Vision does not impact walking performance in Argentine ants

Abstract

1 2 Many walking insects use vision for long-distance navigation, but the influence of vision 3 in detecting close-range obstacles and directing the limbs to maintain stability remains largely 4 untested. We compared Argentine ant workers in light versus darkness while traversing flat and 5 uneven terrain. In darkness, ants reduced flat-ground walking speeds by only 5%. Similarly, 6 neither the approach speed nor the time to cross a step obstacle was affected by lighting. To 7 determine if tactile sensing might compensate for vision loss, we tracked antennal motion and 8 observed shifts in spatiotemporal activity due to terrain structure but not illumination. Together, 9 these findings suggest that vision does not impact walking performance in Argentine ant 10 workers. Our results help contextualize eye variation across ants, including subterranean, 11 nocturnal, and eyeless species that walk in complete darkness. More broadly, our findings 12 highlight the importance of integrating vision, proprioception, and tactile sensing for robust 13 locomotion in unstructured environments. 14 15 16