Galizia, G. | bioRxiv Science

bioRxiv2024

Landmark knowledge overrides optic flow in honeybee waggle dance distance estimation

Honeybees encode in their waggle dances the vector (distance and direction) of an outbound flight to a food source or a new nest side. Optic flow has been identified as the major source of information in the distance estimation. Additional components of distance estimation were also identified, e.g. the sequence of experienced landmarks. Here we address the question of whether bees also use the landscape memory developed during exploratory orientation flights to estimate distance. We took advantage of the fact that flights in a narrow tunnel lead to further distance measures due to higher optic flow. We find that this effect is lost when bees had explored the area in which the tunnel is located and when they have somewhat restricted visual access to the surrounding environment through the mesh on top of the tunnel. These data are interpreted in the context of other findings about the structure of navigational memory in bees that develops during exploratory orientation flights. In particular, the data suggest that bees embed distance measures into a representation of navigational space that stores previously experienced landscape features. Summary statementThe distance code in the honeybee waggle dance is embedded in the landscape memory that bees establish during their exploratory and their foraging flights.

animal behavior and cognition↗

bioRxiv2019

Coding of odour and space in the hemimetabolous insect Periplaneta americana

The general architecture of the olfactory system is highly conserved from insects to humans, but neuroanatomical and physiological differences can be observed across species. The American cockroach, inhabiting dark shelters with a rather stable olfactory landscape, is equipped with long antennae used for sampling the surrounding air-space for orientation and navigation. The antennaes exceptional length provides a wide spatial working range for odour detection; however, it is still largely unknown whether and how this is also used for mapping the structure of the olfactory environment. By selective labelling antennal lobe projection neurons with a calcium sensitive dye, we investigated the logic of olfactory coding in this hemimetabolous insect. We show that odour responses are stimulus-specific and concentration-dependent, and that structurally related odorants evoke physiologically similar responses. By using spatially confined stimuli, we show that proximal stimulations induce stronger and faster responses than distal ones. Spatially confined stimuli of the female pheromone periplanone-B activate sub-region of the male macroglomerulus. Thus, we report that the combinatorial logic of odour coding deduced from holometabolous insects applies also to this hemimetabolous species. Furthermore, a fast decrease in sensitivity along the antenna, not supported by a proportionate decrease in sensillar density, suggests a neural architecture that strongly emphasizes neuronal inputs from the proximal portion of the antenna. Summary statementBy selective labelling the cockroachs antennal lobe output neurons, we investigated the logic of olfactory coding in a hemimetabolous insect, showing that odour responses are stimulus-specific, concentration-dependent, and preserve information on the spatial structure of the stimulus.

neuroscience↗