Surveillance of Belgian honeybees colonies mortality 2017-2018 [1]
In short
An alarming mortality of honeybee colonies (Apis Mellifera) has been reported in many countries since early 2000. In the recent European Epilobee [2] project, the honeybee colonies mortality in Belgium was the highest among the participating countries in 2012-2014. Our Veterinary epidemiology [3] service provides epidemiologic support to the Belgian Federal Agency for the Security of the Food Chain [4] in a recurrent survey of bee mortality. In this project, we describe and monitor the honeybee colony mortality and its spatio-temporal variation across Belgium.
Project description
In this project we describe the honeybee colony mortality monitoring in Belgium and its variation in time (between three visits) for 2017-2018.
According to European Union regulations and using a 2-stage random sampling strategy, 20 apiaries in each Belgian Province and up to 6 hives by apiary were selected among the 6.000 beekeepers officially recorded in Belgium.
Within 174 apiaries (out of 200 selected apiaries), 3 visits were conducted:
- the first one in Fall 2017, when the colonies were preparing for winter
- the second in Spring 2018, after bees started foraging
- the third during the Summer 2018, the active season.
The field survey included direct observations, interviews and measurements performed by trained FASFC inspectors. The questionnaire provided information regarding:
- colony attributes: such as colony mortality, demography, and detection of Varroa Destructor mites
- beekeeping management practices: such as beekeepers experience, number of managed colonies, Varroa Destructor management.
The over winter weighted colony mortality in 2017-2018 was estimated at 23.8% (95% Confidence interval (95%CI): 21.7%-26.1%) for Belgium.
Further risk factors analysis and ranking is now ongoing to check if risk factors and ranking are identical to those identified during previous (2016-2017) winter mortality estimations (29.3%; 95%CI: 23.2%-36.0%). In this study based on Random Forest modelling, risk factors were identified and ranked (by decreasing order) using the Gini impurity criterion:
- Varroa Destructor level of infection
- density of beekeepers in the municipality
- location of the apiary (municipality)
- apiary size (count of hives)
- demographical indicator before winter (vitality)
- bees subspecies
- beekeeper experience.
As a partner in a continuous improvement process, our Veterinary epidemiology [3] service is now supporting the FASFC [4] to refine and adapt the surveillance inquiry form which will be proposed to the beekeepers during the coming surveys.
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