Desert Ants Learn to Avoid Pitfall Traps While Foraging

Abstract

Central-place foragers, such as social insects or nesting birds, repeatedly use the same routes from and to their nests when foraging for food. Such species forage more efficiently after accumulating experience. We examined, here, a relatively neglected aspect of such an improvement with experience—the avoidance of pitfall traps. Similar pits are built by antlions, which co-occur with the ants, but they also resemble other natural obstacles. We used the desert ant Cataglyphis niger, common in sandy habitats, and allowed it to forage for three successive runs for a food reward. Ant workers discovered food more slowly and in smaller numbers when pits were in their path. Pit presence also led to longer tracks by ants and slower movement. However, with experience, the ants fell into such pits less often and reached the food more quickly. To understand how past conditions affect current behavior, we investigated whether removing or adding pits led to a different result to that with a constant number of pits. Workers adjusted their behavior immediately when conditions changed. The only carryover effect was the longer tracks crossed by workers after pit removal, possibly resulting from the mismatch between the past and current conditions. Finally, the workers were more likely to fall into pits that were closer to the nest than those that were further away. This is a good example of the advantage that ambush predators can derive from ambushing their prey in specific locations.

Why are antlion larvae rare under the leaf litter? Testing the hypothesis of improper trap maintenance

“…First, antlions need to invest more energy to keep their pit functional, which has a negative impact on larval performance (Griffiths, 1986; Lucas, 1985). Moreover, the chance of prey falling into a pit is reduced, while the larvae are doing pit maintenance, because the activity of expelling sand can warn of the presence of a trap before the prey can fall into it (Bar et al, 2022; Gotelli, 1996; Hollis, 2017). Second, shallower pits probably capture fewer prey because prey can escape easier from small than from large traps (Farji‐Brener, 2003; Lomascolo & Farji‐Brener, 2001; Scharf et al, 2011).…”

Ecology of fear: predator avoidance reduces seed dispersal in an ant

“…This also suggests that the avoidance behaviour is not an innate response, as seen in naive tephritid fruit flies exposed to volatile cues of spiders and one ant species [ 36 ]. Evidence of ants learning to avoid predators comes from ant–antlions systems [ 37 , 38 ] and such trait of the ants could be adaptive for encountering novel predators in new environments and perhaps it contributes to the explanation of why this ant species is abundant in the neotropics [ 39 ]. Besides, rapid learning in E. ruidum occurs under multimodal stimuli during foraging [ 36 ] and it might occur also in the context of predation risk, which merits further work.…”

Egg-Laying Behavior of Cataglyphis niger Ants Is Influenced More Strongly by Temperature Than Daylength

“…They use a variety of tools to navigate in their habitat, such as path integration, distance estimation (“odometer”), and panoramic view of the environment, to name only a few [ 25 , 26 , 27 ]. They easily learn to solve mazes and avoid falling into pitfall traps, pointing to their developed spatial learning skills [ 24 , 28 , 29 , 30 ]. The number of larvae in the colony reaches its peak in July/August and decreases in autumn with the shortening day and temperature decrease [ 31 ].…”