In vitro study of volatile organic compounds produced by the mutualistic fungus of leaf-cutter ants and the antagonist Escovopsis

Abstract

Occasionally, the symbiosis of the fungus-growing ants is threatened by ascomycetous fungi mainly by species in the genus Escovopsis. GC-MS analyses were conducted to investigate the volatile organic compounds (VOCs) produced by Escovopsis and the mutualistic Leucocoprinus gongylophorus during dual-culture. In dual-culture Escovopsis' development was faster. Hexadecanoic acid (palmitic acid) and VOCs such as the sesquiterpenes α-cedrene, β-cedrene, thujopsene, α-santalene, α-selinene, cedrene, (+)-cuparene and δ-cadinene secreted by L. gongylophorus may be responsible for speeding the germination of Escovopsis’ conidia as well as for the faster hyphal development. Based on this study and available literature we infer that the relationship between these two species is mediated by hyphal interference (HI). Additional studies should unveil if the biological activity of some compounds produced by these fungi is attractive, repellent or toxic to the ants and inhibitory to other fungi.