Thermoregulation dynamics in commercially reared colonies of the bumblebee Bombus terrestris

Thermoregulation, that is, the active control of temperature, is key to ensure proper brood development in both wild and captive bumblebee nests. In this study, thermoregulation dynamics were assessed relative to colony age and ambient temperature using commercially reared Bombus terrestris L. (Hymenoptera, Apidae, Bombus) colonies. We observed a positive relationship between brood and nest temperatures in response to ambient temperature. Thermoregulation investment (by either brooding or fanning) was lowest at brood surface temperatures between 33 and 34 °C and ambient temperatures between 28 and 32 °C. Brood temperature was less stable and thermoregulation investment higher in younger colonies, especially at lower ambient temperatures. Furthermore, queens initiated colonies sooner and colonies developed faster when kept at an ambient temperature of 29 °C as compared to 24 °C. Our results suggest that ambient temperatures are ideally kept between 29 and 31 °C.