The hidden power within: Using the simple, specialized bee microbiota to examine host-symbiont interactions and health in honey bees
Microbial Ecology and Applied Microbiology
Final Report Abstract
The honey bee is because of the association with humans, it’s ecological and economical relevance and eusociality widely studied. Recently, it also became due to it’s simple, yet stable and functionally relevant adult microbiome and the system’s tractability one of the model systems in host-microbiome research. Using the honey bee system, I could gain diverse fundamental insights into host-microbiome relationships, specifically under stress factors and during development. I enjoyed using methodological combinations of different sequencing strategies on field or lab samples as well as controlled experiments including rearing techniques. I was able to bring experimental proof that the larval and adult microbiome stages in honey bees are effectively decoupled. From a host-microbiome point of view, holometabolous insects face a challenge due to the dramatic switch in e.g. host physiology, diet and ecosystem during development. In honey bees the two microbiome stages were assumed to be decoupled. However, this has never been proven. I created in-vitro reared larvae which showed different microbiome compositions and quantities as well as gene expression profile differences in comparison to natural hive controls. Besides strong early variations, no differences in adult microbiome, nor gene expression were observed indicating that pupation effectively separates the two life stages largely overriding early variability. This demonstrates that a strategy of reliable vertical microbiome transfer as shown in social honey bees can help to overcome early life disturbances. Our modern world is characterized by rapid anthropogenic change with widely applied agrichemicals being a new and drastic selection pressure to which organisms must respond. We interestingly detected different chemical-induced effects on host phenotypes which were transmitted trans-generationally by different epigenetic mechanisms. Running lab experiments under chemicals with microbiome transfer across worker generations and a final functional test under high stress in naïve hosts allowed to disentangle microbiome responses from direct host responses. Antibiotics disturbed the microbiome and a negative effect on host health was vertically inherited when transferring this microbiome to later generations. Under a fungicide the opposite was the case and a pre-exposed microbiome caused higher resistance. I was surprised getting the same result when filtering out the microbial cells prior transfer. Taking a deeper look, the same transferable, protective effect was observed when simply allowing exposed bees to interact with newly emerged ones. Even the third generation, which is the second generation of bees never in contact with the chemical, showed the higher resistance. This indicates that honey bees socially exchange molecules which help to prime the next worker generations to be more resistant against abiotic stressors present in the environment. I strongly believe it to be our responsibility as scientists not only to conduct research, but to also communicate this to the public to educate and if possible offer counsel. I was one initiator of the Okinawa “Honey & Coral” project which is in collaboration with Onna Village Office and local beekeepers. It aims to 1. Use honey bees to encourage local farmers to plant diverse flowers to prevent red soil erosion which is the main cause of coral bleaching, while at the same time provide economical security. 2. Educate the local community about environmental protection and sustainable agriculture. 3. Connect OIST and the local community, making research accessible. Since then, we had many public, joint events (e.g. flower planting with kids, open campus day, press conferences) which appeared at least six times across three different Japanese newspapers and two local TV News channels.
Publications
- (2020) Varroa destructor: A Complex Parasite, Crippling Honeybees Worldwide. Trends in Parasitology, 36(7), 592-606
Traynor, K., Mondet, F., de Miranda, J., Techer, M., Kowallik, V., Oddie, M., Chantawannakul, P., McAfee A.
(See online at https://doi.org/10.1016/j.pt.2020.04.004)
