Summer Heat Impacts on Honey Bee (Apis mellifera) Hive Populations

Honey Bee (Apis mellifera) populations are being threatened by several environmental stressors. Climate change induced temperature extremes pose a high risk to agriculture and terrestrial ecosystems. Specific threats of climate change affect honey bee brood rearing because honey bee brood need narrow ranges in temperature otherwise there can be negative effects posed on development. Throughout this experiment we tested whether colony size affects thermoregulation. We hypothesized that smaller colonies would struggle to regulate in-hive temperatures in comparison to larger colonies. To test this, temperature loggers were placed in each hive at the brood center, brood edge, and periphery to log temperatures in the summer months of May to September in Arizona. Day and night temperatures were separated for each logger and the average, median, max, and min temperatures were taken for every two-week period wherein the colony population was assessed. For this experiment, we subtracted the min temperature from the max temperature of the final two-week period to assess differences in colony thermoregulatory capability. Overall, smaller colonies struggled to maintain in-hive temperatures in all three areas measured.