Get access

BLACK YEAST SYMBIONTS COMPROMISE THE EFFICIENCY OF ANTIBIOTIC DEFENSES IN FUNGUS-GROWING ANTS

Authors

  • Ainslie E. F. Little,

    Corresponding author
    1. Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706 USA, and Smithsonian Tropical Research Institute, Apartado Box 2072, Balboa, Ancon, Republic of Panama
    Search for more papers by this author
  • Cameron R. Currie

    1. Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706 USA, and Smithsonian Tropical Research Institute, Apartado Box 2072, Balboa, Ancon, Republic of Panama
    Search for more papers by this author

  • Corresponding Editor: D. H. Feener, Jr.

Abstract

Multiplayer symbioses are common in nature, but our understanding of the ecological dynamics occurring in complex symbioses is limited. The tripartite mutualism between fungus-growing ants, their fungal cultivars, and antibiotic-producing bacteria exemplifies symbiotic complexity. Here we reveal how black yeasts, newly described symbionts of the ant–microbe system, compromise the efficiency of bacteria-derived antibiotic defense in fungus-growing ants. We found that symbiotic black yeasts acquire nutrients from the ants' bacterial mutualist, and suppress bacterial growth. Experimental manipulation of ant colonies and their symbionts shows that ants infected with black yeasts are significantly less effective at defending their fungus garden from Escovopsis, a prevalent and specialized pathogen. The reduction of mutualistic bacterial biomass on ants, likely caused by black yeast symbionts, apparently reduces the quantity of antibiotics available to inhibit the garden pathogen. Success of the ant–fungal mutualism is directly dependent on fungus garden health. Thus our finding that black yeasts compromise the ants' ability to deal with the garden parasite indicates that it is an integral component of the symbiosis. This is further evidence that a full understanding of symbiotic associations requires examining the direct and indirect interactions of symbionts in their ecological community context.

Get access to the full text of this article

Ancillary