Two spatial memories for honeybee navigation.

Insect navigation is thought to be based on an egocentric reference system which relates vector information derived from path integration to views of landmarks experienced en route and at the goal. Here we show that honeybees also possess an allocentric form of spatial memory which allows localization of multiple places relative to the intended goal, the hive. The egocentric route memory, which is called the specialized route memory (SRM) here, initially dominates navigation when an animal is first trained to a feeding site and then released at an unexpected site and this is why it is the only reference system detected so far in experiments with bees. However, the SRM can be replaced by an allocentric spatial memory called the general landscape memory (GLM). The GLM is directly accessible to the honeybee (and to the experimenter) if no SRM exists, for example, if bees were not trained along a route before testing. Under these conditions bees return to the hive from all directions around the hive at a speed comparable to that of an equally long flight along a trained route. The flexible use of the GLM indicates that bees may store relational information on places, connections between landmarks and the hive and/or views of landmarks from different directions and, thus, the GLM may have a graph structure, at least with respect to one goal, i.e. the hive.