Gap perception in bumblebees

Abstract

13 14 A number of insects fly over long distances below the natural canopy where the physical 15 environment is highly cluttered consisting of obstacles of varying shape, size and 16 texture. While navigating within such environments animals need to perceive and 17 disambiguate environmental features that might obstruct their flight. The most 18 elemental aspect of aerial navigation through such environments is gap identification 19 and passability evaluation. We used bumblebees to seek insights into the mechanisms 20 used for gap identification when confronted with an obstacle in their flight path and 21 behavioral compensations employed to assess gap properties. Initially, bumblebee 22 33 the gap, in our case, indicated by the optic flow contrast between the region within the 34 gap and on the obstacle, which increases with decreasing distance between the gap and 35 the background wall. As the optic flow contrast decreased the bees spent increasing 36 time moving laterally across the obstacles. During these repeated lateral maneuvers the 37 bees are likely assessing gap geometry and passability. 38 39 40 65 and path planning. For long distance navigation, flying insects might use, apart from 66 vision, other sensory modalities such as odor and geomagnetic fields (Knaden and 67 Graham, 2016) In order for a flying animal to arrive at its intended destination or ensure 68 safe locomotion, at a basic level, the animal needs to process the obstacles that lie in its 69 path and identify gaps. Obstacle and gap detection may thus be considered the most 70

Obstacle avoidance in bumblebees is robust to changes in light intensity

“…However, it is possible to compare the predicted time-to-contact values obtained here with those of previous studies-using a similar experimental setup-that recorded how B. terrestris respond to changes either in tunnel width (Baird et al 2010) or in the optic flow presented in the lateral visual field (Linander et al 2015). These calculations provide eight time-to-contact predictions that are remarkably similar (Table 1), with an average value of 0.33 ± 0.08 s. This value is also consistent with the time-to-contact prediction of 0.4 s, that could be made from the results of Ravi et al (2019), which found B. terrestris flying at ~ 50 cm s −1 changed their flight at a distance of ~ 20 cm from a gap placed in their flight path (values given are approximate due to the binning method used to make these calculations). Altogether, these results provide evidence that bumblebees may indeed be using a time-to-contact strategy for obstacle avoidance.…”

Bumblebees perceive the spatial layout of their environment in relation to their body size and form to minimize inflight collisions

“…S3, and Movies S2-S4) were similar to peering flights displayed by wasps, honey bees, and bumblebees while memorizing landmarks (15)(16)(17)(18)(19) or for depth estimation and spatial localization tasks (20)(21)(22)(23)(24)(25). Lateral peering is an active vision strategy in which insects vary the roll angle of their body to redirect a component of the aerodynamic force, creating steady, laterally oscillating flight trajectories (20,22,25,26). Bees scanning in the vicinity of the gap presented all of the characteristics of lateral peering, including maintaining the gap in their frontal visual field (SI Appendix, Fig.…”

Information Is Where You Find It: Perception as an Ecologically Well-Posed Problem

“…The horizon ratio is informative about gap size by virtue of the laws of optics and gravity. Other body-scaled information must be available in aerial niches, where goshawks, budgerigars, and bumblebees successfully navigate through narrow gaps (Ravi et al, 2019;Schiffner et al, 2014).…”