The animals, which are native to North Africa and Southern Europe, forage for food up to 100 metres from their nest. They do not rely on scents for orientation, which the heat quickly renders unusable. ‘They memorise their surroundings primarily visually,’ explains study author Sebastian Schwarz, who has been an assistant professor at the Institute of Biology at the University of Graz since the end of 2023.
Until now, it was unclear how the information from both eyes is combined in the brain of the insects. Schwarz, together with colleagues from Toulouse (F) and Münster (D), has investigated how the desert ant (Cataglyphis velox) reacts to a limitation in visual perception. To do this, one eye was carefully covered.
‘One-eyed ants initially had difficulty following familiar routes and had to relearn their way back to the nest. However, they adapted their orientation skills in just a few hours,’ explains Schwarz.
When the animals regained their binocular vision, they had no difficulty following the familiar route that they had previously learned with both eyes. ‘Accordingly, ants are not able to retrieve visual memories that were trained with two eyes with only one eye,’ the biologist concludes. ’We assume that the insects do not store two separate eye memories, but only one, which is based on both visual organs.’
To support this explanation, one-eyed ants were trained on a new route in the course of the study. ‘After that, we removed the cover and observed the homing ability of the workers,’ says Sebastian Schwarz. However, the ants, which were now again two-eyed, were unable to find their way to the nest. “This proved that visual memories are processed binocularly in the insect brain – otherwise the additional information from the second eye would not have been disruptive,” explains the scientist.
‘This confirms,’ says Sebastian Schwarz, ’that the memory and navigation of the desert inhabitants depend on seeing the world as a whole and using both eyes to do so.’
The research results were recently described in an article in the internationally renowned journal PNAS (Proceedings of the National Academy of Sciences).