Abstract:
The honey bee dance language, used to recruit nestmates to food sources, is regarded by many as one of the most intriguing communication systems in animals. What were the ecological circumstances that favoured its evolution? We examined this question by creating experimental phenotypes in which the location information of the dances was obscured. Surprisingly, in two temperate habitats, these colonies performed only insignificantly worse than colonies which were able to communicate normally. However, foraging efficiency was substantially impaired in an Asian tropical forest following this manipulation. This indicates that dance language communication about food source locations may be important in some habitats, but not in others. Combining published data and our own, we assessed the clustering of bee forage sites in a variety of habitats by evaluating the bees' dances. We found that the indicated sites are more clustered in tropical than in temperate habitats. This supports the hypothesis that in the context of foraging, the dance language is an adaptation to the particular habitats in which the honey bees evolved. We discuss our findings in relation to spatial aggregation patterns of floral food in temperate and tropical habitats.
Abstract:
Communication in the context of foraging in bumble bees has received less attention than in other social bees. Yet, recent studies have revealed that information flow mediates colony foraging activity. The species studied do not recruit to specific locations, but bees can learn the scent of food sources at the nest, which may reduce their search time. Location communication may not confer high benefits to bumble bees. But bees react to nectar influx with increased foraging activity, with high quality food eliciting more activity. This shows that bees recognize and sample freshly collected nectar. If the colony has no demand for food, foraging activity does not increase. Successful foragers distribute a tergal gland pheromone in the nest that also elicits higher foraging activity. Information exchange in the nest thus enables bumble bees to base their decision to forage on demand and the presence and profitability of food.
PMID: 14667376;PMCID: PMC1809947;Abstract:
We suggest how individual honeybees might measure the large volumes of potential nest sites and propose a key experimental test for our model.
PMID: 19324679;PMCID: PMC2827444;Abstract:
The problem of how to compromise between speed and accuracy in decision-making faces organisms at many levels of biological complexity. Striking parallels are evident between decision-making in primate brains and collective decision-making in social insect colonies: in both systems, separate populations accumulate evidence for alternative choices; when one population reaches a threshold, a decision is made for the corresponding alternative, and this threshold may be varied to compromise between the speed and the accuracy of decision-making. In primate decision-making, simple models of these processes have been shown, under certain parametrizations, to implement the statistically optimal procedure that minimizes decision time for any given error rate. In this paper, we adapt these same analysis techniques and apply them to new models of collective decision-making in social insect colonies. We show that social insect colonies may also be able to achieve statistically optimal collective decision-making in a very similar way to primate brains, via direct competition between evidence-accumulating populations. This optimality result makes testable predictions for how collective decision-making in social insects should be organized. Our approach also represents the first attempt to identify a common theoretical framework for the study of decision-making in diverse biological systems. © 2009 The Royal Society.
Abstract:
How social insect colonies behave results from the actions of their workers. Individual variation among workers in their response to various tasks is necessary for the division of labor within colonies. A worker may be active in only a subset of tasks (specialist), perform all tasks (elite), or exhibit no particular pattern of task activity (idiosyncratic). Here we examine how worker activity is distributed among and within tasks in ants of the genus Temnothorax. We found that workers exhibited elitism within a situation, i. e., in particular sets of tasks, such as those associated with emigrations, nest building, or foraging. However, there was weak specialization for working in a particular situation. A few workers exhibited elitism across all situations, i. e., high performance in all tasks in all situations. Within any particular task, the distribution of activity among workers was skewed, with few ants performing most of the work and most ants performing very little of the work. We further found that workers persisted in their task preference over days, with the same individuals performing most of the work day after day. Interestingly, colonies were robust to the removal of these highly active workers; they were replaced by other individuals that were previously less active. This replacement was not short-lived; when the removed individuals were returned to the colony, not all of them resumed their prior high activity levels, and not all the workers that replaced them reduced their activity. Thus, even though some workers specialize in tasks within a particular situation and are persistent in performing them, task allocation in a colony is plastic and colonies can withstand removal of highly active individuals. © 2012 Springer-Verlag.
