title: Specific, non-nutritional association between an ascomycete fungus and Allomerus plant-ants.
abstract: Ant-fungus associations are well known from attine ants, whose nutrition is based on a symbiosis with basidiomycete fungi. Otherwise, only a few non-nutritional ant-fungus associations have been recorded to date. Here we focus on one of these associations involving Allomerus plant-ants that build galleried structures on their myrmecophytic hosts in order to ambush prey. We show that this association is not opportunistic because the ants select from a monophyletic group of closely related fungal haplotypes of an ascomycete species from the order Chaetothyriales that consistently grows on and has been isolated from the galleries. Both the ants' behaviour and an analysis of the genetic population structure of the ants and the fungus argue for host specificity in this interaction. The ants' behaviour reveals a major investment in manipulating, growing and cleaning the fungus. A molecular analysis of the fungus demonstrates the widespread occurrence of one haplotype and many other haplotypes with a lower occurrence, as well as significant variation in the presence of these fungal haplotypes between areas and ant species. Altogether, these results suggest that such an interaction might represent an as-yet undescribed type of specific association between ants and fungus in which the ants cultivate fungal mycelia to strengthen their hunting galleries.
authors.affiliation: UPS, Laboratoire Evolution et Diversité Biologique, Université de Toulouse, 118 route de Narbonne, 31062 Toulouse, France.
authors.forename: Mario X
authors.initials: MX
authors.lastname: Ruiz-González
authors.forename: Pierre-Jean G
authors.initials: PJ
authors.lastname: Malé
authors.forename: Céline
authors.initials: C
authors.lastname: Leroy
authors.forename: Alain
authors.initials: A
authors.lastname: Dejean
authors.forename: Hervé
authors.initials: H
authors.lastname: Gryta
authors.forename: Patricia
authors.initials: P
authors.lastname: Jargeat
authors.forename: Angélique
authors.initials: A
authors.lastname: Quilichini
authors.forename: Jérôme
authors.initials: J
authors.lastname: Orivel
mesh_terms: D000818:Animals; D001000:Ants / Q000235:genetics / Q000502:physiology*; D001203:Ascomycota / Q000235:genetics / Q000502:physiology*; D001522:Behavior, Animal; D045469:Chrysobalanaceae / Q000382:microbiology*; D031213:Cordia / Q000382:microbiology*; D006239:Haplotypes; D013045:Species Specificity; D013559:Symbiosis