Comparative and Experimental Studies on the Foraging and Exploratory Behavior of Four Honey Bee Species

One of the primary challenges foraging animals face is deciding how to divide their time between exploitation of known resources and exploration for new resources. As foraging is costly, investment in exploration should be mediated by natural selection to balance its costs and benefits in ways are tuned to species life history (e.g., lifespan, reproduction rate, activity level), individual state (e.g., experience, hunger, cognitive abilities), and environmental conditions (e.g., reward predictability, distribution, abundance). Efforts to understand the role each factor plays in the exploitation-exploration tradeoff are complicated by the complex scenario-specific ways in which they interact. In addition, the lack of comparative information on exploratory behavior limits our ability to draw generalizations. In this dissertation, I use a combination of experiments and comparative studies in four honey bee species to examine how interactions between life history, individual experience, and environmental conditions shape investment in foraging and exploration. Each chapter addresses how the interaction between two factors (e.g., life history and environment, individual experience and environment) shapes honey bee exploration, or provides an in-depth look at a previously understudied aspect of Asian honey bee life history and foraging behavior that could play a role in shaping their exploratory behavior. In Chapter 1, I investigate how evolved differences in life history interact with environmental reward context to shape worker investment in exploration in four honey bee species. Species that face higher mortality costs from exploration were generally less exploratory when confronted by a decrease in a familiar reward, but all species increased their investment in exploration as they experienced larger decreases in resource quality. These findings suggest that exploratory behavior has been tuned by natural selection to species life history but is also sensitive to the current environmental conditions. In Chapter 2, I use Apis mellifera to investigate how different past experiences with environmental predictability in the location or timing of rewards influence how honey bees search when those rewards are no longer available. My results show that honey bees that have had experience with unpredictable rewards are less precise but equally persistent in their search for vanished rewards, as compared with bees that have had experience with predictable rewards. This result suggests that a bee’s experience with resource predictability shapes the way she searches but not her overall investment in exploration. In Chapter 3, I investigate the lifespan and foraging behavior of three honey bee species. For all three species, the age at which a bee first becomes active outside the nest was the primary predictor of her lifespan. Dwarf honey bee (A. florea) workers seem to have the longest lifespan, likely due to their much-delayed onset of flight outside the hive, supporting the idea that species that face higher costs from worker mortality should have longer-lived workers. Finally, in Chapter 4, I examine how investment in diurnal and nocturnal foraging activity by the giant honey bee (A. dorsata) changes across seasons and lunar cycles. I found that this species could be considered both diurnal and crepuscular, as well as facultatively nocturnal. The amount of nocturnal activity performed depended greatly on environmental illumination and the season, whereas crepuscular activity was extremely high regardless of season or illumination. This study paves the way for further investigations into the mortality costs associated with nocturnal foraging, and how those costs might shape their exploratory behavior during the day.