Imprecision in waggle dances of the honeybee (Apis mellifera) for nearby food sources: error or adaptation?

A curious feature of the honeybee's waggle dance is the imprecision in the direction indication for nearby food sources. One hypothesis for the function of this imprecision is that it serves to spread recruits over a certain area and thus is an adaptation to the typical spatial configuration of the bees' food sources, i.e., flowers in sizable patches. We report an experiment that tests this tuned-error hypothesis. We measured the precision of direction indication in waggle dances advertising a nest site (typically a tree cavity, hence a target that is almost a point) and compared it with that of dances advertising a food source (typically a flower patch, hence a target that covers an area). The precision of dances for a nearby nest site was significantly higher than that of dances for an equidistant feeder. This was demonstrated four times with four colonies. Our evidence therefore supports the hypothesis that the level of precision in the direction indication for nearby food sources is tuned to its optimum without being at its maximum. Received: 9 December 1998 / Received in revised form: 24 February 1999 / Accepted 12 March 1999     

Dancing to different tunes: heterospecific deciphering of the honeybee waggle dance

Although the structure of the dance language is very similar among species of honeybees, communication of the distance component of the message varies both intraspecifically and interspecifically. However, it is not known whether different honeybee species would attend interspecific waggle dances and, if so, whether they can decipher such dances. Using mixed-species colonies of Apis cerana and Apis mellifera, we show that, despite internal differences in the structure of the waggle dances of foragers, both species attend, and act on the information encoded in each other’s waggle dances but with limited accuracy. These observations indicate that direction and distance communication pre-date speciation in honeybees.     

Honey bee foragers as sensory units of their colonies

Forager honey bees function not only as gatherers of food for their colonies, but also as sensory units shaped by natural selection to gather information regarding the location and profitability of forage sites. They transmit this information to colony members by means of waggle dances. To investigate the way bees transduce the stimulus of nectar-source profitability into the response of number of waggle runs, I performed experiments in which bees were stimulated with a sucrose solution feeder of known profitability and their dance responses were videorecorded. The results suggest that several attributes of this transduction process are adaptations to enhance a bee's effectiveness in reporting on a forage site. (1) Bees register the profitability of a nectar source not by sensing the energy gain per foraging trip or the rate of energy gain per trip, but evidently by sensing the energetic efficiency of their foraging. Perhaps this criterion of nectar-source profitability has been favored by natural selection because the foraging gains of honey bees are typically limited by energy expenditure rather than time availability. (2) There is a linear relationship between the stimulus of energetic efficiency of foraging and the response of number of waggle runs per dance. Such a simple stimulus-response function appears adequate because the range of suprathreshold stimuli (max/min ratio of about 10) is far smaller than the range of responses (max/min ratio of about 100). Although all bees show a linear stimulus-response function, there are large differences among individuals in both the response threshold and the slope of the stimulus-response function. This variation gives the colony a broader dynamic range in responding to food sources than if all bees had identical thresholds of dance response. (3) There is little or no adaptation in the dance response to a strong stimulus (tonic response). Thus each dancing bee reports on the current level of profitability of her forage site rather than the changes in its profitability. This seems appropriate since presumably it is the current profitability of a forage site, not the change in its profitability, which determines a site's attractiveness to other bees. (4) The level of forage-site quality that is the threshold for dancing is tuned by the bees in relation to forage availability. Bees operate with a lower dance threshold when forage is sparse than when it is abundant. Thus a colony utilizes input about a wide range of forage sites when food is scarce, but filters out input about low-reward sites when food is plentiful. (5) A dancing bee does not present her information in one spot within the hive but instead distributes it over much of the dance floor. Consequently, the dances for different forage sites are mixed together on the dance floor. This helps each bee following the dances to take a random sample of the dance information, which is appropriate for the foraging strategy of a honey bee colony since it is evidently designed to allocate foragers among forage sites in proportion to their profitability.     

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.     

雾霾天气空气污染下户外跳舞对机体呼吸系统的损伤效应研究

雾霾天气对户外跳舞人员呼吸系统损伤极大.为了确定雾霾天气对人体呼吸系统影响的严重程度,文章研究雾霾污染对户外跳舞人员呼吸系统的急慢性危害,通过采集呼吸系统主观感受指标、确定户外跳舞人员痰液中炎性因子含量,建立了雾霾对机体呼吸系统损伤效应研究优化模型.设计仿真对比试验结果表明,所设计模型,能确定雾霾对人体呼吸系统损伤的严重程度,帮助人们提前做好防范工作.     

血红蛋白指标在竞技舞龙训练监控中的应用研究

以备战第六届全国农民运动会竞技舞龙比赛的11名参赛者为研究对象,首次应用血红蛋白指标进行舞龙训练监控,并介绍其具体应用方法.结果表明,Hb指标能较好地反应队员的身体机能状态,可应用于竞技舞龙的训练监控,保证训练科学、有效地进行.     

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     

The modulation of worker behavior by the vibration signal during house hunting in swarms of the honeybee, Apis mellifera

During house hunting, honeybee, Apis melli- fera, workers perform the vibration signal, which may function in a modulatory manner to influence several aspects of nestsite selection and colony movement. We examined the role of the vibration signal in the house-hunting process of seven honeybee swarms. The signal was performed by a small proportion of the older bees, and 20% of the vibrating bees also performed waggle dances for nestsites. Compared to non-vibrating controls, vibrating bees exhibited increased rates of locomotion, were more likely to move into the interiors of the swarms, and were more likely to fly from the clusters and perform waggle dances. Recipients responded to the signal with increased locomotion and were more likely than non- vibrated controls to fly from the swarms. Because vibration signals were intermixed with waggle dances by some vibrators, and because they stimulated flight in recipients, the signals may have enhanced nestsite scouting and recruitment early in the house-hunting process. All swarms exhibited increased vibration activity within 0.5–1 h of departure. During these final periods, numerous vibrating bees wove repeatedly in and out of the clusters while signaling and motion on the swarms increased until it culminated in mass flight. The peaks of vibration activity observed at the end of the house-hunting process may therefore have activated the entire swarm for liftoff once a new nestsite had been selected. Thus, the vibration signal may help to integrate the behavior of numerous groups of workers during nestsite selection and colony relocation. Received: 17 January 2000 / Received in revised form: 5 April 2000 / Accepted: 3 May 2000     

Do honey bees tune error in their dances in nectar-foraging and house-hunting?

The "tuned-error" hypothesis states that natural selection has tuned the divergence angle in the dances of the honey bee to produce an optimal scatter of recruits across a resource. Weidenmüller and Seeley (Behav Ecol Sociobiol 46:190–199, 1999) supported this hypothesis by finding smaller divergence angles in dances indicating potential home sites, which are always point sources, than in dances indicating food sources, which often occur in patches. This study tested for the same effect, but controlled for variables, e.g., substrate and context, that may have confounded those results. When performed on the same substrate, divergence angle does not differ between dances for the two resources. Furthermore, dances performed for food within an observation hive exhibit significantly greater divergence angle when performed on comb (as Weidenmüller and Seeley measured food dances) than on hardware cloth (as they measured home-site dances on a swarm). These findings suggest that the angular variance in direction indication in dances is more likely an artifact of physical constraints, rather than an adaptive modification of a behavior that a bee could perform more precisely.     

The honey bee’s tremble dance stimulates additional bees to function as nectar receivers

If a forager bee returns to her hive laden with high-quality nectar but then experiences difficulty finding a receiver bee to unload her, she will begin to produce a conspicuous communication signal called the tremble dance. The context in which this signal is produced suggests that it serves to stimulate more bees to function as nectar receivers, but so far there is no direct evidence of this effect. We now report an experiment which shows that more bees do begin to function as nectar receivers when foragers produce tremble dances. When we stimulated the production of tremble dances in a colony and counted the number of bees engaged in nectar reception before and after the period of intense tremble dancing, we found a dramatic increase. In two trials, the number of nectar receivers rose from 17% of the colony’s population before tremble dancing to 30–50% of the population after the dancing. We also investigated which bees become the additional nectar receivers, by looking at the age composition of the receiver bees before and after the period of intense tremble dancing. We found that none of the bees recruited to the task of nectar reception were old bees, most were middle-aged bees, and some were even young bees. It remains unclear whether these auxiliary nectar receivers were previously inactive (as a reserve supply of labor) or were previously active on other tasks. Overall, this study demonstrates that a honey bee colony is able to rapidly and strongly alter its allocation of labor to adapt to environmental changes, and it further documents one of the communication mechanisms underlying this ability. Received: 31 May 1996/Accepted after revision: 9 August 1996