Threshold Temperature for the Outdoor Flight Activity of Honey Bee,Apis mellifera under Overwintering Conditions

Recent overwintering honey bee mortality in South Korea has been attributed to various factors, including abnormal temperatures and honey bee mite infestations. The emptying hive during overwintering was considered due to the outdoor flights of honey bees without return during warmer temperature. However, no experimental evidence of flight activities during winter relative to the temperature conditions is available. This study monitored flight activities during winter and related to the temperature profiles to figure out the threshold temperature for the flight within the shade house and open field conditions. Honey bee flight activities were recorded above 9.3°C and increased as temperature rose. Most flights occurred under the rain- cover house condition, but rarely under shading. Shading has significant effects on reducing temperature variability. Food consumption during winter was significantly lower under the shaded condition than open field or rain-cover conditions, which imply lower energy expenditure due to lower temperature variability. Based on these results, we propose season-long and nation-wide flight monitoring relative to the temperature during the winter season to figure out the winter mortality patterns and shading to mitigate the temperature variability during winte.