Memory and chemical communication in the orientation of two mass-recruiting ant species

Abstract

SummaryThe relative contribution of visual and chemical components in the orientation of Lasius niger and Iridomyrmex humilis (Argentine ant) workers during mass recruitment to newly discovered food sources is analyzed over short time intervals. While both species orient in response to the trail pheromone, a large number of L. niger foragers rapidly switch to a more individual orientation, based on their memory of environmental cues. L humilis workers, on the other hand, predominantly use collective chemical cues. The effect of the number of reinforcements on visual learning and its interference with chemical communication show that olfactory cues always prevail in the Argentine ant. In L. niger, the proportion of ants orienting to visual cues is independent of the trail concentration. Detailed observations of the trail-laying behavior of individually marked foragers show that nearly all the L humilis workers initially lay a trail, whereas only half the L. nige~ foragers do so. This proportion decreases considerably with the number of trips performed by L. niger workers, while remaining constant for the Argentine ants. These results are interpreted with respect to the species' behavioral ecology.

Trail Pheromone Disruption of Argentine Ant Trail Formation and Foraging

“…Argentine ants can orientate using cues other than trail pheromones to find food resources. For instance, they are known to use food odors (Wolf and Wehner 2000;Stanley et al 2008), but not vision (Aron et al 1993), to orient toward food sources. As trail following from the edge of the disrupted boards to the central food was unsuccessful, it appears likely that multiple individual discoveries of the food source were made, rather than a single discovery (or few discoveries) complemented by recruitment through trail pheromone.…”

Scene perception and the visual control of travel direction in navigating wood ants

“…Many species of ants lay pheromone trails to mark foraging routes, and some of these species are also helped by remembered visual cues [27][28][29][30]. Once visual cues are acquired, they may dominate pheromone cues in experimental situations in which the two cues indicate different directions of travel [29,30]. Normally, the cues reinforce each other, so we can expect that the sensorimotor strategies for sampling and using visual and odour information are adapted to work together.…”

“…Ants are also interesting because of the multiple sensory cues that contribute to their navigation, particularly olfaction, with long range cues from wind-borne volatiles [23][24][25] and short-range cues from pheromone trails on the ground [26]. Many species of ants lay pheromone trails to mark foraging routes, and some of these species are also helped by remembered visual cues [27][28][29][30]. Once visual cues are acquired, they may dominate pheromone cues in experimental situations in which the two cues indicate different directions of travel [29,30].…”

Optimisation in a natural system: Argentine ants solve the Towers of Hanoi

“…Secondly, our and several previous studies have identified exploration pheromone, laid out in advance of starting the problem-solving exercise, as an important component in reaching good solutions. Finally, as in the addition of heuristic information to ACO schemes, our results suggest that Argentine ants might have more advanced navigational abilities than they are often credited with (Aron et al, 1993). Although in general the link between experiments on ants and ACO is still rather weak, these types of observations show that experiments can continue to provide new inspiration for novel optimisation algorithms and that algorithms can inspire our investigation of biology.…”