Insectes Sociaux

, Volume 59, Issue 2, pp 231–239 | Cite as

Diversity, prevalence and virulence of fungal entomopathogens in colonies of the ant Formica selysi

  • A. Reber
  • M. Chapuisat
Research Article


The richness of the parasitic community associated with social insect colonies has rarely been investigated. Moreover, understanding how hosts and pathogens interact in nature is important to interpret results from laboratory experiments. Here, we assessed the diversity, prevalence and virulence of fungal entomopathogens present around and within colonies of the ant Formica selysi. We detected eight fungal species known to be entomopathogenic in soil sampled from the habitat of ants. Six of these entomopathogens were found in active nests, abandoned nests, and corpses from dump piles or live ants. A systematic search for the presence of three generalist fungal entomopathogens in ant colonies revealed a large variation in their prevalence. The most common of the three pathogens, Paecilomyces lilacinus, was detected in 44% of the colonies. Beauveria bassiana occurred in 17% of the colonies, often in association with P. lilacinus, whereas we did not detect Metarhizium brunneum (formerly M. anisopliae) in active colonies. The three fungal species caused significant mortality to experimentally challenged ants, but varied in their degree of virulence. There was a high level of genetic diversity within B. bassiana isolates, which delineated three genetic strains that also differed significantly in their virulence. Overall, our study indicates that the ants encounter a diversity of fungal entomopathogens in their natural habitat. Moreover, some generalist pathogens vary greatly in their virulence and prevalence in ant colonies, which calls for further studies on the specificity of the interactions between the ant hosts and their fungal pathogens.


Host–parasite Soil fungi Parasite diversity Ant pathogens Social insects Formica selysi 



We thank Timothée Brutsch, Jessica Purcell and two anonymous reviewers for comments on the manuscript, Godefroy Devevey for help in the field, Jessica Purcell for sequencing the EF-1α gene region to identify the Metarhizium species and Marie Ballif for help in the laboratory. This study was supported by the Swiss National Science Foundation (grants 31003A_108263 and 31003A_125306 to MC).


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Copyright information

© International Union for the Study of Social Insects (IUSSI) 2011

Authors and Affiliations

  1. 1.Department of Ecology and EvolutionBiophore, UNIL-Sorge, University of LausanneLausanneSwitzerland

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