Frontiers in Ecology and Evolution (Oct 2018)
Strong Interspecific Differences in Foraging Activity Observed Between Honey Bees and Bumble Bees Using Miniaturized Radio Frequency Identification (RFID)
Abstract
Central place foragers depart from and return to a central location with enough resources for themselves, and in many cases, for the group. Honey bees and bumble bees are eusocial central place foragers. Honey bees have large perennial colonies while bumble bee colonies are annual and considerably smaller. Foraging range, body size, and division of labor also vary between these two bee species. Honey bees use their unique dance language to recruit foragers to the most profitable patches. Bumble bees exploit patches individually and develop trapline foraging patterns. We expect such differences among bee species to engender differences in foraging activity. Moreover, variation in resource availability and in colony needs over the flowering season, can affect bee foraging activity. Finally, spatial variation in resource availability may impact bumble bees to a greater extent than honey bees due to their smaller foraging range. Using miniaturized radio frequency identification (RFID), we tracked the foraging activity of individual bees to and from hives at three sites and over five time periods. Pollen pellets were also collected from bees returning to the hive. We compared the European honey bee, Apis mellifera, and the common eastern bumble bee, Bombus impatiens. Linear mixed effect models determined the impact of bee species, time of season (period) and site, and their interactions, on multiple foraging metrics calculated from the RFID data and on pollen dry weight. Relative to honey bees, individual bumble bees made more foraging trips each day, resulting in a greater time spent foraging. A greater proportion of RFID tagged bumble bees foraged each day and bumble bees brought heavier pollen sacs to the hive compared to honey bees. Foraging bout duration did not vary between bee species and none of the foraging metrics varied among time periods or among sites. Both bee species brought heavier pollen sacs back to the hive at the beginning and the end of the flowering season. These results are discussed in terms of species differences in foraging strategies, size of individuals and colonies, and temporal variation in colony needs and resource availability.
Keywords
