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Saturday, April 28, 2012

Better health through grooming

After individual ants are infected with a pathogen, the rest of their nest mates often become resistant to that pathogen.  How is this immunity aquired? Biologists from the Institute of Science and Technology, Austria, the Helmholtz Center and the University of Regensburg led by Sylvia Cremer and Matthias Konrad have found that healthy ants protect themselves from pathogens by grooming their sick compatriots.

The researchers exposed ants (Lasius neglectus) to the pathogen Metarhizium anisopliae, a fungus that produces tiny infectious spores called conidia. The infected insects were then allowed contact with their healthy nest matesEven when the pathogens were delivered at a dosage that should have killed half of exposed ants, only 2% of the nest mates died. 

The researchers found that direct contact was required to pass on this immunity. The nest mates picked up spores by licking the infected ants clean.  In so doing, the groomers managed to acquire a nonlethal infection. They were then able to fight off future attacks by the same pathogens.

Healthy workers of the invasive garden ant (Lasius neglectus) remove an infectious fungal pathogen (Metarhizium anisopliae) from an exposed nestmate by allogrooming. The pathogen-exposed individual was color-marked in order to distinguish it from the healthy ants.
Credit: Image courtesy of Institute of Science and Technlogy Austria.