OPTOKINETIC SPEED CONTROL AND ESTIMATION OF TRAVEL DISTANCE IN WALKING HONEYBEES

Honeybees returning from foraging trips were video-filmed while they w alked through a narrow transparent gangway to reach the hive entrance. On their way they were presented with black-and-white gratings viewed underneath as well as to both sides of the gangway. Bees could exit t he gangway through one of two or three side exits installed at differe nt distances from the gangway entrance. III one set of experiments, th e substrate on which the bees walked was moved either in the bee's dir ection or against it. In another set of experiments. the substrate was stationary. but the pattern was moved in one or the other direction. The bee's walking speed (WS) was evaluated from the video tapes. When the substrate moved against, or the pattern in the bees direction, in either case decreasing the speed of pattern flow (PFS). the bees incre ased WS. and. at the same time, they preferred the more distant exit. When the substrate moved in, or the pattern against the bee's directio n, thus increasing PFS, WS decreased and the bees preferred the nearer exit. These results suggest that the speed of optic flow controls the speed of locomotion and might therefore also serve for assessing the distance travelled.