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a b s t r a c tWorldwide, wild bumble bees (Bombus spp.) are experiencing marked declines, with potentially up to 11% of species currently under threat. Recent studies from North America suggest that disease transmission from commercially reared bumble bees to wild populations has led to marked range contractions in some species. In Europe, data on the prevalence of pathogen spillover from commercial to wild bumble bee populations is lacking, despite the widespread production and transport of hives within the EU since the early 1980s. We determined the permeability of cropping systems to commercial bumble bees, and quantified the prevalence of four pathogens in commercial Bombus terrestris hives and adjacent conspecific populations at increasing distances from greenhouses in Ireland. Commercial bumble bees collected from 31% to 97% of non-crop pollen, depending on the cropping system, and hives had markedly higher frequencies of two gut parasites, Crithidia spp. and Nosema bombi, compared to adjacent populations, but were free of tracheal mites. The highest prevalence of Crithida was observed within 2 km of greenhouses and the probability of infection declined in a host sex-and pathogen-specific manner up to 10 km. We suggest implementing measures that prevent the interaction of commercially reared and wild bumble bees by integrating the enforcement of national best management practices for users of commercial pollinators with international legislation that regulates the sanitation of commercial hives in production facilities.

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This short article presents loss rates of honey bee colonies over winter 2017/18 from 36 countries, including 33 in Europe, from data collected using the standardized COLOSS questionnaire. The 25,363 beekeepers supplying data passing consistency checks in total wintered 544,879 colonies, and reported 26,379 (4.8%, 95% CI 4.7-5.0%) colonies with unsolvable queen problems, 54,525 (10.0%, 95% CI 9.8-10.2%) dead colonies after winter and another 8,220 colonies (1.5%, 95% CI 1.4-1.6%) lost through natural disaster. This gave an overall loss rate of 16.4% (95% CI 16.1-16.6%) of honey bee colonies during winter 2017/18, but this varied greatly from 2.0 to 32.8% between countries. The included map shows relative risks of winter loss at regional level. The analysis using the total data-set confirmed findings from earlier surveys that smaller beekeeping operations with at most 50 colonies suffer significantly higher losses than larger operations (p < .001). Beekeepers migrating their colonies had significantly lower losses than those not migrating (p < .001), a different finding from previous research. Evaluation of six different forage sources as potential risk factors for colony loss indicated that intensive foraging on any of five of these plant sources (Orchards, Oilseed Rape, Maize, Heather and Autumn Forage Crops) was associated with significantly higher winter losses. This finding requires further study and explanation. A table is included giving detailed results of loss rates and the impact of the tested forage sources for each country and overall.