Home > Papers from 2017 > Visual navigation in dim light

Visual navigation in dim light

The ability of insects to use visual information for navigation, even at very low light levels, shows the fundamental robustness of visual cues for navigation. In a special issue of Phil Trans, themed arounf vision in dim light, two papers show how insects use vision for navigation, even in the most testing circumstances.

Ajay Narendra and Fiorella Ramirez-Esquivel (2017) Subtle changes in the landmark panorama disrupt visual navigation in a nocturnal bull ant. Phil. Trans. R. Soc. B April 5, 2017 372 20160068; doi:10.1098/rstb

Abstract: “The ability of ants to navigate when the visual landmark information is altered has often been tested by creating large and artificial discrepancies in their visual environment. Here, we had an opportunity to slightly modify the natural visual environment around the nest of the nocturnal bull ant Myrmecia pyriformis. We achieved this by felling three dead trees, two located along the typical route followed by the foragers of that particular nest and one in a direction perpendicular to their foraging direction. An image difference analysis showed that the change in the overall panorama following the removal of these trees was relatively little. We filmed the behaviour of ants close to the nest and tracked their entire paths, both before and after the trees were removed. We found that immediately after the trees were removed, ants walked slower and were less directed. Their foraging success decreased and they looked around more, including turning back to look towards the nest. We document how their behaviour changed over subsequent nights and discuss how the ants may detect and respond to a modified visual environment in the evening twilight period.”

James J. Foster, Basil el Jundi, Jochen Smolka, Lana Khaldy, Dan-Eric Nilsson, Marcus J. Byrne, and Marie Dacke (2017) Research article: Stellar performance: mechanisms underlying Milky Way orientation in dung beetles. Phil. Trans. R. Soc. B April 5, 2017 372 20160079; doi:10.1098/rstb.2016.0079

Abstract: “Nocturnal dung beetles (Scarabaeus satyrus) are currently the only animals that have been demonstrated to use the Milky Way for reliable orientation. In this study, we tested the capacity of S. satyrus to orient under a range of artificial celestial cues, and compared the properties of these cues with images of the Milky Way simulated for a beetle’s visual system. We find that the mechanism that permits accurate stellar orientation under the Milky Way is based on an intensity comparison between different regions of the Milky Way. We determined the beetles’ contrast sensitivity for this task in behavioural experiments in the laboratory, and found that the resulting threshold of 13% is sufficient to detect the contrast between the southern and northern arms of the Milky Way under natural conditions. This mechanism should be effective under extremely dim conditions and on nights when the Milky Way forms a near symmetrical band that crosses the zenith. These findings are discussed in the context of studies of stellar orientation in migratory birds and itinerant seals.”

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