Experimental Zoology Group, Wageningen University & Research, 6708WD Wageningen, The Netherlands.
Department of Zoology, Stockholm University, 114 18 Stockholm, Sweden.
J Exp Biol. 2023 Sep 1;226(17). doi: 10.1242/jeb.245956.
Landing is a critical phase for flying animals, whereby many rely on visual cues to perform controlled touchdown. Foraging honeybees rely on regular landings on flowers to collect food crucial for colony survival and reproduction. Here, we explored how honeybees utilize optical expansion cues to regulate approach flight speed when landing on vertical surfaces. Three sensory-motor control models have been proposed for landings of natural flyers. Landing honeybees maintain a constant optical expansion rate set-point, resulting in a gradual decrease in approach velocity and gentile touchdown. Bumblebees exhibit a similar strategy, but they regularly switch to a new constant optical expansion rate set-point. In contrast, landing birds fly at a constant time to contact to achieve faster landings. Here, we re-examined the landing strategy of honeybees by fitting the three models to individual approach flights of honeybees landing on platforms with varying optical expansion cues. Surprisingly, the landing model identified in bumblebees proved to be the most suitable for these honeybees. This reveals that honeybees adjust their optical expansion rate in a stepwise manner. Bees flying at low optical expansion rates tend to increase their set-point stepwise, while those flying at high optical expansion rates tend to decrease it stepwise. This modular landing control system enables honeybees to land rapidly and reliably under a wide range of initial flight conditions and visual landing platform patterns. The remarkable similarity between the landing strategies of honeybees and bumblebees suggests that this may also be prevalent among other flying insects. Furthermore, these findings hold promising potential for bioinspired guidance systems in flying robots.
着陆是飞行动物的一个关键阶段，许多动物依赖视觉线索来进行受控着陆。觅食的蜜蜂依靠定期降落在花朵上收集对蜂群生存和繁殖至关重要的食物。在这里，我们探索了蜜蜂如何利用光学扩展线索来调节垂直表面着陆时的接近飞行速度。已经提出了三种用于自然飞行器着陆的感觉运动控制模型。着陆的蜜蜂保持恒定的光学扩展率设定点，导致接近速度逐渐降低，着陆轻柔。大黄蜂表现出类似的策略，但它们经常切换到新的恒定光学扩展率设定点。相比之下，着陆的鸟类以恒定的时间接触来实现更快的着陆。在这里，我们通过将三个模型拟合到在具有不同光学扩展线索的平台上着陆的单个蜜蜂接近飞行中，重新检查了蜜蜂的着陆策略。令人惊讶的是，在大黄蜂中确定的着陆模型被证明最适合这些蜜蜂。这表明蜜蜂以逐步的方式调整它们的光学扩展率。以低光学扩展率飞行的蜜蜂倾向于逐步增加其设定点，而以高光学扩展率飞行的蜜蜂倾向于逐步降低其设定点。这种模块化的着陆控制系统使蜜蜂能够在广泛的初始飞行条件和视觉着陆平台模式下快速可靠地着陆。蜜蜂和大黄蜂着陆策略之间的惊人相似性表明，这也可能在其他飞行昆虫中普遍存在。此外，这些发现为飞行机器人的仿生制导系统提供了有希望的潜力。
