Dominance and polyethism in the eusocial wasp Mischocyttarus mastigophorus (Hymenoptera: Vespidae)

Dominance interactions affected patterns of non-reproductive division of labor (polyethism) in the eusocial wasp Mischocyttarus mastigophorus. Socially dominant individuals foraged for food (nectar and insect prey) at lower rates than subordinate individuals. In contrast, dominant wasps performed most of the foraging for the wood pulp used in nest construction. Social dominance also affected partitioning of materials collected by foragers when they returned to the nest. Wood pulp loads were never shared with nest mates, while food loads, especially insect prey, were often partitioned with other wasps. Dominant individuals on the nest were more likely to take food from arriving foragers than subordinate individuals. The role of dominance interactions in regulating polyethism has evolved in the eusocial paper wasps (Polistinae). Both specialization by foragers and task partitioning have increased from basal genera (independent-founding wasps, including Mischo-cyttarus spp.) to more derived genera (swarm-founding Epiponini). Dominance interactions do not regulate forager specialization or task partitioning in epiponines. I hypothesize that these changes in polyethism were enabled by the evolution of increased colony size in the Epiponini. Received: 8 December 1997 / Accepted after revision: 28 March 1998     

Forager specialization and the control of nest repair in Polybia occidentalis Olivier (Hymenoptera : Vespidae)

We measured patterns of individual forager specialization and colony-wide rates of material input during periods of response to experimental nest damage and during control periods in three colonies of the tropical social wasp Polybia occidentalis.

Exploitation of carbohydrate food sources in <Emphasis Type="Italic">Polybia occidentalis</Emphasis>: social cues influence foraging decisions in swarm-founding wasps

An efficient exploitation of carbohydrate food sources would be beneficial for social wasp species that store nectar within their nest. In the swarm-founding polistine wasp Polybia occidentalis, we now demonstrate that the decisions of when and where to forage are influenced by information from conspecifics. Only when foragers had been trained to collect at artificial carbohydrate feeders did newcomers (food-source-naive individuals) continuously arrive at these feeders during 2 h of experiment. In control tests, in which no forager had been trained, not a single newcomer alighted at any of the offered carbohydrate food sources. This indicates that, during the foraging process, a nest-based input provided by successful foragers must have stimulated nestmates to search for food. Once activated, the newcomers’ choice on where to collect was strongly influenced by field-based social information. The mere visual presence of accumulated conspecifics (wasp dummies placed on one of the feeders) attracted newcomers to the food sources. Interestingly, however, visual enhancement was not the only decision-biasing factor at the feeding site. In an experimental series where searching wasps had to choose between the experimental feeder at which 3 foragers continuously collected and the control feeder with nine wasp dummies, only 40% of the wasps chose the visually enhanced feeder. This points to the existence of additional mechanisms of local enhancement. The possibility that, in social wasps, recruitment is involved in the exploitation of carbohydrate food sources is discussed.     

Recruitment to food by the German yellowjacket, Vespula germanica

The hypothesis that Vespula germanica foragers can recruit nestmates to food resources was tested using a protocol that controlled for the biasing effects of social factors at the resource, including local enhancement and food-site marking substances. Foragers from an observation colony in the field were trained to visit a dish of scented corn syrup solution 15?m east of the nest. A second feeding station, 22?m northeast of the nest, offered incoming foragers a choice between food with the training scent and food with a control scent. Significantly more naive foragers arriving at that station chose the food with the training scent. We conclude that the German yellowjacket is able to recruit nestmates to carbohydrate food sources, and that recruits use food odor to locate the source of food being brought into the nest.     

Effects of colony food shortage on behavioral development in honey bees

Three experiments were conducted to explore the effects of severe food shortage on the control of two important and interrelated aspects of temporal division of labor in colonies of the honey bee (Apis mellifera): the size and age distribution of a colony's foraging force. The experiments were conducted with single-cohort colonies, composed entirely of young bees, allowing us to quickly distinguish the development of new (precocious) foragers from increases in activity of bees already competent to forage. In experiment 1, colony food shortage caused an acceleration of behavioral development; a significantly greater proportion of bees from starved colonies than from fed colonies became precocious foragers, and at significantly younger ages. Temporal aspects of this starvation effect were further explored in experiment 2 by feeding colonies that we initially starved, and starving colonies that we initially fed. There was a significant decrease in the number of new foragers in starved colonies that were fed, detected 1 day after feeding. There also was a significant increase in the number of new foragers in fed colonies that were starved, but only after a 2-day lag. These results suggest that colony nutritional status does affect long-term behavioral development, rather than only modulate the activity of bees already competent to forage. In experiment 3, we uncoupled the nutritional status of a colony from that of the individual colony members. The behavior of fed individuals in starved colonies was indistinguishable from that of bees in fed colonies, but significantly different from that of bees in starved colonies, in terms of both the number and age distribution of foragers. These results demonstrate that effects of starvation on temporal polyethism are not mediated by the most obvious possible worker-nest interaction: a direct interaction with colony food stores. This is consistent with previous findings suggesting the importance of worker-worker interactions in the regulation of temporal polyethism in honey bees as well as other social insects. Received: 17 April 1997 / Accepted after revision: 26 December 1997     

Manuscript in preparation for <Emphasis Type="Italic">Behavioral Ecology and Sociobiology</Emphasis> Bumble bee pollen foraging regulation: role of pollen quality,storage levels,and odor

The regulation of protein collection through pollen foraging plays an important role in pollination and in the life of bee colonies that adjust their foraging to natural variation in pollen protein quality and temporal availability. Bumble bees occupy a wide range of habitats from the Nearctic to the Tropics in which they play an important role as pollinators. However, little is known about how a bumble bee colony regulates pollen collection. We manipulated protein quality and colony pollen stores in lab-reared colonies of the native North American bumble bee, Bombus impatiens. We debut evidence that bumble bee colony foraging levels and pollen storage behavior are tuned to the protein quality (range tested: 17–30% protein by dry mass) of pollen collected by foragers and to the amount of stored pollen inside the colony. Pollen foraging levels (number of bees exiting the nest) significantly increased by 55%, and the frequency with which foragers stored pollen in pots significantly increased by 233% for pollen with higher compared to lower protein quality. The number of foragers exiting the nest significantly decreased (by 28%) when we added one pollen load equivalent each 5 min to already high intranidal pollen stores. In addition, pollen odor pumped into the nest is sufficient to increase the number of exiting foragers by 27%. Foragers directly inspected pollen pots at a constant rate over 24 h, presumably to assess pollen levels. Thus, pollen stores can act as an information center regulating colony-level foraging according to pollen protein quality and colony need. An erratum to this article can be found at     

Exploration and exploitation of food sources by social insect colonies: a revision of the scout-recruit concept

Social insect colonies need to explore and exploit multiple food sources simultaneously and efficiently. At the individual level, this colony-level behaviour has been thought to be taken care of by two types of individual: scouts that independently search for food, and recruits that are directed by nest mates to a food source. However, recent analyses show that this strict division of labour between scouts and recruits is untenable. Therefore, a modified concept is presented here that comprises the possible behavioural states of an individual forager (novice forager, scout, recruit, employed forager, unemployed experienced forager, inspector and reactivated forager) and the transitions between them. The available empirical data are reviewed in the light of both the old and the new concept, and probabilities for the different transitions are derived for the case of the honey-bee. The modified concept distinguishes three types of foragers that may be involved in the exploration behaviour of the colony: novice bees that become scouts, unemployed experienced bees that scout, and lost recruits, i.e. bees that discover a food source other than the one to which they were directed to by their nest mates. An advantage of the modified concept is that it allows for a better comparison of studies investigating the different roles performed by social insect foragers during their individual foraging histories. Received: 29 December 1999 / Revised: 25 February 2000 / Accepted: 16 October 2000     

Foraging and spatiotemporal territories in the honey ant Myrmecocystus mimicus wheeler (Hymenoptera: Formicidae)

Summary The honey ant Myrmecocystus mimicus is a scavenger, forages extensively on termites, collects floral nectar, and tends homoptera. Individual foragers of M. mimicus usually disperse in all directions when leaving the nest, but there are also groups of foragers that tend to swarm out of the nest primarily in one direction. Such massive departues are usually at irregular intervals, which may last several hours. The results of field and laboratory experiments suggest that these swarms of foragers are organized by a group recruitment process, during which recruiting scout ants lay chemical orientation trails with hindgut contents and simultaneously stimulate nestmates with a motor display and secretions from the poison gland. Usually these columns travel considerable distances (4–48 m) away from the nest, frequently interfering with the foraging activity of conspecific neighboring colonies.To prevent a neighboring colony from access to temporal food sources or to defend spatiotemporal borders, opposing colonies engage in elaborate display tournaments. Although hundreds of ants are often involved during these tournaments almost no physical fights occur. Instead, individual ants confront each other in highly sterotyped aggressive displays, during which they walk on stilt legs while raising the gaster and head. Some of the ants even seem to inflate their gasters so that the tergites are raised and the whole gaster appears to be larger. In addition, ants involved in tournament activities are on average larger than foragers.The dynamics of the tournament interactions were observed in several colonies over several weeks-mapping each day the locations of the tournaments, the major directions of worker routes away from the nest, and recording the general foraging activities of the colonies. The results indicate that a kind of dominance order can occur among neighboring colonies. On the other hand, often no aggressive interactions among neighboring colonies can be observed, even though the colonies are actively foraging. In those cases the masses of foragers of each colony depart in one major direction that does not bring them into conflict with the masses of foragers of a neighboring colony. This stability, however, can be disturbed by offering a new rich food source to be exploited by two neighboring colonies. This invariably leads to tournament interactions.When a colony is considerably stronger than the other, i.e., with a much larger worker force, the tournaments end quickly and the weaker colony is raided. The foreign workers invade the nest, the queen of the resident colony is killed or dirven off, while the larvae, pupae, callow workers, and honey pot workers are carried or dragged to the nest of the raiders. From these and other observations we conclude that young M. mimicus queens are unlikely to succeed in founding a colony within approximately 3 m of a mature M. mimicus colony because they are discovered and killed, or driven off by workers of the resident colony. Within approximately 3–15 m queens are more likely to start colonies, but these incipient groups run a high risk of being raided and exterminated by the mature colony.Although populations of M. mimicus and M. depilis tend to replace each other, there are areas where both species overlap marginally. Foraging areas and foraging habitats of both species also overlap broadly, but we never observed tournament interactions between M. mimicus and M. depilis.The adaptive significance of the spatiotemporal territories in M. mimicus is discussed.     

The regulation of pollen foraging by honey bees: how foragers assess the colony's need for pollen

Summary The honey bee colony presents a challenging paradox. Like an organism, it functions as a coherent unit, carefully regulating its internal milieu. But the colony consists of thousands of loosely assembled individuals each functioning rather autonomously. How, then, does the colony acquire the necessary information to organize its work force? And how do individuals acquire information about specific colony needs, and thus know what tasks need be performed? I address these questions through experiments that analyze how honey bees acquire information about the colony's need for pollen and how they regulate its collection. The results demonstrate features of the colony's system for regulating pollen foraging: (1) Pollen foragers quickly acquire new information about the colony's need for pollen. (2) When colony pollen stores are supplemented, many pollen foragers respond by switching to nectar foraging or by remaining in the hive and ceasing to forage at all. (3) Pollen foragers do not need direct contact with pollen to sense the colony's change of state, nor do they use the odor of pollen as a cue to assess the colony's need for pollen. (4) Pollen foragers appear to obtain their information about colony pollen need indirectly from other bees in the hive. (5) The information takes the form of an inhibitory cue. The proposed mechanism for the regulation of pollen foraging involves a hierarchical system of information acquisition and a negative feedback loop. By taking advantage of the vast processing capacity of large numbers of individuals working in parallel, such a system of information acquisition and dissemination may be ideally suited to promote efficient regulation of labor within the colony. Although each individual relies on only limited, local information, the colony as a whole achieves a finely-tuned response to the changing conditions it experiences.     

Tactile learning in resin foraging honeybees

Honeybees harvest and use plant resins in a mixture called propolis to seal cracks and smooth surfaces in the nest architecture. Resins in the nest may be important in maintaining a healthy colony due to their antimicrobial properties. This study had two main objectives: (1) Provide initial insight on the learning capabilities of resin foraging honeybees; (2) analyze the sensitivity of resin foraging honeybees to tactile stimuli to elucidate its possible role as a mechanism behind resin foraging. The first objective provides insight into the phenotype of these bees as compared to other forager types, while the second creates a starting point for further work on behavioral mechanisms of resin foraging. Using tactile proboscis extension response conditioning, we found that resin foragers learned to associate two different tactile stimuli, the presence of a gap between two plates and a rough sandpaper surface, with a sucrose reward significantly better than pollen foragers. The results of differential tactile conditioning exhibited no significant difference in the ability of resin foragers to discriminate between smooth and rough surfaces as compared to pollen foragers. We also determined that the sucrose response thresholds (SRTs) of returning resin foragers were lower compared to returning pollen foragers, but both resin foragers and pollen foragers learned a floral odor equally well. This is the first study to examine SRTs and conditioning to tactile and olfactory stimuli with resin foraging honeybees. The results provide new information and identify areas for future research on resin collectors, an understudied foraging phenotype.     

Flexible seed selection by individual harvester ants, Pogonomyrmex occidentalis

Summary Individual seed harvester ants (Pogonomyrmex) have been shown to specialize on specific seed types. We examined possible mechanisms for seed specialization and tested whether fidelity to food type limits the foraging decisions of individual western harvester ants, Pogonomyrmex occidentalis. The seed selection regimes of individually marked ants foraging at piles of two seed types were described and related to differences in seed quality and colonial dietary history. Individual foraging choices were affected by multiple factors, including seed caloric rewards, the previous seed selected, and the dietary history of the colony. Individual seed choices generally converged on the most energetically profitable species, suggesting that foragers exhibit labile preference. However, for a portion of the foragers, seed specialization was also partially due to constancy, defined as a tendency to select seed species that were previously collected. When colonies were presented with one seed type for 1 h and then were offered a mix of that seed and a novel seed type, individuals showed a strong preference for the novel seeds. Such rapid changes in seed preference argue strongly that individual P. occidentalis ants are highly flexible in seed choice and that resource assessment by these ants is more complex than simple maximization of net energetic return.Offprint requests to: J.H. Fewell at the current address     

Division of foraging labor in ants can mediate demands for food and safety

Solitary foragers can balance demands for food and safety by varying their relative use of foraging patches and their level of vigilance. Here, we investigate whether colonies of the ant, Formica perpilosa, can balance these demands by dividing labor among workers. We show that foragers collecting nectar in vegetation near their nest are smaller than are those collecting nectar at sites away from the nest. We then use performance tests to show that smaller workers are more likely to succumb to attack from conspecifics but feed on nectar more efficiently than larger workers, suggesting a size-related trade-off between risk susceptibility and harvesting ability. Because foragers that travel away from the nest are probably more likely to encounter ants from neighboring colonies, this trade-off could explain the benefits of dividing foraging labor among workers. In a laboratory experiment, we show that contact with aggressive workers results in an increase in the mean size of recruits to a foraging site: this increase was not the result of more large recruits, but rather because fewer smaller ants traveled to the site. These results suggest that workers particularly susceptible to risk avoid dangerous sites, and suggest that variation in worker size can allow colonies to exploit profitably both hazardous and resource-poor patches.Communicated by L. Sundström     

Potential mechanisms for the communication of height and distance by a stingless bee, Melipona panamica

This study investigates the recruitment communication mechanisms of a stingless bee, Melipona panamica, whose foragers can evidently communicate the three-dimensional location of a good food source. To determine if the bees communicate location information inside or outside the nest, we conducted removal experiments by training marked foragers to one of two identical feeders and then separating these experienced foragers from potential recruits as they left the nest. The feeders were positioned to test the communication of each dimension. The results show that recruits do not simply follow experienced foragers to the food source. Height and distance are communicated within the nest, while direction is communicated outside the nest. We then examined the pulsed sounds produced by recruiting foragers. While unloading food, recruiting foragers produced several short pulses and one or more very long pulses. On average, the longest unloading pulse per performance was 31–50% longer (P ≤ 0.018) for bees foraging on the forest floor than for bees foraging at the top of the forest canopy (40 m high). While dancing, recruiting foragers produced sound pulses whose duration was positively correlated with the distance to the food source (P < 0.001). Dancing recruiters also produced several short sound pulses followed by one or more long pulses. The longest dance pulse per performance was 291 ± 194 ms for a feeder 25 m from the nest and 1858 ± 923 ms for a feeder 360 m away from the nest. The mechanism of directional communication remains a mystery. However, the direction removal experiment demonstrates that newcomers cannot use forager-deposited scent marks for long-distance orientation (>100 m from the nest). Received: 25 September 1997 / Accepted after revision: 31 May 1998     

Colony nutritional status modulates worker responses to foraging recruitment pheromone in the bumblebee Bombus terrestris

Foraging activity in social insects should be regulated by colony nutritional status and food availability, such that both the emission of, and response to, recruitment signals depend on current conditions. Using fully automatic radio-frequency identification (RFID) technology to follow the foraging activity of tagged bumblebees (Bombus terrestris) during 16,000 foraging bouts, we tested whether the cue provided by stored food (the number of full honeypots) could modulate the response of workers to the recruitment pheromone signal. Artificial foraging pheromones were applied to colonies with varied levels of food reserves. The response to recruitment pheromones was stronger in colonies with low food, resulting in more workers becoming active and more foraging bouts being performed. In addition to previous reports showing that in colonies with low food successful foragers perform more excited runs during which they release recruitment pheromone and inactive workers are more prone to leave the nest following nectar influx, our results indicate that evolution has shaped a third pathway that modulates bumblebee foraging activity, thus preventing needless energy expenditure and exposure to risk when food stores are already high. This new feedback loop is intriguing since it involves context-dependent response to a signal. It highlights the integration of information from both forager-released pheromones (signal) and nutritional status (cue) that occurs within individual workers before making the decision to start foraging. Our results support the emerging view that responses to pheromones may be less hardwired than commonly acknowledged. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The use of waggle dance information by honey bees throughout their foraging careers

We studied the extent to which worker honey bees acquire information from waggle dances throughout their careers as foragers. Small groups of foragers were monitored from time of orientation flights to time of death and all in-hive behaviors relating to foraging were recorded. In the context of a novice forager finding her first food source, 60% of the bees relied, at least in part, on acquiring information from waggle dances (being recruited) rather than searching independently (scouting). In the context of an experienced forager whose foraging has been interrupted, 37% of the time the bees resumed foraging by following waggle dances (being reactivated) rather than examining the food source on their own (inspecting). And in the context of an experienced forager engaged in foraging, 17% of the time the bees initiated a foraging trip by following a waggle dance. Such dance following was observed much more often after an unsuccessful than after a successful foraging trip. Successful foragers often followed dances just briefly, perhaps to confirm that the kind of flowers they had been visiting were still yielding forage. Overall, waggle dance following for food discovery accounted for 12–25% of all interactions with dancers (9% by novice foragers and 3–16% by experienced foragers) whereas dance following for reactivation and confirmation accounted for the other 75–88% (26% for reactivation and 49–62% for confirmation). We conclude that foragers make extensive use of the waggle dance not only to start work at new, unfamiliar food sources but also to resume work at old, familiar food sources.     

Demography, demand, death, and the seasonal allocation of labor in the Florida harvester ant (Pogonomyrmex badius)

As a self-organizing entity, an ant colony must divide a limited number of workers among numerous competing functions. Adaptive patterns of labor allocation should vary with colony need across each annual cycle, but remain almost entirely undescribed in ants. Allocation to foraging in 55 field colonies of the Florida harvester ant (Pogonomyrmex badius) followed a consistent annual pattern over 4 years. Foragers preceded larvae in spring and peaked during maximal larval production in summer (0.37). In spring, proportion foraging increased due to an increase in forager number and reduction in colony size, and in late summer, it decreased as colony size increased through new worker birth and a loss of ～3 % of foragers per day. The removal of 50 % of the forager population revealed that, at the expense of larval survival, colonies did not draw workers from other castes to fill labor gaps. To determine if labor allocation was age specific, whole colonies were marked with cuticle color-specific wire belts and released, and each cohort's time to first foraging was noted. Workers that eclosed in summer alongside sexual alates darkened quickly and became foragers at ～43 days of age, whereas autumn-born workers required 200 or more days to do so. Following colony reproduction, these long-lived individuals foraged alongside short-lived, summer-born sisters during the next calendar year. Therefore, the large-scale, predictable patterns of labor allocation in P. badius appear to be driven by bimodal worker development rate and age structure, rather than worker responsiveness to changes in colony demand.     

The role of internal and external information in foraging decisions of Melipona workers (Hymenoptera: Meliponinae)

Social insect foragers have to make foraging decisions based on information that may come from two different sources: information learned and memorised through their own experience (“internal” information) and information communicated by nest mates or directly obtained from their environment (“external” information). The role of these sources of information in decision-making by foragers was studied observationally and experimentally in stingless bees of the genus Melipona. Once a Melipona forager had started its food-collecting career, its decisions to initiate, continue or stop its daily collecting activity were mainly based upon previous experience (activity on previous days, the time at which foraging was initiated the day(s) before, and, during the day, the success of the last foraging flights) and mediated through direct interaction with the food source (load size harvested and time to collect a load). External information provided by returning foragers advanced the start of foraging of experienced bees. Most inexperienced bees initiated their foraging day after successful foragers had returned to the hive. The start of foraging by other inexperienced bees was stimulated by high waste-removal activity of nest mates. By experimentally controlling the entries of foragers (hence external information input) it was shown that very low levels of external information input had large effect on the departure of experienced foragers. After the return of a single successful forager, or five foragers together, the rate of forager exits increased dramatically for 15 min. Only the first and second entry events had large effect; later entries influenced forager exit patterns only slightly. The results show that Melipona foragers make decisions based upon their own experience and that communication stimulates these foragers if it concerns the previously visited source. We discuss the organisation of individual foraging in Melipona and Apis mellifera and are led to the conclusion that these species behave very similarly and that an information-integration model (derived from Fig. 1) could be a starting point for future research on social insect foraging. Received: 16 April 1997 / Accepted after revision: 30 August 1997     

Social foraging by honeybees: how colonies allocate foragers among patches of flowers

Summary To understand how a colony of honeybees keeps its forager force focussed on rich sources of food, and analysis was made of how the individual foragers within a colony decide to abandon or continue working (and perhaps even recruit to) patches of flowers. A nectar forager grades her behavior toward a patch in response to both the nectar intake rate of her colony and the quality of her patch. This results in the threshold in patch quality for acceptance of a patch being higher when the colonial intake rate of nectar is high than when it is low. Thus colonies can adjust their patch selectivity so that they focus on rich sources when forage is abundant, but spread their workers among a wider range of sources when forage is scarce. Foragers assess their colony's rate of nectar intake while in the nest, unloading nectar to receiver bees. The ease of unloading varies inversely with the colonial intake rate of nectar. Foragers assess patch quality while in the field, collecting nectar. By grading their behavior steeply in relation to such patch variables as distance from the nest and nectar sweetness, foragers give their colony high sensitivity to differences in profitability among patches. When a patch's quality declines, its foragers reduce their rate of visits to the patch. This diminishes the flow of nectar from the poor patch which in turn stimulates recruitment to rich patches. Thus a colony can swiftly redistribute its forager force following changes in the spatial distribution of rich food sources. The fundamental currency of nectar patch quality is not net rate of energy intake, (Gain-Cost)/Time, but may be net energy efficiency, (Gain-Cost)/Cost.     

Brood dispersal and multiple central place foraging by Lapland longspur parents

Summary Lapland longspur chicks continued to be fed by their parents for 2 weeks after nest departure. Shortly after they left the nest, broods were divided evenly into two units each tended by a single parent. Female-tended brood units dispersed away from the nest at a faster average distance per day than those tended by males. The distance between offspring within a brood unit also increased as chicks got older. For the first 8–10 d after nest departure, parents were multiple central place foragers, making 1–8 foraging trips away from each dispersed chick (i.e. the central place) before moving on to feed another chick in a similar fashion. During the final 5–7 d before independence, chicks were quite mobile and followed parents on their foraging bouts. A simulation model shows that brood dispersal reduced total parental travel time per chick, primarily because each chick moved closer to a foraging site. By comparing models for a variety of brood division and foraging itinerary scenarios, we also show that multiple central place foraging by parents visiting different, separated brood units is less energetically expensive than other reasonable alternatives.Although brood dispersal is usually considered to be an adaptation for avoiding predation, it can also help parents reduce the energetic costs of parental care.     

Nectar-receiver behavior in relation to the reward rate experienced by foraging honeybees

Since forager honeybees change their food-unloading behavior according to nectar-source profitability, an experiment was performed in order to analyze whether food-receivers modify their within-hive tasks related to different reward conditions. We offered individual foragers two reward conditions at a rate feeder while an additional feeder offered a constant reward and was of free access to the rest of the hive. Both feeders were the only food sources exploited by the colony during the assays since a flight chamber was used. After receiving nectar, hive bees performed processing cycles that involved several behaviors and concluded when they returned to the delivery area to receive a new food sample. During these cycles, receivers mainly performed oral contacts offering food, or inspected cells, and often both. In the latter case, both behaviors occurred simultaneously and at the same distance from the hive entrance. When they performed a single task, either the occurrence of cell inspections increased or contact offerings decreased for the highest reward rate offered to the donor-forager. Receivers also begged for food more often after interacting with low-profit foragers. Thus, the profitability of the food source exploited by nectar-forager honeybees could affect receiver behaviors within the hives based on individual-to-individual interactions.Communicated by R.F.A. Moritz