Abstract:
We conducted two experiments with Temnothorax albipennis ant colonies. In the first, we assessed their ability to select the best nest, in terms of entrance size, among an array of mediocre ones. Small and large ant colonies were equally adept at solving this best-of-N choice problem. However, large colonies were faster than small ones at finding the best nest probably because they could deploy more scouts. As a result, large colonies in nature probably find more of the available nests more quickly than small colonies. Thus larger colonies may have a greater tendency to split than small colonies. Large colonies, however, used larger quorum thresholds to make collective decisions than smaller colonies. Higher quorum thresholds should help to reduce splitting by large colonies. Large colonies also used more reverse tandem runs, a process for recruitment of more active participants into emigrations. More reverse tandem runs may help large colonies to reunite if they do split. In a second experiment, large and small colonies had almost identical preferences for nests with a floor area that would ideally accommodate a fully grown colony. Thus, small colonies behaved in a way that seemed to anticipate their future needs, when they would have grown to fill a larger space. © 2006 The Association for the Study of Animal Behaviour.
PMID: 17426016;PMCID: PMC2176157;Abstract:
We show that ants can reconnoitre their surroundings and in effect plan for the future. Temnothorax albipennis colonies use a sophisticated strategy to select a new nest when the need arises. Initially, we presented colonies with a new nest of lower quality than their current one that they could explore for one week without a need to emigrate. We then introduced a second identical low quality new nest and destroyed their old nest so that they had to emigrate. Colonies showed a highly significant preference for the (low quality) novel new nest over the identical but familiar one. In otherwise identical experiments, colonies showed no such discrimination when the choice was between a familiar and an unfamiliar high-quality nest. When, however, either all possible pheromone marks were removed, or landmarks were re-orientated, just before the emigration, the ants chose between identical low-quality new nests at random. These results demonstrate for the first time that ants are capable of assessing and retaining information about the quality of potential new nest sites, probably by using both pheromones and landmark cues, even though this information may only be of strategic value to the colony in the future. They seem capable, therefore, of latent learning and, more explicitly, learning what not to do. © 2007 The Royal Society.
PMID: 21847618;Abstract:
In some group-living organisms, labor is divided among individuals. This allocation to particular tasks is frequently stable and predicted by individual physiology. Social insects are excellent model organisms in which to investigate the interplay between physiology and individual behavior, as division of labor is an important feature within colonies, and individual physiology varies among the highly related individuals of the colony. Previous studies have investigated what factors are important in determining how likely an individual is, compared to nestmates, to perform certain tasks. One such task is foraging. Corpulence (i. e., percent lipid) has been shown to determine foraging propensity in honey bees and ants, with leaner individuals being more likely to be foragers. Is this a general trend across all social insects? Here we report data analyzing the individual physiology, specifically the percent lipid, of worker bumble bees (Bombus impatiens) from whom we also analyze behavioral task data. Bumble bees are also unusual among the social bees in that workers may vary widely in size. Surprisingly we find that, unlike other social insects, percent lipid is not associated with task propensity. Rather, body size closely predicts individual relative lipid stores, with smaller worker bees being allometrically fatter than larger worker bees. © 2011 Springer-Verlag.
