SEQUENCE LEARNING BY HONEYBEES

Bees of several genera make foraging trips on which they visit a serie s of plants in a fixed order. To help understand how honeybees might a cquire such routes, we examined whether (1) bees learn motor sequences , (2) they link motor instructions to visual stimuli, (3) their visual memories are triggered by contextual cues associated with the bees' p osition in a sequence. 1. Bees were trained to follow a complex route through a series of obstacles inside a large, 250 cm by 250 cm box. In tests, the obstacles were briefly removed and the bees continued to f ly the same zig-zag trajectory that they had when the obstacles were p resent. The bees' complex trajectory could reflect either the performa nce of a sequence of motor instructions or their attempt to reach fixe d points in their environment. When the point of entry to the box was shifted, the bees' trajectory with respect to the new point of entry w as relatively unchanged, suggesting that bees have learnt a motor sequ ence. 2. Bees were trained along an obstacle course in which different flight directions were associated with the presence of different larg e patches of colour. In tests, the order of coloured patches was rever sed, the trajectory followed by the bees was determined by the order o f colours rather than by the learnt motor sequence suggesting that bee s will readily link the performance of a particular trajectory to an a rbitrary visual stimulus. 3. Bees flew through a series of 3 similar c ompartments to reach a food reward. Passage from one compartment to th e next was only possible through the centre of one of a pair of patter ns, e.g. white + ve vs. black - ve in the first box, blue + ve vs. yel low - ve in the second, vertical + ve vs. horizontal - ve in the last. In some tests, bees were presented with a white vs. a vertical stimul us in the front compartment, while, in other tests, the same pair of s timuli was presented in the rear compartment. Bees preferred the white stimulus when tested in the first compartment, but chose the vertical stimulus in the last compartment. Bees reaching a compartment are thu s primed to recall the stimulus which, they normally encounter there. We argue that the elements which are linked together to form a route a re ''path-segments'', each of which takes a bee for a given distance i n a given direction.