Visual tracking of moving targets by freely flying honeybees

AbstractThe ability of freely-flying honeybees to track moving targets was examined by training to collect a reward on a target, and then videotaping their approach to the target while it was in motion. Training experiments were carried out with several groups of bees, using various colors for the target and the background. Computer-aided frame-by-frame analysis of video recordings was used to plot the instantaneous positions of the target, as well as the position and orientation of the approaching bee in three dimensions. The results show that bees are perfectly capable of tracking moving targets and landing on them. When the distance of the target is greater than 15 cm, approaching bees correct for angular deviations of the target from the midline, both in the horizontal and in the vertical plane. In either plane, the input vaariables that are important to the tracking system seem to be (1) the angular bearing of the target with respect and (2) the angular velocity of the target with respect to the eye. The tracking control system tends to orient the bee such that the target is located frontally, at an angle of Ca. 35 deg below the bee's long axis. The chromatic properties of tracking behavior were investigated by employing combinations of colors for the target and background such that the boundary between the target and the background presented a contrast that was visible either only to the green-sensitive receptors of the bee's eye, or only to theblue-sensitive receptors. The results of these experiments suggest that, in controlling tracking, the measurement of the angular velocity of the target is derived almost exclusively from signals from the green-sensitive receptors, as is the case with previously studied movement-sensitive behavior. However, the measurement of the angular bearing of the target is derived from the blue-sensitive receptors as well as the green-sensitive noes. When the target is closer than Ca. 15 cm, approaching bees use translational maneuvers, in addition to rotational ones, to track the moving target. Translational target tracking appears to be driven primarily by signals from the green-sensitive receptors.