A QUESTION, which has been puzzling researchers for a long time is: How do ants find their way straight to the uncovered food in the kitchen? The humble wood ant, with poor eyesight, navigates through confusing and changing landmarks over proportionally huge distances.
Scientists at the University of Sussex have shown precisely how the ant's visual navigation strategy works. On a wood ant's first trip to a food site it follows a chemical trail left by earlier ants.
Learning strategy
This initial routeforms the basis of an efficient learning strategy.
Ants store images of the route as they travel on the first trip and on later trips to the food site will navigate using a combination of landmarks and memories of the whole landscape.
Ants store many memories and have mechanisms to activate the right ones.
Different sets of landmark memories depending on whether they were on their way to food, or whether they were full and heading back to the nest were used by the ants, the scientists found.
The researchers refined their research on ant visual memory selection in lab experiments, according to a University of Sussex press release. Research leader, Professor Tom Collett from the University of Sussex's Centre for Neuroscience, explained: "To show that ants use visual memory to navigate we trained ants to find food 10 cm from a cylinder.
We then doubled the size of the cylinder and the ants searched for the food at 20 cm away where the retinal size of the landmark was the same." To observe how ants deal with an ambiguous situation, they were trained to search for food placed between two cylinders of different sizes. The cylinders were then replaced with a pair of equal size.
Would the ants know which cylinder is which? They were only able to search in the predicted place when a patterned background was introduced as a retrieval cue. Professor Collett said.
Storing large panorama
"To know which cylinder was which, ants needed the patterned background to be in a different position on the retina when they faced one or other cylinder. Accurate memory retrieval often relies on ants storing a large panorama."
A better understanding of ant navigation could help to develop autonomous robots. Professor Collett said.
"Insect behaviour is much more `machine-like' than that of mammals, and ants are a lot less flexible in their use of navigational strategies." — Our Bureau
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