CORDIS - EU research results

How to help the hive? Incidence and impact of heritable microbes on bee health

Periodic Reporting for period 2 - BeeSymOverSpace (How to help the hive? Incidence and impact of heritable microbes on bee health)

Reporting period: 2018-06-01 to 2019-05-31

Honey bees provide both economic and societal benefits, from the honey and other commodities that they produce to the pollination services they provide. The loss of honey bee colonies and the current threats to their health are of considerable concern to bee-keepers and biologists alike.This project seeks to examine how a particular aspect of honey bee biology – the symbiotic microbiome – impacts upon honey bee health. Studies in other systems reveal heritable microbes as important modulators of disease susceptibility, for instance protecting against virus or other natural enemies. This project utilizes the extensive network of bee samples across the US and UK to establish geographical patterns of heritable microbe presence in bees, and links to apiculture practice. It then uses state of the art transcriptomic and genomic approaches to establish the links between Arsenophonus, a heritable symbiont known in bees, and bee health. It then combines with professional agencies responsible for bee health to use these results to modify apiculture practice to establish better bee husbandry. Aside the research science completed, the project will provide training in state of the art genomic technologies and translation from discovery to applied science. It further transfers the training gained to the Liverpool return phase host, both in discovery science and application.
WP1 involved the assessment of incidence of heritable symbionts and wider microbiome of bees across the USA and UK. Arsenophonus and Spiroplasma microbes were detected in USA honey bees, with Arsenophonus widespread (with obvious spatial patterns, and some evidence of seasonality); Arsenophonus was also seasonally common int the UK. We have succeeded in culturing, sequencing and formally describing the Arsenophonus symbiont as a novel species for onward work by ourselves and others. A wider look at the microbiome of bees has also been completed with respect to gaining a view on the effects of apiculture on bee microbiome - this involves comparison of feral honey bees to those in apiculture. Analysis of these samples is ongoing.

WP2 is based around the impact that heritable symbionts have in their honeybee hosts. We have completed the genome sequence for Arsenophonus from bees, alongside its first isolation in cell free culture and formal description is ongoing, with Dr Burritt and lab members. Experimental analysis of the impact of Spiroplasma and Arsenophonus on bee survival, and also susceptibility to other pathogens (Nosema, deformed wing virus) has been completed, and indicates these are not primary pathogens, in that healthy bees were able to clear infection with little ill effect. However, impacts in unhealthy bees are suspected, making these microbes opportunistic pathogens that may be important under colony stress. We have also completed an experiment examining how these microbes affect host immune function directly.

WP3 involves interface with users; our results indicate these symbionts are not key to bee health, but may emerge as important agents in combination with other external issues (pesticides, mite attack). Thus husbandry to avoid these attacks are key in minimizing deleterious impacts of these microbial symbionts. We have met with representatives of fera (food and environment research agency) and the national bee unit (part of UK DEFRA) to outline the results and their consequences for husbandry. We have also written a report for Bee Disease Insurance, a commercial company that insures beekeepers against losses from hive declines, with respect to our work.

Dissemination activities have additionally involved the academic community, and school children in the UK.

Overall, our work provides the first comprehensive picture of Arsenophonus and Spiroplasma in honey bees, and their impact on the host.
Culture of the Arsenophonus from bees was achieved for the first times, alongside the genome sequence and microbiological characerization. This allows its formal description as a new associate of honey bees, and onward study by the wider community.

Description of the geographic and temporal basis of the symbiosis is completed for the first time, alongside analyses of patterns of infection. These demonstrate profound seasonal dynamics, with Arsenophonus increasing towards autumn, and Spiroplasma in the Spring. Thus these microbes impact honey bees at different times of year.

Impact of Spiroplasma and Arsenophonus on bee health were determined under laboratory assay, alongside impacts on host transcriptional profile. These demonstrate neither is an important associate of healthy bees, though they may be pathological in unhealthy or stressed hives.

Together, these have demonstrated these symbionts are common in honey bees, have seasonal incidence, but are not major impactors on health in the 'healthy hive' scenario.
A honey bee being fed with Arsenophonus - will this make the bee sick or healthier?