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Innate turning preference of leaf-cutting ants in the absence of external orientation cues




Many ants use a combination of cues for orientation but how do ants find their way when all external cues are suppressed? Do they walk in a random way or are their movements spatially oriented? Here we show for the first time that leaf-cutting ants (Acromyrmex lundii) have an innate preference of turning counter-clockwise (left) when external cues are precluded. We demonstrated this by allowing individual ants to run freely on the water surface of a newly-developed treadmill. The surface tension supported medium-sized workers but effectively prevented ants from reaching the wall of the vessel, important to avoid wall-following behaviour (thigmotaxis). Most ants ran for minutes on the spot but also slowly turned counter-clockwise in the absence of visual cues. Reconstructing the effectively walked path revealed a looping pattern which could be interpreted as a search strategy. A similar turning bias was shown for groups of ants in a symmetrical Y-maze where twice as many ants chose the left branch in the absence of optical cues. Wall-following behaviour was tested by inserting a coiled tube before the Y-fork. When ants traversed a left-coiled tube, more ants chose the left box and vice versa. Adding visual cues in form of vertical black strips either outside the treadmill or on one branch of the Y-maze led to oriented walks towards the strips. It is suggested that both, the turning bias and the wall-following are employed as search strategies for an unknown environment which can be overridden by visual cues.

Author(s): Endlein, Thomas and Sitti, Metin
Journal: Journal of Experimental Biology
Year: 2018
Month: June
Day: 7
Publisher: The Company of Biologists Ltd

Department(s): Physical Intelligence
Bibtex Type: Article (article)
Paper Type: Journal

DOI: 10.1242/jeb.177006
Eprint: http://jeb.biologists.org/content/early/2018/06/01/jeb.177006.full.pdf
URL: http://jeb.biologists.org/content/early/2018/06/01/jeb.177006


  title = {Innate turning preference of leaf-cutting ants in the absence of external orientation cues},
  author = {Endlein, Thomas and Sitti, Metin},
  journal = {Journal of Experimental Biology},
  publisher = {The Company of Biologists Ltd},
  month = jun,
  year = {2018},
  eprint = {http://jeb.biologists.org/content/early/2018/06/01/jeb.177006.full.pdf},
  url = {http://jeb.biologists.org/content/early/2018/06/01/jeb.177006},
  month_numeric = {6}