Thermal investigations of a nest of the stingless bee Tetragonisca angustula Illiger in Colombia

Thermal investigations were performed in Colombia on a colony of the stingless bee Tetragonisca angustula by means of thermometry and direct calorimetry. To this end, a nest with approximate 5000 individuals was collected in the field and transferred to a twin calorimeter, where the bees continued their normal life and development. Two camping boxes (Poor Man's Calorimeter, PMC) with Peltier elements as cooling systems were used as a differential system. Each box had a volume of 8 L and a sensitivity of 19.2 mV W−1. The PMCs were modified to give forager bees a free access to the environment. The thermal situation within the colony was monitored calorimetrically and thermometrically. 10 kΩ of NTC resistors were distributed at special points of the brood combs, storage pots and involucrum. The thermometric and calorimetrical signals were recorded continuously over 3 months by a four-channel data logger.