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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

Advancement of ovulation in yellowtail founder (Pleuronectes ferrugineus) using gonadotropic hormone-releasing hormone analogue (GnRHa) /

Bettles, Stephen Paul, January 1997 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. / Bibliography: leaves 55-69.
12

Efeitos do ataque de Costalimaita ferruginea (FABR.) (Coleoptera: Chrysomelidae) sobre crescimento e produção de Eucalyptus grandis Hill ex Maiden / The attack effects of Costalimaita ferruginea (FABR.) (Coleoptera: Chrysomelidae) to the growth and the production of Eucalyptus grandis Hill ex Maiden

Mendes, Jose Eduardo Petrilli 30 October 2003 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-03-30T18:08:15Z No. of bitstreams: 1 texto completo.pdf: 497483 bytes, checksum: 799187a8040ab486030824a44f88bfca (MD5) / Made available in DSpace on 2017-03-30T18:08:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 497483 bytes, checksum: 799187a8040ab486030824a44f88bfca (MD5) Previous issue date: 2003-10-30 / O gênero Eucalyptus é o mais freqüente entre as árvores plantadas no Brasil. Sabendo-se que os besouros desfolhadores são as mais importantes pragas em florestas de eucaliptos em vários países e, que a principal espécie de besouro desfolhador de eucaliptos no Brasil é Costalimaita ferruginea (Fabr.) (Coleoptera: Chrysomelidae). Tornou-se necessário conhecer com mais detalhes o comportamento daninho desta espécie, bem como as conseqüências do seu ataque às árvores de eucalipto. Para tanto foram identificadas quatro intensidades de ataque do besouro C. ferruginea, em plantio de Eucalyptus grandis, com idade entre 7 e 9 meses, e avaliadas as conseqüências deste ataque, durante o ciclo desta floresta, até a época de corte (sete anos). As árvores foram avaliadas quanto ao seu crescimento, produção de madeira, formato do fuste e sobrevivência. A descrição da ocorrência foi feita por meio do uso do sistema de monitoramento da praga, em uso no local. Para conhecer as conseqüências do ataque da praga sobre o povoamento florestal, nove medições foram realizadas entre os 12 e 84 meses de idade da floresta, sendo a sobrevivência das árvores quantificada nestas ocasiões. Aos 84 meses foi feita a cubagem rigorosa de árvores, segundo as quatro intensidades de ataque avaliadas para verificar as conseqüências do ataque na forma do fuste das árvores. Os dados das variáveis de interesse, que foram: diâmetro a 1,3 m de altura (dap); altura (Ht); área basal (B); volume de madeira por hectare (V); relação hipsométrica (Ht x dap); forma do fuste (taper); e sobrevivência das árvores, foram submetidos a análises de regressão. De posse das equações ajustadas para cada variável de interesse, procedeu-se um teste de identidade de modelos, que comparou, para cada variável, as diferentes intensidades de ataque causado pela praga às árvores com a testemunha. Verificou-se que todas as variáveis estudadas foram negativamente alteradas, de forma significativa, por todas as intensidades de ataque da praga, causando efeitos indesejáveis, tanto para as árvores como para o povoamento, gerando informações de fundamental importância na prática do manejo integrado deste importante grupo de pragas florestais, os besouros desfolhadores. / The eucalyptus species has been the most cultivated tree in Brazil and the leaf- beetles have been the most important pests in eucalyptus forests in some countries. The main species of eucalyptus leaf-eating beetles is Costalimaita ferruginea (Fabr.) (Coleoptera: Chrysomelidae) and it is necessary to know more details about the harmful behavior of this specie, as well as the consequences of its attack on eucalyptus trees. For this reason, four attack intensities of C. ferruginea beetles in Eucalyptus grandis plantation in the age between 7 and 9 months were identified and their consequences during the forest cycle until the cut period (seven years) were evaluated. The trees were analyzed in relation to their growth, wood production, bole format and survival. The description of the occurrence was made through the pest monitoring system used in the place. In order to know the consequences of the pest attack in the forest stand, nine measurements were carried out when the forest was between 12 and 84 months and the survival of the trees was quantified in these periods. When the forest reached 84 months a rigorous tree scaling was made according to four evaluated intensities of attack to verify its consequences in the tree bole form. The data of the variable of interest, that were: diameter: 1,3 m high (dap); height (Ht); basal area (B); wood volume for hectare (V); hypsometric relation (Ht x dap); bole form (to taper); and the survival of the trees, were submitted to the regression analysis. Through these equations adjusted for each variable of interest, a model identity test was made. It compared for each variable the different intensities of attack caused by the pest to the trees with the control. It was verified that all the studied variables were modified in a negative and significant way for all the intensities of the pest attack causing an undesirable effect as for the trees as for the stand. The resulting information has a great importance for the integrated management practice and for this important group of forest pest: the leaf-beetles. / Não foram localizados o cpf e o currículo lattes do autor.
13

Lipid utilization and feeding of juvenile yellowtail flounder (Pleuronectes ferrugineus) /

Whalen, Karen S., January 1999 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Restricted until November 2000. Bibliography: leaves 117-126.
14

The behaviour, growth, and survival of witch flounder and yellowtail flounder larvae in relation to prey availability /

Rabe, Jessica, January 1999 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves 124-132.
15

Atividade antiulcerogenica de extratos brutos, frações semi-purificadas e substancia ativa de duas especies do genero Vernonia : Vernonia polyanthes e Vernonia ferruginea / Antiulcerogenic activity of crude extracts, fractions and active compound from the species Vernonia polyanthes e Vernonia ferruginea

Barbastefano, Victor 23 February 2007 (has links)
Orientador: Alba Regina Monteiro Souza Brito / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-08T13:29:12Z (GMT). No. of bitstreams: 1 Barbastefano_Victor_D.pdf: 8030940 bytes, checksum: fafb57fc17a39a72e222df9d06055b31 (MD5) Previous issue date: 2007 / Resumo: O gênero Vernonia (Asteraceae) compreende cerca de 1000 espécies, figurando como o gênero mais representativo da sua família. Do ponto de vista sistemático, Vernonia é um dos gêneros mais complexos da família Asteraceae, principalmente pela extrema diversidade de formas biológicas que exibe, desde pequenas ervas até grandes árvores. O gênero possui um grande potencial farmacológico e é sempre mencionado em trabalhos etnofarmacológicos. Só no banco de dados Pubmed o termo ¿Vernonia¿ foi citado 126 vezes até Dezembro de 2006. No presente trabalho, a atividade antiulcerogênica de duas espécies do gênero Vernonia (Vernonia polyanthes Less. e Vernonia ferruginea Less.) foi investigada. Ambas as espécies estão presentes no cerrado, embora possuam ampla distribuição pelo território brasileiro, e são empregadas popularmente para o tratamento de bronquite, tosse, asma, cálculo renal, etc. Inicialmente foram realizados ensaios fitoquímicos e farmacológicos nos extratos brutos, clorofórmico e metanólico, de cada espécie. Foi identificada a presença de flavonóides e terpenóides em ambas as espécies, além da presença de atividade antiulcerogênica em todos os extratos brutos avaliados. Investigamos a seguir alguns dos possíveis mecanismos de ação dos extratos mais eficazes de cada espécie, do extrato metanólico da V. ferruginea (EMVF), rico em flavonóides e do extrato clorofórmico da V. polyanthes (ECVP), rico em terpenóides. Concluímos que eles estão relacionados a um aumento na produção de muco aderido à mucosa gástrica e dependem em parte da presença de óxido nítrico (NO) e radicais sulfidríla (SHs). O extrato ECVP foi então fracionado em fração clorofórmica (FCVP) e metanólica (FMVP) e o extrato EMVF foi particionado em fração acetato (FAVF) para avaliação farmacológica em modelos de úlcera crônica e aguda induzida. A fração FMVP, a mais eficaz dentre as duas espécies estudadas, foi então submetida a ensaios fitoquímicos objetivando a identificação da sua substância majoritária. O lupeol, triterpeno pentacíclico da família dos lupanos, foi identificado como o princípio ativo da espécie V. polyanthes e novos ensaios farmacológicos foram então realizados para elucidação dos seus mecanismos de ação. Foi identificado um aumento na produção de muco em animais pré-tratados com o lupeol, relacionado à presença de NO. Observou-se também uma boa atividade antiinflamatória na mucosa gástrica, através da diminuição da infiltração de neutrófilos, relacionada a uma diminuição na produção de PGE2. O lupeol, na dose investigada, não promoveu aumento significativo no pH do suco gástrico, o que descarta uma possível atividade anti-secretória. Por fim, nos estudos crônicos de indução de úlcera, o lupeol não apresentou toxicidade in vivo e demonstrou possuir uma grande atividade cicatrizante das lesões gástricas, provavelmente não relacionada à presença da Heat Shock Protein 70 (HSP70) e proliferação celular (PCNA) na borda da lesão. No presente trabalho, através do fracionamento biomonitorado das espécies V. polyanthes e V. ferruginea, identificamos a substância antiulcerogênica lupeol. A sua alta atividade gastroprotetora aliada à sua baixa toxicidade in vivo fazem do lupeol um fármaco potencial para o tratamento de úlceras gástricas / Abstract: The genus Vernonia (Asteraceae), which includes about 1.000 species, figures as the most representative from its family. From a systematic point of view, Vernonia is one of the most complex genus of its family, mainly because of its diverse biological forms, from small herbs through big trees. This genus possesses a great pharmacological potential and is always mentioned by ethnopharmacological works. Evidence for the interest in this genus is the number of citations in the database Pubmed. This exceeds 126 for the keyword ¿Vernonia¿, as of December, 2006. In the present work, the antiulcerogenic effect of two species from genus Vernonia (Vernonia polyanthes Less. and Vernonia ferruginea Less.) was evaluated. Both species are found predominately in Brazilian savannah, although they are widespread over Brazilian territory. They are used in traditional medicine for the treatment of bronchitis, cough, asthma and renal calculus. Initially, phytochemical and pharmacological assays were done with the crude methanolic and chloroformic extracts from each species. Flavonoids and terpenoids were identified in both species, and all crude extracts presented an antiulcerogenic effect. Soon afterward we evaluated some of the action mechanisms from the most effective crude extracts, the methanolic extract from V. ferruginea (EMVF), a flavonoid rich extract, and the chloroformic extract from V. polyanthes (ECVP), a terpenoid rich extract. They both presented an increase in gastric mucus content, and depended in part of the nitric oxide (NO) and sulfhydryls (SHs) presence. ECVP was then fractionated in a chloroformic (FCVP) and methanolic fraction (FMVP), while EMVF was partitioned in an acetate fraction (FAVF) for pharmacological approaches in chronic and acute models. FMVP, the most effective fraction, had its majority compound identified. Lupeol, a lupane pentacyclic triterpene, was identified as the active compound from V. polyanthes, and new assays were done to evaluate its action mechanisms. Lupeol increased gastric mucus content in rats, probably mediated by NO presence. It also presented anti-inflammatory properties in gastric mucosa, reducing PGE2 production and neutrophil infiltration. On its effective dose, it didn¿t decreased the gastric acid output. On the other hand, Lupeol showed on a chronic model of ulcer induction a great healing effect with no toxicity in vivo, probably not related to the presence of Heat Shock Protein 70 (HSP70) and cellular proliferation (PCNA) on the ulcer border. In the present work, in a biomonitored fractionation process of the species V. polyanthes and V. ferruginea, we identified the antiulcerogenic compound lupeol. Its high gastroprotective effect allied to its low toxicity in vivo, turns it a potential drug for treating gastric ulcers / Doutorado / Fisiologia / Doutor em Biologia Funcional e Molecular
16

A seasonal study of male reproduction and sperm physiology of three coldwater flatfish /

Shangguan, Bumin, January 1998 (has links)
Thesis (Ph.D.)--Memorial University of Newfoundland, 1999. / Restricted until June 2000. Bibliography: leaves 222-240.
17

Tubetes e substratos na produção de mudas de cássia-rosa (Cassia grandis L.f) e canafístula (Cassia ferruginea (Schrad.) Schrader ex DC) / Tubes and substrates in the production of seedlings of cassia-rosa (Cassia grandis L.f) and canafistula (Cassia ferruginea (Schrad.) Schrader ex DC)

Duarte, Marciel Lelis 25 February 2016 (has links)
Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2016-08-19T12:36:52Z No. of bitstreams: 1 texto completo.pdf: 584198 bytes, checksum: b64e23bded0c89e30160a1a288e3bc37 (MD5) / Made available in DSpace on 2016-08-19T12:36:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 584198 bytes, checksum: b64e23bded0c89e30160a1a288e3bc37 (MD5) Previous issue date: 2016-02-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Diante da exploração, muitas vezes desordenada, dos recursos naturais, culminando na degradação das áreas e perda da biodiversidade, a recuperação ambiental por meio do plantio de espécies nativas é importante para reestabelecer o equilíbrio dos ecossistemas e para preservar as espécies. Mudas de qualidade são fundamentais para garantir o sucesso dos plantios florestais, pois possibilitam o maior crescimento e sobrevivência pós-plantio no campo. Para a produção de mudas de boa qualidade, entre vários fatores, a escolha adequada do recipiente e do substrato no qual as espécies serão cultivadas é de vital importância. Entretanto, para muitas espécies arbóreas nativas esse conhecimento ainda é escasso. O objetivo deste estudo foi avaliar o crescimento de mudas de cássia- rosa (Cassia grandis L.f) e canafístula (Cassia ferruginea (Schrad.) Schrader ex DC.), produzidas em tubetes de diferentes capacidades e substratos. Foi utilizado um fatorial 4 x 5, constituído de quatro substratos e cinco tubetes (35; 50; 120; 180 e 288 cm3 de capacidade) disposto em delineamento estatístico de blocos casualizados, com três repetições e 25 plantas por parcela. Os substratos testados foram: 100% substrato comercial (tropstrato florestal); 50% substrato comercial + 50% de casca de arroz carbonizada; 50% substrato comercial + 50% fibra da casca de coco; e 25% substrato comercial + 25% casca de arroz carbonizada + 25% fibra da casca de coco + 25% terra de subsolo). Ao fim do experimento foram determinadas a altura, o diâmetro, a massa de matéria seca da parte aérea (MSPA), a massa de matéria seca de raízes (MSR) e a massa de matéria seca total (MST), além das relações altura/diâmetro (RHDC), massa de matéria seca da parte aérea/massa de matéria seca de raízes (RMSPAMSR), altura/massa de matéria seca da parte aérea (RHMSPA) e índice de qualidade de Dickson (IQD). A capacidade dos tubetes e os substratos tiveram influência significativa no crescimento das mudas. O melhor crescimento das mudas de cássia-rosa ocorreu nos tubetes de 288 e 180 cm3 de capacidade, usando substrato composto por 50% de fibra da casca de coco + 50% substrato comercial. Já para as mudas de canafístula o melhor crescimento ocorreu nos tubetes de 288, 180 e 120 cm3 de capacidade, usando substrato composto por 50% de fibra da casca de coco + 50% substrato comercial e o substrato composto por 25% substrato comercial + 25% casca de arroz carbonizada + 25% fibra da casca de coco + 25% terra de subsolo. / Given to the exploration of natural resources, many times disordered, culminating in degradation of areas and loss of biodiversity, the environmental recovery through native species is important to reestablish the equilibrium of ecosystems and to preserve the species. Seedlings quality are fundamental to ensure the success of forest plantations, since they allow a better growth and survival once planted. For the production of quality seedlings it is necessary to know the proper choice of the container and the substrate in which species are cultivated. However, for many native woody species this knowledge is still scarce. The aim of this study was to evaluate the effect of size of tubes and types of substrates on the quality of seedlings of Cassia grandis L.f e Cassia ferruginea (Schrad.) Schrader ex DC, produced in tubes of different size and types of substrates. A factorial 4 x 5 consisting of four types of substrate and five volumes of tubes (35, 50, 120, 180 and 288 cm3 capacity) arranged in a randomized block design, with three replicates and 25 plants per repetition was used. Substrates tested were: 100% commercial substrate (forest tropstrato); 50% commercial substrate + 50% carbonized rice husk; 50% commercial substrate + 50% coconut fiber; and 25% commercial substrate + 25% carbonized rice hulls + 25% coconut fiber + 25% subsoil). An the end of the experiment data regarding to height, collar diameter, aerial part dry weight and root, and the ration between height and collar diameter (RHDC), height aerial part and dry weight (RHMSPA), aerial part dry weight root and dry weight (RMSPAMSR) and Dickson quality index (IQD) were collected. The best development of seedlings of cássia-rosa occurred in tubes of 288 and 180 cm3 capacity, using substrate composed of 50% coconut fiber + 50% commercial substrate. Regarding to seedlings of canafístula, the best development occurred in tubes of 288, 180 and 120 cm3 capacity, using substrate composed of 50% commercial substrate + 50% coconut fiber and the substrate composed of 25% commercial substrate + 25% carbonized rice hull + 25% coconut fiber + 25% subsoil.
18

Metab?litos especiais isolados de folhas e galhos de Ouratea ferruginea Engl. (Ochnaceae).

Fidelis, Queli Cristina 25 February 2011 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-07-27T13:08:18Z No. of bitstreams: 1 2011 - Queli Cristina Fidelis.pdf: 8250271 bytes, checksum: f51d246c251bca4327f02da1e892ff77 (MD5) / Made available in DSpace on 2016-07-27T13:08:18Z (GMT). No. of bitstreams: 1 2011 - Queli Cristina Fidelis.pdf: 8250271 bytes, checksum: f51d246c251bca4327f02da1e892ff77 (MD5) Previous issue date: 2011-02-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico, CNPq, Brasil. / This work describes the phytochemical study of the stems and leaves of Ouratea ferruginea Engl., Ochnaceae. The material for study was collected in the campus of Embrapa in Bel?m, Par? state, and identified by Dra Silvane Taveres Rodrigues. The compounds described in this phytochemistry investigation were isolated by the solvents partition and chromatographyc techniques of the extracts obtained by maceration at room temperature with hexane, ethyl acetate and methanol. The structures were determined through analysis of data provided by IR, 1H and 13C NMR (1D an 2D techniques), mass spectrometry including GCMS and HPLC-MS of natural compounds and some derivatives. From the stem dichloromethane extract friedelin, friedelinol, sitosterol, stigmasterol, campesterol, 3-b-O-Dglucopyranosyl- stigmasterol, 2,6-dimethoxy?benzoquinine, 2,6-dimethoxy-hydroquinone, the isoflavones: 5,4'-dihydroxy-7,3',5'-trimethoxy-isoflavone, 5-hydroxy-7,3',4',5'-tetramethoxyisoflavone, 5,4'-dihydroxy-7,3'-dimethoxy-isoflavone, 7,5-dihydroxy-3',4',5'-trimethoxyisoflavone, 7,5,4?-trihydroxy-3?,5?-dimethoxy-isoflavone, and ferulic and syringic aldehyde were isolated. From the dichloromethane partition of the methanol extract of the stem vanillic acid, 4 ((1E)-3-hydroxy-1-propenyl)-2-methoxyphenol and 3,5-dimethoxy-4-hydroxydihydrocinamaldehyde were isolated. From hexane fraction of methanol extract from the leaves lupeone was isolated, and from the dichloromethane methanol partition were identified the biflavonoids amentoflavone and 7-methyl-amentoflavone, known as sequoiaflavone, along with syringic acid. From the ethyl acetate of the methanol extracts partition the epicatechin which absolute configuration was defined by circular dichroism spectral analysis was isolated. The sequioflanove is been identified in Ochnaceae for the first time. From the polar fraction the total phenol were determined by adapted Folin-Denis and precipitation with casein methods and by NMR spectral analysis. / Este trabalho descreve o estudo fitoqu?mico de caule e folhas da esp?cie vegetal Ouratea ferruginea Engl, Ochnaceae. O material para estudo foi coletado no campus da Embrapa em Bel?m do Par? e identificado pela Dra Silvane Tavares Rodrigues. As subst?ncias descritas nesta investiga??o fitoqu?mica foram isoladas atrav?s de parti??o com solventes e t?cnicas cromatogr?ficos de extratos obtidos atrav?s de macera??o a frio com hexano, acetato de etila e metanol. As estruturas foram determinadas atrav?s da an?lise de dados fornecidos por espectrometria na regi?o do infravermelho, RMN 1H e 13C (t?cnicas 1D e 2D), de massas incluindo CG-EM e CLAE-EM das subst?ncias naturais e de alguns derivados. Do extrato em diclorometano do caule foram isolados friedelina, friedelinol, sitosterol, estigmasterol, campesterol, 3-b-O-D-glicopiranosil-estigmasterol, 2,6-dimetoxi benzoquinona, 2,6-dimetoxi hidroquinona, as isoflavonas 5,4?-diidroxi-7,3?,5?-trimetoxiisoflavona, 5,4?-diidroxi-7,3?-dimetoxi-isoflavona, 5-hidroxi-7,3?,4?,5?-tetrametoxiisoflavona, 7,5-diidroxi-3?,4?,5?-trimetoxi-isoflavona, 7,5,4?-triidroxi-3?,5?-dimetoxiisoflavona, al?m dos alde?dos sir?ngico e fer?lico. Da parti??o em diclorometano do extrato metan?lico do caule foram isolados ?cido van?lico, 4((1E)-3-hidroxi-1-propenil)-2- metoxifenol e 3,5-dimetoxi-4-hidroxi-diidrocinamalde?do. Das folhas foi isolada a lupeona na parti??o em hexano do extrato metan?lico; e na parti??o em diclorometano foram identificados os biflavon?ides amentoflavona e 7-metil-amentoflavona, conhecida como sequoiaflavona, e o ?cido sir?ngico. Na parti??o em acetato de etila foi isolado a epicatequina cuja configura??o absoluta foi definida com an?lise do espectro de dicro?smo circular. A sequioflavona est? sendo registrada pela primeira vez em Ochnaceae. Das fra??es polares foram determinados o teor de fen?is totais e taninos por m?todos de Folin-Denis e precipita??o com case?na, adaptados, al?m de an?lise com espectros de RMN.
19

Etude phytochimique et évaluation biologique de Derris ferruginea Benth. (Fabaceae)

Morel, Sylvie 09 June 2011 (has links) (PDF)
Les plantes du genre Derris (Fabaceae) sont connues pour contenir des flavonoïdes, en particulier des isoflavonoïdes dont des roténoïdes. Derris ferruginea (Benth.), liane originaire d'Asie, est utilisée traditionnellement comme insecticide, poison de pêche et dans la lutte contre les ectoparasites. L'étude phytochimique d'extraits de tiges et de feuilles de Derris ferruginea a permis d'isoler et de caractériser 14 composés essentiellement de type flavanones et isoflavonoïdes. Ces composés comportent pour la plupart des prénylations. Une évaluation biologique étendue à la fois des extraits et de certains composés a été réalisée. Pour deux composés, des méthodes d'obtention alternatives ont été utilisées. La chromatographie de partage centrifuge a permis d'obtenir en quantité plus importante la cajaflavanone qui s'avère posséder des propriétés intéressantes du point de vue biologique (effet anti-inflammatoire sur cellules microgliales, inhibiteur de la formation des produits terminaux de glycation par un mécanisme non-antioxydatif, effet proangiogénique ex vivo). La synthèse d'un composé original a été entreprise et a permis de valider sa structure. Enfin, le composé majoritaire des feuilles a fait l'objet d'une étude préliminaire sur un modèle d'étude de l'activité insecticide : les DUM neurones de Periplaneta americana. Cette technique électrophysiologique a permis d'appréhender le mécanisme d'action de ce composé.
20

The ecology and conservation of endangered saproxylic hoverflies (Diptera, Syrphidae) in Scotland

Rotheray, Ellen L. January 2012 (has links)
Hoverflies are important for their roles in ecological and environmental services, and are also charismatic species of conservation interest in their own right. Almost half of all hoverflies are saprophages, which are organisms that feed on dead or decaying organic matter, and these include saproxylic species that depend on deadwood. Deadwood and its associated community are a rich source of forest biodiversity and are fundamental to forest function, but due to poor management, many saproxylics are threatened or endangered, and techniques for conserving saproxylic species are poorly developed. In this thesis I study the ecology and conservation management of an endangered UK saproxylic fly, the Pine hoverfly, Blera fallax (Linnaeus) (Diptera, Syrphidae) and the dispersal ability of the similarly endangered Aspen hoverfly, Hammerschmidtia ferruginea (Fallén) (Diptera, Syrphidae). My main goals were to clarify methods to support their recovery in active programmes of species conservation in Scotland, UK. For B. fallax, this included experimenting with habitat creation techniques, investigating the best conditions for larval growth and assessing competition effects. In addition, I evaluated the genetic variability of the remaining population in Scotland by comparing it with one in Europe to determine whether genetic constraints may limit recovery. For H. ferruginea, I determined dispersal ability with field experiments involving mark and recapture techniques. By cutting holes at the surface of stumps of Pinus sylvestris, breeding habitat was created artificially for B. fallax at the remaining known locality for this species in the UK. Over 4 years, 81 % of holes were colonized by B. fallax, and by up to six other saproxylic syrphid species. The most successful holes were those cut into the heartwood, seeded with pine chips and sawdust and partially covered, as indicated by a combination of field occupancy monitoring and lab growth experiments. Observations of larval morphology and behaviour within rot holes revealed specializations that largely segregate the species in both time and space, and may mitigate interspecific competition between B. fallax and three more common syrphid species. I further demonstrated that B. fallax has a life history that features facultative semivoltine development, which may be a bet-hedging strategy to cope with fluctuating levels of larval food. Fifty B. fallax larvae were successfully reared and bred in captivity and from these, 430 descendent laboratory reared larvae and adults were released across three relocation sites. After initial success at the first re-location site when a new generation of larvae appeared in holes in 2010, a population crash at all sites occurred in the following year, possibly caused by adverse weather conditions. This disappointing result highlights the vulnerability of small populations to stochastic events, and means that survival of B. fallax may now depend on those larvae that are semivoltine, supplemented by animals currently being reared in captivity. My genetic analyses revealed similarly troubling information that highlights the precarious existence of B. fallax in Scotland: compared with a population in Sweden, Scottish B. fallax had significant less neutral genetic variation, and showed signs of a recent and severe bottleneck that reduced the effective population size to just 12 (CI: 0 - 266) individuals at some point in the last 200 years. Mindful of these challenges, I exploit my new data on the ecology and life history of B. fallax and combine it with techniques for captive rearing and for monitoring the genetic health of B. fallax into specific protocols and general prescriptions for the on-going recovery and management of this species. In order to assess the dispersal ability of H. ferruginea (and therefore its potential for recolonizing newly created habitat), in May to July over two years, adults were marked and released from a central point and subsequently monitored at the breeding site, decaying aspen wood Populus tremula, where adults tend to assemble for mating and oviposition. Adults were resighted visiting logs of decaying aspen set out at 1 km intervals along transects up to 7 km away. Up to 10 % of released individuals were resighted up to 5 km from the central release point. Most dispersing individuals (68 %) were resighted at 1 km, which I propose as the optimal distance for managing aspen for this species. Both of these hoverflies are case studies of techniques for recovering endangered saproxylic flies. Overall, my findings greatly increase fundamental knowledge of the ecology and natural history of these flies, and clarify some of the practical approaches that will be required in their conservation.

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