Natureza do parasitismo de Escovopsis e Escovopsioides sobre Leucoagaricus gongylophorus, fungos associados aos jardins de formigas cortadeiras

• Ano de defesa: 2014
• Autor(a) principal: Haifig, Sadala Schmidt Varanda [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Fungi; Fungos; Parasitismo; Escovopsis; Formiga-cortadeira; Formiga
• Link de acesso: http://hdl.handle.net/11449/110413

The leaf-cutting ants, across the evolution, developed the ability to grow fungi and use them as food resource. These insects use fresh leaves and flowers as substrate to grow the mutualistic fungus (Leucoagaricus gongylophorus). The farming of these insects are continuously threatened by fungi of the genus Escovopsis, considered parasites of the fungus reared by the ants. Although the harmful effects on L. gongylophorus are known, the mechanism of action of the parasitism of Escovopsis sp. is still poorly understood. In this context, we evaluated the nature of the antagonism of various strains of Escovopsis sp. towards the fungus cultivated by the leaf-cutting ants. In addition, we evaluated the potential antagonistic role of Escovopsioides sp., a recently described fungus for which its role in the ant nests is unknown. First, in vitro co-culture assays were carried out to evaluate the interaction between L. gongylophorus and the two filamentous fungi. Then, the antifungal activities of compounds secreted by the filamentous fungi against L. gongylophorus were evaluated. Crude extracts were obtained using grows of Escovopsis sp. and Escovopsioides sp. (i) in the absence (EBA) and (ii) in the presence (EBP) of the mutualistic fungus, in addition to (iii) acetate and (iv) butanol fractions. These extracts were incorporated in the culture medium and the micelial growth of L. gongylophorus was evaluated. The physical interaction between the filamentous fungi and the fungus cultivated by the ants was evaluated using antagonism assays associated with scanning electron microscopy. In the co-culture assays, all the Escovopsis sp. and Escovopsioides sp. filamentous fungi negatively affected the growth of L. gongylophorus. In general, the majority of the EBA and EBP crude extracts from Escovopsis sp. and Escovopsioides sp. significantly inhibited the growth of the mutualistic fungus. The results indicate that both Escovopsis sp. and Escovopsioides sp