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<a href = "https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2018/desertantsha.jpg" title = "The Ant of the Desert Cataglyphis fortis has an extraordinary memory for different food odors. The insect is able to learn many food smells very quickly and never forgets them for the rest of his life. Credit: Markus Knaden / Max Planck Institute for Chemical Ecology ">
The ant of the desert Cataglyphis fortis has an extraordinary memory for different food odors. The insect is able to learn many food smells very quickly and never forgets them for the rest of his life. Credit: Markus Knaden / Max Planck Institute for Chemical Ecology
Scientists at the Max Planck Institute of Chemical Ecology have used behavioral experiments to show that desert ants quickly learn many food odors and remember them for the rest of their lives. However, their memory for nest odors seems to differ from their memory of food odor. While food odors are learned and preserved after a single contact, ants need several attempts to memorize nest odors. In addition, ants quickly forget an odor associated with the nest after it has been removed from the nest. As a result, ants transform food and nest odors into their brain differently.
The desert ant Cataglyphis fortis has amazing abilities to trace food and return to its nest in the North African desert. Its sense of smell has a central function for orientation. The ant is not just a master browser, it is also an artist of memory. Markus Knaden behavior scientists at the Max Planck Institute for Chemical Ecology have been studying the navigation skills of this species of ant for years. Previously, he was particularly interested in how small insects find their nest after an intensive search for food in the vast salt marshes of the Tunisian Sahara. After all, the entrance to the nest is only a small, unobtrusive hole on the surface of the desert. He and his team found that, aside from other factors, the specific smell of the nest plays a crucial role. However, in their experiments, researchers had noticed that ants learned food odors much faster than nest odors. "Our central question was whether different types of memory existed for foraging and nesting. The idea of comparing the two learning processes appeared when we found that ants could learn so incredibly fast food odors. driven much longer, "says first author Roman Huber.
Scientists have developed a simple experiment to test the response of ants to over 30 different food odors. They were holding the end of a stick that had been scented with an odor about two meters from an ant on the ground, so that the wind was blowing the smell of the ant. At first, most odors were ignored by the ants and did not elicit any reaction. "After giving a crumb of food to the ants that had been scented with one of those smells, however, the ants were almost always attracted to that smell afterwards," said Knaden. "We were amazed at how quickly the ants learned about the odors associated with food and how long they could remember it, even the ants, which had learned a smell more than 25 days ago, could be remembered. " In the wild, most ants have a short life and are usually killed by a predator within six days. Therefore, it is particularly surprising that ants that have reached more than four times the average age can still remember what they have learned.
On the other hand, ants could not learn the odors associated with nests as quickly as food odors. When the researchers attached an odor to the nest entrance, the ants needed five to ten attempts to learn the odor as a benchmark. It is only after several trainings that they focused their nest search on this smell. When the odor was removed from the nest and the ants returned to the nest a few times, they completely stopped responding to the old landmark. In ants, odors are obviously treated differently in the brain, depending on whether they are food or nest signals.
Knaden provides an explanation: "The two different olfactory memories make sense, and all through life an ant encounters many pieces of food in search of food.As the insect finds its food mainly through olfactory cues, it is The nest, however, should always have the same odor during the short life of the ant.Thus, it does not take extraordinary memory to locate the entrance of the nest following the olfactory signals.An ant knows how the nest felt when he left to look for food, to find him on his way back.It is unlikely that the smell of the nest changes as an ant is looking for food
Scientists now want to design laboratory studies to support the results of behavioral experiments in the natural habitat of desert ants. Their goal is to use imaging techniques, such as calcium imaging, to locate and visualize the different memories in the ant brain and to compare brain activities during foraging and feeding. nest. "We already use similar techniques for visualizing brain activity in flies and moths. It would be good to establish these techniques for ants as well, because ants have a particularly complex behavior", explains Markus Knaden.
Desert ants have developed impressive abilities to survive in the salt marshes of the Tunisian Sahara, which are rather barren habitats. Credit: Markus Knaden / Max Planck Institute for Chemical Ecology.
The study is published in the Proceedings of the National Academy of Sciences.
Explore more:
Desert ants can assess the reliability of landmarks when they search the way back
More information:
Roman Huber el al., "Desert ants have distinct memories for food and nest odors", PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1809433115
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