Made available in DSpace on 2014-12-17T15:37:15Z (GMT). No. of bitstreams: 1 RaulFDS_DISSERT.pdf: 3514530 bytes, checksum: 5a7cb4478b93d4050ccdf9c56e02ddbb (MD5) Previous issue date: 2013-03-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This study investigated the influence of intrinsic and extrinsic factors on the feeding ecology and foraging behavior of the whiptail lizard Ameivula aff. ocellifera, a new species widely distributed in the Brazilian Caatinga, and that is in process of description. In attendance to the objectives, the Dissertation was structured in two chapters, which correspond to scientific articles, one already published and the other to be submitted for publication. In Chapter 1 were analyzed the general diet composition, the relationship between lizard size and prey size, and the occurrence of sexual and ontogenetic differences in the diet. Chapter 2 contemplates a seasonal analysis of diet composition during two rainy seasons interspersed with a dry season, and the quantitative analysis of foraging behavior during two distinct periods. The diet composition was determined through stomach analysis of lizards (N = 111) collected monthly by active search, between September 2008 and August 2010, in the Esta??o Ecol?gica do Serid? (ESEC Serid?), state of Rio Grande do Norte. Foraging behavior was investigated during a rainy and a dry month of 2012 also in ESEC Serid?, by determining percent of time moving (PTM), number of movements per minute (MPM) and prey capture rate by the lizards (N = 28) during foraging. The main prey category in the diet of Ameivula aff. ocellifera was Insect larvae, followed by Orthoptera, Coleoptera and Araneae. Termites (Isoptera) were important only in numeric terms, having negligible volumetric contribution (<2%) and low frequency of occurrence, an uncommon feature among whiptail lizards. Males and females did not differ neither in diet composition nor in foraging behavior. Adults and juveniles ingested similar prey types, but differed in prey size. Maximum and minimum prey sizes were positively correlated with lizard body size, suggesting that in this population individuals experience an ontogenetic change in diet, eating larger prey items while growing, and at the same time excluding smaller ones. The diet showed significant seasonal differences; during the two rainy seasons (2009 and 2010), the predominant prey in diet were Insect larvae, Coleoptera and Orthoptera, while in the dry season the predominant prey were Insect larvae, Hemiptera, Araneae and Orthoptera. The degree of mobility of consumed prey during the rainy seasons was lower, mainly due to a greater consumption of larvae (highly sedentary prey) during these periods. Population niche breadth was higher in the dry season, confirming the theoretical prediction that when food is scarce, the diets tend to be more generalized. Considering the entire sample, Ameivula aff. ocellifera showed 61,0 ? 15,0% PTM, 2,03 ? 0,30 MPM, and captured 0,13 ? 0,14 per minute. Foraging mode was similar to that found for other whiptail lizards regarding PTM, but MPM was relatively superior. Seasonal differences were verified for PTM, which was significantly higher in the rainy season (66,4 ? 12,1) than in the dry season (51,5 ? 15,6). It is possible that this difference represents a behavioral adjustment in response to seasonal variation in the abundance and types of prey available in the environment in each season / Este estudo investigou a influ?ncia de fatores intr?nsecos e extr?nsecos sobre a ecologia alimentar e o comportamento de forrageamento do lagarto cauda-de-chicote (whiptail) Ameivula aff. ocellifera, uma esp?cie nova com ampla distribui??o na Caatinga, e que est? em fase de descri??o. Em atendimento aos objetivos, a Disserta??o foi estruturada na forma de dois cap?tulos, os quais correspondem a artigos cient?ficos, um j? publicado e o outro a ser submetido ? publica??o. No Cap?tulo 1 s?o analisadas a composi??o geral da dieta, a rela??o entre o tamanho corporal dos lagartos e o tamanho das presas consumidas, e a ocorr?ncia de diferen?as sexuais e ontogen?ticas na dieta. O Cap?tulo 2 contempla a composi??o da dieta em termos sazonais, durante duas esta??es chuvosas intercaladas por uma esta??o seca, e an?lise quantitativa do comportamento de forrageamento durante dois per?odos distintos. A composi??o da dieta foi identificada atrav?s da an?lise do conte?do estomacal de lagartos (N = 111) coletados mensalmente por busca ativa entre setembro de 2008 e agosto de 2010, na Esta??o Ecol?gica do Serid? (ESEC Serid?), estado do Rio Grande do Norte. O comportamento de forrageamento foi investigado durante um m?s chuvoso e um m?s seco do ano de 2012 tamb?m na ESEC Serid?, avaliando-se a porcentagem do tempo gasta em movimento (PTM), o n?mero de movimentos por minuto (MPM) e taxa de captura de presas pelos lagartos (N = 28) durante o forrageamento. A principal categoria de presa na dieta de Ameivula aff. ocellifera foi Larvas de insetos, seguido por Orthoptera, Coleoptera e Araneae. T?rmitas (Isoptera) foram importantes somente em n?mero, com contribui??o volum?trica desprez?vel (<2%) e baixa frequ?ncia de ocorr?ncia, um tra?o incomum entre os lagartos whiptails. Machos e f?meas n?o diferiram nem na composi??o da dieta nem no comportamento de forrageamento. Adultos e juvenis se alimentaram de categorias de presa similares, mas diferiram no tamanho das presas. Os tamanhos m?ximo e m?nimo das presas foram positivamente correlacionados com o tamanho dos lagartos, sugerindo que na popula??o estudada os indiv?duos sofrem uma mudan?a ontogen?tica na dieta, consumindo itens alimentares maiores ? medida que crescem, e ao mesmo tempo excluindo presas menores. A dieta apresentou diferen?as sazonais significativas; durante as duas esta??es chuvosas (2009 e 2010), as presas predominantes na dieta foram Larvas de inseto, Coleoptera e Orthoptera, enquanto na esta??o seca as presas predominantes foram Larvas de inseto, Hemiptera, Araneae e Orthoptera. O grau de mobilidade das presas consumidas durante as esta??es chuvosas foi menor, principalmente devido ao maior consumo de larvas (presas altamente sedent?rias) durante esses per?odos. A largura de nicho da popula??o foi maior na x esta??o seca, confirmando a predi??o te?rica de que quando o alimento ? escasso, as dietas tendem a ser mais generalizadas. Considerando a amostra total, Ameivula aff. ocellifera apresentou 61,0 ? 15,0% PTM, 2,03 ? 0,30 MPM, e capturou 0,13 ? 0,14 presas por minuto. O modo de forrageamento foi similar ao encontrado para outros lagartos whiptails quanto a PTM, mas MPM foi relativamente superior. Diferen?as sazonais foram verificadas quanto a PTM, que foi significativamente maior na esta??o chuvosa (66,4 ? 12,1) que na esta??o seca (51,5 ? 15,6). ? poss?vel que essa diferen?a represente um ajuste comportamental em resposta ? varia??o sazonal na abund?ncia e tipos de presas dispon?veis no ambiente nas diferentes esta??es

A soja (Glycine max (L.) Merrill) com o evento DAS-81419-2 (ConkestaTM technology) que expressa as proteínas de Bacillus thuringiensis (Bt) Cry1F e Cry1Ac protege a cultura de danos de alimentação de lepidópteros-praga primários e secundários. Experimentos de campo foram conduzidos de 2011 à 2016 na região sul e central do Brasil para caracterizar a eficácia da soja DAS-81419-2 infestada com Anticarsia gemmatalis (Lepidoptera: Erebidae), Chrysodeixis includens (Lepidoptera: Noctuidae), Chloridea virescens (Lepidoptera: Noctuidae), Spodoptera cosmioides (Lepidoptera: Noctuidae), Elasmopalpus lignosellus (Lepidoptera: Pyralidae), Agrotis ipsilon (Lepidoptera: Noctuidae) e Helicoverpa armigera (Lepidoptera: Noctuidae) durante os estágios vegetativo (V4) e reprodutivo (R2 e/ou R4) da cultura. A eficácia da soja DAS-81419-2 foi comparada com a variedade isogênica não-Bt manejada com ou sem inseticidas foliares comerciais para controle de lepidópteros. DAS-81419-2 reduziu significantemente o dano de alimentação causado por A. gemmatalis, C. includens, C. virescens, S. cosmioides e H. armigera durante os estágios vegetativo e reprodutivo, bem como, a mortalidade de plântulas causada por E. lignosellus. Entretanto, DAS-81419-2 apresentou moderada atividade em A. ipsilon. Além disto, um estudo de campo de três anos avaliou os potenciais efeitos adversos de DAS-81419-2 por meio da inspeção da diversidade e abundância de artrópodes não-alvos comparado com a isolinha não-Bt com ou sem aplicações convencionais de inseticidas. Estes estudos foram conduzidos em três regiões produtoras de soja onde os artrópodes não-alvos da parte aérea e da superfície do solo foram monitorados. Em geral, a abundância e diversidade total não foram afetadas signifativamente pela soja Bt. Desta maneira, DAS-81419-2 mostrou eficácia consistente ao longo dos anos, localidades e diferente estágios da cultura contra lepidópteros-pragas primários e secundários de importância econômica da cultura da soja e não afetou adversamente os artrópodes não-alvos que ocorrem nos campos de soja. / Soybean (Glycine max (L.) Merrill) event DAS-81419-2 (ConkestaTM technology) expresses Bacillus thuringiensis (Bt) Cry1F and Cry1Ac proteins to provide protection against primary and secondary lepidopteran pest feeding damage. Field experiments were conducted from 2011 to 2016 in southern and central Brazil to characterize the efficacy of DAS-81419-2 soybean infested with Anticarsia gemmatalis (Lepidoptera: Erebidae), Chrysodeixis includens (Lepidoptera: Noctuidae), Chloridea virescens (Lepidoptera: Noctuidae), Spodoptera cosmioides (Lepidoptera: Noctuidae), Elasmopalpus lignosellus (Lepidoptera: Pyralidae), Agrotis ipsilon (Lepidoptera: Noctuidae), and Helicoverpa armigera (Lepidoptera: Noctuidae) during vegetative (V4) and reproductive (R2 and/or R4) crop developmental stages. The efficacy of DAS-81419-2 was compared to a non-Bt isogenic variety managed with or without applications of commercial foliar insecticides for lepidopteran control. DAS-81419-2 significantly reduced the feeding damage caused by A. gemmatalis, C. includens, C. virescens, S. cosmioides, and H. armigera during both vegetative and reproductive crop growth stages as well as the seedling stage plant mortality caused by E. lignosellus. However, DAS-81419-2 showed moderate activity on A. ipsilon. In addition, a 3-yr in-field study evaluated the potential adverse effects of DAS-81419-2 by examining the diversity and abundance of non-target arthropods (NTAs) compared to the non-Bt near isoline with and without conventional insecticide applications. These studies were conducted in three Brazilian soybean producing regions where both soil surface and aerial NTA were monitored. Overall, the total abundance and diversity were not significantly affected by Bt soybean. Therefore, DAS-81419-2 showed consistent efficacy across years, locations, and crop stages against the most economically important primary and secondary lepidopteran pests of soybean and did not adversely affect non-target arthropods occurring in soybean field.

En outre, nous avons fait une expérience sur les nouveaux outils pour identifier les tiques par MALDI-TOF MS protéines profilage et des méthodes moléculaires. Notre étude visant à explorer les bactéries dans les ixodidae prélevés sur des animaux domestiques en Éthiopie a révélé une prévalence globale de 6% (46/767) des rickettsies de SFG, 3,8% (29/767) ADN de Borrelia et 6,4% (54/842) de C. burnetii dans différentes espèces de tiques. L'étude pour étudier les bactéries dans 303 puces prélevés sur des chiens et des chats domestiques en Ethiopie qui ont été identifiés comme étant morphologiquement Ctenocephalides felis felis, Ctenocephalides canis, Pulex irritans et Echidnophaga gallinacé montré Rickettsia felis dans 21% des puces, principalement dans Ctenocephalides felis, avec un semblable prévalence dans les puces de chiens et de chats. La présence d'Acinetobacter spp. dans M. ovinus, Heterodoxus spiniger, Bovicola ovis et Linognathus vituli. La séquence du gène rpoB partiel a révélé la présence de A. soli, A. lowffii, A. Pitti et 3 nouveaux Acinetobacter spp. dans les poux et Keds. Bartonella melophagi a été identifié par une PCR standard, suivi par un séquençage du fragment de la gltA et gène rpoB chez M. ovinus. Dans l'ensemble, nos résultats alerte les médecins en charge des patients avec fièvre d'étiologie inconnue en Ethiopie et ceux qui se soucient de voyageurs en provenance de l'Ethiopie à prendre en compte la présence de plusieurs espèces zoonotiques à transmission vectorielle de bactéries, y compris SFG rickettsies, C. burnetii, R. felis, B. henselae et B. melophagi comme agents pathogènes potentiels. / Our study to explore bacteria in ixodid ticks collected from domestic animals in Ethiopia revealed an overall prevalence of 6% (46/767) SFG rickettsiae, 3.8% (29/767) Borrelia DNA and 6.4% (54/842) C. burnetii in different tick species. The study to investigate bacteria in 303 fleas collected from domestic dogs and cats in Ethiopia that were morphologically identified as Ctenocephalides felis felis, Ctenocephalides canis, Pulex irritans and Echidnophaga gallinacean showed Rickettsia felis in 21% of fleas, mainly in Ctenocephalides felis, with a similar prevalence in fleas from dogs and cats. The study to investigate bacteria in lice and sheep ked (Melophagus ovinus) revealed Acinetobacter spp. in M. ovinus, Heterodoxus spiniger, Bovicola ovis and Linognathus vituli. Partial rpoB gene sequence revealed A. soli, A. lowffii, A. pitti and 3 new Acinetobacter spp. in the lice and keds. Molecular identification of lice using an 18S rRNA gene analysis confirmed the morphological methods of lice identification. Bartonella melophagi was identified by standard PCR followed by sequencing of fragments of the gltA and rpoB genes in M. ovinus.Overall, our findings alert physicians managing patients with fever of unknown aetiology in Ethiopia and those who care for travellers from Ethiopia to consider the presence of several vector-borne zoonotic species of bacteria including SFG rickettsiae, C. burnetii, R. felis, B. henselae and B. melophagi as potential causative agents.

The thesis aims for relationship between military-caused disturbance intensity and species richness, conservation value and composition of arthropods communities in the Brdy Mts. In the Brdy abandoned military area (MTA), a highly heterogeneous habitat mosaic developed by the long-term influence of military disturbances on two shooting areas of Jordán and Tok. The habitats range from strongly disturbed sites with sparse vegetation, through heterogeneous growths of Erica and Vaccinium in moderately disturbed sites, to sparse woodlands in the least disturbed sites. Based on the shooting areas history reconstruction, 24 study plots of 4 categories of different disturbance intensity were selected in both shooting areas together. Standardized sampling of seven groups of arthropods was performed in summer 2017 by pitfall traps, yellow pan traps, and light traps. More intensive disturbances positively influenced species richness of Aculeates and conservation value of spiders and beetles, but negatively affected species richness of moths. Simultaneously, the intensity of disturbances affected community composition of spiders, moths, beetles, Aculeates and Orthopteroids. Endangered species mostly affiliated to the more intensively disturbed plots. This results should be helpful in understanding of influence...

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Die vorliegende Arbeit beinhaltet verschiedene Aspekte der Embryogenese des Pfeilschwanzkrebses Limulus polyphemus (Chelicerata, Xiphosura), darunter die frühe Neurogenese, die Axogenese, eine Analyse der "Kopf"segmentierung bei Cheliceraten und anderen Arthropoden, sowie das Expressionsmuster des Homöoboxgens Distal-less insbesondere in neuronalen Zusammenhängen. Darüber hinaus wurde eine neue Embryonalstadieneinteilung geleistet. Markierungen mit Phalloidin sowie weiterer neurospezifischer Marker ergaben, daß die frühe Neurogenese bei Limulus polyphemus durch die Immigration von Zellclustern erfolgt. Die Zellen nehmen eine flaschenförmige Gestalt annehmen, bevor sie sich aus dem ventralen Neuroektoderm lösen. Die Anzahl der Zellen pro Zellcluster steigt mit fortschreitender Entwicklung. Die Zellcluster konzentrieren sich in in Zentrum jedes Hemisegmentes, und in ihrem dorsalen Bereich beginnt die rasch voranschreitende Axogenese. Die Untersuchung der "Kopf"segmentierung mittels alpha-Tubulin-Markierungen bei Limulus polyphemus, Triops cancriformis (Crustacea) und Lepisma saccharina (Hexapoda) ergab sowohl bei der Entwicklung des circumoesophagealen Neuropilringes und der Innervierung der dazugehörigen Anhangspaare als auch hinsichtlich des Verlaufs des Stomatogastrischen Nervensystems beachtliche Übereinstimmungen, die entgegen der klassischen Auffassung den Schluß zulassen, daß das Deutocerebrum der Cheliceraten keineswegs reduziert wurde oder mit dem Tritocerebrum verschmolzen ist, sondern die Chelicere innerviert. Somit wäre das Chelicerenneuromer homolog zum Deutocerebrum der Crustacea und Hexapoda (1. Antenne). Der Vergleich des Expressionsmuster des Homöoboxgens Distal-less bei Limulus und Lepisma saccharina ergab neben den typischen Expressionen in auswachsenden Extremitäten- und andern Anhangsknospen bei beiden Vertretern Expressionen in neuronalen Zusammenhängen (im Lobus opticus, Ganglien bei Limulus oder in das ZNS umgebende Zellen bei Lepisma), an den verschiedensten Positionen späterer Sinnesorgane wie Mechano- oder Chemorezeptoren. Doppelmarkierungen mit Synorf-1 deuten darauf hin, daß es sich bei den Dll-positiven Zellen zum größten Anteil um Glia-Zellen handelt. / The following study contains different aspects of the embryology of the horseshoe crab Limulus polyphemus (Chelicerata, Xiphosura) with the main focus on early neurogenesis, axogenesis and the "head"segmentation in chelicerates and other arthropods. The expression pattern of the homeobox gene Distal-less was examined with main focus on neuronal correlations. In addition, a new staging was provided. Phalloidin stainings and other markers showed that the early neurogenesis in Limulus polyphemus happens via immigration of cell clusters. Cellclusters in the prosoma contain cells that become bottle shaped before they immigrate from the ventral neuroectoderm. The number of these cells increases during further development, and the cells concentrate in the middle of each hemisegment. Axogenesis starts at the dorsal edge of these concentrated cellclusters and progresses quite fast building the typical ladder like CNS of arthropods. The investigation of the "head"segmentation using alpha-tubulin stainings in Limulus polyphemus, Triops cancriformis (Crustacea), and Lepisma saccharina (Hexapoda) showed remarkable similarities in the development of the circumesophageal neuropil ring, the related appendages, and the course of the stomatogastric nerves. These results lead to the thesis that the deutocerebrum of chelicerates is neither completely reduced nor totally merged into the tritocerebrum but innervates the chelicerae which contradicts the classical view. According to these results the neuromer of the chelicerae would be homologous to the deutocerebrum of Crustaceans and Hexapods (first antennae). The expression pattern of the homeobox gene Distal-less was examined and compared in Limulus polyphemus and Lepisma saccharina. Beside the typical expression pattern in the developing appendages a participation of the gene in development of the nervous system was observed. Dll positve cells were found in or at least in direct contact with the CNS (optical lobe, ganglia in Limulus or surrounding the entire CNS including the brain of Lepisma), at different positions of later mechano- and chemoreceptors (lateral spines, bristles, flabellum, Johnstons organ etc.). Double stainings using Dll and Synorf-1 showed that at least most of these Dll-postive cells are most likely glia cells.

<p>Effects of prairie restoration on arthropod diversity was investigated at Gabis Arboretum, Valparaiso, Indiana. A total of 35,408 arthropods belonging to 13 taxa in the restored prairie (RP1 and RP2), old field (OF), and monoculture stand of Phalaris arundinacea (reed canary grass – RCG) sites, were captured, counted, and compared. The enhanced plant species diversity in the restored prairies did not appear to promote the diversity of arthropod taxa. However, the restoration led to a more balanced composition of arthropod functional groups and thus elevated the diversity of functional groups. The arthropod assemblages in the three sites diverged clearly according to my canonical correspondence analysis (CCA) ordination. Pollinator abundance was greatest at RP and least at RCG site, positively correlating with greater forb diversity, and suggesting greater potential for nectar feeding and pollination potential at RP sites. Herbivore abundance was greatest at the RP sites, positively correlating with increasing plant species diversity. Predator abundance was significantly greater at the RCG site compared to the OF and RP sites; it was positively correlated with greater C3 grass cover, a characteristic of the structurally homogenous RCG site, and negatively correlated with increasing plant diversity and forb cover, a characteristic of the diverse and more structurally complex RP sites. Given the apparent non-random distribution of arthropods among the field types, my results suggest plant species composition has a significant effect on arthropod assembly. The monoculture grass stand was found to have a predator dominated arthropod community supported by a small, diverse herbivore community. It is concluded that the prairie restoration has resulted in alteration of arthropod communities supporting greater pollinator and herbivore abundance and a more balanced ratio of herbivores to predators due, in part, to increased plant structural diversity.</p>

A modificação antropogênica da paisagem nos trópicos tem causado perdas da biodiversidade de diferentes grupos taxonômicos, ameaçando importantes processos ecológicos. Agroflorestas de café manejadas de forma tradicional são os únicos remanescentes de vegetação com considerável sombra em algumas regiões tropicais, e têm sido enfatizadas como importantes áreas de refúgio para a biodiversidade e pela sua contribuição na supressão de pragas devido a sua complexa estrutura vegetacional. O manejo de agroflorestas varia grandemente entre cafeicultores e pode influenciar padrões populacionais através de mudanças nas condições ambientais. Experimentos sobre interações ecológicas entre organismos são geralmente usados para predizer e explicar padrões e processos encontrados no campo. Não obstante, muitos fatores que influenciam populações, como variáveis ambientais são determinados pelo uso da terra, tornando padrões reais no campo difíceis de prever a partir de experimentos conduzidos em escalas menores. O estudo foi conduzido em pequenas propriedades rurais localizadas na região cafeicultora de Jipijapa, na província de Manabi, Equador. Essa região é considerada importante para a conservação da biodiversidade (hotspot) e sua vegetação original foi convertida em agricultura. Foram selecionadas três agroflorestas de café, de acordo com o manejo local praticado pelos cafeicultores: agroflorestas com baixa diversidade arbórea, agroflorestas com diversidade arbórea intermediária, e agroflorestas abandonadas com uma alta diversidade arbórea. No capítulo 2, estudou-se o papel do manejo de agroflorestas e da sazonalidade na comunidade de ácaros na cultura do café. A intensificação do manejo de agroflorestas afetou negativamente a riqueza de espécies de ácaros na cultura do café. Ademais, foram encontradas mais espécies e maiores densidades de ácaros na época seca comparada com a época chuvosa. No capítulo 3, investigou-se a dinâmica populacional de pragas de café (ácaro-vermelho-do-cafeeiro, bicho-mineiro-do-cafeeiro, e broca-do-cafeeiro) em relação ao manejo de agroflorestas. Adicionalmente, foi acessado o efeito do manejo de agroflorestas sobre as diversas fases de desenvolvimento de cada praga. O manejo de agroflorestas influenciou padrões populacionais de pragas do café, sendo que maiores picos populacionais ocorreram em agroflorestas manejadas de forma mais intensiva. Além disso, houve uma interação entre a diversidade vegetacional e a estrutura populacional, na qual diferentes fases de desenvolvimento das pragas atingiram maiores densidades em agroflorestas manejadas de forma mais intensiva. No capítulo 4, foi determinada a importância relativa de variáveis ambientais sobre densidades de pragas do café usando análises de partição hierárquica. As variáveis ambientais temperatura, umidade relativa, e diversidade arbórea explicaram a maior parte da variância da densidade das pragas de café. A temperatura influenciou positivamente densidades do ácaro-vermelho-do-cafeeiro, enquanto a umidade relativa e a diversidade arbórea influenciaram negativamente densidades do bicho-mineiro-do-cafeeiro e da broca-do-cafeeiro, respectivamente. No capítulo 5, experimentos de laboratório e de campo foram combinados, para se estudar a importância relativa de interações bióticas e do manejo de agroflorestas sobre a densidade de pragas de café no campo. Preferência e sucesso reprodutivo equipararam-se em condições de laboratório, levando-se a predição de que as pragas iriam evitar competidores coespecíficos e heteroespecíficos no campo. No entanto, densidades das pragas de café foram positivamente correlacionadas no campo, portanto, contrastando com predições baseadas em experimentos de laboratório. Ademais, a intensidade de manejo, definida por variáveis bióticas e abióticas, foi mais importante do que a preferência e o sucesso reprodutivo sobre densidades de pragas de café no campo. Concluindo, agroecossistemas com intermediária e alta diversidade arbórea têm o potencial de conservar a diversidade de ácaros, e portanto, deveriam ser incorporados em programas de conservação de paisagens. Sazonalidade e estrutura populacional devem ser consideradas em estudos de dinâmica populacional de artrópodes em diferentes hábitats, pois as respostas mudam com a época do ano e com as diferentes fases de desenvolvimento. Variáveis abióticas e bióticas determinando um dado hábitat podem ter um importante papel no entendimento dos efeitos do uso da terra sobre densidades populacionais de pragas. O entendimento da relação entre a densidade populacional de espécies e variáveis ambientais ajuda na predição e manejo de pragas no campo. Estudos de laboratório e de campo devem ser combinados para se determinar a importância relativa de experimentos conduzidos em pequenas e grandes escalas espaciais sobre densidades populacionais de artrópodes no campo.

Landnutzungsänderungen, Habitatverlust und Fragmentierung gehören zu den Hauptursachen des weltweiten Biodiversitätsrückgangs. In Mitteleuropa zählen Kalkmagerrasen zu den artenreichsten Lebensräumen. Sie weisen eine hohe Vielfalt an xero- und thermophilen Pflanzen- und Invertebratenarten auf, sind jedoch zunehmend durch landwirtschaftliche Intensivierung und Nutzungsaufgabe gefährdet. Sie sind auf Beweidung und Mahd angewiesen, was jedoch für die Landwirte heutzutage unwirtschaftlich geworden ist. Daher finden sich zunehmend kleine Fragmente innerhalb einer für die meisten der spezialisierten Magerrasenarten ungeeigneten, von intensiver Landwirtschaft geprägten Umgebung. Der erste Teil dieser Arbeit untersucht den Einfluss der Fragmentgröße, der Habitatkonnektivität, der Zusammensetzung der umgebenden Landschaft und der Pflanzenartenzahl auf die Zusammensetzung der Zikadengemeinschaft. Zikaden sind eine überaus artenreiche Gruppe phytophager Insekten mit enger Bindung an die Vegetationsstruktur und -zusammensetzung. In der Umgebung von Göttingen wählten wir 14 große (>1 ha) und 14 kleine (<1 ha) Kalkmagerrasenflächen entlang von Gradienten zunehmender Konnektivität mit anderen Magerrasenflächen, zunehmender Pflanzenartenzahl und zunehmender Landschaftskomplexität, d.h. dem Prozentsatz Ackerfläche innerhalb eines 500 m-Radius, aus. Zunehmende Isolation verringerte die Zikadenartenzahl in einfachen (von Feldern geprägten), jedoch nicht in komplexen Landschaften. Dieser Effekt wurde von den Generalisten getrieben. Die Artenzahl der Generalisten nahm auf kleinen Fragmenten mit zunehmender Konnektivität zu, wogegen sie auf großen Flächen unverändert blieb. Weiterhin nahm die Artenzahl der Generalisten mit steigender Pflanzenartenzahl auf vernetzten Magerrasen stärker zu als auf unvernetzten. Unsere Ergebnisse zeigen, dass die Insektenartenvielfalt auf Kalkmagerrasenfragmenten nicht nur durch Konnektivität allein geprägt wird, sondern vielmehr von einem Zusammenspiel aus Konnektivität, Landschaftszusammensetzung und Pflanzenartenzahl bestimmt wird. Im zweiten Teil dieser Arbeit verfolgen wir das Ziel, zur Lösung der sogenannten SLOSS-Debatte (“Single Large Or Several Small”) beizutragen, in der diskutiert wird, ob es besser ist, wenige große oder mehrere kleine Fragmente eines Habitattyps zu erhalten. Man nimmt an, dass kleine Fragmente aufgrund der größeren abgedeckten geographischen Distanzen eine größere Heterogenität und dadurch eine höhere Gesamtartenzahl aufweisen. Dagegen weisen große Fragmente stabilere Lebensraumbedingungen und größere Populationen auf. Neben Zikaden und Pflanzen wurden auch Daten zu Wanzen und 114 Schnecken aufgenommen. Sowohl die Gesamtartenzahl aller vier Taxa als auch die Zahl der Spezialisten war auf mehreren kleinen Fragmenten wesentlich höher als auf einem oder zwei großen Fragmenten gleicher Gesamtgröße. Jedoch war die Artenzusammensetzung auf großen und kleinen Fragmenten unterschiedlich und einige der seltensten Spezialisten waren an große Flächen gebunden. Hingegen spielte die Zusammensetzung der umgebenden Landschaft keine wichtige Rolle für Artenzahl und -zusammensetzung. Diese Ergebnisse stellen den Fokus auf entweder große oder kleine Habitatfragmente infrage. Für einen erfolgreichen Biodiversitätserhalt ist daher der Schutz sowohl großer als auch kleiner Habitatfragmente zwingend notwendig. Im dritten Teil dieser Arbeit untersuchen wir den Einfluss der Bewirtschaftungsart (Beweidung, Mahd, Nutzungsaufgabe), der Landschaftszusammensetzung und Konnektivität auf die Artenzahl, Artenzusammensetzung und merkmalsbasierte Reaktionen (Körpergröße und Rote Liste-Status) von neun Taxa: Pflanzen, Schmetterlinge, Bienen, Heuschrecken, Schwebfliegen, Spinnen, Wanzen, Kurzflügler und Zikaden. Wir wählten 30 kleine Kalkmagerrasenfragmente (<1 ha) entlang von unabhängigen Konnektivitäts- und Landschaftskomplexitätsgradienten aus. Ein zunehmender Prozentsatz an Ackerfläche in der Umgebung der Fragmente führte zu einem Verlust von 29 % der Gesamtartenzahl. Wir nehmen an, dass Landschaften, die von Ackerfläche dominiert werden, weniger Alternativhabitat und Nahrungsressourcen bieten, was zu einer verringerten Artenzahl führt. Habitatkonnektivität erhöhte im Allgemeinen die Artenzahl. Dieser Effekt war bei den großen, vermutlich ausbreitungsfähigeren Arten eines Taxons stärker ausgeprägt als bei den kleinen Arten. Beweidung hatte einen deutlich negativeren Einfluss auf die Artenzahl als Mahd (einmal jährlich) oder kurzzeitige Nutzungsaufgabe (5-15 Jahre). Der Grund dafür könnte der durch Beweidung verursachte größere Schaden und die Entnahme der Nahrungsressourcen phytophager Insekten sein. Zudem führte jeder der drei Bewirtschaftungsweisen zu einer unterschiedlichen Artenzusammensetzung aller Taxa. Daher sollte die bevorzugte Bewirtschaftungsoption kleiner Kalkmagerrasenfragmente ein Wechsel zwischen Mahd und kurzzeitiger Nutzungsaufgabe in Kombination mit einer Diversifizierung der umgebenden Landschaft sein. Zusammenfassend lässt sich sagen, dass die allgemein verbreitete Konzentration auf große Habitatfragmente überdacht werden sollte, da der Schutz sowohl kleiner als auch großer Fragmente unerlässlich ist. Bei der Planung von Schutzmaßnahmen für fragmentierte Offenlandlebensräume sind lokale Einflüsse wie Fragmentgröße und Bewirtschaftung zwar wichtig, aber nicht ausreichend: Landschaftsfaktoren wie Habitatkonnektivität und Landschaftszusammensetzung müssen ebenfalls in die Schutzbemühungen mit einbezogen werden um das langfristige Überleben von spezialisierten Pflanzen- und Invertebratenarten zu sichern.

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