Decline of honey bee colonies remains a global problem. It may affect catastrophically both ecosystems and the global economy. Here we present the results of the fourth year of a research project on bee colony losses in Ukraine over winter 2017-2018, conducted in the framework of international monitoring coordinated by the non-profit honey bee research association COLOSS. Overall winter loss rate and the mortality rate over winter 2017-2018 were significantly lower compared to the previous year: overall winter loss rate – 11.3% (95 % СІ 10.0-12.6); mortality rate – 6.7% (95 % СІ 5.8-7.7); rate of colony loss due to unsolvable queen problems – 2.1% (95 % СІ 1.6-2.7) and due to natural disasters – 2.4% (95 % СІ 2.0-3.0). Likewise previous years, the highest losses were observed in small operations (with 50 or fewer colonies). The highest overall loss rate was observed in the Steppe zone, with the highest both mortality rate and losses due to natural disasters compared to the other physiographic zones of Ukraine. Minimum mortality was recorded from deciduous forests 5.6 % (95 % CI 4.4-7.2) and the Ukrainian Carpathians 5.5 % (95 % CI 4.2-7.2). Winter losses related to queen problems varied greatly with a minimum in the Forest-Steppe zone 0.71 % (95 % CI 0.3-1.5). 83.3% of beekeepers treated their colonies against Varroa. The r-rank correlation analysis identified two potential risk factors (no or only a few dead bees in or in front of the empty hive; dead workers in cells and no food present) which revealed a weak positive correlation with both mortality rate and the rate of losses due to unsolvable queen problems.

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Purpose. To estimate honey bee (Apis mellifera Linnaeus, 1758) colony winter loss rate for Ukraine after the winter 2019–2020 in the context of international COLOSS survey. Methods. Analysis of the results of the survey of Ukrainian beekeepers on A. mellifera colonies survival after the winter 2019-2020 by using the questionnaire developed by the coordinators of COLOSS international monitoring group. Unified approaches to data collection and statistical processing have been used. Valid protocols from 702 respondents from five physical-geographical zones of Ukraine have been analysed. Results. Honey bee colony winter loss rates for Ukraine after the winter 2019-2020 was 9.29%, the mortality rate was 5.41 %; the losses due to unsolvable queen problems – 2.19 %, and due to natural disasters – 1.69 %. The total losses in the steppe zone of Ukraine were 16.08%, significantly exceeding this indicator in the forest-steppe zone (8.94%), the zone of deciduous forests (6.73%) and the Ukrainian Carpathians (8.14%). The most common sign of dead colonies in Ukraine was the presence of a large number of dead bees in or in front of the hive (31.3 %) and unknown symptoms (37,3 %). The majority of Ukrainian beekeepers (50.7%) did not notice any difference in wintering of the colonies going into winter with a new queen in comparison with the old one. Among antivarroa drugs, the majority of respondents preferred products based on amitraz (fumigation – 50.8%, in plates – 15.7%) and flumethrin (20.0%). We confirmed statistically lower level of winter losses in colonies treated with amitraz (fumigation), whereas colonies treated with formic acid (long-term) had higher losses. Conclusions. Honey bee (Apis mellifera Linnaeus, 1758) colony winter loss rate for Ukraine after the winter 2019–2020 was 9.29% and decreased slightly compared to the last year (11.18%) and the year before last (11.26%). It was almost twice lower than the average for the countries participating in COLOSS international monitoring (18,1%) (Gray, 2021). The highest losses were observed in the steppe zone of Ukraine, whereas the lowest in the Ukrainian Carpathians. The smaller beekeeping operations with at most 50 colonies suffered significantly higher losses 12.66%) compared to medium and large ones (9.48% and 6.52%, respectively). The number of beekeepers treating colonies against varroosis was 90.6%, and all of them mentioned that they had pre-monitored the level of Varroa infestation.

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