Navigational strategies underlying temporal phototaxis in Drosophila larvae

Abstract

Navigating across light gradients is essential for survival for many animals. However, we still have a poor understanding of the algorithms that underlie such behaviors. Here we develop a novel closed-loop phototaxis assay for Drosophila larvae in which light intensity is always spatially uniform but updates depending on the location of the animal in the arena. Even though larvae can only rely on temporal cues during runs, we find that they are capable of finding preferred areas of low light intensity. Further detailed analysis of their behavior reveals that larvae turn more frequently and that heading angle changes increase when they experience brightness increments over extended periods of time. We suggest that temporal integration of brightness change during runs is an important – and so far largely unexplored – element of phototaxis.

Algorithms underlying flexible phototaxis in larval zebrafish

“…Phototaxis occurs in many domains of life, from bacteria and unicellular eukaryotes (Berthold et al, 2008;Nultsch, 1973) to plants (Legris and Boccaccini, 2020;Thimann and Curry, 1960) and animals (Brockerhoff et al, 1995;Chen and Engert, 2014;Hadler, 1964;Kane et al, 2013;Zhu et al, 2021). While phototaxis benefits photosynthetic organisms by allowing them to find sources of energy (Jékely, 2009), the purpose of phototaxis in heterotrophic animals that do not derive energy from light is not as obvious.…”