Novas espécies de Escovopsis, sua dispersão e virulência na simbiose formigas Attini Leucoagaricus gongylophorus

• Autor(a) principal: Augustin, Juliana de Oliveira
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/897
• topic: Formigas cortadeiras; Simbiose; Transmissão; Parasitismo; Hypocreales; Ants; Symbiosis; Transmission; Parasitism; Hypocreales; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA

A notable example of mutualism is the symbiotic relationship between attine ants (Formicidae: Attini) and their fungal gardens (Leucocoprineae and Pterulaceae) cultivated for food. Although a classic example of mutualism, empirical data shows that this symbiosis represents a complex association of hosts and parasites. Escovopsis spp. is a prevalent specific mycoparasite that attacks the ant s cultivars. From an evolutionary point of view, there is great interest in this mycoparasite although little is known about its biology and diversity. This thesis makes a start at assessing the diversity of Escovopsis morphotypes isolated from Acromyrmex colonies and its mode of transmission. The major findings are: i) Using both morphological and molecular data, four new species of Escovopsis are described and illustrated: E. niveo-chlamydosporiformans, E. lentecrescens, E. microsporum and E. moelleri. A dichotomous key separates them from one another and from the two previously described species in the genus. As this survey concentrates on only a small region of the Zona da Mata Mineira in Brazil, this finding indicates there may be many more species of Escovopsis throughout the geographic range of the Attini. ii) Field work reveals that Escovopsis is probably horizontally transmitted. Whether this mycoparasite relies solely on this mode of transmission we currently do not know and we are presently studying the possibility of vertical transmission. iii) Escovopsis is not a virulent parasite, contrary to its portrayal in the literature. This information is based not only on our experimental procedures but also on the fact that healthy laboratory colonies can naturally inhabit at least two Escovopsis morphotypes (J.O. Augustin, H.C. Evans & S.L. Elliot, unpublished data) and the abundant evidence in the literature for its consistent presence throughout the geographic range of the Attini. The fungus-growing ant symbiosis is a fruitful system for future research on the study of host-parasite interactions, because infection in attine gardens can be accessed over time and space and since the symbionts can be isolated and maintained in laboratory conditions for long periods of time. Moreover, if one considers the great diversity of other micro-organisms currently known from the attine symbioses, it seems possible there could be parasites other than Escovopsis inhabiting attine colonies. If this is true then we can predict they may represent promising avenues for future studies.