Directional change in a suite of foraging behaviors in tropical and temperate evolved honey bees (<Emphasis Type="Italic">Apis mellifera</Emphasis> L.)

The concept of a suite of foraging behaviors was introduced as a set of traits showing associative directional change as a characterization of adaptive evolution. I report how naturally selected differential sucrose response thresholds directionally affected a suite of honey bee foraging behaviors. Africanized and European honey bees were tested for their proboscis extension response thresholds to ascending sucrose concentrations, reared in common European colonies and, captured returning from their earliest observed foraging flight. Race constrained sucrose response threshold such that Africanized bees had significantly lower sucrose response thresholds. A Cox proportional hazards regression model of honey bee race and sucrose response threshold indicated that Africanized bees were 29% (P<0.01) more at risk to forage over the 30-day experimental period. Sucrose response threshold organized age of first foraging such that each unit decrease in sucrose response threshold increased risk to forage by 14.3% (P<0.0001). Africanized bees were more likely to return as pollen and water foragers than European foragers. Africanized foragers returned with nectar that was significantly less concentrated than European foragers. A comparative analysis of artificial and naturally selected populations with differential sucrose response thresholds and the common suite of directional change in foraging behaviors is discussed. A suite of foraging behaviors changed with a change in sucrose response threshold that appeared as a product of functional ecological adaptation.Communicated by R.F.A. Moritz     

The communal crop: modulation of sucrose response thresholds of pre-foraging honey bees with incoming nectar quality

We examined whether the quality (concentration) of incoming sucrose solutions returned by foraging honey bees affected the response thresholds of pre-foraging members of the colony. Six pairs of colonies were given ad libitum access to sucrose solution feeders. A colony from each pair was switched from 20–50% sugar concentration feeders while the other continued to have access to 20% sucrose feeders. Proboscis extension response (PER) scores to an increasing series of sucrose concentrations were significantly higher in pre-foragers of colonies foraging on 20% sucrose throughout compared to pre-foragers in colonies where foraging was switched to 50% sucrose. Although all colonies had honey stores, the concentration of sugar solution in non-foraging bees crops were significantly lower in bees from colonies foraging on 20% sucrose compared to those from colonies foraging on 50% sucrose. Because response thresholds to sugar of young bees were modulated by the concentration of sucrose solution returned to colonies, we repeated the 2000 study of Pankiw and Page that potentially confounded baseline response thresholds with modulated scores due to experience in the colony. Here, we examined PER scores to sucrose in bees within 6 h of emergence, prior to feeding experience, and their forage choice 2 to 3 weeks later. Pollen foragers had higher PER scores as newly emerged bees compared to bees that eventually became nectar foragers. These results confirm those of the 2000 study by Pankiw and Page. Combined, these experiments demonstrate that variation in pre-forager sucrose response thresholds are established prior to emerging as adults but may be modulated by incoming resources later on. Whether this modulation has long-term effects on foraging behavior is unknown but modulation has short-term effects and the potential to act as a means of communication among all bees in the colony.Communicated by M. Giurfa     

Reward rate and forager activation in honeybees: recruiting mechanisms and temporal distribution of arrivals

We analyzed the foraging and recruitment activity of single foragers ( Apis mellifera), exploiting low reward rates of sucrose solution. Single employed foragers (test bees) were allowed to collect 2.0 m sucrose solution delivered by a rate-feeder located at 160 m from the hive for 2 h. Flow rates varied between 1.4 and 5.5 µl/min. The individual behavior of the test bees was registered both at the hive and the food source, and the social output was calculated as the number of incoming bees arriving at the feeder per hour (henceforth: arrival rate). Incoming bees were captured once they landed at the feeder and assigned to one of three categories according to their foraging experience and hive interactions with the test bee: inspector, reactivated, or inexperienced bees. Both the waggle-runs performed per hour of foraging by test bees and the social output attained, increased with the reward rate. Also the number of hive-stays and the trophallactic-offering contacts performed by test bees were positively correlated with the arrival rate. For the highest reward rates, the duration of Nasonov-gland exposure at the feeding place was higher, and the arrival of most of the incoming bees occurred shortly after the test bee landed at the feeding platform. Thus, in addition to hive-interactions, landing of incoming bees at the food source is promoted by olfactory and/or visual information provided by the test bees. The proportions of inspector, reactivated, and inexperienced bees changed depending on the reward rate offered. Therefore, not only the occurrence and intensity of the recruitment-related behaviors performed by the test bees, but also the stimulation required by each category of incoming bees, determined the social output observed.     

Collective decision-making in honey bees: how colonies choose among nectar sources

Summary A honey bee colony can skillfully choose among nectar sources. It will selectively exploit the most profitable source in an array and will rapidly shift its foraging efforts following changes in the array. How does this colony-level ability emerge from the behavior of individual bees? The answer lies in understanding how bees modulate their colony's rates of recruitment and abandonment for nectar sources in accordance with the profitability of each source. A forager modulates its behavior in relation to nectar source profitability: as profitability increases, the tempo of foraging increases, the intensity of dancing increases, and the probability of abandoning the source decreases. How does a forager assess the profitability of its nectar source? Bees accomplish this without making comparisons among nectar sources. Neither do the foragers compare different nectar sources to determine the relative profitability of any one source, nor do the food storers compare different nectar loads and indicate the relative profitability of each load to the foragers. Instead, each forager knows only about its particular nectar source and independently calculates the absolute profitability of its source. Even though each of a colony's foragers operates with extremely limited information about the colony's food sources, together they will generate a coherent colonylevel response to different food sources in which better ones are heavily exploited and poorer ones are abandoned. This is shown by a computer simulation of nectar-source selection by a colony in which foragers behave as described above. Nectar-source selection by honey bee colonies is a process of natural selection among alternative nectar sources as foragers from more profitable sources survive (continue visiting their source) longer and reproduce (recruit other foragers) better than do foragers from less profitable sources. Hence this colonial decision-making is based on decentralized control. We suggest that honey bee colonies possess decentralized decision-making because it combines effectiveness with simplicity of communication and computation within a colony. Offprint requests to: T.D. Seeley     

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     

The effect of foraging specialization on various learning tasks in the honey bee (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Honey bee foragers may collect nectar, pollen, water, or propolis, and their foraging specialization has been associated with several behavioral traits. By conditioning of the proboscis extension response (PER), we compared the performance of foragers that collected nectar, pollen, both nectar and pollen, or water in several learning and choice assays. Foragers were first tested in a three-trial olfactory associative learning assay. For further tests, we selected only good learners that responded in two out of three conditioning trials. One group was tested in an additional olfactory associative learning assay involving different reward volumes and concentrations. Another group was tested for risk sensitivity in a two-alternative forced-choice PER procedure and then in a latent inhibition (LI) assay. Levels of acquisition in olfactory associative learning were highest in pollen and water foragers, and better acquisition was associated with collection of heavier pollen loads and smaller and lighter nectar loads of lower sugar concentration. Among the good learners, pollen foragers still showed better acquisition than nectar foragers when rewarded with several volumes and concentrations of sucrose solution. Pollen and nectar foragers were equally risk averse, preferring a constant reward to a variable one, and choice was not affected by pollen load weight. Contrary to a previous study, pollen and nectar foragers were similarly affected by LI. We discuss possible explanations for the discrepancy between the two studies. Overall, our results suggest that differences between foraging groups in sensitivity to various stimuli may not correspond to differences in choice behavior.     

The role of a scent beacon in the communication of food location by the stingless bee, Melipona panamica

Melipona panamica foragers can deposit a scent beacon that influences the orientation of foragers near a food source. In misdirection experiments, newcomers (bees from the same colony as trained foragers) consistently preferred the feeder at which trained foragers had fed (training feeder) over an identical feeder at which bees had never fed (control feeder) even when the training feeder was placed at a site where experienced foragers had never foraged. Through similar misdirection experiments, the effective radius of the scent beacon was determined to be greater than 6 and less than 12 m. Foragers may deposit this beacon during a sequence of departure behaviors performed at the feeder. Prior to leaving the feeder with a load of sugar solution, bees tended to perform the following sequence of behaviors: (1) spinning, (2) grooming, (3) abdomen dragging, (4) excreting anal droplets, and (5) producing sounds, although not all behaviors were performed prior to each departure or at all sucrose concentrations (0.5–2.5 m). As sucrose concentration increased, the number of newcomers significantly increased, and the number of experienced foragers producing sounds and spinning on the feeder increased. The exact source of the scent beacon remains a mystery. However, three important sources have been excluded. When choosing between identical paired feeders, foragers were not attracted to the feeders with (1) anal droplets, (2) extracts of sucrose solution at which foragers had fed, or (3) mandibular gland extracts. They were indifferent to the first two preparations and exhibited only typical alarm behavior towards the mandibular gland (MG) extract: they oriented towards the feeder with MG extract but consistently landed on the feeder with no MG extract. Other authors have suggested that Melipona foragers deposit anal droplets to attract recruits, however the frequency of anal droplet production and the mass of anal droplets produced by M. panamica foragers are negatively correlated with sucrose concentration. Thus the scent beacon is evidently not deposited with anal droplets, infused into the feeder solution, or produced by mandibular glands. Received: 2 September 1997 / Accepted after revision: 30 January 1998     

Worker piping in honey bees (<Emphasis Type="Italic">Apis mellifera</Emphasis>): the behavior of piping nectar foragers

This study investigates the brief piping signals ("stop signals") of honey bee workers by exploring the context in which worker piping occurs and the identity and behavior of piping workers. Piping was stimulated reliably by promoting a colony's nectar foraging activity, demonstrating a causal connection between worker piping and nectar foraging. Comparison of the behavior of piping versus non-piping nectar foragers revealed many differences, e.g., piping nectar foragers spent more time in the hive, started to dance earlier, spent more time dancing, and spent less time on the dance floor. Most piping signals (approximately 99%) were produced by tremble dancers, yet not all (approximately 48%) tremble dancers piped, suggesting that the short piping signal and the tremble dance have related, but not identical, functions in the nectar foraging communication system. Our observations of the location and behavior of piping tremble dancers suggest that the brief piping signal may (1) retard recruitment to a low-quality food source, and (2) help to enhance the recruitment success of the tremble dance.     

Social foraging in stingless bees: how colonies of Melipona fasciata choose among nectar sources

In an experimental set-up, a colony of the stingless bee Melipona fasciata demonstrated its ability to choose the better of two nectar sources. This colony pattern was a result of the following individual behavioural decisions: continue foraging, abandon the feeder, restart foraging and initiate foraging. Only very rarely did individuals switch from one feeder to the other. With the first combination of a rich (2.7 M) and a poor (0.8 M) feeder M. fasciata behaved differently from Apis mellifera. Recruitment occurred to both feeders and the poor feeder was not abandoned completely. When the poor feeder was set to 0.4 M, M. fasciata abandoned the poor feeder rapidly and allocated more foragers to the rich feeder. These patterns were similar to those reported for A. mellifera with the first combination of feeders. Over a sequence of 4 days, experienced bees increasingly determined the colony patterns, and the major function of communication between workers became the reactivation of experienced foragers. The foragers modulated their behaviour not only according to the profitability of the feeder, but also according to previous experience with profitability switches. Thus, experience and communication together regulated colony foraging behaviour. These findings and the results of studies with honeybees suggest that M. fasciata and honeybees use similar decision-making mechanisms and only partly different tools. Received: 21 December 1998 / Accepted: 5 January 1999     

Effects of ambient temperature on regulated gaseous and particulate emissions from gasoline-, E10- and M15-fueled vehicles

• Emissions from two sedans were tested with gasoline, E10 and M15 at 30°C and -7°C. • As the temperature decreased, the PM, PN and BC emissions increased with all fuels. • Particulate emissions with E10 and M15 were more sensitive to the temperature. • The PN and BC generated during cold start-up dominated those over the WLTC. Ambient temperature has substantial impacts on vehicle emissions, but the impacts may differ between traditional and alcohol gasolines. The objective of this study was to investigate the effects of temperature on gaseous and particulate emissions with both traditional and alcohol gasoline. Regulated gaseous, particle mass (PM), particle number (PN) and black carbon (BC) emissions from typical passenger vehicles were separately quantified with gasoline, E10 (10% ethanol and 90% gasoline by volume) and M15 (15% methanol and 85% gasoline by volume) at both 30°C and -7°C. The particulate emissions with all fuels increased significantly with decreased temperature. The PM emissions with E10 were only 48.0%–50.7% of those with gasoline at 30°C but increased to 59.2%-79.4% at -7°C. The PM emissions with M15 were comparable to those with gasoline at 30°C, but at -7°C, the average PM emissions were higher than those with gasoline. The variation trend of PN emissions was similar to that of PM emissions with changes in the fuel and temperature. At 30°C, the BC emissions were lower with E10 and M15 than with gasoline in most cases, but E10 and M15 might emit more BC than gasoline at -7°C, especially M15. The results of the transient PN and BC emission rates show that particulate emissions were dominated mainly by those emitted during the cold-start moment. Overall, the particulate emissions with E10 and M15 were more easily affected by ambient temperature, and the advantages of E10 and M15 in controlling particulate emissions declined as the ambient temperature decreased.     

Why are bumble bees risk-sensitive foragers?

Summary In a controlled laboratory experiment, we re-examined the question of bumble bee risk-sensitivity. Harder and Real's (1987) analysis of previous work on bumble bee risk aversion suggests that risk-sensitivity in these organisms is a result of their maximizing the net rate of energy return (calculated as the average of expected per flower rates). Whether bees are risk-sensitive foragers with respect to minimizing the probability of energetic shortfall is therefore still an open question. We examined how the foraging preferences of bumble bees for nectar reward variation were affected by colony energy reserves, which we manipulated by draining or adding sucrose solution to colony honey pots. Nine workers from four confined colonies of Bombus occidentalis foraged for sucrose solution in two patches of artificial flowers. These patches yielded the same expected rate of net energy intake, but floral volumes were variable in one patch and constant in the other. Our results show that bumble bees can be both risk-averse (preferring constant flowers) and risk-prone (preferring variable flowers), depending on the status of their colony energy reserves. Diet choice in bumble bees appears to be sensitive to the target value a colony-level energetic requirement. Offprint requests to: R.V. Cartar     

Brood pheromone stimulates pollen foraging in honey bees (Apis mellifera)

Foraging and the mechanisms that regulate the quantity of food collected are important evolutionary and ecological attributes for all organisms. The decision to collect pollen by honey bee foragers depends on the number of larvae (brood), amount of stored pollen in the colony, as well as forager genotype and available resources in the environment. Here we describe how brood pheromone (whole hexane extracts of larvae) influenced honey bee pollen foraging and test the predictions of two foraging-regulation hypotheses: the indirect or brood-food mechanism and the direct mechanism of pollen-foraging regulation. Hexane extracts of larvae containing brood pheromone stimulated pollen foraging. Colonies were provided with extracts of 1000 larvae (brood pheromone), 1000 larvae (brood), or no brood or pheromone. Colonies with brood pheromone and brood had similar numbers of pollen foragers, while those colonies without brood or pheromone had significantly fewer pollen foragers. The number of pollen foragers increased more than 2.5-fold when colonies were provided with extracts of 2000 larvae as a supplement to the 1000 larvae they already had. Within 1 h of presenting colonies with brood pheromone, pollen foragers responded to the stimulus. The results from this study demonstrate some important aspects of pollen foraging in honey bee colonies: (1) pollen foragers appear to be directly affected by brood pheromone, (2) pollen foraging can be stimulated with brood pheromone in colonies provided with pollen but no larvae, and (3) pollen forager numbers increase with brood pheromone as a supplement to brood without increasing the number of larvae in the colony. These results support the direct-stimulus hypothesis for pollen foraging and do not support the indirect-inhibitor, brood-food hypothesis for pollen-foraging regulation. Received: 5 March 1998 / Accepted after revision: 29 August 1998     

The effect of ambient temperature on forager sound production and thoracic temperature in the stingless bee, <Emphasis Type="Italic">Melipona panamica</Emphasis>

Foragers of the stingless bees genus Melipona may produce intranidal sounds that are correlated with food location and quality. In this study, we provide the first detailed analysis of pulsed sounds produced by Melipona panamica foragers while feeding on a carbohydrate food source. We trained foragers to a 2.5-M sucrose feeder under normal, ambient temperature (23–33°C) and lower temperature (11–25°C) conditions. We recorded forager sounds under both conditions and tested the effect of temperature of the thorax, feeder plate, and air on sound temporal characteristics. Forager energetic expenditure and the number of pulses per visit were significantly higher in the cold condition than in the normal condition. Foragers spent a longer time at the feeder under the cold condition than during the normal condition. Interpulse durations were significantly shorter in the cold condition than in the normal condition and became progressively and significantly shorter at the end of each performance. Thus, pulse production increased before departure. Foragers increased their thoracic temperatures above ambient at all experimental air temperatures. Under chilled conditions, foragers had a significantly greater difference between thorax temperature and ambient air temperature than under normal conditions. Foragers must achieve a minimum flight muscle temperature before take-off, and thus forager sounds may be linked to muscle warm-up.     

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.     

Foraging habitats and migration corridors utilized by a recovering subpopulation of adult female loggerhead sea turtles: implications for conservation

From 1998 to 2008, 68 adult female loggerhead sea turtles (Caretta caretta) were instrumented with platform transmitter terminals at nesting beaches in Georgia, North Carolina (NC) and South Carolina (SC) on the East Coast of the United States of America (30°48′N, 81°28′W to 33°51′N, 77°59′W). The majority of post-nesting loggerheads (N = 42, 62 %) migrated to foraging habitats in the Mid-Atlantic Bight during May–October, with a subsequent migration occurring during November–March to foraging habitats south of Cape Hatteras, NC. Nine (13 %) loggerheads initially foraged in the near-shore, coastal areas of the South Atlantic Bight, but moved to offshore habitats—closer to the Gulf Stream—during November–March, while fourteen (21 %) loggerheads remained in foraging areas along the mid-continental shelf off of the eastern coast of Florida and/or continued southward to Florida Bay and the Bahamas. The present study delineates important, post-nesting foraging habitats and migration corridors where loggerheads may interact with commercial fisheries—providing managers opportunities to develop and implement optimally effective conservation actions for the recovery of this threatened species.     

Synthesis of butyl butyrate in 93 % yield by <Emphasis Type="Italic">Thermomyces lanuginosus</Emphasis> lipase on waste eggshells

There is a high demand for immobilized enzymes in the industry because it is a green technology, it improves the efficiency of the crude enzyme and it minimizes the step of product recovery. Selection of a suitable carrier for enzyme immobilization is crucial. Eggshells are abundantly available as an organic waste. Here, lipase from Thermomyces lanuginosus was immobilized on eggshell to produce butyl butyrate. We evaluated the effect of lipase loading, from 0.5 to 3.0 %, size of eggshells, lower than 1, 1–2 and 2–4 mm, and temperature, from 30 to 50 °C. Results show that the optimum conditions calculated by response surface methodology analysis for butyl butyrate synthesis were 40 % w/v of immobilized lipase loading and 0.2 M of substrate concentration at 38 °C during 24 h. The predicted yield was 92.78 %, and the yield obtained during synthesis was 93.48 %.     

Differential effects of temperature variability on the transmission of a marine parasite

Temperature variability is particularly pronounced in intertidal systems. The importance of considering this variability has been increasingly recognised, especially in the context of climate change and disease dynamics. Here, we investigated the effects of temperature variability on the transmission of the intertidal trematode Maritrema novaezealandensis. The experimental treatments were 15 °C (control), 15 + 5 °C daily, 15 + 10 °C every second day, 15 + 15 °C every third day (overall equal thermal loading), and a heat wave treatment (15 + 10 °C daily). Daily 6 h incubations were carried out corresponding to daytime low tides over a 12-day period. Effects on output of transmission stages (cercariae) from infected Zeacumantus subcarinatus snail hosts and transmission success of cercariae to Paracalliope novizealandiae amphipod hosts were quantified, as well as the survival of amphipods. Results showed differential effects on output and transmission success. The number of cercariae emerging was similar for treatments with equal thermal loading, but was substantially increased in the heat wave treatment. Transmission success was highest and comparable for the treatments with regular daily temperature increases (i.e. 15 + 5 °C and heat wave), compared to other treatments. Amphipod survival was not affected by temperature treatment directly, but by the number of parasites infecting an amphipod, as well as amphipod sex. These results demonstrate that cercarial output depends mostly on total thermal loading, whereas successful infection of amphipods is determined by total time above 15 °C. Repeated exposure to ~25 °C, as expected under a heat wave scenario, therefore increases both transmission pressure and success, and hence, the risk of parasite-induced mortality in amphipods.     

Temperature and salinity interactively impact early juvenile development: a bottleneck in barnacle ontogeny

When juvenile mortality or juvenile growth is impacted by temperature and salinity, these factors have a substantial effect on recruitment success and population dynamics in benthic ecosystems. Using freshly settled cyprids of Amphibalanus improvisus, we investigated the combined effects of temperature (12, 20 and 28 °C) and salinity (5, 15 and 30 psu) on early juvenile stage performance. Mortality as well as size (basal diameter, dry weight, and ash-free dry weight) was monitored for a period of 40 days. Mortality was high (42–63 %) during the first week following attachment, regardless of the temperature and salinity treatments. Subsequently, mortality and size were interactively influenced by temperature and salinity. Highest mortality and lowest size of juveniles occurred at lowest temperature (12 °C) and salinity (5 psu). Apparently, low temperature (12 °C) narrowed the barnacles’ salinity tolerance. Juvenile barnacles constructed more shell material compared to body mass at high temperature and high salinity, while a reverse situation was observed at low temperature and low salinity. Our results demonstrate that environmental changes can directly and/or indirectly alter patterns of survivorship and size. Warming and desalination as predicted for the Baltic Sea in the course of climate change may, however, act antagonistically and compensate each other’s isolated effect on barnacles.     

Worker allocation in insect societies: coordination of nectar foragers and nectar receivers in honey bee (Apis mellifera) colonies

Nectar collection in the honey-bee is partitioned. Foragers collect nectar and take it to the nest, where they transfer it to receiver bees who then store it in cells. Because nectar is a fluctuating and unpredictable resource, changes in worker allocation are required to balance the work capacities of foragers and receivers so that the resource is exploited efficiently. Honey bee colonies use a complex system of signals and other feedback mechanisms to coordinate the relative and total work capacities of the two groups of workers involved. We present a functional evaluation of each of the component mechanisms used by honey bees – waggle dance, tremble dance, stop signal, shaking signal and abandonment – and analyse how their interplay leads to group-level regulation. We contrast the actual regulatory system of the honey bee with theory. The tremble dance conforms to predicted best use of information, where the group in excess applies negative feedback to itself and positive feedback to the group in shortage, but this is not true of the waggle dance. Reasons for this and other discrepancies are discussed. We also suggest reasons why honey bees use a combination of recruitment plus abandonment and not switching between subtasks, which is another mechanism for balancing the work capacities of foragers and receivers. We propose that the waggle and tremble dances are the primary regulation mechanisms, and that the stop and shaking signals are secondary mechanisms, which fine-tune the system. Fine-tuning is needed because of the inherent unreliability of the cues, queueing delays, which foragers use to make recruitment decisions. Received: 15 December 1998 / Received in revised form: 6 March 1999 / Accepted: 12 March 1999