Do zombie ant fungi turn their hosts into light seekers?

Specialized parasites can modify host behavior to benefit transmission and reproduction. Such behavior is considered an extended phenotype of the parasite. The interactions between certain ant species and fungi of the genus Ophiocordyceps form an evident example. Once infected by Ophiocordyceps camponoti-atricipis, Camponotus atriceps ants die, biting at specific sites where abiotic conditions are optimal for fungal development. For many species of free-living fungi, light is needed to induce growth of the reproductive stage. However, the role of light in Ophiocordyceps behavioral manipulation and fruiting body development is largely unknown. Here, we investigated the association between illuminance and the incidence of dead manipulated C. atriceps ants. We identified ant graveyards in the field and experimentally changed the incident illumination for half of each graveyard using shading screens. Such screens resulted in a clear reduction of incident light, as well as slightly higher, m...