Fungal communities in the garden chamber soils of leaf‐cutting ants

Abstract

Leaf-cutting ants modify the properties of the soil adjacent to their nests. Here, we examined whether such an ant-altered environment impacts the belowground fungal communities. Fungal diversity and community structure of soil from the fungus garden chambers of Atta sexdens rubropilosa and Atta bisphaerica, two widespread leaf-cutting ants in Brazil, were determined and compared with non-nest soils. Culture-dependent methods revealed similar species richness but different community compositions between both types of soils. Penicillium janthinellum and Trichoderma spirale were the prevalent isolates in fungus chamber soils and non-nest soils, respectively. In contrast to cultivation methods, analyses of clone libraries based on the internal transcribed spacer (ITS) region indicated that richness of operational taxonomic units significantly differed between soils of the fungus chamber and non-nest soils. FastUnifrac analyses based on ITS sequences further revealed a clear distinction in the community structure between both types of soils. Plectania milleri and an uncultured Clavariaceae fungus were prevalent in fungus chamber soils and non-nest soils, respectively. FastUnifrac analyses also revealed that fungal community structures of soil from the garden chambers markedly differed among ant species. Our findings suggest that leaf-cutting ants affect fungal communities in the soil from the fungus chamber in comparison to non-nest soils.

Unraveling Trichoderma species in the attine ant environment: description of three new taxa

“…Previous work demonstrated the occurrence of eight Trichoderma species: T. aureoviride, T. harzianum, T. koningii, T. longibrachiatum, T. pseudokoningii, T. hamatum, T. virens and T. spirale (Fisher et al 1996;Barbosa, 2004;Rodrigues et al 2005Rodrigues et al , 2008Augustin et al 2011;Rodrigues et al 2011Rodrigues et al , 2014. Our results showed that attine ant colonies harbor more Trichoderma species than previously reported, since the 68 isolated correspond to 19 species, including three new species described in this study, along with a new phylogenetic strain.…”

“…The remaining three previously reported species (T. aureoviride, T. koningii and T. pseudokoningii) were not found in our sample set. However, it is important to note that previous studies used only classical taxonomy methods (morphological markers) or sequenced the ITS region (Fisher et al 1996;Barbosa, 2004;Rodrigues et al 2005Rodrigues et al , 2008Rodrigues et al , 2011Rodrigues et al , 2014. Identification of Trichoderma species based solely on morphological characterization has proven very difficult due to morphological plasticity among species (Chaverri et al 2003a;Chaverri et al 2015).…”

“…On the other hand, Augustin et al (2011) and Rodrigues et al (2014) suggested that the soil could also be an alternative source for diversity of Trichoderma species present in colonies of leaf-cutting ants. For example, Rodrigues et al (2014) showed that soil samples distant from the ant colonies have fungal species frequently isolated from the fungus gardens, standing out T. spirale (Rodrigues et al 2014).…”

“…Since the first report of Trichoderma in colonies of leaf-cutting ants (Kreisel 1972), several studies reported the occurrence of this genus in colonies of these insects (Barbosa 2004;Poulsen and Currie 2006;Rodrigues et al 2008Rodrigues et al , 2009Augustin 2011;Rodrigues et al 2014). However, none of these studies used a detailed taxonomic approach to identify Trichoderma species that occur in this environment.…”

“…Such microbes are found in the soil that composes the nest tunnels and chambers (Rodrigues et al 2014) as well as in the fungus garden, structure that houses the substrate foraged by the ants and mycelium of the fungal cultivar (Weber 1972). Möller (1893) was the first to study fungi cultivated by attine ants and also showed the presence of Aspergillus, Mucor, Penicillium and Rhizopus in gardens of Acromyrmex disciger.…”