The use of visual landmarks by honeybees: Bees weight landmarks according to their distance from the goal

1. Honeybees learn the location of a source of sucrose in relation to the positions of visual landmarks. It is shown here that bees pay most attention to those landmarks which are close to the sucrose and which will therefore guide a bee most accurately to its goal. 2. Individually marked bees were trained to collect sucrose from a reservoir whose location was specified by an array of landmarks, with individual landmarks placed at different distances from the reservoir. Once trained, the bees' flight path was recorded in tests with the sucrose removed. In these tests, the array of landmarks was transformed from the training configuration to provide two possible sites for the sucrose. One was defined by the landmarks close to the sucrose reservoir in training, the other by more distant landmarks. In all experiments (Figs.1, 2 and 3), bees spent more time flying in the site defined by the close landmarks. They did so even when the apparent sizes of the close and distant landmarks viewed from the reservoir were the same. We conclude that bees learn the distance of landmarks from the goal, and that, during their search for the goal, they weight nearer landmarks more heavily than distant ones. 3. Landmarks are also weighted according to their (apparent) size. Bees were trained to find sucrose at a reservoir placed equidistantly from different-sized landmarks. Tests were given with the training array stretched to provide two possible sites for the sucrose. One site was specified by the large, the other by the small landmarks. Bees spent more time flying in the site defined by the larger landmarks (Fig. 5). 4. We discuss, with the aid of computer simulation, different ways in which the distance between landmark and goal could influence a bee's searching behaviour.