Antagonism of Trichoderma isolates against Leucoagaricus gongylophorus (Singer) Möller

Abstract

Filamentous fungi from the genus Trichoderma are commonly found in soil. They are considered facultative mycoparasites, and are antagonists of other fungi such as the cultivar of leaf-cutting ants (Leucoagaricus gongylophorus). The aim of the present study was to bioprospect Trichoderma spp. from different soils collected from Gurupi, Tocantins, Brazil, for antagonistic effects against the mutualistic fungus of leaf-cutting ants. To isolate filamentous fungi, samples were collected from six locations. Preliminarily, isolates were identified by morphological analysis as belonging to Trichoderma. Trichoderma spp. had their internal transcribed spacer region (ITS) of ribosomal RNA genes (rRNA) sequenced to confirm species-level taxonomy. L. gongylophorus was isolated from a laboratory ant colony. Antagonistic properties of seven isolates of Trichoderma against L. gongylophorus were measured using paired disks in Petri dishes with potato dextrose agar medium (PDA). All Trichoderma isolates inhibited the growth of L. gongylophorus in Petri dishes. Isolate 2 of Trichoderma spirale group exhibited slow mycelial growth in the Petri dish, and a high rate of inhibition against L. gongylophorus. This isolate is a promising fungus for field tests of biological control methods for leaf-cutting ants.

Screening of Fungi Isolated from the Brazilian Restinga for Insecticidal Activity

“…Even if Trichoderma is not directly pathogenic to the ants, it could be used as an additional tool for ant control as it can act as an antagonist of the symbiotic fungus which the ants cultivate and feed on [36]. Notwithstanding the production of metabolites that adversely act on ant colonies.…”

Host Susceptibility Modulates Escovopsis Pathogenic Potential in the Fungiculture of Higher Attine Ants

“…However, these putative mechanisms seem not enough to outcompete Escovopsis growth, which was attracted to both fungal cultivars and inhibited their growth in the majority of FEI ( Figure 1 ). It is worthy to point that fungal cultivar inhibition is not an outcome particular to interactions with Escovopsis , as it also results from in vitro interactions between cultivar and other filamentous fungi ( Ortiz and Orduz, 2001 ; Silva et al, 2006 ; Barcoto et al, 2017 ; do Nascimento et al, 2017 ; Bizarria et al, 2018 ). Instead of being considered as a consequence of Escovopsis pathogenicity ( Currie, 2001 ; Currie et al, 2003 ; Reynolds and Currie, 2004 ; Folgarait et al, 2011 ; Varanda-Haifig et al, 2017 ), we suggest that such outcomes also integrate the fungal cultivar responses.…”

Soluble Compounds of Filamentous Fungi Harm the Symbiotic Fungus of Leafcutter Ants

“…Trichoderma species have been reported as potential biological control agents against leafcutter ants, due to its antagonism towards the mutualistic fungal partner [28,30]. In addition, Trichoderma is a well-known biological control agent of several plant pathogens [49,50].…”

“…Nevertheless, the real impact and modes of action of the invading filamentous fungi against the ant cultivar are still elusive. Considering fungus-fungus interactions, several studies showed growth inhibition of L. gongylophorus by filamentous fungi [14,[28][29][30][31][32]. Such interactions can be understood as interference and/or exploitation competition [33].…”