BIOLOGICAL COMPASSES AND THE COORDINATE FRAME OF LANDMARK MEMORIES IN HONEYBEES

MANY hymenopterans use visual landmarks to guide the last stages of their return to a familiar place, moving so that the pattern of landmarks imaged on their retina matches the pattern stored on previous visits to that place(1,2). What is the coordinate frame of these landmark memories, and how is it established? On the one hand, bees and flies learn complex visual shapes retinotopically(3,4), and landmark memories probably share this characteristic. On the other hand, bees record the position of landmarks in compass coordinates. Thus, Lindauer(5) showed that bees that had been trained to feed at the southernmost corner of a square table recognized the corner by its compass bearing from the table's centre. Taken together, these results suggest that these insects place retinotopically localized memories in Earth-based coordinates. We report here that honeybees accomplish this very simply: when learning about or searching for a goal, they face consistently in one compass direction, aided by the Earth's magnetic field. We suggest that the main benefit of inspecting the world from one favoured direction is to simplify the storage and retrieval of retinotopic memories.