Influence of the alarm pheromone on olfactory behavior and neurophysiology in the honey bees

- description du projet (2 pages maximum)

Sensory coding and perception are influenced by both external sensory cues and internal states. In many vertebrate and invertebrate species, alarm signals can rapidly suppress food-related behaviors, triggering a fight-or-flight response. Likewise, in honey bees, exposure to alarm pheromone components shifts behavior from foraging to aggression and disrupts olfactory appetitive learning and memory retention capability. A potential neural mechanism underlying such a behavioral shift is the modulation of olfactory processing. Previous studies in bees have already linked a reduction in appetitive behaviors to a decreased neural activity in the antennal lobe, the primary olfactory processing center of the insect brain. Given the central role of olfaction in honey bee ecology, we hypothesize that this alarm-induced behavioral switch may also arise from changes in olfactory coding and perception.

Within this project, the doctoral candidate will investigate how alarm pheromone components influence honey bee olfactory behavior and neurophysiology through three complementary working packages (WP):

WP1. The doctoral candidate will compare olfactory behaviors—including appetitive olfactory learning, odor discrimination, and short/long-term memory—across groups of bees pre-exposed to alarm pheromone components (e.g., isoamyl acetate, 2-heptanone), floral odorants (e.g. linalool, benzaldehyde), or clean air. Movement tracking will allow precise quantification of proboscis extension and antennal dynamics. This will establish a baseline assessment of how external olfactory cues shape ecologically relevant behaviors.

WP2. Using functional calcium imaging of the honey bee antennal lobe, the candidate will evaluate whether the pre-exposure to alarm pheromone influences the neural representation odorants with appetitive (e.g., linalool or lavander), social (e.g., 2-heptanone or geraniol) or neutral valence (e.g., hexanol or octanol). This neuroimaging approach will complement the behavioral study (WP1), linking behavioral changes to the underlying neural mechanisms.

WP3. If alarm pheromone components are found to modulate olfactory behaviors (WP1) and/or neurophysiology (WP2), the candidate will investigate the underlying neuromodulatory pathways using a pharmacological approach. Serotonin has been associated with aggression, while dopamine plays a central role in the "liking" and "wanting" systems of bees. Both neurotransmitters influence the initiation and termination of food-related behaviors. Hence, the doctoral candidate will repeat WP1 and WP2 experiments under pharmacological interference (i.e., with serotonin and dopamine receptor agonists and antagonists) to gain insight into the neuromodulatory pathways mediating alarm state-induced changes in olfactory perception and behavior.

In conclusion, this project combines behavioral assays, neuroimaging, and pharmacological manipulation to investigate how the alarm pheromone influences honey bee olfactory behavior and neurophysiology. Understanding how alarm signals modulate olfactory perception and the underlying neuromodulatory pathways in honey bees will enhance our knowledge of sensory coding and behavioral plasticity and improve our broader understanding of how external cues shape animal behavior and ecological dynamics.