Abstract: The honey bee time memory enables foragers to return to a profitable food source in anticipation of the time of day at which they previously collected food from that source. The time memory thus allows foragers to quickly resume exploiting a source after interruption, at the appropriate time of day, without the costs associated with having to rediscover it. A portion of a foraging group (the persistent foragers) will reconnoiter a previously profitable source and may do so for several days. The remaining bees (the reticent foragers) await confirmation of availability before revisiting the source. Recent work has shown that both persistent and reticent bees make extracurricular flights to alternative sources when one food source ceases being productive. Little else, however, is known about reticent foragers. In the present study, we determined that reticent bees congregate near the hive entrance in anticipation of the learned foraging time as do persistent foragers. We then confirmed that the food-anticipatory clustering takes place on the waggle dance floor, as suspected, but also found differences in the number of days that persistent and reticent foragers continue clustering. Finally, we found that persistent foragers had significantly more rewards per day at the source than did reticent foragers, supporting the hypothesis that experience at a food source influences a forager’s decision to become either persistent or reticent. Our findings demonstrate that persistence and reticence are not immutable characteristics of foragers themselves but rather strategies they employ toward different food sources. Significance statement: Much has been learned in recent years about the honey bee time memory and foraging behavior. Receiving scant attention, however, is the phenomenon of forager bees gathering near the hive entrance, anticipating the time of day when previously productive food sources become available. We show that both persistent and reticent bees (foragers that do and do not investigate the source, respectively) congregate on the waggle dance floor at the appropriate time of day, but, in the absence of food at the source, persistent bees continue to show this behavior a day or two longer than reticent bees do. We also show that experience with the source influences the decision to become persistent or reticent. Our results reveal how foraging experience influences the individual bee’s decision making, thereby providing insights into how foragers are reallocated efficiently among different resources in the environment.

Forager honey bees exhibit a robust time memory, based on an endogenous circadian clock, enabling them to schedule their flights to coincide with the nectar presentation of known food sources. They retain this time memory for several consecutive days even in the absence of nectar rewards. Recent work has identified 2 classes of forager: "persistent" foragers that reconnoiter a known food source to ascertain its status and "reticent" foragers that apparently wait in the hive for a waggle dance confirming source availability. Surprisingly, a foraging group contains 40-90% persistent foragers, depending on experience at the source. What is the benefit in sending so many foragers to investigate a source when only a few foragers are required to reactivate the entire group? We used an agent-based software model to test the energetics underlying several different ratios of persistent and reticent individuals in the foraging group while varying 6 ecological factors: forager group size, source distance, source sucrose concentration, source availability in hours, number of days the source is known to the colony, and the rate at which new unemployed foragers appear on the dance floor. Our model demonstrates 2 primary explanations. First, a large number of persistent foragers are needed to ensure that at least some foragers will reconnoiter their source early in its availability, thus enabling the group to effectively exploit the source. Second, the cost of a reconnaissance flight is negligible compared with even a single successful foraging trip.

Classical experiments demonstrated that honey bee foragers trained to collect food at virtually any time of day will return to that food source on subsequent days with a remarkable degree of temporal accuracy. This versatile time-memory, based on an endogenous circadian clock, presumably enables foragers to schedule their reconnaissance flights to best take advantage of the daily rhythms of nectar and pollen availability in different species of flowers. It is commonly believed that the time-memory rapidly extinguishes if not reinforced daily, thus enabling foragers to switch quickly from relatively poor sources to more productive ones. On the other hand, it is also commonly thought that extinction of the time-memory is slow enough to permit foragers to 'remember' the food source over a day or two of bad weather. What exactly is the time-course of time-memory extinction? In a series of field experiments, we determined that the level of food-anticipatory activity (FAA) directed at a food source is not rapidly extinguished and, furthermore, the time-course of extinction is dependent upon the amount of experience accumulated by the forager at that source. We also found that FAA is prolonged in response to inclement weather, indicating that time-memory extinction is not a simple decay function but is responsive to environmental changes. These results provide insights into the adaptability of FAA under natural conditions.

Forager honey bees can associate the time of day with the presence of food at locations outside the hive. It is thought that this time-memory enables the bee to make a spatio-temporal match between its behavior and floral nectar secretion rhythms. Despite a long tradition of research, the mechanisms by which the time-memory becomes established are unknown. We investigated the influences of two experiential factors on the acquisition of time-memory: (1) the number of collecting visits made by the forager within a feeding bout during a restricted time of day and (2) the number of days of exposure to the restricted feeding time. Our results indicate that these two factors control different processes. The number of days of experience influences the temporal accuracy of reconnaissance behavior to the food source. The cumulative number of collecting visits within the feeding bouts has no apparent effect on time-accuracy but, instead, determines the probability of exhibiting food-anticipatory behavior and, if that overt behavior is performed, the intensity of its expression.

Honey bee (Apis mellifera) foragers can remember both the location and time of day food is collected and, even in the absence of a reward, reconnoiter the food source at the appropriate time on subsequent days. This spatiotemporal memory (time-memory) is linked to the circadian clock and enables foragers to synchronize their behavior with floral nectar secretion rhythms, thus eliminating the need to rediscover productive food sources each day. Here, we asked whether the establishment of one time-memory influences the formation of another time-memory at the same time of day. In other words, can two time-place memories with the same ‘time-stamp’ coexist? We simultaneously trained two groups of foragers from a single hive to two separate feeders at the same restricted time of day. After 5 days of training, one feeder was shut off. The second feeder continued being productive 4 more days. Our results showed that (1) foragers with high experience levels at the first source were significantly more likely than low-experience foragers to maintain fidelity to their original source and resist recruitment to the alternative source, (2) nearly one-third of foragers demonstrated multiple, overlapping time-memories by visiting both feeders at the correct time and (3) significantly more high-experience than low-experience foragers exhibited this multitasking behavior. The ability to maintain and act upon two different, yet contemporaneous, time-memories gives the forager bee a previously unknown level of versatility in attending to multiple food sources. These findings have major implications for understanding the formation and management of circadian spatiotemporal memories.

Experiments were performed to investigate the influence of water availability on the diel patterns of nectar secretion (volume, concentration, sugar production) in male squash flowers as well as to discover what physical component of nectar honey bees use to trigger their time-memory. Squash plants were grown in the greenhouse and in the field under both constant and variable watering regimes. Throughout anthesis, nectar volume and sugar concentration were recorded. In the field, the temporal distribution of arrivals to squash was observed with and without blossoms present. In the greenhouse and in the field, squash flowers exhibit a consistent diel pattern of nectar secretion that does not significantly alter during drought conditions; flowers open just before sunrise (with low volume and sugar and high concentration) and close at midday (with high volume and sugar and low concentration). Honey bees preferentially arrived early in anthesis possibly cueing on either the sugar concentration or the first availability of nectar.

Experiments were performed to determine the influence of the honey bee time-memory on a forager bee's sensitivity to recruitment. Two groups of foragers from one colony were trained to separate food stations at the same restricted time of day for several consecutive days. Feeding then was canceled at one station but continued for four more days at the other. Bees with more days of training at a non-productive source were significantly less likely than foragers with less training to be recruited to an alternative food source presented at the same time of day. Furthermore, the ability of a forager to be recruited recovered after several days, but this recovery period was longer for bees with greater experience. These findings demonstrate a long-term influence of time-memory on subsequent foraging behavior, in contrast to currently accepted models for the allocation and re-allocation of honey bee foragers to food patches in the environment.

Speculative fiction allows an expanded view of literature and so allows scholars to explore new boundaries in the way words and ideas work. In the titular character of The Last Unicorn by Peter S. Beagle, the reader sees an expansion of self through liminality while A Scanner Darkly by Philip K. Dick explores its collapse. In order to portray each of these the character examined must move though one seems to move upward and the other downward. This idea of movement is only part of what expands the idea of liminality past the traditional idea of a doorway to create a hallway that the character might traverse on the way from place to place. This is not a redefinition of the term but a revision, a change in the way that we look at the concept as we accept and explore newer genres.

Classical experiments on honey bee time-memory showed that foragers trained to collect food at a fixed time of day return the following day with a remarkable degree of time-accuracy. A series of field experiments revealed that not all foragers return to a food source on unrewarded test days. Rather, there exist two subgroups: "persistent" foragers reconnoiter the source; "reticent" foragers wait in the hive for confirmation of source availability. A forager's probability of being persistent is dependent both on the amount of experience it has had at the source and the environmental conditions present, but the probability is surprisingly high (0.4-0.9). Agent-based simulation of foraging behavior indicated these high levels of persistence represent an energetically optimal strategy, which is likely a compromise solution to an ever-changing environment. Time-memory, with its accompanying anticipation, enables foragers to improve time-accuracy, quickly reactivating the foraging group to more efficiently exploit a food source.