Integrating two-dimensional paths: do desert ants process distance information in the absence of celestial compass cues?

SUMMARYAlthough several studies have examined how honeybees gauge and report the distance and direction of a food source to their nestmates, relatively little is known about how this information is combined to obtain a representation of the position of the food source. In this study we manipulate the amount of celestial compass information available to the bee during flight, and analyse the encoding of spatial information in the waggle dance as well as in the navigation of the foraging bee. We find that the waggle dance encodes information about the total distance flown to the food source, even when celestial compass cues are available only for a part of the journey. This stands in contrast to how a bee gauges distance flown when it navigates back to a food source that it already knows. When bees were trained to find a feeder placed at a fixed distance in a tunnel in which celestial cues were partially occluded and then tested in a tunnel that was fully open to the sky, they searched for the feeder at a distance that corresponds closely to the distance that was flown under the open sky during the training. Thus, when navigating back to a food source, information about distance travelled is disregarded when there is no concurrent input from the celestial compass. We suggest that bees may possess two different odometers -a ʻcommunityʼ odometer that is used to provide information to nestmates via the dance, and a ʻpersonalʼ odometer that is used by an experienced individual to return to a previously visited source.

Section: The Encoding Of Spatial Informationsupporting

confidence: 87%

Two odometers in honeybees?

Dacke

Srinivasan

2008

“…Portions of the flight channel that had been covered with opaque lids were not fed into the personal distance estimate. This is in striking agreement with findings in desert ants (Ronacher et al, 2006;Sommer and Wehner, 2005). As strictly individual foragers, these animals may not exhibit a community odometer.…”

Section: Distance Cues: Optic Flow and Stride Integrationsupporting

confidence: 91%

Odometry and insect navigation

Wolf

2011

SummaryAnimals have needed to find their way about almost since a free-living life style evolved. Particularly, if an animal has a homeshelter or nesting site -true navigation becomes necessary to shuttle between this home and areas of other activities, such as feeding. As old as navigation is in the animal kingdom, as diverse are its mechanisms and implementations, depending on an organism's ecology and its endowment with sensors and actuators. The use of landmarks for piloting or the use of trail pheromones for route following have been examined in great detail and in a variety of animal species. The same is true for senses of direction -the compasses for navigation -and the construction of vectors for navigation from compass and distance cues. The measurement of distance itself -odometry -has received much less attention. The present review addresses some recent progress in the understanding of odometers in invertebrates, after outlining general principles of navigation to put odometry in its proper context. Finally, a number of refinements that increase navigation accuracy and safety are addressed.

“…In preliminary experiments we noticed that the ants tended to turn back at the sharp transition from a 0deg to a 90deg e-vector. To reduce confusion of the ants, we covered the border between the two e-vector orientations with a 15cm piece of orange Perspex, so that at the transition the ants had to walk a 15cm distance without POL-compass information (see Ronacher et al, 2006); this 15cm distance is not included in the length details given above. In the first cue conflict experiment (Fig.1D), however, the bend was not covered by orange Perspex, thus the ants performed their turning movement under sight of the (orthogonal) e-vector.…”

Section: Methodsmentioning

confidence: 99%

The polarization compass dominates over idiothetic cues in path integration of desert ants

Lebhardt

Koch

Ronacher

2012

SUMMARYDesert ants, Cataglyphis, use the skyʼs pattern of polarized light as a compass reference for navigation. However, they do not fully exploit the complexity of this pattern, rather -as proposed previously -they assess their walking direction by means of an approximate solution based on a simplified internal template. Approximate rules are error-prone. We therefore asked whether the ants use additional cues to improve the accuracy of directional decisions, and focused on ʻidiotheticʼ cues, i.e. cues based on information from proprioceptors. We trained ants in a channel system that was covered with a polarization filter, providing only a single e-vector direction as a directional ʻcelestialʼ cue. Then we observed their homebound runs on a test field, allowing full view of the sky. In crucial experiments, the ants were exposed to a cue conflict, in which sky compass and idiothetic information disagreed, by training them in a straight channel that provided a change in e-vector direction. The results indicated that the polarization information completely dominates over idiothetic cues. Two path segments with different e-vector orientations are combined linearly to a summed home vector. Our data provide additional evidence that Cataglyphis uses a simplified internal template to derive directional information from the skyʼs polarization pattern.