Winter honeybee colony mortality in France: Results from a retrospective national survey
Résumé
Since 2018 and following reports of significant honeybee colony losses during winter 2017-2018 from several regions in France, a retrospective national survey is launched every year to estimate winter mortality rate and to record the opinion of beekeepers on their winter losses and the possible causes along with information on varroa management and wintering preparation. The survey was conceived in the framework of the national platform on epidemiosurveillance in animal health at the request of the French Ministry of Agriculture and Food. An online questionnaire is sent each spring to beekeepers registered in the national list the previous year and who agreed to be reached by mail. The 2021-2022 survey took place from March 9th to May 2nd and was sent to 64 361 beekeepers registered at the end of 2021. The participation rate was of 32.4 % (20 858 respondents) namely the higher rate since the start of the survey (30.7, 19.1, 15.3 and 26.4 in 2018, 2019, 2020 and 2021 respectively). After consistency analysis with the national list of beekeepers and identification of duplicates and nonsense the final dataset was of 18 952 respondents. Winter colony mortality rate was weighted by the response rates of each bee operation category (less than ten colonies, ten to 49 and more than 50 colonies) in each French department. The national average mortality rate was 26.75% [25.9-27.6] for winter 2021-2022 considering all losses and 18.1% [17.4-18.8] considering only colony mortality. Winter mortality rate was lower the previous year 29.4% [28.3-30.4]. A similar trend was observed for each bee operation category. On a geographic level, a cluster of departments with rates higher than 30% was observed in Center East compared to 2021 where it was in South West. Results should be used taking into account bias of the survey (memorisation of respondents, measurement of mortality, selection of respondents…). This survey enables to have an image of French winter situation that could be further explored at the local level. Mortality results might change as analysis is under way. Analysis of other variables of the questionnaire will come.