title: Ectosymbionts and immunity in the leaf-cutting ant Acromyrmex subterraneus subterraneus.
abstract: Associations with symbiotic organisms can serve as a strategy for social insects to resist pathogens. Antibiotics produced by attine ectosymbionts (Actinobacteria) suppress the growth of Escovopsis spp., the specialized parasite of attine fungus gardens. Our objective was to evaluate whether the presence or absence of symbiotic actinobacteria covering the whole ant cuticle is related to differential immunocompetence, respiratory rate and cuticular hydrocarbons (CHs). We evaluated these parameters in three worker groups of Acromyrmex subterraneus subterraneus: External workers (EXT), internal workers with actinobacteria covering the whole body (INB) and internal workers without actinobacteria covering the whole body (INØ). We also eliminated the actinobacteria by antibiotic treatment and examined worker encapsulation response. INB ants showed lower rates of encapsulation and respiration than did the EXT and INØ ants. The lower encapsulation rate did not seem to be a cost imposed by actinomycetes because the elimination of the actinomycetes did not increase the encapsulation rate. Instead, we propose that actinobacteria confer protection to young workers until the maturation of their immune system. Actinobacteria do not seem to change nestmate recognition in these colonies. Although it is known that actinobacteria have a specific action against Escovopsis spp., our studies, along with other independent studies, indicate that actinomycetes may also be important for the individual health of the workers.
authors.affiliation: Universidade Federal do Tocantins, Campus de Gurupi, Gurupi 77402-970, TO, Brazil. danivalbr@yahoo.com.br
authors.forename: Danival José
authors.initials: DJ
authors.lastname: de Souza
authors.forename: Alain
authors.initials: A
authors.lastname: Lenoir
authors.forename: Maria Catarina Megumi
authors.initials: MC
authors.lastname: Kasuya
authors.forename: Myriam Marques Ramos
authors.initials: MM
authors.lastname: Ribeiro
authors.forename: Séverine
authors.initials: S
authors.lastname: Devers
authors.forename: Joel da Cruz
authors.initials: Jda C
authors.lastname: Couceiro
authors.forename: Terezinha Maria Castro
authors.initials: TM
authors.lastname: Della Lucia
mesh_terms: D039903:Actinobacteria / Q000187:drug effects / Q000276:immunology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001000:Ants / Q000276:immunology* / Q000382:microbiology / Q000502:physiology; D007107:Immune System / Q000276:immunology / Q000502:physiology; D012119:Respiration / Q000276:immunology; D012919:Social Behavior; D013559:Symbiosis / Q000276:immunology*
chemical_list: D000900:Anti-Bacterial Agents