Geometry gives polarity to ant pheromone trails

Jackson, Duncan E, Holcombe, Mike and Ratnieks, Francis L W (2004) Geometry gives polarity to ant pheromone trails. Nature, Vol 43. pp. 907-909. ISSN 0028-0836

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Pheromone trails are used by many ants to guide foragers between nest and food1, 2, 3, 4. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone3, 5, 6, 7. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment8. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies.

Item Type: Article
Additional Information: Discovery of novel mechanism, the angle of trailbifurcations, that forager ants can use to determine if they are walking the wrong way along a trail.
Schools and Departments: School of Life Sciences > Evolution, Behaviour and Environment
Depositing User: Francis Ratnieks
Date Deposited: 06 Feb 2012 19:12
Last Modified: 20 Mar 2012 14:07
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