Water homeostasis in bees, with the emphasis on sociality.

Avenues of water gain and loss in bees are examined here at two levels of organisation: the individual and the colony. Compared with the majority of terrestrial insects, bees have a high water turnover. This is due to their nectar diet and, in larger species, substantial metabolic water production during flight, counteracted by high evaporative and excretory losses. Water fluxes at the colony level can also be very high. When incoming nectar is dilute, honeybees need to remove large volumes of water by evaporation. On the other hand, water is not stored in the nest and must be collected for evaporative cooling and for feeding the brood. Water regulation has many similarities at individual and colony levels. In particular, manipulation of nectar or water on the tongue is extensively used by bees to increase evaporation for either food-concentrating or cooling purposes.