# 3D mapping of disease in ant societies reveals a strategy of a specialized parasite

## TL;DR

A study found that a specialized fungus infects all ant colonies in a Brazilian Rainforest and manipulates infected ants to die near the colony entrance, helping the fungus spread.

## Contribution

The study reveals a novel strategy used by a fungal parasite to exploit ant colonies despite their social immunity.

## Key findings

- All studied ant colonies were infected by the fungal parasite Ophiocordyceps unilateralis s.l.
- The parasite manipulates infected ants to die at the colony entrance, optimizing transmission.
- Disease remains a permanent feature in ant colonies over a 20-month period.

## Abstract

Despite the widely held position that the social insects have evolved effective ways to limit infectious disease spread, many pathogens and parasites do attack insect societies. Maintaining a disease-free nest environment is an important evolutionary feature, but since workers have to leave the nest to forage they are routinely exposed to disease. Here we show that despite effective social immunity, in which workers act collectively to reduce disease inside the nest, 100% of studied ant colonies of Camponotus rufipes in a Brazilian Rainforest were infected by the specialized fungal parasite Ophiocordyceps unilateralis s.l. Not only is disease present for all colonies but long-term dynamics over 20 months revealed disease is a permanent feature. Using 3D maps, we showed the parasite optimizes its transmission by controlling workers’ behavior to die on the doorstep of the colony, where susceptible foragers are predictable in time and space. Therefore, despite social immunity, specialized diseases of ants have evolved effective strategies to exploit insect societies.