Early gut colonizers shape parasite susceptibility and microbiota composition in honey bee workers

Authors: SCHWARZ, RYAN - Fort Lewis College; MORAN, NANCY - University Of Texas; Evans, Jay

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2016
Publication Date: 12/9/2016
Citation: Schwarz, R., Moran, N., Evans, J.D. 2016. Early gut colonizers shape parasite susceptibility and microbiota composition in honey bee workers. Proceedings of the National Academy of Sciences. 113(33):9345-9350.

Interpretive Summary: The newly described gut parasite Lotmaria passim is a widesprad and important factor in honey bee health. In the hopes of identifying control methods for this and other honey bee disease agents, we studied interactions between this parasite and bacteria carried byt honey bees. One common bacterial species was found to affect parasite lod. Surprisingly the effects were at times positive for bees and at times negative. The results show that the development of bee probitoics should be done with caution and with testing against a range of honey bee parasites. Novel disease controls are needed for honey bees and probiotic supplements offer one avenue for beekeepers to improve colony health and survivorship.

Technical Abstract: Microbial symbionts living within animal guts are largely composed of resident bacterial species, forming communities that often provide benefits to the host. Gut microbiomes of adult honey bees (Apis mel- lifera) include core residents such as the betaproteobacterium Snod- grassella alvi, alongside transient parasites such as the protozoan Lotmaria passim. To test how these species affect microbiome compo- sition and host physiology, we administered S. alvi and/or L. passim inocula to newly emerged worker bees from four genetic backgrounds (GH) and reared them in normal (within hives) or stressed (protein- deficient, asocial) conditions. Microbiota acquired by normal bees were abundant but quantitatively differed across treatments, indicating treatment-associated dysbiosis. Pretreatment with S. alvi made normal bees more susceptible to L. passim and altered developmental and detoxification gene expression. Stressed bees were more susceptible to L. passim and were depauperate in core microbiota, yet supplemen- tation with S. alvi did not alter this susceptibility. Microbiomes were generally more variable by GH in stressed bees, which also showed opposing and comparatively reduced modulation of gene expression responses to treatments compared with normal bees. These data provide experimental support for a link between altered gut microbiota and increased parasite and pathogen prevalence, as observed from honey bee colony collapse disorder.