Meeting Abstract
Insects exhibit impressive navigational abilities, from long distance migrations of monarch butterflies to path integration of desert ants in the genus Cataglyphis. Although not generally considered migratory, mark-recapture experiments indicate that Drosophila can cover 10 km of open desert in perhaps as little as a few hours without stopping to refuel. This impressive feat required flies to adopt a fairly straight path, likely accomplished by visually guided navigation using celestial cues. Using a flight simulator with machine-vision wing tracking, we found that tethered D. melanogaster can use the position of a simulated sun to fly straight, and individuals adopt arbitrary headings. A preferred heading is maintained over short intervals, but fidelity decays as the time between flights is increased. Furthermore, we found that by restricting visual stimuli to one-half of the arena during flight, we could bias subsequent headings towards the direction of the initial stimulus. Recent advances in our understanding of Drosophila central complex function during navigation reveal that wedge neurons of the ellipsoid body, a homologous structure to the lower division of the central body in other insects, are important for visually guided locomotion both in walking and flying flies. Using 2-photon functional imaging we found that the activity of these neurons tracks the position of a simulated sun, similar to results obtained from flies responding to other visual objects. Genetic silencing of wedge neurons using the inwardly rectifying potassium channel KiR2.1 appears to restrict the distribution of flies’ headings. Future experiments on these and other neuron types in the central complex are likely to reveal neural elements that are highly conserved in insect navigation.
