The hidden power within: Using the simple, specialized bee microbiota to examine host-symbiont interactions and health in honey bees

• Applicant: Dr. Vienna Kowallik
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Microbial Ecology and Applied Microbiology
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 398253496

All multicellular organisms are closely associated with diverse microbial communities, which have profound effects on their host's life history. This insight has revolutionized our understanding of animal biology. The ability to fully understand microbiomes with all the associated interactions would shed light on a new dimension of the ecology and evolution of organisms. Moreover, the from such an understanding derived ability of manipulating microbiomes, could be applied as a natural improvement method to diverse research areas such as health or agriculture. Yet, the complexity of microbiomes with interactions between members, and their consequences for hosts, make most host-microbiota systems difficult to study. The experimentally tractable system of the honey bee offers an ideal opportunity to fundamentally explore functions and interactions of symbionts on host fitness, as the associated microbial communities are small, specialized, and individually cultivable. I want to confirm that a key microbiome function is to protect the honey bee from environmental stressors, which also increases host fitness when invading new environments.First, I will take advantage of a historical, unique data set consisting of 3,800 honey bees sampled for more than a decade in the U.S. and Mexico, to generate a detailed picture of the internal microbiota by Illumina-sequencing of honey bee-associated bacteria and fungi. During this time, a hybridization event from introduced African with wild US-European bee lines occurred, leading to one of the most rapid, successful biological invasions known. Diverse genetic bee backgrounds in the same natural environment will allow me to examine how host genetics affect microbiomes in the field. As Africanized hybrids are more resistant to the same stress factors than European bees, I will identify microbial compositional differences in these lineages, which may have affected host fitness. I will confirm microbiome-mediated effects by experimentally transferring microbiomes and measure bee life history traits under important stressors like pathogens, pesticides and poor diets due to agricultural mono culture. Further controlled inoculation experiments using single and mixed microbe communities will reveal the function of each symbiont and its interactions on host fitness. The proposed study will give fundamental insights into host-microbiome function which will have analogs across the tree of life. Moreover, the knowledge acquired may enable us to improve the health of honey bees, which is declining worldwide.

• DFG Programme: Research Fellowships
• International Connection: Japan
• Host: Professor Alexander Mikheyev, Ph.D.