GRAYSON, D. L.*; HARRISON, J. F.; FEWELL, J. H.; Arizona State Univsersity; Arizona State Univsersity; Arizona State Univsersity: Foraging Effort and Metabolism in European and African Honey Bees
African honey bees (Apis mellifera scutellata) are one of the most successful invasive species known, for they have spread from Southern Brazil throughout the Americas in less than 50 years. During their spread they have out-competed, hybridized with, and eventually replaced existing European honey bee populations (mainly Apis mellifera mellifera). The success of the African honey bee is largely due to faster colony growth, and this growth is dependent upon obtaining more resources, in particular pollen. Little is known about how African honey bees achieve a higher rate of pollen collection, but one proposed mechanism is that African honey bees collect more pollen by greater individual foraging effort. A line of evidence that suggests this is that African honey bees have repeatedly been found to have higher mass-specific metabolic rates. Assuming equal efficiency, that higher metabolic rate will translate into increased power output which we should see in various aspects of foraging effort. This study determined whether co-fostered African and European honey bees differed in several aspects of foraging effort including: number of trips per hour, trip length, load size, and percentage of pollen foragers. To characterize the relationship between metabolism and foraging effort, we also looked for correlations between these aspects of foraging effort and metabolism. Our data show that even though African foragers had higher mass-specific metabolic rates, they did not show increased foraging effort in the majority of variables measured. Additionally, no strong correlation existed between metabolism and aspects of foraging effort. These data show that African bees are using a mechanism other than increased foraging effort to collect more pollen, and cast doubt on the validity of our assumption of equal efficiency. Supported by NSF IBN 093410 to JHF, JFH, & GJH.
