Substituição de pastagem nativa por braquiária: impactos na estrutura e funções ecológicas da comunidade de escarabeíneos (Coleoptera)

• Ano de defesa: 2010
• Autor(a) principal: Almeida, Sabrina da Silva Pinheiro de
• Orientador(a): Sperber, Carlos Frankl
• Banca de defesa: Louzada, Júlio Neil Cassa , Campos, Ricardo Ildefonso de , Neves, Frederico de Siqueira
• Tipo de documento: Tese
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Entomologia
• Departamento: Ciência entomológica; Tecnologia entomológica
• País: BR
• Palavras-chave em Português: Scarabaeinae; Cerrado; Campo limpo; Ivermectina; Espécies exóticas
• Palavras-chave em Inglês: Scarabaeinae; Cerrado; Grassland; Ivermectin; Exotic species
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/885

The replacement of native grasslands and bush savanna by exotic pastures has being implemented in many different regions to increase the livestock carrying capacity. These changes are particularly noticeable in the Brazilian savanna (Cerrado), the second largest biome in Brazil and one of the biodiversity conservation priority areas in the world. Brazil has one of the largest bovine livestock in the world and around half of all Brazilian pastures, composed by introduced and native pasture, are placed in the Cerrado region. Although these changes have obvious consequences for plant community, the ecological consequences for the native fauna are poorly known. Cerrado is a fire-shaped biome and besides the introduction of exotic grasses, there is a recent concern about the use of fire as a management tool in native Cerrado grasslands (each two years) on inhabiting invertebrate fauna. There is still a lack of information about the impact of these factors on insect s communities when we compare studies about impact on plant communities. Among insects, dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) can be used as cost-effective indicators of anthropogenic disturbance. Furthermore, dung beetles provided important ecological function such as faeces removal from pastures and soil bioturbation. However, even performing those useful ecological functions for farmers, the irresponsible use of parasiticides in bovine livestock can affect negatively the dung beetles. Here, we investigate the conversion of native pastures to exotic pastures on dung beetle community structure and upon the ecological functions performed by these beetles in Cerrado pastures. We evaluate the agropastoral management in dairy farms throught the time since the conversion and the fire management on native pastures and also, the management of cattle with the ivermectin parasiticide. As results, we found differences in community structure and species composition between pasture systems, and introduced pastures were dominated by few abundant species. Our results showed that the conversion of native grasslands to introduced pastures can trigger a restructuring of dung beetle communities, particularly in terms of local diversity, species composition and overall dung beetle activity. These results highlight the importance of maintaining native pastures in the Cerrado agropastoral landscape, to help prevent widespread loss of biodiversity and ecosystem functions. Evaluating the drivers of dung beetle community within each pasture system (native and introduced), we found that for both pasture systems, richness was driven by regional species pool. Sand proportion, soil penetrability, surrounding habitat and time since disturbance were determinants of dung beetle abundance in both pastures systems. However, the introduction of exotic pastures changed the effects of the environmental drivers on dung beetle communities, probably through soil management practices. We showed that habitat replacement goes beyond changes in vegetation cover: exotic grass introduction changes community-environment relationship for dung beetles. Finally, we observed that the ivermectin use does not affect in a direct way the ecological functions (faeces removed and excavated soil). However, ivermectin use broke down the positive correlation of faeces removal with dung beetle abundance and species richness. Therefore, ivermectin-treated cattle faeces was less attractive to dung beetles and reduced dung beetle activity. We suggest that ivermectin can cause beetle intoxication, working as a partial ecological trap . We concluded that the replacement of native to exotic pastures leads to biodiversity loss, changes in soil characteristics and the stagnation of ecological functions performed by dung beetles due to ivermectin use and, therefore, causing disavantage to agropastoral landscape of Cerrado.