scholarly journals Geosmin suppresses defensive behaviour and elicits unusual neural responses in honey bees.

2021 ◽  
Author(s):  
Florencia Scarano ◽  
Mukilan Deivarajan Suresh ◽  
Ettore Tiraboschi ◽  
Amélie Cabirol ◽  
Morgane Nouvian ◽  
...  
Keyword(s):  
Honey Bees ◽  
Olfactory Receptor ◽  
Antennal Lobe ◽  
Alarm Pheromone ◽  
Behavioural Change ◽  
Computational Modelling ◽  
Isoamyl Acetate ◽  
Olfactory Receptor Neurons ◽  
Defensive Behaviour ◽  
Receptor Neurons

Geosmin is an odorant produced by bacteria in moist soil. It has been found to be extraordinarily relevant to some insects, but the reasons for this are not yet fully understood. Here we report the first tests of the effect of geosmin on honey bees. A stinging assay showed that the defensive behaviour elicited by the bee's alarm pheromone is strongly suppressed by geosmin. Surprisingly, the suppression is, however, only present at very low geosmin concentrations, and completely disappears at higher concentrations. We investigated the underlying mechanisms of the behavioural change at the level of the olfactory receptor neurons by means of electroantennography and at the level of the antennal lobe output via calcium imaging. Unusual effects were observed at both levels. The responses of the olfactory receptor neurons to mixtures of geosmin and the alarm pheromone component isoamyl acetate (IAA) were lower than to pure IAA, suggesting an interaction of both compounds at the olfactory receptor level. In the antennal lobe, the neuronal representation of geosmin showed a glomerular activation that decreased with increasing concentration, correlating well with the concentration dependence of the behaviour. Computational modelling of odour transduction and odour coding in the antennal lobe suggests that a broader than usual activation of different olfactory receptor types by geosmin in combination with lateral inhibition in the antennal lobe could lead to the observed non-monotonic increasing-decreasing responses to geosmin and thus underlie the specificity of the behavioural response to low geosmin concentrations.

scholarly journals Cooperative defence operates by social modulation of biogenic amine levels in the honey bee brain

2018 ◽  
Vol 285 (1871) ◽  
pp. 20172653 ◽  
Author(s):  
Morgane Nouvian ◽  
Souvik Mandal ◽  
Charlène Jamme ◽  
Charles Claudianos ◽  
Patrizia d'Ettorre ◽  
...  
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Alarm Pheromone ◽  
Neural Mechanism ◽  
Isoamyl Acetate ◽  
Neural Mechanisms ◽  
Response Threshold ◽  
Defensive Behaviour ◽  
Personal Risk ◽  
Main Component

The defence of a society often requires that some specialized members coordinate to repel a threat at personal risk. This is especially true for honey bee guards, which defend the hive and may sacrifice their lives upon stinging. Central to this cooperative defensive response is the sting alarm pheromone, which has isoamyl acetate (IAA) as its main component. Although this defensive behaviour has been well described, the neural mechanisms triggered by IAA to coordinate stinging have long remained unknown. Here we show that IAA upregulates brain levels of serotonin and dopamine, thereby increasing the likelihood of an individual bee to attack and sting. Pharmacological enhancement of the levels of both amines induces higher defensive responsiveness, while decreasing them via antagonists decreases stinging. Our results thus uncover the neural mechanism by which an alarm pheromone recruits individuals to attack and repel a threat, and suggest that the alarm pheromone of honey bees acts on their response threshold rather than as a direct trigger.

scholarly journals Cholinergic calcium responses in cultured antennal lobe neurons of the migratory locust

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gregor A. Bergmann ◽  
Gerd Bicker
Keyword(s):  
Olfactory Receptor ◽  
Intracellular Signaling ◽  
Antennal Lobe ◽  
Locusta Migratoria ◽  
Cytosolic Calcium ◽  
Olfactory Receptor Neurons ◽  
Future Research ◽  
Migratory Locust ◽  
Local Interneurons ◽  
Receptor Neurons

AbstractLocusts are advantageous organisms to elucidate mechanisms of olfactory coding at the systems level. Sensory input is provided by the olfactory receptor neurons of the antenna, which send their axons into the antennal lobe. So far, cellular properties of neurons isolated from the circuitry of the olfactory system, such as transmitter-induced calcium responses, have not been studied. Biochemical and immunocytochemical investigations have provided evidence for acetylcholine as classical transmitter of olfactory receptor neurons. Here, we characterize cell cultured projection and local interneurons of the antennal lobe by cytosolic calcium imaging to cholinergic stimulation. We bulk loaded the indicator dye Cal-520 AM in dissociated culture and recorded calcium transients after applying cholinergic agonists and antagonists. The majority of projection and local neurons respond with increases in calcium levels to activation of both nicotinic and muscarinic receptors. In local interneurons, we reveal interactions lasting over minutes between intracellular signaling pathways, mediated by muscarinic and nicotinic receptor stimulation. The present investigation is pioneer in showing that Cal-520 AM readily loads Locusta migratoria neurons, making it a valuable tool for future research in locust neurophysiology, neuropharmacology, and neurodevelopment.

scholarly journals Non-synaptic interactions between olfactory receptor neurons, a possible key feature of odor processing in insects

2020 ◽  
Author(s):  
Mario Pannunzi ◽  
Thomas Nowotny
Keyword(s):  
Lateral Inhibition ◽  
Olfactory Receptor ◽  
Olfactory System ◽  
Antennal Lobe ◽  
Olfactory Receptor Neurons ◽  
Inhibition Mechanism ◽  
Alternative Mechanism ◽  
Odor Processing ◽  
Synaptic Interactions ◽  
Receptor Neurons

AbstractWhen flies explore their environment, they encounter odors in complex, highly intermittent plumes. To navigate a plume and, for example, find food, flies must solve several tasks, including reliably identifying mixtures of odorants and discriminating odorant mixtures emanating from a single source from odorants emitted from separate sources and mixing in the air. Lateral inhibition in the antennal lobe is commonly understood to help solving these two tasks. With a computational model of the Drosophila olfactory system, we analyze the utility of an alternative mechanism for solving them: Non-synaptic (“ephaptic”) interactions (NSIs) between olfactory receptor neurons that are stereotypically co-housed in the same sensilla. For both tasks, NSIs improve the insect olfactory system and outperform the standard lateral inhibition mechanism in the antennal lobe. These results shed light, from an evolutionary perspective, on the role of NSIs, which are normally avoided between neurons, for instance by myelination.

Sensillum-specific, topographic projection patterns of olfactory receptor neurons in the antennal lobe of the cockroach Periplaneta americana

2012 ◽  
Vol 520 (8) ◽  
pp. 1687-1701 ◽  
Author(s):  
Hidehiro Watanabe ◽  
S. Shuichi Haupt ◽  
Hiroshi Nishino ◽  
Michiko Nishikawa ◽  
Fumio Yokohari
Keyword(s):  
Olfactory Receptor ◽  
Antennal Lobe ◽  
Periplaneta Americana ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons

scholarly journals EAG Responses Increase of Spodoptera littoralis Antennae after a Single Pheromone Pulse

2014 ◽  
Vol 9 (8) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Carmen Quero ◽  
Berta Vidal ◽  
Angel Guerrero
Keyword(s):  
Olfactory Receptor ◽  
Spodoptera Littoralis ◽  
Antennal Lobe ◽  
Life Time ◽  
Olfactory Receptor Neurons ◽  
Average Life ◽  
Antennal Response ◽  
Behavioral Sensitivity ◽  
Response Increase ◽  
Receptor Neurons

Increased behavioral sensitivity to the pheromone after brief exposure of the whole insect to the sex pheromone has been documented in antennal lobe neurons of Spodoptera littoralis. We investigated whether a brief stimulus of the major component of the pheromone on naïve antenna separated from the head increased the electroantennographic responses after successive stimulations at different times. The response increase was clear 30 min after the first stimulation, and this effect lasted at least 60 min, the average life time of the antenna. Our results suggest that the olfactory receptor neurons, and not only the neurons in the antennal lobe, may be involved in the increased antennal response after a single pheromone pulse.

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