Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-05-18T13:49:36Z No. of bitstreams: 1 2011 - Andr? Barbosa Vargas.pdf: 2899416 bytes, checksum: 591d199971aaae8acb1b26b67d4b22a3 (MD5) / Made available in DSpace on 2017-05-18T13:49:36Z (GMT). No. of bitstreams: 1 2011 - Andr? Barbosa Vargas.pdf: 2899416 bytes, checksum: 591d199971aaae8acb1b26b67d4b22a3 (MD5) Previous issue date: 2011-04-25 / Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ, FAPERJ, Brasil. / The region of Vale do Para?ba is part of the Atlantic Forest and presents a history of environmental degradation, like many other regions in Brazil, caused at first by wood extraction and coffee plantations, and later by other crops and cattle farming. Now, despite the remarkable headways in this biome?s biodiversity research, some groups still show little knowledge of the geographic scope and neglect the research when conducting management and conservation studies. This study?s greater objective was to assess the composition and abundance of ant species in different forest fragments in Vassouras, RJ, over the influence of environmental and structural attributes. the research was developed between march and april 2008. The ant fauna was analyzed through 620 litter samples of 1m2 each, submitted to the Winkler extractor for 48 hours. They were equally distributed in 31 forest fragments belonging to three different landscapes (A, B and C), creating a gradient of forest covering and altitude with different uses of the soil. 170 ant species were found, belonging to 10 subfamilies and 49 genera, with an average of 10 (? 3.3 of standard deviation) species by square meter. The average of species for fragment was 50 ? 9.2. The highest richness was found on landscape A with 133 species (187 estimated), followed by B with 122 spp. (160 estimated) and C with 100 (111 estimated). The largest composition and richness differences were found between landscapes A and C. Despite being fragmented, all three landscapes obtained a good representation of the ant fauna, showing distinct values for the biodiversity?s conservation. The results showed that more heterogeneous landscapes have greater richness and a more heterogeneous composition of species, although no significant relation to the size of the fragments was found and the ant fauna between landscapes. The results can still suggest that the differences found could be related to the succession state and the floristic composition of the forest fragments. / A regi?o do Vale do Para?ba, inserida no dom?nio da Mata Atl?ntica, apresenta como outras regi?es do Brasil um hist?rico comum de degrada??o ambiental, ocasionado em princ?pio pela explora??o madeireira, o ciclo do caf? e posteriormente por outras culturas agr?colas e a pecu?ria. Atualmente, apesar do not?vel avan?o das pesquisas sobre a biodiversidade neste Bioma, determinados grupos ainda apresentam conhecimento restrito em abrang?ncia geogr?fica ou mesmo s?o negligenciados em estudos de conserva??o e manejo. Neste sentido, o objetivo maior deste estudo foi avaliar a riqueza e composi??o em esp?cies de formigas sobre a influ?ncia de atributos ambientais e estruturais em fragmentos florestais de diferentes paisagens no munic?pio de Vassouras, RJ. O estudo foi realizado no per?odo de mar?o a abril de 2008. A fauna de formigas foi estudada atrav?s de 620 amostras de 1m2 de serapilheira, submetidas ao extrator de Winkler por 48 horas, distribu?das igualmente em 31 fragmentos florestais, inseridos em tr?s paisagens (A, B e C), compondo um gradiente de cobertura florestal e altitude com distintos usos do solo. Foram obtidas 170 esp?cies de formigas distribu?das em 10 subfam?lias e 49 g?neros, com m?dia de 10 (? 3,3 de desvio padr?o) esp?cies por metro quadrado. A m?dia de esp?cies por fragmentos foi de 50 ? 9,2. A maior riqueza foi registrada na paisagem A com 133 esp?cies, sendo 187 estimadas, seguida da paisagem B com 122 spp., sendo 160 estimadas e C com 100 sendo 111 estimadas. As maiores diferen?as tanto para a riqueza quanto para a composi??o foram apontadas entre as paisagens A e C. Apesar de fragmentadas as paisagens estudadas tiveram boa representatividade da fauna de formigas, demonstrando valores distintos para a conserva??o da biodiversidade. Os resultados mostraram que paisagens mais heterog?neas possuem maior riqueza e sua composi??o em esp?cies ? mais heterog?nea. Embora n?o tenha sido encontrada rela??o significativa com o tamanho dos fragmentos a fauna de formigas variou entre as paisagens. Os resultados permitem ainda sugerir que tais diferen?as podem estar ainda relacionadas ao estado de sucess?o e a composi??o flor?stica dos fragmentos florestais.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-05-19T18:08:20Z No. of bitstreams: 1 2016 - Corina Anah? Barrera.pdf: 2798404 bytes, checksum: 56ddd89ceb87a772a2bc0299c858947e (MD5) / Made available in DSpace on 2017-05-19T18:08:20Z (GMT). No. of bitstreams: 1 2016 - Corina Anah? Barrera.pdf: 2798404 bytes, checksum: 56ddd89ceb87a772a2bc0299c858947e (MD5) Previous issue date: 2016-02-24 / CNPq / Habitat loss is one of the main threats to global biodiversity. In fragmented habitats, species have more limited capacity for dispersal and as a result are at higher risk of extinction. However, different species respond differently to this kind of disturbance. Therefore, community structure, interspecific interactions, and ecological functions become altered, and the magnitude and direction of the changes are unpredictable. Host-parasitoid interactions are an example of interactions that can be highly impacted, and in the tropics, interactions between parasitoids and ants are among the most relevant. In the Neotropics, leaf-cutting ants are considered dominant herbivores and play a key role in ecosystem functioning. These ants can also become agricultural pests, and therefore their biological control is of high economic importance. An important group of natural enemies of leaf-cutting ants are the dipteran parasitoids of the family Phoridae. Interactions between phorid parasitoids and leaf-cutting ants in a fragmented region of the Atlantic Forest of Southeastern Brazil comprise a promising model system to study the impacts of habitat fragmentation, since phorids are the most important parasitoids of these ants and show a high degree of specialization for host ant species. The overall goal of this work was to study the effects of reduction in forest cover, one of the most important negative impacts of fragmentation, upon phorid parasitoids of the leaf-cutting ant Acromyrmex niger, a common species in the Southeastern Atlantic Forest. This work was conducted at the Guapia?u Ecological Reserve (REGUA) and surrounding areas in the State of Rio de Janeiro. Ten forest fragments of different sizes (five large >80 ha and five small <20 ha) were sampled, as well as three regions of continuous forest (>1000 ha). One to five colonies of A. niger were marked in the interior of each fragment and continuous forest location. At each nest, all of the phorids in interaction with the worker ants were collected for a period of 15 minutes and later identified in the laboratory. Additionally, approximately 200 worker ants were collected from each colony and maintained in the laboratory for the rearing of parasitoids. For the data analysis were made analysis of variance and simple regression. Were identified three genus of phorids: Myrmosicarius, Apocephalus and Neodohrniphora both observed in the field in interactions with the workers as reared in the laboratory from workers collected in the field. The total phorid abundance, total parasitism percentage, and genus richness of immature phorids were significantly greater in continuous forest sites than forest fragments, while there were no significant differences between large and small fragments. The abundance of Apocephalus and the parasitism percentage of Myrmosicarius were also greater in the continuous forest sites, but the difference was only significant in comparison to small forest fragments. These results have provided the first evidence about the effects of habitat size on the phorid-Acromyrmex system in tropical rain forest, through an evaluation of the abundance and richness of parasitoids as adults in the field and the reared of immature phorids in the laboratory. / A perda de habitats ? uma das principais amea?as para a biodiversidade global. Em ambientes fragmentados as esp?cies ficam com menor capacidade de dispers?o e suas intera??es s?o mais propensas ? extin??o. Todavia, as esp?cies s?o afetadas de maneira diferente por este tipo de perturba??o. Desta forma, a estrutura da comunidade, as intera??es interespec?ficas e as fun??es ecol?gicas s?o alteradas e a magnitude e dire??o das mudan?as s?o imprevis?veis. As intera??es parasit?ide-hospedeiro s?o um exemplo das que podem ser muito afetadas. Dentre elas, as intera??es entre parasit?ides e formigas est?o entre as mais relevantes. Certos grupos de formigas, como as cortadeiras, podem se tornar pragas agr?colas, portanto seu controle biol?gico ? de suma import?ncia. Essas formigas possuem um papel chave nos ecossistemas, pois s?o consideradas os herb?voros dominantes da regi?o Neotropical. Um grupo importante de inimigos naturais de formigas cortadeiras s?o os d?pteros parasit?ides da fam?lia Phoridae. Intera??es entre for?deos parasit?ides e formigas cortadeiras em uma regi?o fragmentada da Mata Atl?ntica comp?em um modelo bastante promissor para sua investiga??o como indicador dos impactos causados pela fragmenta??o de habitats, pois os for?deos s?o os parasit?ides mais importantes dessas formigas e possuem uma forte especializa??o nas mesmas. O objetivo geral deste trabalho foi estudar os efeitos da perda da superf?cie florestal sobre os for?deos parasit?ides da formiga cortadeira Acromyrmex niger, uma esp?cie comum na Mata Atl?ntica. Este trabalho foi realizado na Reserva Ecol?gica de Guapia?u (REGUA) e arredores no Estado do Rio de Janeiro. Foram amostrados dez fragmentos florestais de diferentes tamanhos (cinco grandes >80 ha e cinco pequenos <20 ha) e tr?s regi?es de floresta cont?nua (>1000 ha). Uma a cinco col?nias de A. niger foram marcadas no interior de cada fragmento e local de mata cont?nua. Sobre cada ninho, durante 15 minutos, todos os for?deos em intera??o com as oper?rias foram coletados e depois identificados. Tamb?m, em cada col?nia amostrada, foram coletadas aproximadamente 200 oper?rias e mantidas para cria??o dos parasit?ides. Para a an?lise de dados foram feitas an?lises de vari?ncia e regress?es simples. Foram identificados tr?s g?neros de for?deos: Myrmosicarius, Apocephalus e Neodohrniphora, tanto observados no campo em intera??es com as oper?rias quanto criados em laborat?rio a partir de oper?rias coletadas no campo. A abund?ncia total, a porcentagem de parasitoidismo total, a riqueza de g?neros de for?deos adultos observados no campo e a riqueza de g?neros de for?deos imaturos, foram significativamente maiores nos locais de floresta cont?nua sem diferen?as significativas entre fragmentos grandes e pequenos. A abund?ncia de Apocephalus e a porcentagem de parasitoidismo de Myrmosicarius tamb?m foram maiores em locais de mata cont?nua, mas com diferencias significativas s? em rela??o aos fragmentos pequenos. Os resultados ofereceram a primeira evidencia dos efeitos do tamanho do habitat sobre o sistema for?deo-Acromyrmex em floresta tropical ?mida, avaliando em conjunto a presen?a de for?deos adultos no campo e a porcentagem de parasitoidismo determinada atrav?s de m?todos experimentais no campo e no laborat?rio.