Fixed Thoracic Lead Tags Are Associated with Distinct Landing-Approach Trajectories in Honey Bees (Apis mellifera)

Load carriage is common during honey bee foraging, but its effects on the final approach to the hive remain unclear. We recorded one three-dimensional landing trajectory from each of 80 returning Apis mellifera foragers carrying fixed lead tags of 0, 20, 40, or 60 mg attached externally to the dorsal thorax (n = 21, 22, 16, and 21, respectively) using three high-speed cameras. We calculated a discrete estimate of trajectory curvature, flight velocity, and vertical velocity. The 20, 40, and 60 mg loads represented approximately 25.69%, 51.37%, and 77.06% of the mean body mass of a separate reference sample (n = 60), respectively. Control and 20 mg honey bees generally flew more slowly along more curved paths than 40 and 60 mg honey bees. The 40 mg group had the highest average velocity and lowest average curvature. In the 60 mg group, velocity and curvature varied among recording zones. These results show that landing trajectories differed among load treatments. However, the experimental loads differed from natural nectar or pollen loads, and without measurements of wing kinematics or flight forces, the observed trajectory differences do not identify a specific flight-control mechanism.