The Characterization of Apis mellifera Gut Microbiome Structure


Mahesh Karki

Document Type


Degree Name

Master of Science (MS)


Biological and Environmental Sciences

Date of Award

Spring 2023


The Western honey bees, Apis mellifera, have an essential role in pollination. They are responsible for the pollination of almost 16% of flowering plants and 400 agricultural plants contributing to almost $15 billion in the US economy. Along with their importance in pollination, honey production is another significant contribution of Apis mellifera. Because nurse bees gather pollen and nectar from a wide variety of flowers in the environment, they are exposed to a variety of factors including insects and parasites that might be infesting the plants. If such insects and parasites enter the bee hives, it could lead to colony loss. Colony Collapse Disorder (CCD), first noticed in 2006 in the United States, is a condition in which adult bees disappeared from the hives leaving only young broods and queens. CCD has become a long-term problem in apiculture. Pesticides, pathogens, and environmental factors can cause colonies to collapse. There is a need for more scientific research on honey bees (Apis mellifera) to counter the loss of colonies. There are a few research projects on honey bee gut microbiome structures conducted in the past, but most of them focus on a molecular level. This study examines viable microbiome populations in the honey bee gut of strong and weak hives through classical microbiological techniques followed by qPCR analysis. The selected hives were examined for environmental parameters including temperatures, humidity levels, predation, and honey and brood production. Based on these parameters, strong hives (SH) and weak hives (WH) were categorized. Nurse bees from two SH and two weak WH were collected, aseptically dissected, homogenized in phosphate-buffered saline (PBS), and inoculated onto LB and Blood agar. Bacterial colonies were examined for their morphology and Gram response. Colonies were also examined via qPCR in parallel. Both SH and WH had stable community structures during the summer and the fall. qPCR analysis showed that Firmicutes and Bacteroidetes had higher concentrations based on lower average Cq values. The study suggests that the viable honey bee gut microbiome structure has higher concentrations of Firmicutes, Bacteroidetes, and moderate levels of Gammaproteobacteria, Actinobacteria and Alphaproteobacteria, and is less affected by the different environmental parameters.


DongWon Choi

Subject Categories

Biology | Life Sciences