Yeasts and filamentous fungi carried by the gynes of leaf-cutting ants

Abstract

Insect-associated microbes exhibit a wide range of interactions with their hosts. One example of such interactions is the insect-driven dispersal of microorganisms, which plays an essential role in the ecology of several microbes. To study dispersal of microorganisms by leaf-cutting ants (Formicidae: Attini), we applied culture-dependent methods to identify the filamentous fungi and yeasts found in two different body parts of leaf-cutting ant gynes: the exoskeleton and the infrabuccal pocket. The gynes use the latter structure to store a pellet of the ants' symbiotic fungus during nest founding. Many filamentous fungi (n = 142) and yeasts (n = 19) were isolated from the gynes' exoskeleton. In contrast, only seven filamentous fungi and three yeasts isolates were recovered from the infrabuccal pellets, suggesting an efficient mechanism utilized by the gynes to prevent contamination of the symbiotic fungus inoculum. The genus Cladosporium prevailed (78%) among filamentous fungi whereas Aureobasidium, Candida and Cryptococcus prevailed among yeasts associated with gynes. Interestingly, Escovopsis, a specialized fungal pathogen of the leaf-cutting ant-fungus symbiosis, was not isolated from the body parts or from infrabuccal pellets of any gynes sampled. Our results suggest that gynes of the leaf-cutter ants Atta laevigata and A. capiguara do not vertically transmit any particular species of yeasts or filamentous fungi during the foundation of a new nest. Instead, fungi found in association with gynes have a cosmopolitan distribution, suggesting they are probably acquired from the environment and passively dispersed during nest foundation. The possible role of these fungi for the attine ant-microbial symbiosis is discussed.

Diversity of Fungi Associated withAtta bisphaerica(Hymenoptera: Formicidae): The Activity ofAspergillus ochraceusandBeauveria bassiana

“…Cladosporium fungi are phytopathogens [26] and may be transported by various insects causing their death. In a study of leaf-cutting queen ants, the Cladosporium fungus was prevalent in Atta laevigata and in A. capiguara [27]. It is believed that these fungi are frequently found due to their cosmopolitan distribution, being acquired from the environment and dispersed during the founding of a colony by queens or forage worker ants carrying leaves.…”

Absence of the Parasite Escovopsis in Fungus Garden Pellets Carried by Gynes of Atta sexdens

“…This neighborhood includes some study areas where Escovopsis was previously found: in a small colony of Rodrigues et al (2014) and in another work (NS Nagamoto et al, unpublished data), it was demonstrated that one of the colonies studied by Pagnocca et al (2008), denominated "Atta capiguara colony 1", was indeed infected with this parasite. Additionally, based on the long persistence of these ants' colonization in these areas (NS Nagamoto, personal obs.…”

“…On the other hand, a second study evaluated the integument and fungal pellets of gynes collected immediately before the mating flight (when gynes were leaving the parental colony). Although, Pagnocca et al (2008) used a larger sampling size in comparison to the Currie et al's (1999) study (Table 1) only one colony of Atta laevigata F. Smith and two colonies of Atta capiguara Gonçalves were sampled, in Brazil. In addition, the variation of Escovopsis prevalence between ant species and locations are aspects that prompt for additional studies to extend the existing data on the mode of transmission of this parasite (Currie, 2001a;Yek et al, 2012).…”

“…Two studies, Currie et al (1999) and Pagnocca et al (2008) evaluated the transmission of the parasite between colonies. These reports indicate that no vertical transmission appears to occur (Table 1).…”

Diversidad de micobiota en diferentes especies de hormigas cortadoras de hojas y sitios de Argentina

“…Microorganisms within this microbiota include: asexual fungi (Rodrigues et al 2005a,b;Pinto-Tomás et al 2009;Ribeiro et al 2012), yeasts (Carreiro et al 1997;Pagnocca et al 2008) and bacteria (Haeder et al 2009). Functionally, they include symbionts, saprotrophs, entomopathogens and pathogens of Leucoagaricus spp.…”