Non-spatial information on the presence of food elevates search intensity in ant workers, leading to faster maze solving in a process parallel to spatial learning

Abstract

Experience can lead to faster exploitation of food patches through spatial learning or other parallel processes. Past studies have indicated that hungry animals either search more intensively for food or learn better how to detect it. However, fewer studies have examined the contribution of non-spatial information on the presence of food nearby to maze solving, as a parallel process to spatial learning. We exposed Cataglyphis niger ant workers to a food reward and then let them search for food in a maze. The information that food existed nearby, even without spatial information, led to faster maze solving compared to a control group that was not exposed to the food prior to the experiment. Faster solving is probably achieved by a higher number of workers entering the maze, following the information that food is present nearby. In a second experiment, we allowed the ants to make successive searches in the maze, followed by removing them after they had returned to the nest and interacted with their naïve nestmates. This procedure led to a maze-solving time in-between that displayed when removing the workers immediately after they had reached the food and preventing their return to the colony, and that of no removal. The workers that interacted upon returning to the nest might have transferred to naïve workers information, unrelated to spatial learning, that food existed nearby, and driven them to commence searching. Spatial learning, or an increase in the correct movements leading to the food reward relative to those leading to dead-ends, was only evident when the same workers were allowed to search again in the same maze. However, both non-spatial information on the presence of food that elevated search intensity and spatial learning led to faster maze solving. OPEN ACCESSCitation: Bega D, Samocha Y, Yitzhak N, Saar M, Subach A, Scharf I (2020) Non-spatial information on the presence of food elevates search intensity in ant workers, leading to faster maze solving in a process parallel to spatial learning. PLoS ONE 15 (2): e0229709. https://doi.org/10.We collected 59 colonies of Cataglyphis niger from the Tel-Baruch sand dunes in Tel Aviv, Israel (32.132N, 34.788E), a public land. These sand dunes are an enclave of a disturbed natural Non-spatial information and maze solving in ants PLOS ONE | https://doi.

Evidence for the effect of brief exposure to food, but not learning interference, on maze solving in desert ants

“…Other studies on the same ant species demonstrated supporting results. First, pre-exposure to food, even out of the maze context, resulted in faster solving times (in comparison to a nonexposed control; Bega et al 2020). Second, switching mazes at mid-experiment slowed food-discovery time, but never down to the level of a naïve colony at its first run (Saar et al 2020).…”

“…In short, more successful foraging can result from both spatial learning and higher search persistence (Bega et al . 2020).…”

“…In social insects, higher search persistence can be achieved also by allocating more workers to foraging when deemed necessary. In short, more successful foraging can result from both spatial learning and higher search persistence (Bega et al 2020).…”

Leg or antenna injury inCataglyphisants impairs survival but does not hinder searching for food

“…Indeed, shortening the legs in other studies led to space misperception and the underestimation of movement distances, at least temporarily ( Wittlinger et al 2007 ). However, previous studies on C. niger in mazes of a similar size and complexity revealed differences in food-discovery time and linked them to the type of food reward and previous exposure to food immediately before searching in the maze ( Bega et al 2020 ; Saar et al 2020 ). Second, it is possible that focusing on other foraging-related response variables could result in a stronger effect of injury, such as injured individuals carrying smaller loads or settling for food of lower quality than healthy ones, as demonstrated in bees ( Higginson and Barnard 2004 ; Johnson and Cartar 2014 ).…”

Desert Ants Learn to Avoid Pitfall Traps While Foraging

“…We expected the deteriorating conditions to make more workers fall into pits and to reach the food reward more slowly than the control because the workers were first trained that a straight path leads to the food reward, a path that is of no use after adding pits. The studied species had already demonstrated its ability to improve quickly in maze-solving owing to a mixture of spatial learning and elevated searching motivation [ 46 , 47 , 48 ].…”