Sky compass orientation in the central complex of the dung beetle brain
-
1
Lund University, Dept. of Biology, Sweden
-
2
University of the Witwatersrand, School of Animal, Plant and Environmental Sciences, South Africa
Some dung beetle species have developed a unique orientation behavior to avoid the strong competition for food at the dung pat. After forming a ball of dung, they roll their balls backwards, head down, along straight paths. This behavior ensures that they get away with their treasure from the busy dung pile in the most efficient way possible. While rolling, dung beetles use celestial compass cues such as the sun and moon, the pattern of polarized light and even the Milky Way for directional reference (Dacke et al., 2003; 2012). How these compass cues for straight-line orientation are processed in the tiny beetle brain has never been investigated. The central complex is a brain area that is believed to act as the internal sky compass during migration of locusts and monarch butterflies (Heinze and Homberg, 2007; Heinze and Reppert, 2011). To investigate whether the central complex is a key processing area also in the dung beetle brain, we analyzed the orientation behaviour and the neural substrate of the nocturnal dung beetle species Scarabeus satyrus.
Behavioural data shows that S. satyrus orient to polarized moonlight with high precision. By placing a polarizing filter over a ball-rolling beetle we could manipulate the skylight so that the moon´s polarization pattern appeared to turn by 90°. In response to this rotation, the beetles turned close to the expected 90°, either left or right.
Immunohistochemical and 3D techniques were used to characterize the general layout of the beetle brain, with the main focus on the central complex. This revealed a neural network that is strikingly similar to the ones found in migrating insects. In addition, central complex cells were analyzed through intracellular recordings while stimulating the beetles with artificial compass cues, such as polarized light from the zenith. When stimulating the cells with a rotating polarizer the neurons typically responded with a sinusoidal modulation of their firing rate. This suggests that the central complex cells also encode the skylight polarization pattern for straight-line orientation.
Despite the different orientation behaviours displayed by locusts, butterflies and dung beetles, the present data suggest that the central complex serves as the internal sky compass in all of these diverse groups of insects. This indicates that the neuronal architecture and the function of the central complex are highly conserved across different insect taxa.
Keywords:
navigation,
Orientation,
central complex,
polarized light,
dung beetles
Conference:
International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013.
Presentation Type:
Poster presentation preferred
Topic:
Navigation and orientation
Citation:
El Jundi
B,
Smolka
J,
Baird
E,
Byrne
MJ,
Warrant
E and
Dacke
M
(2019). Sky compass orientation in the central complex of the dung beetle brain.
Front. Physiol.
Conference Abstract:
International Conference on Invertebrate Vision.
doi: 10.3389/conf.fphys.2013.25.00048
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
27 Feb 2013;
Published Online:
09 Dec 2019.
*
Correspondence:
Dr. Basil El Jundi, Lund University, Dept. of Biology, Lund, 22362, Sweden, basil.el.jundi@ntnu.no