Low Virulence of the Fungi Escovopsis and Escovopsioides to a Leaf-Cutting Ant-Fungus Symbiosis
Eusocial insects interact with a diversity of parasites that can threaten their survival and reproduction. The amount of harm these parasites cause to their hosts (i.e., their virulence) can be influenced by numerous factors, such as the ecological context in which the parasite and its host are inse...
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| Published in: | Frontiers in microbiology Vol. 12; p. 673445 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Frontiers Media S.A
29-07-2021
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Eusocial insects interact with a diversity of parasites that can threaten their survival and reproduction. The amount of harm these parasites cause to their hosts (i.e., their virulence) can be influenced by numerous factors, such as the ecological context in which the parasite and its host are inserted. Leaf-cutting ants (genera
Atta
,
Acromyrmex
and
Amoimyrmex
, Attini: Formicidae) are an example of a eusocial insect whose colonies are constantly threatened by parasites. The fungi
Escovopsis
and
Escovopsioides
(Ascomycota: Hypocreales) are considered a highly virulent parasite and an antagonist, respectively, to the leaf-cutting ants’ fungal cultivar,
Leucoagaricus gongylophorus
(Basidiomycota: Agaricales). Since
Escovopsis
and
Escovopsioides
are common inhabitants of healthy colonies that can live for years, we expect them to have low levels of virulence. However, this virulence could vary depending on ecological context. We therefore tested two hypotheses: (i)
Escovopsis
and
Escovopsioides
are of low virulence to colonies; (ii) virulence increases as colony complexity decreases. For this, we used three levels of complexity: queenright colonies (fungus garden with queen and workers), queenless colonies (fungus garden and workers, without queen) and fungus gardens (without any ants). Each was inoculated with extremely high concentrations of conidia of
Escovopsis moelleri
,
Escovopsioides nivea
, the mycoparasitic fungus
Trichoderma longibrachiatum
or a blank control. We found that these fungi were of low virulence to queenright colonies. The survival of queenless colonies was decreased by
E. moelleri
and fungus gardens were suppressed by all treatments. Moreover,
E. nivea
and
T. longibrachiatum
seemed to be less aggressive than
E. moelleri
, observed both
in vivo
and
in vitro
. The results highlight the importance of each element (queen, workers and fungus garden) in the leaf-cutting ant-fungus symbiosis. Most importantly, we showed that
Escovopsis
may not be virulent to healthy colonies, despite commonly being described as such, with the reported virulence of
Escovopsis
being due to poor colony conditions in the field or in laboratory experiments. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Reviewed by: Katrin Kellner, The University of Texas at Tyler, United States; Pepijn Wilhelmus Kooij, Universidade Estadual Paulista, Brazil; Nicole Marie Gerardo, Emory University, United States Edited by: Mariana Mateos, Texas A&M University, United States This article was submitted to Microbial Symbioses, a section of the journal Frontiers in Microbiology |
| ISSN: | 1664-302X 1664-302X |
| DOI: | 10.3389/fmicb.2021.673445 |