Effects of DWV and temperature on the metabolic rate of honeybees, Apis mellifera

Metabolic rate serves as a biomarker of physiological function and health in organisms by providing information on energy expenditure and physical condition. Deformed Wing Virus (DWV) arrests translation of protein Nf-kB in honeybees (Apis mellifera), thereby impairing immune response cascades and affecting metabolic processes.  This study investigated the effects of administration of DWV and ambient temperature on the rate of oxygen consumption and metabolic rate in 5-day old honeybees.  Oxygen consumption was determined for 5 treatment groups using flow-through respirometry:  healthy bees at 35°C (control), healthy bees at 35°C injected with a saline solution (sham), healthy bees exposed to 15°C (temp), bees at 35°C injected with DWV (DWV), and bees exposed to 15°C and injected with DWV (DWV+temp). Mean oxygen consumption rates in the control and sham groups did not differ from one another, and were significantly higher than those in the temp, DWV, and DWV+temp groups. Oxygen consumption rates for the temp, DWV, and DWV+temp groups did not differ from one another. These results suggest that decreased ambient temperature and the presence of DWV both decrease the rate of oxygen consumption and therefore compromise the metabolic rate of honeybees, while the combination of decreased ambient temperature and DWV are not additive in suppressing metabolic function.  It is possible that cooler temperatures and increases in DWV viral loads in hives are factors that contribute to CCD by disrupting individual honeybee metabolic processes.