-This review will focus on the relationships between sensory responses of bees and behavior. Sensory responsiveness constrains individual foraging plasticity and skews collective foraging decisions of colonies. We will concentrate on pollen, nectar, and water foraging behavior and will show that differences in the sucrose responsiveness of bees correlate with different behavioral roles, which supports the response threshold model of division of labor. We will also show how a colony's "allocation" of foragers into foraging roles results from individual differences in responsiveness to task-related stimuli and discuss hypotheses on the behavioral relevance of these differences.behavioral plasticity / sucrose responsiveness / foraging behavior / collective decision / response threshold model

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Using the proboscis extension response we conditioned pollen and nectar foragers of the honey bee (Apis mellifera L.) to tactile patterns under laboratory conditions. Pollen foragers demonstrated better acquisition, extinction, and reversal learning than nectar foragers. We tested whether the known differences in response thresholds to sucrose between pollen and nectar foragers could explain the observed differences in learning and found that nectar foragers with low response thresholds performed better during acquisition and extinction than ones with higher thresholds. Conditioning pollen and nectar foragers with similar response thresholds did not yield differences in their learning performance. These results suggest that differences in the learning performance of pollen and nectar foragers are a consequence of differences in their perception of sucrose. Furthermore, we analysed the effect which the perception of sucrose reward has on associative learning. Nectar foragers with uniform low response thresholds were conditioned using varying concentrations of sucrose. We found significant positive correlations between the concentrations of the sucrose rewards and the performance during acquisition and extinction. The results are summarised in a model which describes the relationships between learning performance, response threshold to sucrose, concentration of sucrose and the number of rewards.

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Aging is associated with cognitive impairment in numerous animal species. Across taxa, decline in learning performance is linked to chronological age. The honey bee (Apis mellifera), in contrast, offers an opportunity to study such aspects of aging largely independent of age per se. This is because foraging onset can be decoupled from chronological age, although workers typically first perform tasks inside the nest and later forage outside the hive. Further, early phases of foraging are characterized by growth of specific brain neuropiles, whereas late phases of the forager life-stage are accompanied by accelerated rates of physiological senescence. Yet, it is unclear if these patterns of senescence include cognitive function. The flexibility of worker ontogeny, however, suggests that the bee can become an attractive model for studies of plasticity in cognitive aging that ultimately may lead to insight into mechanisms that govern age-related cognitive decline. To address this potential, we studied effects of honey bee chronological age and of social role on sensory sensitivity and associative olfactory learning performance. Our results show a decline in olfactory acquisition performance that is linked to social role, but not to chronological age. This decline occurs only in foragers with long foraging duration, but at the same time the foragers show less generalization of odors, which is indicative of more precise learning. Foragers that are reversed from foraging to nest tasks, furthermore, do not show deficits in olfactory acquisition. These results point to complex effects of aging on associative learning in honey bees.

How does complex social behavior evolve? What are the developmental building blocks of division of labor and specialization, the hallmarks of insect societies? Studies have revealed the developmental origins in the evolution of division of labor and specialization in foraging worker honeybees, the hallmarks of complex insect societies. Selective breeding for a single social trait, the amount of surplus pollen stored in the nest (pollen hoarding) revealed a phenotypic architecture of correlated traits at multiple levels of biological organization in facultatively sterile female worker honeybees. Verification of this phenotypic architecture in "wild-type" bees provided strong support for a "pollen foraging syndrome" that involves increased senso-motor responses, motor activity, associative learning, reproductive status, and rates of behavioral development, as well as foraging behavior. This set of traits guided further research into reproductive regulatory systems that were co-opted by natural selection during the evolution of social behavior. Division of labor, characterized by changes in the tasks performed by bees, as they age, is controlled by hormones linked to ovary development. Foraging specialization on nectar and pollen results also from different reproductive states of bees where nectar foragers engage in prereproductive behavior, foraging for nectar for self-maintenance, while pollen foragers perform foraging tasks associated with reproduction and maternal care, collecting protein.

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In tactile learning, sucrose is the unconditioned stimulus and reward, which is usually applied to the antenna to elicit proboscis extension and which the bee can drink when it is subsequently applied to the extended proboscis. The conditioned stimulus is a tactile object that the bee can scan with its antennae. In this paper we describe the quantitative relationships between gustatory antennal stimulation, gustatory proboscis stimulation, and tactile learning and memory. Bees are 10-fold more responsive to sucrose solutions when they are applied to the antenna compared to proboscis stimulation. During tactile conditioning, the sucrose solution applied to the proboscis determines the level of acquisition, whereas antennal input is of minor importance. Bees differing in their gustatory responsiveness measured at the antenna differ strongly in their tactile acquisition and memory. We demonstrate how these differences in tactile acquisition and memory can be greatly reduced by calculating equal subjective rewards, based on individual gustatory responsiveness.Learning in animals depends on many factors including the salience of the conditioned stimulus (CS) and the strength of the unconditioned stimulus (US) (Rescorla and Wagner 1972). Even under controlled laboratory conditions, individuals show variance in the rate of acquisition, the asymptote of acquisition, and in retention (Scheiner et al. 2001a(Scheiner et al. ,b, 2003Matzel et al. 2003;Hedden and Gabrieli 2004;Dellu-Hagedorn 2005). Multiple intrinsic factors can contribute to these behavioral differences. Some of these factors may be related to individual differences in evaluating CS and US (Scheiner et al. 1999;Chester et al. 2003). These differences could reflect genetic heterogeneity at the individual level.Studies in honeybees (Apis mellifera L.) can be very useful to identify important factors leading to inter-individual learning differences and their potential sources of control. Associative learning plays an important part in honeybee behavior. Bees learn very fast the location of a foraging site and the numerous characteristics of reward-yielding plants (for review, see Menzel