Impact of soil contamination on the growth and shape of ant nests

As entomopathogens are detrimental to the development or even survival of insect societies, ant colonies should avoid digging into a substrate that is contaminated by fungal spores. Here, we test the hypotheses that Myrmica rubra ant workers (i) detect and avoid fungus-infected substrates and (ii) e...

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Main Authors: Jean-Baptiste Leclerc, Jennifer Pinto Silva, Claire Detrain
Format: Article
Language:English
Published: The Royal Society 2018-01-01
Series:Royal Society Open Science
Subjects:
Online Access:https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.180267
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author Jean-Baptiste Leclerc
Jennifer Pinto Silva
Claire Detrain
author_facet Jean-Baptiste Leclerc
Jennifer Pinto Silva
Claire Detrain
author_sort Jean-Baptiste Leclerc
collection DOAJ
description As entomopathogens are detrimental to the development or even survival of insect societies, ant colonies should avoid digging into a substrate that is contaminated by fungal spores. Here, we test the hypotheses that Myrmica rubra ant workers (i) detect and avoid fungus-infected substrates and (ii) excavate nest patterns that minimize their exposure to entomopathogenic spores. Small groups of M. rubra workers were allowed to dig their nest in a two-dimensional sand plate of which one half of the substrate contained fungal spores of Metarhizium brunneum, while the other half was spore-free. We found that the overall digging dynamics of M. rubra nests was not altered by the presence of fungus spores. By contrast, the shape of the excavated areas markedly differed: control nests showed rather isotropic patterns, whereas nests that were partially dug into a fungus-contaminated substrate markedly deviated from a circular shape. This demonstrates that the sanitary risks associated with a digging substrate are key factors in nest morphogenesis. We also found that M. rubra colonies were able to discriminate between the two substrates (fungus-infected or not). Furthermore, some colonies unexpectedly showed a high consistency in excavating mainly the infected substrate. This seemingly suboptimal preference for a contaminated soil suggests that non-lethal doses of fungal spores could help ant colonies to trigger ‘immune priming’. The presence of fungi may also indicate favourable ecological conditions, such as humid and humus-rich soil, that ants use as a cue for selecting suitable nesting sites.
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spelling doaj.art-7d088694457e485394bf5c607afd2b982022-12-22T00:00:55ZengThe Royal SocietyRoyal Society Open Science2054-57032018-01-015710.1098/rsos.180267180267Impact of soil contamination on the growth and shape of ant nestsJean-Baptiste LeclercJennifer Pinto SilvaClaire DetrainAs entomopathogens are detrimental to the development or even survival of insect societies, ant colonies should avoid digging into a substrate that is contaminated by fungal spores. Here, we test the hypotheses that Myrmica rubra ant workers (i) detect and avoid fungus-infected substrates and (ii) excavate nest patterns that minimize their exposure to entomopathogenic spores. Small groups of M. rubra workers were allowed to dig their nest in a two-dimensional sand plate of which one half of the substrate contained fungal spores of Metarhizium brunneum, while the other half was spore-free. We found that the overall digging dynamics of M. rubra nests was not altered by the presence of fungus spores. By contrast, the shape of the excavated areas markedly differed: control nests showed rather isotropic patterns, whereas nests that were partially dug into a fungus-contaminated substrate markedly deviated from a circular shape. This demonstrates that the sanitary risks associated with a digging substrate are key factors in nest morphogenesis. We also found that M. rubra colonies were able to discriminate between the two substrates (fungus-infected or not). Furthermore, some colonies unexpectedly showed a high consistency in excavating mainly the infected substrate. This seemingly suboptimal preference for a contaminated soil suggests that non-lethal doses of fungal spores could help ant colonies to trigger ‘immune priming’. The presence of fungi may also indicate favourable ecological conditions, such as humid and humus-rich soil, that ants use as a cue for selecting suitable nesting sites.https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.180267social immunitysoil contaminationnest topologymyrmica antsmetarhizium fungus
spellingShingle Jean-Baptiste Leclerc
Jennifer Pinto Silva
Claire Detrain
Impact of soil contamination on the growth and shape of ant nests
Royal Society Open Science
social immunity
soil contamination
nest topology
myrmica ants
metarhizium fungus
title Impact of soil contamination on the growth and shape of ant nests
title_full Impact of soil contamination on the growth and shape of ant nests
title_fullStr Impact of soil contamination on the growth and shape of ant nests
title_full_unstemmed Impact of soil contamination on the growth and shape of ant nests
title_short Impact of soil contamination on the growth and shape of ant nests
title_sort impact of soil contamination on the growth and shape of ant nests
topic social immunity
soil contamination
nest topology
myrmica ants
metarhizium fungus
url https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.180267
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