TY - JOUR
T1 - Ant colonies prefer infected over uninfected nest sites
AU - Pontieri, Luigi
AU - Vojvodic, Svjetlana
AU - Graham, Riley
AU - Pedersen, Jes Søe
AU - Linksvayer, Timothy A.
PY - 2014/11/5
Y1 - 2014/11/5
N2 - During colony relocation, the selection of a new nest involves exploration and assessment of potential sites followed by
colony movement on the basis of a collective decision making process. Hygiene and pathogen load of the potential nest
sites are factors worker scouts might evaluate, given the high risk of epidemics in group-living animals. Choosing nest sites
free of pathogens is hypothesized to be highly efficient in invasive ants as each of their introduced populations is often an
open network of nests exchanging individuals (unicolonial) with frequent relocation into new nest sites and low genetic
diversity, likely making these species particularly vulnerable to parasites and diseases. We investigated the nest site
preference of the invasive pharaoh ant, Monomorium pharaonis, through binary choice tests between three nest types:
nests containing dead nestmates overgrown with sporulating mycelium of the entomopathogenic fungus Metarhizium
brunneum (infected nests), nests containing nestmates killed by freezing (uninfected nests), and empty nests. In contrast to
the expectation pharaoh ant colonies preferentially (84%) moved into the infected nest when presented with the choice of
an infected and an uninfected nest. The ants had an intermediate preference for empty nests. Pharaoh ants display an
overall preference for infected nests during colony relocation. While we cannot rule out that the ants are actually
manipulated by the pathogen, we propose that this preference might be an adaptive strategy by the host to ‘‘immunize’’
the colony against future exposure to the same pathogenic fungus.
AB - During colony relocation, the selection of a new nest involves exploration and assessment of potential sites followed by
colony movement on the basis of a collective decision making process. Hygiene and pathogen load of the potential nest
sites are factors worker scouts might evaluate, given the high risk of epidemics in group-living animals. Choosing nest sites
free of pathogens is hypothesized to be highly efficient in invasive ants as each of their introduced populations is often an
open network of nests exchanging individuals (unicolonial) with frequent relocation into new nest sites and low genetic
diversity, likely making these species particularly vulnerable to parasites and diseases. We investigated the nest site
preference of the invasive pharaoh ant, Monomorium pharaonis, through binary choice tests between three nest types:
nests containing dead nestmates overgrown with sporulating mycelium of the entomopathogenic fungus Metarhizium
brunneum (infected nests), nests containing nestmates killed by freezing (uninfected nests), and empty nests. In contrast to
the expectation pharaoh ant colonies preferentially (84%) moved into the infected nest when presented with the choice of
an infected and an uninfected nest. The ants had an intermediate preference for empty nests. Pharaoh ants display an
overall preference for infected nests during colony relocation. While we cannot rule out that the ants are actually
manipulated by the pathogen, we propose that this preference might be an adaptive strategy by the host to ‘‘immunize’’
the colony against future exposure to the same pathogenic fungus.
U2 - 10.1371/journal.pone.0111961
DO - 10.1371/journal.pone.0111961
M3 - Journal article
SN - 1932-6203
VL - 9
JO - PLOS ONE
JF - PLOS ONE
IS - 11
M1 - e111961
ER -