Ants may not seem particularly germaphobic, since they
live in bacteria-rich dirt and often eat decaying plants and
animals. But some ants have evolved to be quite fastidious
sanitizers, regularly bathing themselves in antimicrobial
secretions emitted from glands in their rear ends.
Now, research from scientists based at the University of Sussex in
the United Kingdom suggests some ants also take it upon themselves
to sanitize young, vulnerable members of their colonies by
scrubbing their broods and nesting material with their
cleaning fluids.
"We knew that [the secretions] help adults, and we knew that the
brood survives and isn't constantly being affected by fungi," study
co-author Christopher Tranter told LiveScience. "So we predicted
that these secretions would help in keeping the brood healthy as
well, and it was nice to find strong evidence showing
that."
Tranter and his colleagues studied the cleaning mechanisms in the
Brazillian leaf cutting ants(Acromyrmex subterraneus
subterraneus) and the Southeast Asian weaver ant
(Polyrhachis dives) by sealing off the
antimicrobial-producing glands in a subgroup of their sample using
a thin enamel polish. They then placed these adults with broods for
about two weeks. They did the same with nonsealed-off ants for
comparison. The team also placed sealed-off and nonsealed-off
adults among brood-free nesting materials and measured the fungal
growth in the materials after about two weeks.
The team found that broods protected by ants with sealed-off glands
were less likely to survive than broods protected by
antimicrobial-producing ants. In addition, the nesting materials of
sealed-off ants contained more fungal growths than nests of
nonsealed-off ants did, proving these secretions play an important
role in keeping a colony's nursery healthy.
Not all ant species have evolved to produce these secretions,
Tranter said, and some appear to produce them in greater quantities
than others. The team next hopes to conduct analyses to gain a
better understanding of why certain species have the cleaning
glands and others don't.
The team reported their findings earlier this month in the journal
Behavioral Ecology and Sociobiology.
