One at a time, please.
At the individual level, the mechanisms of thermoregulation in bees are not well understood. However there are some identified processes which act to retain heat inside the thoracic cavity, or lose heat across the skin surface. Three basic mechanisms allow the necessary thoracic temperatures to achieve high power production required for flight. These mechanisms balance heat gain and heat loss, and are convection, evaporation and metabolic heat production (Roberts & Harrison 1999).
Species Dependent mechanisms
Which mechanisms a bee uses is dependent on the species. For example. the evaporative heat loss of Apis mellifera is proportional to increases in ambient temperatures higher than 33°C, indicating that evaporation is important in preventing overheating. One mechanism by which this is achieved is through the regurgitation of contents from their honey stomach, forming a droplet on the outer surface which then evaporates (Cooper and Schaffer 1985).
During flight, A.mellifera and Centris pallida decrease their metabolic rate when ambient temperatures increase, independent of aerodynamic requirements. Other bees, for example bumblebee species, can vary convective heat loss by actively distributing thoracic heat during flight to the abdomen, where the surface is not insulated by bristles (Heinrich & Vogt 1993).
- Convection: a mechanism of heat production or loss through the transfer of heat by the movement of air or liquid moving past the body.
- Evaporation: a mechanism of heat loss only, in which a liquid is converted to a gas.
- Metabolic heat production: a mechanism by which body temperature increases with metabolic rate.
Species Dependent mechanisms
Which mechanisms a bee uses is dependent on the species. For example. the evaporative heat loss of Apis mellifera is proportional to increases in ambient temperatures higher than 33°C, indicating that evaporation is important in preventing overheating. One mechanism by which this is achieved is through the regurgitation of contents from their honey stomach, forming a droplet on the outer surface which then evaporates (Cooper and Schaffer 1985).
During flight, A.mellifera and Centris pallida decrease their metabolic rate when ambient temperatures increase, independent of aerodynamic requirements. Other bees, for example bumblebee species, can vary convective heat loss by actively distributing thoracic heat during flight to the abdomen, where the surface is not insulated by bristles (Heinrich & Vogt 1993).