforms to activate regional collaborative alliances to achieve what is often challenging for large-scale contributory projects. I describe our hands-on experience of conceiving and launching a regional network and outline a model that could serve as a guide for catalyzing networks. Drawing on direct experience and interviews with network partners, I developed a description of key categories related to network node success, and a linked assessment tool that could be used to evaluate network node capacity and project outcomes. The assessment tool will be used to test preliminary findings in a more formal quantitative and qualitative exploration in future studies. In Chapter 5, I explored an exceptional long-term, community-level phenology data set that spans New York State, USA (1802-2017), and found interesting and significant patterns of phenological change over time. The data set provides statewide phenology and temperature data that extend further back in time than any previously known data set for the region, extending to years prior to or at the beginning of recent human-caused global warming. I found that most species are flowering and leafing earlier in recent years (2009-2017) than they did in the early 19th century (1802-1861). Plants are flowering 11 days earlier and leafing 18.8 days earlier, with some species flowering up to 27 days earlier and leafing up to 31 days earlier over that time period. Most of this change was driven by warming mean spring temperatures (MST) over that time; mean spring temperatures warmed by 1.0°C statewide (2.5°C in New York City) on average between the historical and contemporary periods. Seasonality, Life Form, and the interaction between Seasonality and Life Form explained variation in phenology among species. The large number of geographically distinct sites in this dataset permitted novel investigation into differential changes in phenology between urban and rural areas (urban areas have more advanced phenology than their rural counterparts) and between insect and wind pollinated trees by seasonal category (insect pollinated trees are showing more advanced phenology than wind pollinated trees in both early and late spring). This analysis has brought the efforts of a historical network into a modern context and has illustrated how organized long-term monitoring efforts can be valuable for ecological discovery. This combined work provides a diverse contribution to the field of public participation in monitoring and conservation efforts. While thorough and disciplined ecological theories drive the design of the research, I simultaneously strove to help meet the ongoing demand for useable, purposeful insights into how to support public efforts to restore plant-pollinator habitats, monitor key ecological dynamics such as phenology, and scale networks capable of collecting data that address issues of global change.
44

Mating systems, insect pollination and chemical ecology of grassland Protea species (Proteaceae)

Steenhuisen, Sandy-Lynn. January 2012 (has links)
Major transitions between vertebrate and insect pollination systems have occurred many times during the angiosperm radiation and are associated with evolutionary modifications in floral traits. In the large ancestrally bird-pollinated African genus Protea (Proteaceae), an evolutionary shift from bird to insect pollination in the genus is suggested by the fruity diurnal scent of flowers in a recently evolved clade of grassland species. In this study, I confirm that four of these grassland Protea species have mixed mating systems and are indeed insect pollinated, and furthermore demonstrate the functional significance of their floral presentation and scent chemistry for attraction of pollinators, specifically cetoniine beetles. The study species, Protea caffra, Protea dracomontana, Protea simplex and Protea welwitschii, have colourful bowl-shaped inflorescences that produce copious amounts of pollen and dilute, xylose-rich nectar. Cetoniine beetles were found to be the most suitable pollinators due to their abundance, size, relatively pure Protea pollen loads, and their preference for the fruity scent and low growth form of these scented Protea species, as demonstrated by choice experiments in which inflorescences were offered at either end of a y-maze or at various heights above the ground, respectively. Bagging and hand pollinations revealed that these Protea species are self-compatible and capable of autonomous selfing. Self progeny of P. caffra were as vigorous as cross progeny in terms of germinability and survivorship to two months. Vertebrate-excluded and open-pollinated inflorescences yielded similar seed numbers for all species. Supplemental hand-pollinations, however, failed to increase seed set substantially, an indication of resource limitation. Outcrossing rates estimated using polymorphisms at eight allozyme loci in progeny from vertebrate-excluded and open-pollinated treatments of P. caffra were no different (t=0.59), indicating outcrossing by insects and an equal or insubstantial contribution from bird pollinators. The fruity-sweet scents of these species were more complex, with higher whole flower and mass-specific emission rates, than those in eight bird-pollinated congenerics. The overall floral scent is shown to be a blend of emissions from various plant parts, especially nectar. Electroantennography (EAG) revealed that the generalist pollinator Atrichelaphinis tigrina responds to a variety of volatile compounds found in fruity Protea scents. Field trapping confirmed that this cetoniine beetle is strongly attracted to ß-linalool (up to 60% of scent profile) and methyl benzoate. In conclusion, this study demonstrates the evolution of beetle pollination and mixed mating systems in a grassland clade of Protea. Volatile compounds that make up the unique (within Protea) fruity scent of the study species are shown to attract beetles, and the emission of large amounts of these compounds was probably a key step in the transition from bird to insect pollination in Protea. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
45

Studies on Forcipomyia spp. midges (Diptera, Ceratopogonidae) related to the pollination of Theobroma cacao L.

Vasco, Saulo de Jesus Soria. January 1970 (has links) (PDF)
Abstract of Thesis (Ph. D.)--University of Wisconsin, 1970.
46

Conservation genetics and ecology of two rare grevillea species

Llorens, Tanya M. January 2004 (has links)
Thesis (Ph.D.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: p. 241-260.
47

Pollinator visitation preference on native and non-native congeneric plants

Cerqueira, Nicole. January 2005 (has links)
Thesis (M.S.)--University of Delaware, 2005. / Principal faculty advisor: Dewey M. Caron, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.
48

Impacto de inseticidas botânicos sobre Apis mellifera, Nannotrigona testaceicornis e Tetragonisca angustula (Hymenoptera: Apidae) / Impact of botanical insecticide on Apis mellifera, Nannotrigona testaceicornis and Tetragonisca angustula (Hymenoptera: Apidae)

Xavier, Vânia Maria 16 February 2009 (has links)
Made available in DSpace on 2015-03-26T13:30:22Z (GMT). No. of bitstreams: 1 texto completo.pdf: 282210 bytes, checksum: 541094cd1f70a9eb50e462fe6513aedd (MD5) Previous issue date: 2009-02-16 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Adverse effects of organo-synthetic products have motivated search in alternative control of pests. Among this alternative, botanical insecticides present a viable option for the management of these organisms. However, before the choice of the botanical insecticide, some criteria must be analyzed, such as: efficiency to control the pest and selectivity to beneficial organisms in the agroecosystem. Intensive use of insecticides to control pests has caused negative impacts on the agents pollinators. Bees Apis mellifera, Nannotrigona testaceicornis and Tetragonisca angustula (Hymenoptera: Apidae) are extremely important in pollination of various crops. Thus, the objective of this work was to evaluate the impacts of botanical insecticides rotenone, Andiroba, garlic extract and oil of Neem, citronella and eucalyptus on A. mellifera, N. testaceicornis and T. angustula. Thus, the toxicity bioassays of botanical insecticides were performed with the A. mellifera, N. testaceicornis and T. angustula. Additionally, tests of food preference and handling behavior were conducted with adults of pollinators. The most toxic insecticide to adults of A. mellifera was the oil of Neem. Rotenone and the oil of citronella were also toxic for larvae of this pollinator. Citronella of oil was the most toxic for T. angustula. None of botanical insecticides studied showed toxicity to N. testaceicornis. All botanical insecticides caused repellency to adults of A. mellifera. In the bioassay of handling behavior, rotenone, oil of eucalyptus, Neem and garlic extract decreased the speed of A. mellifera, but the distance traveled and time of walking were not affected by any of the botanical insecticides tested. Insecticides did not affect the behavior of handling of N. testaceicornis and T. angustula. Our results provide important information for pest management in order to preserve the beneficial pollinators agents present in agroecosystem. / Os efeitos adversos dos produtos organo-sintéticos têm motivado a busca por alternativas no controle de pragas. Dentre estas, os inseticidas botânicos se apresentam como uma opção para o manejo desses organismos. Contudo, antes da escolha do inseticida botânico, alguns critérios devem ser analisados, tais como: eficiência no controle da praga e seletividade aos organismos benéficos presentes no agroecossistema. As abelhas Apis mellifera, Nannotrigona testaceicornis e Tetragonisca angustula (Hymenoptera: Apidae) são extremamente importantes na polinização de várias culturas. Entretanto, a utilização intensiva de inseticidas no controle de pragas tem ocasionado impactos negativos sobre os agentes polinizadores. Desta forma, objetivou-se com este trabalho avaliar os impactos dos inseticidas botânicos rotenona, andiroba, extrato de alho e óleos de neem, citronela e eucalipto sobre A. mellifera, N. testaceicornis e T. angustula. Para tanto, foram realizados bioensaios de toxicidade com os inseticidas botânicos extrato de alho, óleo de andiroba, óleo de citronela, óleo de eucalipto, neem e rotenona a A. mellifera, N. testaceicornis e T. angustula. Adicionalmente, testes de preferência alimentar e de comportamento de movimentação foram conduzidos com adultos dos polinizadores. O inseticida mais tóxico aos adultos de A. mellifera foi o óleo de neem. Já para larvas desse polinizador, além deste inseticida, a rotenona e o óleo de citronela também foram tóxicos. Para T. angustula o óleo de citronela foi o mais tóxico. Nenhum dos inseticidas botânicos estudados apresentou toxicidade a N. testaceicornis. Todos os inseticidas botânicos causaram repelência aos adultos de A. mellifera. No bioensaio de comportamento de movimentação, a rotenona, o óleo de eucalipto, o neem e o extrato de alho diminuíram a velocidade de A. mellifera, porém à distância percorrida e o tempo de caminhamento não foram afetados por nenhum dos inseticidas botânicos testados. Para N. testaceicornis e T. angustula os inseticidas não afetaram o comportamento de movimentação. Nossos resultados fornecem informações importantes para o manejo de pragas com o intuito de preservar os agentes polinizadores.
49

Abelhas visitantes florais de Richardia grandiflora (Rubiaceae) ao longo de um gradiente urbano-rural / Bee visitors of the flowers of Richardia grandiflora (Rubiaceae) along an urban-rural gradient

Cruz, Renata Marinho 29 July 2013 (has links)
Made available in DSpace on 2015-04-17T14:55:29Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2715376 bytes, checksum: 8445aab8d1e45ea4006c9cd3f1d3930e (MD5) Previous issue date: 2013-07-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Increasing urbanization is among the main drivers of the loss and fragmentation of habitats, that affect pollinator communities and change the plant-pollinator interactions. Although studies focusing on the influence of landscape on pollinators have increased , in Brazil this knowledge is incipient. Here, we analysed the bee visitors and reproductive success of Richardia grandiflora (Cham. & Schltdl.) Steud along an urban-rural gradient, relating to possible changes in the plant-pollinator interactions. This study was carried out in six areas located in the state of Paraíba, belonging to three different categories: urban, peri-urban and rural areas. We estimated the percentage of vegetation cover (woody and herbaceous-shrub), impervious surfaces, bare soil and water, in two spatial scales. Moreover, bee visitors of the flowers of R. grandiflora were observed monthly since February 2012 until January 2013, and the species composition, richness, frequency of occurrence and number of visits was recorded. Finally, we estimated the reproductive success from pollination treatments (open-pollination and supplementary cross-pollination) to obtain the Reproductive Efficacy of R. grandiflora in each area. In the clusters from the landscape characterization and species composition the urban areas were differentiated from the remaining, but peri-urban and country areas were not differentiated from each other. The little change in the richness of eusocial bees and the number of visits by stingless bees along the urban-rural gradient indicated good tolerance to urbanization. Non-eusocial bees had higher richness and frequency in rural and peri-urban areas. Moreover, the positive correlation between the number of non-eusocial bee visits and herbaceous-shrub vegetation, in the smallest spatial scale, suggests a greater influence of the local landscape on these species. The introduced species Apis mellifera had a higher frequency in urban areas, which may be related to lower availability of resources, as well as its ecological flexibility and competitive power. Finally, rural areas had the highest rates of Reproductive Efficacy while urban areas showed lower values. Possibly, A. mellifera was not as efficient as a native pollinator species, which may be a consequence of the fragmentation of the populations of Richardia grandiflora in the most urbanized areas. / A crescente urbanização tem sido um dos principais fatores causadores da perda e fragmentação de habitats, que afetam as comunidades de polinizadores e modificam as relações planta-polinizador. Embora tenha crescido o número de estudos focando na influência da paisagem sobre os polinizadores, no Brasil esse conhecimento ainda é incipiente. Neste estudo, as abelhas visitantes florais e o sucesso reprodutivo de Richardia grandiflora (Cham. & Schltdl.) Steud foram analisados ao longo de um gradiente urbano-rural, associando a possíveis alterações nas relações planta-polinizador. O estudo foi desenvolvido em seis áreas localizadas no estado da Paraíba, divididas em três diferentes categorias: urbanas, periurbanas e rurais. Para cada área foram estimados os percentuais de cobertura vegetal (arbórea e herbáceo-arbustiva), superfícies impermeáveis, solo livre e água, em duas escalas espaciais. As abelhas visitantes florais foram observadas mensalmente, de fevereiro de 2012 a janeiro de 2013, sendo registrada a composição de espécies, riqueza, frequência de ocorrência e número de visitas. Por fim, o sucesso reprodutivo foi estimado a partir de experimentos de polinização (livre e cruzada manual complementar) para obtenção da Eficácia Reprodutiva (ER) de R. grandiflora em cada área. Nos agrupamentos a partir da caracterização da paisagem e composição de espécies, as áreas urbanas se diferenciaram das demais, mas as áreas periurbanas e rurais não foram diferenciadas entre si. A pouca alteração na riqueza das abelhas eussociais e no número de visitas por meliponíneos, ao longo do gradiente urbano-rural, indicaram uma boa tolerância à urbanização. As abelhas não eussociais apresentaram uma maior riqueza e frequência nas áreas periurbanas e rurais. Além disso, a correlação positiva entre o número de visitas de abelhas não eussociais e a vegetação herbáceo-arbustiva, na escala espacial menor, sugere uma maior influência da paisagem local nessas espécies. A espécie introduzida Apis mellifera apresentou uma maior frequência nas áreas urbanas, que pode estar relacionada à menor disponibilidade de recursos, bem como à sua flexibilidade ecológica e poder competitivo. Finalmente, as áreas rurais apresentaram as maiores taxas de Eficácia Reprodutiva, enquanto as áreas urbanas, valores mais baixos. Nas áreas mais urbanizadas, possivelmente, A. mellifera não foi um polinizador tão eficiente quanto as espécies nativas, o que pode ser consequência da fragmentação das populações de Richardia grandiflora.
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Polinační ekologie \kur{Impatiens sakeriana} / Pollinatieon biology of \kur{Impatiens sakeriana}

PATÁČOVÁ, Eliška January 2011 (has links)
The pollination biology of Impatiens sakeriana was studied in Northwest province, Cameroon. The most efficient way of reproduction was examined, futhermore nectar production was neasured and bird pollinators was observed.

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