Anatomical organization of the brain of a diurnal and a nocturnal dung beetle

Abstract

To avoid the fierce competition for food, South African ball-rolling dung beetles carve a piece 4 of dung off a dung-pile, shape it into a ball and roll it away along a straight line path. For this 5 unidirectional exit from the busy dung pile, at night and day, the beetles use a wide repertoire 6 of celestial compass cues. This robust and relatively easily measurable orientation behavior has 7 made ball-rolling dung beetles an attractive model organism for the study of the neuroethology 8 behind insect orientation and sensory ecology. Although there is already some knowledge 9 emerging concerning how celestial cues are processed in the dung beetle brain, little is known 10 about its general neural layout. Mapping the neuropils of the dung beetle brain is thus a 11 prerequisite to understand the neuronal network that underlies celestial compass orientation. 12Here, we describe and compare the brains of a day-active and a night-active dung beetle species 13 based on immunostainings against synapsin and serotonin. We also provide 3D reconstructions 14 for all brain areas and many of the fiber bundles in the brain of the day-active dung beetle. 15Comparison of neuropil structures between the two dung beetle species revealed differences 16 that reflect adaptations to different light conditions. Altogether, our results provide a reference 17 framework for future studies on the neuroethology of insects in general and dung beetles in

The brain of a nocturnal migratory insect, the Australian Bogong moth

“…The posterior boundary is defined by the horizontal crossing of the lateral antennal lobe tract behind the LAL, which defines the plane that separates the LAL from the more posterior regions of the ventromedial protocerebrum. While this border is somewhat arbitrary, it is consistent with the LAL definitions in other species (Heinze & Reppert, 2012;Immonen et al, 2017;Ito et al, 2014). More clearly defined than the LAL, the bulb is wedged between the dorsal LAL margin and the posterio-medial surface of the mushroom body lobes ( Figure 8I-K).…”

“…To this end, we have carried out a combination of immunohistochemical stainings and 3D reconstructions of wholemount and sectioned Bogong moth brains to produce a comprehensive description of all major regions in the brain of this species, similar to those published for example for the Monarch butterfly (Heinze & Reppert, 2012), the dung beetle (Immonen, Dacke, Heinze, & el Jundi, 2017), the fruit fly (Ito et al, 2014;Jenett et al, 2012), and the locust (von Hadeln, Althaus, Häger, & Homberg, 2018). To account for inter-individual variation, we additionally produced a standardised brain atlas, which robustly describes the average shape of the male Bogong moth brain.…”

Encoding of wind direction by central neurons inDrosophila

“…Although morphologically similar regions of the brain have been described in other insects (Immonen, Dacke, Heinze, & el Jundi, 2017;von Hadeln, Althaus, Häger, & Homberg, 2018), to our knowledge, little is known about the function of these regions of the brain. Neurons in the central complex of other insects have been shown to respond to mechanosensory stimuli (U.…”

Principles of Insect Path Integration

“…In many insects, these cells carry global compass information derived from the skylight polarization pattern and other celestial cues. This compass-pathway has been most extensively studied in locusts (reviewed in [10,88]), but has also been identified in the Monarch butterfly [86,89], dung beetles [87,90], ants [91], and bees [64]. When presenting a rotating polarizer to the animal from above, polarization sensitive neurons (POL-neurons) of this pathway respond with sinusoidal changes in their action potential frequency [88].…”