WP4 – Bee diseases and pathogen transmission
Diseases immensely contribute to colony losses in honeybees worldwide. The parasitic mite Varroa destructor and the viruses transmitted by it (deformed wing virus, black queen cell virus, acute bee paralysis virus, slow bee paralysis virus, sacbrood virus) are of greatest concern, but the list of honeybee pathogens comprises various infectious agents, such as fungi Nosema apis, N. ceranae, and Ascosphaera apis, bacteria Paenibacillus larvae and Melisoccoccus plutonius, and trypanosomatids Crithidia mellificae and Lotmaria passim. Many of honeybee associated diseases have been recently found in wild bees, although the direct impact on their health status remains unclear. With the increasing number and range of man-managed honeybee hives, a risk of pathogen dispersal into the wild bee communities arises, and can possibly be aggravated by increased honeybee density. Moreover, little is known about transmission routes (intra- and interspecific) of these pathogens. Flowers as transmission hubs are considered the most plausible route, but the studies on the influence of flower abundance on pathogen prevalence and spread, especially combined with agricultural measures, are scarce and often present contradictory results.

During the project, the prevalence of pathogens will be evaluated in experimental colonies of honeybees and bumblebees as well as in wild bees collected from the landscapes. In the consecutive year, honeybee density will be increased to examine the impact of honeybee density on pathogen prevalence. The flower-transmission hypothesis will be tested, with special impact put on the potential of morphologically different flower species and different flower abundance levels in augmentation of pathogen dispersal.

The outcomes of our study will shed light on pathogen transmission routes and pathogen spillover from honeybees to wild bees. With the broad gradient of landscapes, differing in flower, organic farming and semi-natural habitats abundance, our results will be highly measurable and applicable to various regions.