Path integration in walking bumblebees

Abstract

Listen

Translate article

Many animals make direct paths back to their homes after tortuous foraging trips using a navigational strategy called path integration. During path integration, sensory information for direction and distance measurements are used to estimate the straightest path back to home. Decades of work with honeybees have established that they are excellent path integrators that rely primarily on celestial cues for orientation and optic flow for measuring speed/distance while in flight. While path integration has been well studied behaviorally, the neural basis of vector memory formation is unknown in any animal. A detailed 3D electron-microscopical map of the navigation center of the bumblebee’s brain, the central complex, and a comprehensive anatomically-grounded computational circuit model suited to carry out path integration from these data predicts concrete cellular substrates for all computations required for path integration in the central complex. However, the ability to test the hypotheses the model raises in bumblebees is lacking. Working towards this goal, we have developed circular navigation arenas with a hidden nest entrance and feeder to demonstrate that bumblebees (Bombus terrestris) use path integration over relatively short distances while walking. By manipulating artificial celestial cues in the arena, we demonstrate that bumblebees orient to overhead polarization patterns and artificial sunspots when navigating back to their nest while walking. Also, by displacing actively foraging bumblebees to an identical arena lacking a nest, we show that bumblebees accurately estimate the distances they must travel while walking home to find their nests. These result, when paired with neuroanatomical data of the bumblebee central complex and hypotheses generated by computational models, offer the potential to investigate the neural basis of path integration in bumblebees in the near future.