Pfeffer Sarah E, Wittlinger Matthias
Institute of Neurobiology, University of Ulm, Ulm D-89069, Germany
Institute of Neurobiology, University of Ulm, Ulm D-89069, Germany.
J Exp Biol. 2016 Jul 15;219(Pt 14):2119-26. doi: 10.1242/jeb.137786. Epub 2016 Jul 20.
Cataglyphis ants are renowned for their impressive navigation skills, which have been studied in numerous experiments during forward locomotion. However, the ants' navigational performance during backward homing when dragging large food loads has not been investigated until now. During backward locomotion, the odometer has to deal with unsteady motion and irregularities in inter-leg coordination. The legs' sensory feedback during backward walking is not just a simple reversal of the forward stepping movements: compared with forward homing, ants are facing towards the opposite direction during backward dragging. Hence, the compass system has to cope with a flipped celestial view (in terms of the polarization pattern and the position of the sun) and an inverted retinotopic image of the visual panorama and landmark environment. The same is true for wind and olfactory cues. In this study we analyze for the first time backward-homing ants and evaluate their navigational performance in channel and open field experiments. Backward-homing Cataglyphis fortis desert ants show remarkable similarities in the performance of homing compared with forward-walking ants. Despite the numerous challenges emerging for the navigational system during backward walking, we show that ants perform quite well in our experiments. Direction and distance gauging was comparable to that of the forward-walking control groups. Interestingly, we found that backward-homing ants often put down the food item and performed foodless search loops around the left food item. These search loops were mainly centred around the drop-off position (and not around the nest position), and increased in length the closer the ants came to their fictive nest site.
箭蚁以其令人印象深刻的导航技能而闻名，在众多关于向前移动的实验中对其进行了研究。然而，直到现在，还没有研究过箭蚁在拖着大食物负载向后归巢时的导航表现。在向后移动过程中，里程计必须应对不稳定的运动和腿部间协调的不规则性。向后行走时腿部的感觉反馈不仅仅是向前迈步动作的简单反转：与向前归巢相比，蚂蚁在向后拖拽时面朝相反方向。因此，罗盘系统必须应对翻转的天空视野（就偏振模式和太阳位置而言）以及视觉全景和地标环境的视网膜拓扑图像的倒置。风线索和嗅觉线索也是如此。在本研究中，我们首次分析了向后归巢的蚂蚁，并在通道和开阔场地实验中评估了它们的导航表现。与向前行走的蚂蚁相比，向后归巢的福氏箭蚁在归巢表现上有显著相似之处。尽管向后行走时导航系统面临众多挑战，但我们表明蚂蚁在我们的实验中表现相当出色。方向和距离测量与向前行走的对照组相当。有趣的是，我们发现向后归巢的蚂蚁经常放下食物，在左侧食物周围进行无食物搜索循环。这些搜索循环主要围绕投放位置（而不是巢穴位置），并且蚂蚁离它们虚构的巢穴位置越近，循环长度就越长。
