Bacterial Entrapment by Honey Bees through Foraging

Anderson, K. E., Sheehan, T. H., Mott, B. M., Maes, P., Snyder, L., Schwan, M. R., Walton, A., Jones, B. M., & Corby-Harris, V.  2013.  Microbial Ecology of the Hive and Pollination Landscape:  Bacterial Associates from Floral Nectar, the Alimentary Tract and Stored Food of Honey Bees (Apis mellifera).  Public Library of Science ONE.  8(12):  1-16.

http://www.ncbi.nlm.nih.gov/pubmed/24358254

Many bacteria are associated with the honey bee alimentary tract.  These bacteria can be absorbed from the environment through the consumption of nectar from flowers.  Bacteria play an important role in regulating honey bee gut health, and they are not all detrimental to the welfare of the hive.  Worker bees deposit their honey and packed pollen within the honey comb of the hive.  The packed pollen is referred to as “bee-bread.”  Both of these sources can be cultured by researchers to determine the bacterial content.  Another indicator of bacterial consistency within individuals of a hive is the content of bacteria within each region of the honey bee gut:  foregut or crop, midgut, and hindgut.  Honey bees within the hive can be infected with bacteria from source of honey and bee-bread.  For these reasons, Anderson et al. 2013 have cultured bacterial samples from honey bee colonies in order to understand the bacterial associations honey bees make and their implications to individual and overall hive health.

                The honey bee hive as a whole can be labeled as a macro-organism made up of many individuals, honey, honey comb, and bee bread.  All of these elements have diverse temperature gradients, pH fluctuations, and other homeostatic elements.  This inconsistency provides variation in the bacterial diversity of the hive as well.  Anderson et al. 2013 studied nine different honey bee colonies in the Carl Hayden Bee Research Center in Tucson AZ.  They focused on the transient nature of bacteria in the honey bee crop and midgut with an emphasis on the differences among nectar sources.  Newly emergent bees were compared based on their exposure to honey and bee-bread, their exposure to older bees within the hive, neither, or both.  These emergent bees’ crops were sampled for bacterial consistency and compared with the bacteria found within pollen, bee-bread, honey, and older bee samples.  Bacterial were cultured on various media and their DNA signatures were determined using PCR (polymerase chain reaction).  The outcome of these experiments demonstrated that the emergent bees exposed to food sources (honey and bee-bread) were infected with a more diverse range of bacteria than random in-hive bees.  This indicated that the food sources had a greater effect than the individual to individual transmission of bacteria.

                Anderson et al. 2013 were able to refute their hypothesis of the importance of peer to peer transmission of disease and confirm the importance of environmental contribution of bacterial vectors.  Depending on the presence of proper bacteria in the nectar food sources of honey bees, bacteria could become associated with the macro-organism of the honey bee hive.  These sources could contribute to the alimentary health and therefore overall health of the hive.  Because honey bees are generalist consumers, farmers and cultivars can place strategically located nectar sources near hives to contribute to healthy hives.  These hives are mutually beneficial as they pollinate crops, native plants, and other plant species.  Healthy honey bee gut health can contribute to the functionality and diversity of the overall ecosystem.