Bumblebee flight performance in environments of different proximity

Abstract

Flying animals are capable of navigating through environments of different complexity with high precision. To control their flight when negotiating narrow tunnels, bees and birds use the magnitude of apparent image motion (known as optic flow) generated by the walls. In their natural habitat, however, these animals would encounter both cluttered and open environments. Here, we investigate how large changes in the proximity of nearby surfaces affect optic flow-based flight control strategies. We trained bumblebees to fly along a flight and recorded how the distance between the walls--from 60 cm to 240 cm--affected their flight control. Our results reveal that, as tunnel width increases, both lateral position and ground speed become increasingly variable. We also find that optic flow information from the ground has an increasing influence on flight control, suggesting that bumblebees measure optic flow flexibly over a large lateral and ventral field of view, depending on where the highest magnitude of optic flow occurs. A consequence of this strategy is that, when flying in narrow spaces, bumblebees use optic flow information from the nearby obstacles to control flight, while in more open spaces they rely primarily on optic flow cues from the ground.

How bumblebees use lateral and ventral optic flow cues for position control in environments of different proximity

“…The walls of the flight tunnel were lined with a black-and-white pattern to enable a direct comparison with the previous studies that used the same arrangement (e.g., Linander et al 2015, 2016). To minimize lateral optic flow input, the walls displayed a uniform grey pattern.…”

“…The floor of the flight tunnel was white or lined with a red-and-white dead leaves pattern that facilitated the tracking of the bees in the recorded sequences while still maintaining a high pattern contrast. We lined the floor with white to enable comparison with earlier studies (e.g., Linander et al 2015, 2016). Figure 1 illustrates the different experimental conditions for one tunnel width.

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Spatial Vision and Visually Guided Behavior in Apidae

“…This was investigated in honeybees and bumblebees flying through experimental tunnels, in which patterns on the walls of provided optic cues (e.g., [68,89,90]. Bees estimate flight distance using only the green receptor contrast of the patterns, independent of chromatic contrast and brightness contrast [91], and because translational optic flow depends on distance, the estimate depends on the distance of bees to the contrasting patterns (e.g., [92]). Bees also use optic flow to control flight speed and flight height [93], and to avoid flying too close to obstacles, by balancing the optic flow on both sides (e.g., [64,89]).…”

The role of lateral optic flow cues in hawkmoth flight control

“…It is interesting to note that bumblebees, when flying in very wide tunnels lined with patterns inducing strong translational optic flow (120 and 240 cm width), also display a large variation in flight speed (Linander et al, 2016)even larger than that observed in hawkmoths. Thus, the regulation of flight speed by lateral optic flow cues might depend on the perceived relative proximity of the environmentand this might differ for different insect species.…”