Wind and obstacle motion affect honeybee flight strategies in cluttered environments

Abstract

Bees often forage in habitats with cluttered vegetation and unpredictable winds. Navigating obstacles in wind presents a challenge that may be exacerbated by wind-induced motions of vegetation. Although wind-blown vegetation is common in natural habitats, we know little about how the strategies of bees for flying through clutter are affected by obstacle motion and wind. We filmed honeybees Apis mellifera flying through obstacles in a flight tunnel with still air, headwinds or tailwinds. We tested how their ground speeds and centering behavior (trajectory relative to the midline between obstacles) changed when obstacles were moving versus stationary, and how their approach strategies affected flight outcome (successful transit versus collision). We found that obstacle motion affects ground speed: bees flew slower when approaching moving versus stationary obstacles in still air but tended to fly faster when approaching moving obstacles in headwinds or tailwinds. Bees in still air reduced their chances of colliding with obstacles (whether moving or stationary) by reducing ground speed, whereas flight outcomes in wind were not associated with ground speed, but rather with improvement in centering behavior during the approach. We hypothesize that in challenging flight situations (e.g. navigating moving obstacles in wind), bees may speed up to reduce the number of wing collisions that occur if they pass too close to an obstacle. Our results show that wind and obstacle motion can interact to affect flight strategies in unexpected ways, suggesting that wind-blown vegetation may have important effects on foraging behaviors and flight performance of bees in natural habitats.

Close encounters of three kinds: impacts of leg, wing, and body collisions on flight performance in carpenter bees

“…Wind direction was constant: bees flying in one direction experienced headwinds and in the other direction tailwinds. Up to 12 flights through the obstacles were elicited per bee, using full spectrum lights at each end of the tunnel [10,24]. Obstacle motion (stationary versus moving) was fixed for a given bee, but all bees experienced wind and still air, with wind condition switched after approximately six flights and the order of wind conditions alternated between bees.…”

“…In each case, animals navigate around a series of vegetative structures that functionally serve as obstacles and constrain navigable paths [5,6]. Traversing obstacles while in flight requires coordinated detection of obstacles (e.g., visually) and rapid alteration of the flight path, for example by decelerating, accelerating, or changing body orientation [7][8][9][10][11]. However, most studies of obstacle traversal in flight focus on behaviors required to completely avoid obstacles, with little consideration of what happens when animals do make contact with obstacles (e.g., collisions).…”

“…Tolerance for collisions may vary between taxa -for instance, birds of prey can suffer bone fractures that eventually heal, whereas wing damage in insects is permanent [1,15]. Because wing damage can increase mortality in insects, the avoidance and consequences of wing collisions has been emphasized in many insect flight studies [9,10,[16][17][18]. Furthermore, numerous insect species have wing morphologies that minimize damage by flexibly deforming during obstacle encounters, and these features have become the focus of studies aimed at extracting wing designs for bio-inspired flying vehicles [19][20][21].…”

Minding the gap: learning and visual scanning behaviour in nocturnal bull ants

“…Other experiments showed that the majority of domestic dogs tended to replicate their previous successful learning trips, but it was more challenging for the more experienced dog to adapt to a novel path again in their subsequent trips ( Pongrácz et al, 2001 , 2003 ). A few recent studies have analysed insects such as bumblebees and honeybees in minimally cluttered environments ( Baird and Dacke, 2016 ; Ong et al, 2017 ; Ravi et al, 2019 ; Burnett et al, 2020 ). These studies indicated that when individuals were confronted with obstacles with various spacing, insects chose the larger gap ( Ong et al, 2017 ; Ravi et al, 2019 ) and used a brightness-based strategy for choosing among the different gaps ( Baird and Dacke, 2016 ).…”

Avoiding attack: How dune wasps leverage colour and motion to detect their cryptic spider predators

“…Visual detection of a predator depends on the spectral sensitivity of the prey’s eye (the ability of the eye to respond to specific wavelengths of the light spectrum; Cronin et al, (2014)), spatial acuity (the capacity to discriminate shape and pattern details; Caves et al, (2018)) and temporal resolution (time taken to process visual information; Cronin et al, (2014)). Furthermore, abiotic factors such as wind or obstacles can add to the visual clutter in a habitat (Burnett et al, 2020; Hennessy et al, 2020) and consequently hinder predator detection.…”