Associate Professor Tufts University, United States
Background/Question/Methods
Understanding how the behaviors of insect pollinators are affected by environmental change is critical to the development of effective conservation strategies. Honey bees are perhaps the best studied insect pollinator due to their economic and cultural importance. Of particular interest are the wide variety of mechanisms honey bees use for thermoregulation, such as fanning cool air currents around the hive and careful selection of insulated nest sites. These behaviors help honey bees remain active through both winter freezes and summer heatwaves, and may allow them to more readily deal with the ongoing climate crisis. While the mechanisms honey bees use to manage acute heat stress are well studied, how they manage chronic heat stress is less well understood. One possible mechanism for reducing the effect of chronic heat stress is the rearrangement of comb stores to protect thermosensitive brood. We placed heating pads set to 42°C 8 hours/day and 32°C 16 hours/day on the left and right interior wall of ten Langstroth hives, and measured the quantity and location of honey, nectar, pollen, and brood within each hive after 0, 3, and 6 weeks of heating.
Results/Conclusions
We found that the comb arrangement of heated hives diverged significantly from that of unheated controls. While overall brood quantity remained unchanged, brood were significantly less clustered in the center of heated hives. This indicates that honey bee colonies do not reduce the rate of ovipositing in response to dangerous temperatures, but do modify the location of ovipositing. Additionally, food stores were significantly reduced in heated hives, which indicates workers may have been consuming more honey and nectar in order to facilitate active cooling. To our knowledge, this study is the first to show that temperature gradients play a role in how honey bees arrange their comb contents in full sized hives. This study likely has implications on honey bee’s ability to cope with a rapidly changing environment, and can be used to facilitate the creation of new and effective management strategies.
