Losses of Western honey bee colonies (Apis mellifera L.) represent a globally significant phenomenon with profound ecological and economic implications, yet the underlying causes remain a subject of ongoing investigation (Insolia et al., 2022). This study aimed to evaluate colony losses following the 2022–2023 wintering season in Ukraine in the conditions of the ongoing war, as part of the annual international monitoring effort coordinated by the COLOSS. The survey was conducted employing the standardized COLOSS protocol and covered all physiographic zones of Ukraine except for the Crimean Mountains, with data from 751 valid protocols synthesized for analysis.
The average overall loss rate after the 2022-2023 wintering season in Ukraine was 10.8 %, slightly exceeding the previous year's rate (8.9% after the 2021-2022 wintering season). Notably, the loss of bee colonies (6.55 %) nearly doubled compared to the previous year (3.72% after the 2021-2022 wintering season), while losses due to unsolvable queen problems (3.07 %) remained consistent with the previous year (3.07% after the 2021-2022 wintering season), and losses attributable to adverse natural phenomena (1.27%) decreased by over 1.5 times (2.08% after the 2021-2022 wintering season). The highest overall loss rate of bee colonies was observed in the steppe zone (17.0%), with significantly lower losses in the Ukrainian Carpathians (7.3%), mixed (8.6%), and broad-leaved (9.0%) forest zones. The distribution of loss components across different physiographic zones mirrored the national trend: dead/missing colonies (4.19 % - 10.13 %), unresolved queen issues (2.16 % - 5.24 %), losses due to adverse natural events (0.74 % - 1.85 %). Among the reported characteristics of lost colonies, starvation-induced mortality (19 %) and unexplained bee deaths (17.8 %) were most frequently cited, while bee disappearances (9.1%) and dead bees within hives despite available food (10.4 %) were less common.
Over 12% of analysed beekeeping operations were situated in areas affected by armed conflict, with some experiencing direct damage to apiaries (2.4%) and associated equipment (0.1% - 0.5%). Once again, the inverse relationship between apiary size and total losses was reaffirmed, though no correlations between colony losses and migratory beekeeping were identified.
76.4 % of respondents monitored their colonies for Varroa mite infestations, with 97.5% treating for varroosis. Notably, 19.6% of respondents treated their colonies without prior monitoring of mite infestation levels. Amitraz-based veterinary products remained the most commonly used acaricides in Ukraine, applied through fumigation or aerosols (32.2 %) and strips (21.7 %). Additionally, 22.9 % of surveyed beekeepers practiced drone brood removal. The applying of traditional beekeeping methods increased (10,4% this year, compared to 2.18 % and 3.60 % before the wintering seasons of 2020-2021 and 2019-2020, respectively).
Keywords: honey bee, Apis mellifera, colony losses, monitoring, mortality, beekeeping, varroosis
