Olfactory subsystems in the honeybee: sensory supply and sex-specifity
-
1
University of Wuerzburg, Behavioral Physiology and Sociobiology, Germany
Primary odor reception on insect antennae takes place in sensilla that house olfactory receptor neurons (ORNs), which transmit olfactory input to the antennal lobe (AL). Three types of olfactory sensilla are present in honeybees (Apis mellifera): Sensilla basiconica (SB), Sensilla placodea and Sensilla trichoidea. ORN axons project via four distinct sensory tracts (T1-T4) to four corresponding glomeruli clusters in the AL, the first central relay station for processing of olfactory information in the insect brain. Here, ORN axons synapse on local interneurons and projection (output) neurons (PNs). The axons of PNs terminate on Kenyon cells in the mushroom bodies (MBs), higher sensory integration centers and brain centers associated with learning and memory. In Hymenoptera, uniglomerular PNs project to the MBs via two parallel tracts, the medial and the lateral antennal lobe - protocerebral tract (m- and l-APT), forming a dual olfactory pathway (Galizia and Rössler, 2010). As the functional role of these parallel tracts in olfactory processing is unclear, we test two hypotheses: 1. Whether ORNs from a specific sensillum type project to glomeruli associated with PNs from either both or only one APT. 2. Whether the two pathways transmit information about different coding aspects of similar odors. A key feature of many hymenopterans is a social lifestyle, which involves olfactory communication with pheromones and colony-specific odors. Due to their different tasks, these odors are of varying importance for different castes. This was shown to be associated with caste-specific differences in the olfactory system: in drones the antennae lack SB and the ALs contain less glomeruli (especially in the T3 region) compared to the female castes (Nishino et al., 2009). We tested the hypothesis whether ORNs housed in SB project to the T3 cluster in workers, which would explain the reduced T3 cluster in drones. To test this, we selectively labeled axonal projections of ORNs from SB into AL glomeruli. The results suggest that ORNs housed in SB mainly project to glomeruli of the T3 glomerulus cluster. Most interestingly, the T3 cluster is mainly innervated by PNs of the m-APT in honeybee workers (Kirschner et al., 2006). Therefore, we retrogradely labeled the m-APT in drones. APT labeling together with successive AL reconstructions in drones indicate that the drone m-APT innervates less glomeruli compared to the m-APT in workers. The two results combined lead to the conclusion that information transmitted by SB associated ORNs is preferentially transferred via the m-APT subsystem. The absence of SB and T3 glomeruli in drones may indicate that the m-APT carries information especially important for worker bees, such as floral odors, colony odors, or certain pheromones.
Acknowledgements
Supported by DFG SPP 1392
References
Galizia, C. G., and Rössler, W. (2010). Parallel olfactory systems in insects: anatomy and function. Annu. Rev. Entomol. 55, 399-420.
Kirschner, S., Kleineidam, C. J., Zube, C., Rybak, J., Grünewald, B., and Rössler, W. (2006). Dual olfactory pathway in the honeybee, Apis mellifera. J. Comp. Neurol. 499, 933-952.
Nishino, H., Nishikawa, M., Mizunami, M., and Yokohari, F. (2009). Functional and topographic segregation of glomeruli revealed by local staining of antennal sensory neurons in the honeybee Apis mellifera. J. Comp. Neurol. 515, 161-180.
Keywords:
antennal lobe,
Honey bee,
Neuroanatomy,
Olfaction,
Sensillum staining,
sexual dimorphism
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for participant symposium and student poster award)
Topic:
Sensory: Olfaction and Taste
Citation:
Kropf
J,
Bieringer
K,
Kelber
C and
Roessler
W
(2012). Olfactory subsystems in the honeybee: sensory supply and sex-specifity.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00239
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:
30 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Mr. Jan Kropf, University of Wuerzburg, Behavioral Physiology and Sociobiology, Wuerzburg, 97074, Germany, jan.kropf@cncb.ox.ac.uk