The white material on the underside of this South American leafcutter ant comprises bacteria called Pseudonocardia. The microbes live in a symbiotic relationship with the ants, which survive by farming a specialised fungus that constitutes food for the colony larvae.
Research led by Matt Hutchings of the University of East Anglia in the UK reveals that Pseudonocardia plays a vital role in the leafcutter ants’ ongoing war with a parasitic micro-fungus called Escovopis.
The microfungus has evolved to eat the same food as the ants. Hutchings and colleagues discovered that the species releases two chemical attack weapons – a molecule that kills Pseudonocardia, and another that alters the ants’ behaviour, making them give up their farming duties, leading to catastrophic colony collapse.
Knocking out the bacteria is critical for the parasite, because it is a rich source of antibiotics – deployed by patrolling ants to lethal effect.
The research is published in the journal Nature Communications.