• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 139
  • 129
  • 24
  • 20
  • 17
  • 8
  • 8
  • 6
  • 4
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 418
  • 144
  • 116
  • 73
  • 65
  • 63
  • 40
  • 38
  • 38
  • 36
  • 24
  • 24
  • 23
  • 22
  • 22
  • 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.
121

Toxicological Analysis of Acaricides for Varroa Mite Management

Vu, Philene Dung 15 June 2016 (has links)
The varroa mite is a primary driver behind periodical losses of honey bee colonies. The mite requires bees for food and reproduction and, in turn, elicits physiological deficiencies and diseases that compromise bee colony health. The mite nervous system is a target site for existing acaricides. These acaricides not only have adverse health effects on bees, but resistance limits their use to reduce mites and diseases in bee colonies. Voltage-gated chloride channels are involved in the maintenance of nerve and muscle excitability in arthropod pests, which suggests that these channels might be exploited as targets for acaricides. Apistan® (the pyrethroid tau-fluvalinate), Checkmite+® (the organophosphate coumaphos), and Apivar® (the formamidine amitraz) are control products for mite management. The effectiveness of these chemistries has diminished as a result of the increasing incidence resistance in mite populations. I report a toxicological analysis of stilbene products against acaricide-susceptible and -resistant mites. My results find a significant increase in metabolic detoxification enzyme activities in acaricide-resistant mites compared to susceptible mites. Acetylcholinesterase of coumaphos-resistant mites was significantly less sensitive to the toxic coumaphos metabolite compared to susceptible mites, which suggests target-site insensitivity as a mechanism of acaricide resistance. The stilbene product DIDS had significantly higher field efficacy to acaricide-resistant mites compared to Apistan®- and CheckMite+®. These data suggest that DIDS, and other stilbene products, might serve as candidate chemistries to continue field efficacy testing of alternative acaricides for Apistan® and CheckMite+® resistant mites. / Master of Science in Life Sciences
122

Forage Production and Nutritive Value in a Temperate Appalachian Silvopasture

Buergler, Alicia Lenore 24 May 2004 (has links)
Integrating trees into pasture may be an effective management tool to improve water, nutrient, and light allocation and increase total system productivity in Appalachia. We tested this hypothesis in a silvopasture near Blacksburg, VA. In 1995, black walnut and honey locust trees were planted within plots (r=3) of predominantly tall fescue pasture. Across a 12% slope, trees were planted to create treatments of low, medium, and high tree densities at shoulder, mid, and toe slope positions within plots of honey locust and black walnut. Sampling sites (n=54) under tree density and slope position combinations were harvested May to October at 35-d intervals in 2002 and 2003 for determination of yield and nutritive value characteristics. Soil surface temperature, forage canopy temperature, soil moisture, and photosynthetically active radiation were measured to determine forage responses to field treatments as functions of resource allocation. Tree density had the greatest effect on forage production and nutritive value. Across both years, yields were 16% greater (P=0.0006) at medium density (6130 kg/ha) compared to forage mass at low (5280 kg/ha)) and high density (4970 kg/ha, SE=130). Increasing tree density did not affect (P>0.2) ADF, CP, P, K, and Mg levels, but reduced (P<0.001) NDF and TNC, and increased (P<0.0001) ADL and Ca. Elevated soil surface and forage canopy temperatures limited forage production and nutritive value at low density, while low light levels were the limiting factor at high density. Moderating forage microclimate with appropriately spaced trees is an effective way to improve forage production in temperate pastures. / Master of Science
123

Vybrané kvalitativní ukazatele jednodruhových medů z oblastí České republiky / Selected Qualitatives Parameters of Monofloral Honey from The Czech Republic

JURÁKOVÁ, Andrea January 2015 (has links)
The theme of this thesis is a comparison of selected quality indicators of samples from single-flower honeys from the area of the Czech Republic and honeys from different retail chains. The theoretical part focuses on the characteristics of the individual kinds of honey and how different their composition is. There are described basic physical and chemical requirements for honey including sensory requirements which are specified in Regulation No.76/2003 Code. The practical part contains a physically-chemical analysis according to the Harmonized methods of European Honey and a sensory evaluation of selected single-flower honeys (honeydew, acacia, lime, sunflower and rape). There were analysed twenty samples of honey from Czech beekeepers and fifteen samples of honey bought in different retail chains in the Czech Republic. Subsequently, these parameters were monitored - water content and acidity. Next step was a test for evidence of disruption by starchy sugar and malt extracts. Then, sensory requirements such as colour, smell, taste and consistence were evaluated. The conclusion of the comparison of honey samples indicates that individual honey samples differed the most in the taste and smell criteria and in addition the samples were often disrupted by starchy sugar and malt extracts. The samples collected from the beekeepers from the area of the Czech Republic complied with Regulation No.76/2003 Code. On the contrary, the samples from the chosen retail chains in the Czech Republic weren't in accordance with the criteria specified in Regulation No.76/2003 Code.
124

Výskyt melecitózního medu u včelstev na Českokrumlovsku, jeho jakost a způsoby využití / The occurence of cemented honey in bee colonies around Český Krumlov, guality and way of processing of cemented honey

KOPŘIVOVÁ, Eva January 2018 (has links)
The thesis deals with an incidence of so-called cement (melecitose) honey, which can cause serious problems to a beekeeper in the form of losses of bee colonies, honey as well as beewax works. It is a honeydew honey with a higher content of the trisaccharide of melezitose, which causes a quick crystallization in comb cells. A high concentration of this trisaccharide which consists of two molecules of glucose and one molecule of fructose is caused by some representatives of hemipteran insect. Reverse invertases present in hemipteran bodies cause synthesis of oligosaccharides, including the trisaccharide melezitose, from monosaccharides. Content of this trisaccharide is determining for the formation of the cement honey. Above 10 % it can cause quick crystallization of honey. Incidence of the melezitosis is increased by many factors of which the most important is weather suitable for reproduction of honeydew producers followed by a dry period during which water content in the honeydew decreases and the content of saccharides increases. Other important factors are health of the bee colony and species composition of the honeydew sources. Aim of the thesis was to analyse incidence of melecitose honey in the region of Český Krumlov over the period of several years depending of the length of active period of the individual bee keepers. Influence of altitude, year, weather, number of bee colonies, and species composition of honey flow sources was also evaluated. The thesis also presents methods of cement honey processing as used by beekeepers who have recently experienced this problem. The most frequently used method is dipping combs in water with subsequent reworking of the solution by honeybees. Zootechnical methods of beekeeping reflecting the problems of the incidence of cement honey are outlined in the theoretic part of the thesis.
125

Estudo químico e potencial antioxidante do mel e geoprópolis coletados pela abelha sem ferrão mandaçaia (Melipona mandacaia)

SILVA, Paulo Ricardo da 17 July 2015 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2017-03-30T12:33:21Z No. of bitstreams: 1 Paulo Ricardo da Silva.pdf: 2807070 bytes, checksum: a396ead3497c7e6defcd09112e6c5043 (MD5) / Made available in DSpace on 2017-03-30T12:33:21Z (GMT). No. of bitstreams: 1 Paulo Ricardo da Silva.pdf: 2807070 bytes, checksum: a396ead3497c7e6defcd09112e6c5043 (MD5) Previous issue date: 2015-07-17 / ] The species of stingless bee Melipona mandacaia is popularly known as mandaçaia and is native to northeastern Brazil. This study analyzed honey and geopropolis of mandaçaia. For honey were carried out pollen, physical and chemical analysis such as moisture, pH, free acidity, hydroxymethylfurfural, ash content, reducing sugars and water activity, amino acids, minerals and antiradical activity of four samples of honey. The major phenolic constituents of honey were extracted and analyzed by High Performance Liquid Chromatography Efficiency coupled to the Diode Array Detector (HPLC-DAD). Pollen analysis showed that the dominant pollen in honey samples was the plant species Mimosa arenosa (Fabaceae / Mimosoideae) ranging from 44.4% to 61.7%. The identified flavonoids quercetin, luteolin, and kaempferol acid derivatives: 3,4-dihydroxybenzoic, 1,2-dihydroxybenzoic, caffeic, cinnamic and ferulic were quantified. All honey samples showed the amino acid proline, alanine, serine and threonine. The minerals were the predominant calcium and potassium. All honeys showed scavenging activity of free radical front to DPPH and ABTS. For geopropolis of mandaçaia was determined to botanical origin, phenolics were quantified by HPLC-DAD and the antioxidant activity was determined by testing with DPPH, ABTS and beta carotene / linoleic acid system. Pollen analysis of nine samples geopropolis showed the presence of 25 types of pollen representing fifteen families. The Senna species (Leguminoseae) was the predominant pollen in eight of the nine samples. The phenol content in the geopropolis of mandaçaia were identified as caffeic acid, coumaric acid, trans-3-hydroxycinnamic acid, 4-methoxycinnamic acid and abscisic. All samples geopropolis showed antioxidant activity, except hexanic fractions that have been inactive for the free radical DPPH. / A espécie de abelha sem ferrão Melipona mandacaia é conhecida popularmente como mandaçaia e é nativa do Nordeste brasileiro. Neste estudo foi analisado o mel e a geoprópolis da mandaçaia. Foram realizadas as análises palinológicas, físico-químicas tais como umidade, pH, acidez livre, hidroximetilfurfural, teor de cinzas, açucares redutores e atividade de água, aminoácidos, minerais e atividade antirradicalar em quatro amostras de mel. Os principais constituintes fenólicos do mel foram extraídos e analisados por Cromatografia Líquida de Alta Eficiência acoplada ao Detector de Arranjo de Diodos (CLAE-DAD). A análise palinológica mostrou que o pólen predominante nas amostras de mel foi da espécie vegetal Mimosa arenosa (Fabaceae/Mimosoideae), variando de 44,4% a 61,7%. Os flavonoides identificados quercetina, luteolina, kampferol e os derivados de ácido: 3,4-dihidroxibenzoico, 1,2-dihidroxibenzoico, cafeico, cinâmico e ferúlico foram quantificados. Todas as amostras de mel apresentaram os aminoácidos prolina, alanina, serina e treonina. Os minerais predominantes foram o cálcio e potássio. Todos os méis apresentaram atividade sequestradora de radical livre frente ao DPPH e ABTS. A origem botânica da geoprópolis da mandaçaia foi determinada e os compostos fenólicos foram quantificados por CLAE-DAD e a atividade antioxidante foi determinada pelos testes com DPPH, ABTS e o sistema beta caroteno/ácido linoleico. A análise palinológica das nove amostras de geoprópolis mostraram a presença de 25 tipos de pólen representando quinze famílias. O tipo polínico Senna (Leguminoseae) foi o predominante em oito das nove amostras analisadas. Os fenólicos presentes na geoprópolis da mandaçaia foram identificados como sendo ácidos cafeico, cumárico, trans-3-hidroxicinâmico, abscísico e 4-metoxicinâmico. Todas as amostras de geoprópolis apresentaram atividade antioxidante, exceto as frações hexânicas que foram inativas para o radical livre DPPH.
126

Life History of Mayatrichia ponta Ross (Trichoptera: Hydroptilidae) in Honey Creek, Turner Falls Park, Oklahoma

Wang, Yi-Kuang 12 1900 (has links)
The life history and ontogenetic microhabitat change of Mayatrichia ponta Ross were investigated in Honey Creek, Turner Falls Park, Murray Co., Oklahoma, U.S.A. from August 1994 to August 1995. The shape of larval cases changed from a small cone to a cylinder. M. ponta had an asynchronous multivoltine life history with considerable cohort and generation overlap; five generations were estimated. The development rate was reduced in winter. The winter generations of M. ponta had wider head capsule widths (136-165 μm) than summer generations (121-145 μm). The sex ratio of adults was 1.43 ♂ : 1 ♀. Fecundity ranged from 46 to 150 eggs/female. Fifth instar larvae and pupae aggregated on the bottom side of substrates. Early instars were distributed evenly on all sides of substrates. General patterns of ontogenetic microhabitat shift in aquatic insects are categorized as flow mediated, flow independent, and population interactions and other resources mediated.
127

Atraktivita výsadeb druhů potencionálně rozšiřujících včelí pastvu pro včely / Attractive planting of species of potentially expanding bee pastures for bees

ŠEBESTA, Tomáš January 2019 (has links)
This diploma thesis entitled "Attractiveness of Planting Species with a Potential to Extend Bee Forage for Bees" discusses pollen and nectar plants planted in the Brník municipality in the Central Bohemian Region. The thesis consists of two parts. The theoretical part describes honeybees, bee plants and their pollen- and nectar production ability as well as bee forage from early spring until late autumn so as to reflect the needs of pollinators as best as possible. The practical part uses pollen analysis to microscopically analyse the representation of pollen grains of plants in the honey produced by local bee colonies. Pollen analyses of honey from own bee colonies are compared with that from bee colonies belonging to neighbouring beekeepers.
128

Feral Africanized honey bee ecology in a coastal prairie landscape

Baum, Kristen Anne 30 September 2004 (has links)
Honey bees, Apis mellifera, play an important role in many ecosystems, pollinating a wide variety of native, agricultural, and exotic plants. The recent decline in the number of feral and managed honey bee colonies in North America, as well as the arrival of Africanized honey bees, have caused concern about adequate pollination for agricultural crops and natural plant communities. However, little is known about feral colonies, and the feral population is the source for Africanized honey bees as they spread and infiltrate managed populations. The goal of my dissertation was to examine the ecology of feral honey bee colonies, adding the spatial context necessary to understand the population ecology and patterns of resource use by feral honey bees on the Welder Wildlife Refuge. I defined the functional heterogeneity of feral honey bee habitat by identifying the suitability of different habitats for feral colonies based on the distribution and abundance of important resources (cavities, nectar, and pollen). I evaluated the distribution and abundance of feral colonies by examining nest site characteristics, population trends, and spatial and temporal patterns in cavity use. Lastly, I examined resource use by evaluating patterns in pollen collection and identifying where and when honey bees searched for resources. Overall, the Welder Wildlife Refuge provided excellent habitat for feral honey bees, supporting a high density of feral colonies. The dense live oak habitat was the best overall source for cavities, nectar, and pollen. Nectar and pollen were abundant throughout the year, with the exception of December and January, when a large number of honey bees searched for resources. Cavities did not appear to vary in their suitability for feral colonies based on measured structural and environmental attributes, since no cavity attributes were correlated with indices of cavity quality. However, the cavity quality indices varied between cavities, suggesting some cavities were more suitable for feral honey bees than others. Colonies were aggregated within the study area, probably due to the distribution of resources. The invasion of Africanized honey bees appeared to fragment the existing European population, with Africanized colonies aggregated in distribution and European colonies random in distribution.
129

Atraktivita porostů pohanky pro včely / Atractivity of buckwheat for bees

KOSCHANT, Jan January 2017 (has links)
This diploma thesis ,,buckwheat attractivity for bees" deals mainly with native nectar plants for the processing of bees to honey. Work is folded in two parts. The theoretical part deals with the migration of colonies, both for nectar crops and plants with bee pollination needs. In ractical part of this thesis microscopic pollen analysis were performed and contents of pollen grains in honey from colonies, which were relocated to buckwheat growth was evaluated. Comparison of this honey with honey from the hives with similaar location, but without access to buckwheat growth was done.
130

Arranjo produtivo local e apicultura como estratégias para o desenvolvimento do sudoeste de Mato Grosso

Amaral, Anderson Marques do 20 May 2010 (has links)
Made available in DSpace on 2016-06-02T19:29:27Z (GMT). No. of bitstreams: 1 3157.pdf: 1685283 bytes, checksum: 5b0ce4290ca01438b5787e5b0a470517 (MD5) Previous issue date: 2010-05-20 / This study aims to characterize the honey production and the local productive honey arrangement, through the evaluation of the land use, honey production, regional flora and product quality. It also aims to stimulate local process of development, rural protagonist and social inclusion of the agricultural workers from the southeast of Mato Grosso. We have evaluated the production of honey during the period of 1987 to 2007, of the towns engaged in APL of apiculture which is available on the SIDRA System by IBGE. The quantification of the use and the topsoil of the soil were obtained through satellite images. We have used SPRING and ArcGIS software for the date using field information and appropriate terminology. We have identified the most important vegetal species for the production of honey. We have determined ten physic-chemistry parameters and we have evaluated the characteristics of the labeling of the commercialized honey. The town of Cáceres (42%) presents the biggest honey production fallowed by the towns of Comodoro (11%), then Poconé (7%), then Reserva do Cabaçal (7%), then Conquista do Oeste (6%), and Porto Espiridião (6%). The production of honey is not the principal economic activity of the apiculture of this region. Most of them have just one apiary with a small number of beehives and they lack time of experience on this activity. The extraction and benefit of honey is done in manufactured fashion and the commercialization of their honey is done directly to the consumers, in the local retailer market. The level of technology implemented in this activity is low and the farmers have also a low level of professionalization. Natural Vegetation was the predominant class of the use of the soil on the majority of the apiaries. The kinds of vegetal covering were summarized as it follows: Savannas; Ecological Tension; Seasonal Forest; Riparian Formation. Grazing was the only kind of entropic agriculture use. Not Agriculture Entropic Areas were less representative. The classes of the use of soil and the different kinds of vegetal covering printed differences in the richness of plants and in the production of honey of the apiaries. The evaluation of the use of the soil and the vegetal covering of it around the apiaries allows the establishment of the appropriate management and the ways of sustainable uses of the natural resources. The results of physic-chemistry analysis for the samples of honey showed that the median for humidity, redactor and non redactor sugars were among the required patterns by the MAPA. The percentage of insolates solids and the fixed mineral residuals remained over. The Fiehe reaction indicated the presence HMF in others samples. All of the brands evaluated presented some parameters over the maximum limit allowed by the Brazilian legislation, pointing out production problems, as well as collecting and processing of honey. Only two kinds of honey available in the local market, from Cáceres and some other regions, have the sanitary inspection validity. The labeling of the majority of the trades are not in conformity with nowadays legislation, and it ignores the important instrument of identification of origins of honey, which is a guarantee of products with quality and security to the customer. The apiaries represent a way of sustainable use of preserved natural vegetation areas, degradation grazing areas and existing capoeiras, besides, this activity shows itself compatible with some others activities already consolidated in the region of southeast of Mato Grosso. / O estudo teve o objetivo de caracterizar a produção apícola e o arranjo produtivo local de apicultura, por meio da avaliação dos usos da terra, produção de mel, flora regional e qualidade do produto, visando estimular processos locais de desenvolvimento, protagonismo rural e inclusão social de agricultores da região Sudoeste de Mato Grosso. Foi avaliada a produção de mel no período de 1987 a 2007, dos municípios participantes do APL de Apicultura, disponíveis no Sistema SIDRA do IBGE. A quantificação do uso e cobertura da terra foi obtida por imagens de satélite, tratadas nos software SPRING e ArcGIS, utilizando informações de campo e terminologia apropriada. Foram identificadas as espécies vegetais, importantes para a produção do mel. Foram determinados dez parâmetros físico-químicos do mel e avaliado características de rotulagem do mel comercializado. O município de Cáceres (42%) é o maior produtor de mel, seguido por Comodoro (11%), Poconé (7%), Reserva do Cabaçal (7%), Conquista do Oeste (6%) e Porto Esperidião (6%). A apicultura não é a principal atividade econômica dos apicultores da região, a maioria deles tem apenas um apiário, com pequeno número de colméias e possui pouco tempo de experiência na atividade. A extração e beneficiamento do mel são realizados de forma artesanal e a comercialização é feita de forma direta ao consumidor, no mercado varejista local. O nível tecnológico empregado na atividade é baixo e o apicultor tem pouco grau de profissionalização na atividade. A Vegetação Natural foi a classe predominante de uso da terra na maioria dos apiários. Os tipos de cobertura vegetal foram reunidos em: Savanas, Tensão Ecológica, Floresta Estacional e Formações Ripárias. Pastagem foi a única forma de uso Antrópico Agrícola. Áreas Antrópicas Não Agrícola foram pouco representativas. As classes de uso da terra e os tipos de cobertura vegetal do entorno dos apiários imprimiram diferenças na riqueza de plantas e na produção de mel dos apiários. A avaliação do uso e cobertura da terra permite o planejamento e a gestão da apicultura, possibilitando estabelecer manejo apropriado e formas de utilização sustentável dos recursos naturais. Os resultados da análise físico-química das amostras de mel mostraram que as médias para umidade, açúcares redutores e não redutores ficaram dentro dos padrões estabelecidos pelo MAPA. Os percentuais de sólidos insolúveis e resíduos minerais fixos ficaram acima. A reação de Fiehe indicou a presença de HMF em outras amostras. Todas as marcas avaliadas apresentaram algum parâmetro acima do limite máximo permitido pela legislação brasileira, evidenciando problemas na produção, coleta ou processamento do mel. Somente duas marcas de mel disponíveis no mercado local, oriundas de Cáceres e outras regiões, possuem selo de inspeção sanitária. O rótulo da maioria das marcas não está em conformidade à legislação vigente e ignora importante instrumento de identificação da origem do mel, garantia de produtos com qualidade e segurança ao consumidor. A apicultura representa uma forma de uso sustentável de áreas de vegetação natural preservadas, áreas de pastagens degradadas e capoeiras existentes, além disso, a atividade mostra-se ainda compatível com outras atividades já consolidadas na região Sudoeste de Mato Grosso.

Page generated in 0.0408 seconds