A pan-European epidemiological study reveals honey bee colony survival depends on beekeeper education and disease control

Reports of honey bee population decline has spurred many national efforts to understand the extent of the problem and to identify causative or associated factors. However, our collective understanding of the factors has been hampered by a lack of joined up trans-national effort. Moreover, the impacts of beekeeper knowledge and beekeeping management practices have often been overlooked, despite honey bees being a managed pollinator. Here, we established a standardised active monitoring network for 5 798 apiaries over two consecutive years to quantify honey bee colony mortality across 17 European countries. Our data demonstrate that overwinter losses ranged between 2% and 32%, and that high summer losses were likely to follow high winter losses. Multivariate Poisson regression models revealed that hobbyist beekeepers with small apiaries and little experience in beekeeping had double the winter mortality rate when compared to professional beekeepers. Furthermore, honey bees kept by professional beekeepers never showed signs of disease, unlike apiaries from hobbyist beekeepers that had symptoms of bacterial infection and heavy Varroa infestation. Our data highlight beekeeper background and apicultural practices as major drivers of honey bee colony losses. The benefits of conducting trans-national monitoring schemes and improving beekeeper training are discussed

Data: Temporal increase of Varroa mites in trap frames used for drone brood removal during the honey bee season

Varroa mites are highly attracted to drone brood of Apis mellifera as it increases the chances of successful reproduction. Therefore, drone brood removal (DBR) with trap frames is common practice among beekeepers in Europe and part of sustainable varroa control management. However, it is considered labor-intensive and there are doubts about the effectiveness of this measure. At present, it is mostly unknown how many mites a drone frame can carry at different times of the season and how many mites can be removed on average if this measure is performed frequently. Therefore, we sampled a total of 262 drone frames with varying proportions of capped cells (5-100%) from 18 different apiaries. Mites were washed out from brood collected from mid-April to mid-July using a standard method to obtain comparable results. We found that a drone frame carried an average of 71.5 mites (median), and with the removal of four trap frames, about 286 mites can be removed per colony and season. In addition, mite counts were significantly higher in June and July than in April and May (Tukey-HSD, P < 0.05). Our results suggest that DBR is effective in reducing Varroa destructor numbers in colonies, supporting the findings of previous studies on the efficacy of DBR. Although mite counts varied, we believe that increasing sample size over different seasons and locations could elucidate infestation patterns in drone brood and ultimately improve DBR as an integrated pest management tool for a wider audience of beekeepers

Risk indicators affecting honeybee colony survival in Europe : one year of surveillance

The first pan-European harmonized active epidemiological surveillance program on honeybee colony mortality (EPILOBEE) was set up across 17 European Member States to estimate honeybee colony mortality over winter and during the beekeeping season. In nine Member States, overwinter losses were higher and statistically different from the empirical level of 10 % under which the level of overwinter mortality was considered as acceptable with usual beekeeping conditions. In four other countries, these losses were lower. Using multivariable Poisson regression models, it was showed that the size of the operation and apiary and the clinically detected varroosis, American foulbrood (AFB), and nosemosis before winter significantly affected 2012-2013 overwinter losses. Clinically detected diseases, the size of the operation and apiary, and the non-participation to a common veterinary treatment significantly affected 2013 summer losses. EPILOBEE was a prerequisite to implement future projects studying risk factors affecting colony health such as multiple and co-exposure to pesticides