BEE-MATURATION: Individual experience and plasticity

Honey bee workers undergo continuous maturation of their brain and learning abilities over their lifetime, in relationship with their capacity to take different roles in the colony as they age. Still, this neural and cognitive maturation does not follow a fully fixed developmental program. On the one hand, it can be modulated by social signals contributing to adapt individual behaviours to colony needs. On the other hand, they may be disturbed if the individual is exposed to a stressor. Our project aims at understanding how individual experience of different stimuli, and at different times during life, affect this maturation process, both at the behavioural and neural level. For this, we use olfactory learning tasks involving the resolution of ambiguities  as a major readout of cognitive maturation. We showed that the capacity to solve such tasks is acquired by bees through a maturation process involving early exposure to the hive environment, and foraging experience. Besides, this ability relies on the maturation of neural circuits in specific brain centers, the mushroom bodies, which are otherwise dispensable for non-ambiguous learning tasks such as absolute or differential learning.

• based on our previous finding on the fundamental role of GABAergic feedback circuits for solving olfactory ambiguities, we will explore the role of inhibitory transmission for solving ambiguous olfactory discriminations and study the plasticity inherent to this mechanism. How do inhibitory circuits develop and how does their maturation contribute to ambiguity resolution?
• alarm pheromone is a social signal emitted by conspecifics in response to potentially noxious stimuli, inducing task shifts to promote colony defence. In line with such shifts, it has detrimental effects on appetitive learning performance, an effect mimicked by allatostatins (brain neuropeptides). How does alarm pheromone modulate ambiguity resolution and/or mushroom body maturation, and which modulatory role do allatostatins play?
• because stress can hinder brain development and learning capacities, and because such capacities are important for efficient foraging, we will ask whether sublethal levels of certain stressors can impact on learning. Exposure to heavy metals or to an unbalanced diet due to impoverished floral resources, are effects of human activities: can such stressors impair learning and/or brain maturation to the extent of endangering foraging efficiency?

Collaborations: A.B. Barron (Macquarie University, Sydney), C. Groh & W. Rössler (Würzburg University)