Year 1. Clustering of honey bee foragers at the dance floor in anticipation of previously productive feeding times. (Case Study) After several days of feeding at a restricted time of day, forager bees return to that station on subsequent days (unrewarded test days) in anticipation of the previously rewarded time, thus expressing a food-anticipatory activity (FAA) that is known as the time memory (Moore 2001). The temporal accuracy of the honey bee FAA on unrewarded test days is a function of the number of days of experience at the food source whereas the intensity of the FAA (i.e., number of anticipatory reconnaissance flights to the source) depends on the number of rewards received during training (Moore & Doherty 2009). Recent experiments (Moore, Van Nest, & Seier 2011) reveal that the honey bee time-memory undergoes extinction (diminution of FAA directed toward a previously productive feeding station) over several days and that the rate of extinction varies according to the experience accumulated at the feeding station by the individual forager. These experiments indicate one forager is not the same as any other forager -- individuals show differences in their time-memory behavior, with each individual acting as an independent agent that is influenced by its previous, unique set of experiences.
One aspect of the honey bee time-memory that has received relatively little attention is the phenomenon of foragers gathering at the dance floor. The dance floor, not precisely defined, is simply a relatively small portion of the honeycomb near the hive entrance on which returning foragers perform their recruitment dances, including the famous "waggle dance" that indicates both the direction and distance of a profitable food source (von Frisch 1967). We have observed that some trained foragers (referred to as "persistent" foragers) visit the feeding station on unrewarded test days while others ("reticent" foragers) do not. Interestingly, both persistent and reticent foragers cluster at the colony's dance floor in anticipation of the training time. Outside of the training time, both types of foragers disperse away from the dance floor. What are the dynamics of this rhythmic clustering and dispersing behavior? Foragers will be trained to collect 2M sucrose from a feeding station located 100 m from the colony. The food will be presented only at a restricted time of the day for several consecutive days. Newly recruited foragers will be individually marked with dots of paint applied to the thorax and abdomen, allowing us to keep track of all visits to and from the food source as well as the location of the forager within a glass-walled observation colony. The locations of foragers within the colony will be done by scan sampling the hive at hourly intervals. A grid pattern will be drawn on the glass walls, enabling accurate recording of spatial locations. We need to describe (1) the timing of the movements of foragers to and from the dance floor as the training time approaches and passes, (2) the paths taken by individually marked foragers with different experiences at the food source, and (3) the nature of the clustering that occurs at the dance floor. There are a number of questions that can be addressed. For example, what is the relationship between the spatial positioning in the hive and the number and timing of anticipatory flights to the food source? What are the differences in clustering between persistent and reticent foragers? Do they occupy different positions on the dance floor? Does the clustering change in parallel with extinction of the time memory? We will use diffusion-based mathematical models to describe the spatiotemporal dynamics of forager clustering and dispersal patterns with respect to the dance floor.
Year 2. Influence of biogenic amines on time-memory behavior. (Brief Description) Octopamine has been shown to play a role in the honey bee forager's assessment of the profitability of a food source: forager bees given exogenous octopamine have a higher probability of performing the waggle dance upon their return to the colony (Barron et al. 2007). We will test the influence of octopamine on several aspects of the time-memory, including the timing of the individual forager's movements within the hive toward the dance floor in anticipation of its foraging time. Our working hypothesis is that elevated octopamine will represent a highly rewarding food source and thus will result in a more accurate time memory which, in turn, will result in a change in dance floor clustering.
Year 3. Agent-based modeling of dance floor clustering. (Brief Description) Despite a long history of work on the waggle dance (and its role in recruitment of foragers to new food sources), very little is known about a very important component of the recruitment process the dance floor. This is where foragers advertise productive food sources and where unemployed foragers go to become recruited. Although referred to often in the literature, it is defined simply as the area of honeycomb within the colony on which recruitment dances take place. Its exact location and size may change from day to day, although it is almost always located near the hive entrance. What are the rules by which the dance floor is established each day? What are the signals used by previously trained foragers to migrate to and from the dance floor in anticipation of their own training time? How does the location of the dance floor change as the number of dancing bees increase or decrease? We will use agent-based models to test several hypotheses concerning the distribution of foragers with respect to the dance floor