Med. Weter. 68 (10), 626-629, 2012

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Kasperek K.
Impact of selected atmospheric factors on winter losses in Apis mellifera L.
Some of the bees in a winter cluster die during winter nesting and fall to the bottom board of the hive, accumulating as the so-called winter debris. The rest of the losses is accounted for by the insects that abandon the hive in winter – the out-fliers. In most studies to date, only bees from the winter hive debris have been analysed to determine the factors critical for adequate winter nesting. The author decided to examine the impact of selected atmospheric factors on both: winter within-hive mortality and winter out-flying mortality. Buckfast bees and M Augustowska Central European bees were investigated. Out-fliers (that had abandoned the hive) and bees from the winter hive debris were collected. Worker bees were counted in both groups. Altogether, 856 samples were analysed. Selected atmospheric factors were monitored during the experiment. It was found that winter out-flying is less dependent on atmospheric factors than winter within-hive mortality. The dependence was not universal but breed-specific. Moreover, during warmer winters in Poland there may be more winter out-flyers in proportion to within-hive fatalities.
Key words: Apis mellifera, winter within-hive mortality, winter out-flying of bees, atmospheric factors.