Non-numerical Distance and Size Effects in an Ant (original) (raw)
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Journal of Insect Physiology, 2007
Leaf-cutting ants of the genus Atta have highly size-polymorphic workers, and size is related to division of labor. We studied trailfollowing behavior of different-sized workers in a laboratory colony of Atta vollenweideri. For small and large workers, we measured responsiveness and preference to artificial conspecific and heterospecific pheromone trails made from poison gland extracts of A. vollenweideri and A. sexdens. Responsiveness was measured as the probability of trail-following, and preference was measured by testing the discrimination between one conspecific and one heterospecific trail. Minute amounts of the releaser component methyl-4methylpyrrole-2-carboxylate (0.4 pg/1 m), present in both, conspecific and heterospecific trails, suffice to elicit trail-following behavior. Workers followed heterospecific trails, and these trails (after normalizing their concentration) were as effective as conspecific trails. Small workers were less likely to follow a trail of a given concentration than large workers. In the discrimination test, small workers preferred the conspecific trail over the heterospecific trail, whereas large workers showed no significant preference. It is suggested that large workers primarily respond to the releaser component present in both trails, whereas small workers focus more on the conspecific traits provided by the blend of components contained in the trail pheromone. r
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Behavioral Ecology and Sociobiology, 2010
Visual cues are important navigational tools for many solitary foraging insects. In addition to information provided by path integration, desert ants learn and use visual cues for homing back to their nest. In this study, we compared the visually based learning of two desert ant species: the North African Cataglyphis fortis and the Australian Melophorus bagoti, each of which lives in ecologically similar but visually different environments. In our experiment, ants' choice performance was measured by training foragers in a channel system. We used a decision box with two visual stimuli during their homebound trips, with one of the stimuli always being the correct one that provided thoroughfare. To determine any habitat effects on learning, we examined intraspecific comparisons in C. fortis with different nest surroundings. The intraspecific comparison in C. fortis revealed no differences in learning the task. In general, C. fortis showed little learning in our task and the results were similar for ants from barren and cluttered environments. Overall, M. bagoti learned the task faster and had a higher level of accuracy than C. fortis. One explanation for this species-specific difference could be that the cluttered habitat of M. bagoti favours the evolution of visual associative learning more so than the plain habitat of C. fortis.
Influence of Shape, Color, Size and Relative Position of Elements on Their Counting by an Ant
International Journal of Biology, 2020
It was previously shown that workers of the ant Myrmica sabuleti can discriminate small numbers of elements during testing when these elements were identical to those learned during training. Here we examine if this numerosity ability still subsists if the shape, color, size or location of the elements (dots) to count are modified between training and testing. We found that the ants’ counting ability was not significantly affected by changing one of these features although a somewhat lesser ability was observed. Among the changes, it was that of the relative position of the elements which disrupted the most the ants’ counting ability, followed by a change of their size. A change in the color or the shape affected the least the ants’ counting. These impacts of feature changes in the learned cues on the ants’ counting can be explained by characteristics of the visual perception of the species as well as by its behavioral ecology.
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Certain navigating insects home in on their goal by moving so that currently viewed images of landmarks fall on the same retinal locations memorized during previous visits. Here we show that ants can use similar retinotopic learning to guide lengthy routes, by memorizing and walking parallel to a distinct visual edge. We induced workers of the ant Leptothorax albipennis to travel parallel to a prominent wall. When the wall's height was changed, the ants' paths consistently shifted toward a lowered wall and away from a raised wall, as would be expected if they attempt to keep the wall's image at a constant retinal position. These path shifts were smaller than would be expected if the wall was the only guide to navigation, suggesting that other cues are also important. Signi®cantly larger shifts were seen when edge guidance was enhanced by using two walls, one on each side of the path.
Ants Learn Geometry and Features
Current Biology, 2009
Rats trained to relocate a particular corner in a rectangular arena systematically confound the correct corner and the diametrically opposite one-this rotational error demonstrates the use of the geometry of space (i.e., the spatial arrangement of the different components of a visual scene). In many cases, geometric information is preferentially used over other spatial cues, suggesting the presence of a dedicated geometric module located in the parahippocampus [1] and processing only geometric information. Since rotational errors were first demonstrated in 1986 [2], the use of the geometry of space has attracted great interest and now seems to be widespread in vertebrate species, including humans . Until now, rotational errors have only been considered in vertebrate species. Here, for the first time, rotational errors are demonstrated in an insect. Our results, similar to those obtained with vertebrates, can be parsimoniously explained by a view-based matching strategy well known in insects, thereby challenging the hypothesis of a ''geometric module'' located in the animal's brain. While introducing a new concept of flexibility in the view-based matching theory, this study creates a link between two major topics of animal navigation: rotational errors in vertebrates and view-based navigation in insects.
Scene perception and the visual control of travel direction in navigating wood ants
Philosophical Transactions of the Royal Society B: Biological Sciences, 2014
This review reflects a few of Mike Land's many and varied contributions to visual science. In it, we show for wood ants, as Mike has done for a variety of animals, including readers of this piece, what can be learnt from a detailed analysis of an animal's visually guided eye, head or body movements. In the case of wood ants, close examination of their body movements, as they follow visually guided routes, is starting to reveal how they perceive and respond to their visual world and negotiate a path within it. We describe first some of the mechanisms that underlie the visual control of their paths, emphasizing that vision is not the ant's only sense. In the second part, we discuss how remembered local shape-dependent and global shape-independent features of a visual scene may interact in guiding the ant's path.
Ants are known to use the terrestrial visual panorama in navigation. Recent evidence has accumulated for the use of the currently perceived visual panorama to determine a direction to head in. The pattern of the height of the terrestrial surround, the skyline, is one key cue for the Central Australian red honey ant Melophorus bagoti in determining a direction of travel. But ants might also possess some mechanism to match the skyline heights encountered during training, which functions to steer away from regions whose skyline is too high and towards regions whose skyline is too low. We made an initial test of this hypothesis by training ants to visit a feeder centred between two experimentally constructed walls of black cloth. Trained ants were then tested for their initial homing direction with the walls retaining their heights as encountered in training (controls), with one of the walls lowered or raised in height, or with one wall lowered and the opposite wall raised. Wall-height manipulations deflected the initial headings of ants towards the lower wall, with combined wall lowering and wall raising changing the initial headings by~30°w hen compared with controls. The results suggest that the ants combined the dictates of the panorama in determining the best direction of travel (a heading towards the nest) with some attractor mechanism that functions to establish the skyline heights of training conditions (a heading towards the lower wall).