What view information is most important in the homeward navigation of an Australian bull ant, Myrmecia midas?

Abstract

Many insects orient by comparing current panoramic views of their environment to memorised views. We tested the navigational abilities of night-active Myrmecia midas foragers while we blocked segments of their visual panorama. Foragers failed to orient homewards when the front view, lower elevations, entire terrestrial surround, or the full panorama was blocked. Initial scanning increased whenever the visual panorama was blocked but scanning only increased along the rest of the route when the front, back, higher, or lower elevations were blocked. Ants meandered more when the front, the back, or the higher elevations were obscured. When everything except the canopy was blocked, the ants were quick and direct, but moved in random directions, as if to escape. We conclude that a clear front view, or a clear lower panorama is necessary for initial homeward headings. Furthermore, the canopy is neither necessary nor sufficient for homeward initial heading, and the back and upper segments of views, while not necessary, do make finding home easier. Discrepancies between image analysis and ant behaviour when the upper and lower views were blocked suggests that ants are selective in what portions of the scene they attend to or learn.

Intricacies of running a route without success in night-active bull ants (Myrmecia midas).

“…When no useful views were available, rewound ants headed neither in the vector direction (something that they had done on the immediately preceding [ninth] rewinding trial) nor in the foraging-tree-to-nest direction (Islam et al, 2022). The mean direction was toward the brighter portion of the sky at test time, so that the response might reflect positive phototactic behavior (Wehner, 1997).…”

“…The ratio of the straight-line distance from the displacement site to the end of the path to the total recorded path length (obtained by using another R function, TrajStraigtness) defined the straightness measure. The range of path straightness was between 0 and 1, with larger values indicating straighter paths (Islam, Deeti, Mahmuda, et al, 2021; Islam et al, 2022). Scan rate (number of scans per meter of path traveled, defined by Wystrach et al, 2019) and initial heading directions of all ants in each trial were calculated.…”

Detouring while foraging up a tree: What bull ants (Myrmecia midas) learn and their reactions to novel sensory cues.

“…As discussed, the tested ants were affected adversely when a part of the surrounding visual scene was blocked. Changes of visual panorama may affect the navigation of ants, sometimes severely, although their performance recovers within a few days or over several trials (Freas et al, 2018;Freas & Cheng, 2019;Graham & Cheng, 2009;Islam et al, 2020Islam et al, , 2021Islam et al, 2022;Julle-Daniere et al, 2014;Narendra & Ramirez-Esquivel, 2017;Schwarz et al, 2014;Wystrach et al, 2011). When Myrmecia midas foragers encountered a symmetrical panoramic barrier on and off their familiar foraging route with a gap in the middle for the first time, their initial heading was not directed, they performed characteristic scans, and a large proportion of foragers were unsuccessful (Islam et al, 2021).…”

Directed retreat and navigational mechanisms in trail following Formica obscuripes

“…As highlighted by Cheng’s research (Cheng, 2022 ; Cheng et al, 2009 ; Freas & Cheng, 2022 ; Freas et al, 2019a , b , c ; Graham & Cheng, 2009 ; Islam et al, 2020 , 2021 , 2022 ; Schultheiss et al, 2016 ), research on ant species living in different ecologies has revealed a rich toolkit of navigational mechanisms that function together to produced impressive navigational behaviours. Here we show that Formica obscuripes attend to both the visual panorama and a path integrator for orientation, with the pheromone’s presence acting as a cross sensory, non-directional verification cue, confirming the correct path and continued orientation to these other strategies.…”