Patterns of endothermy in bumblebee queens, drones and workers

Abstract

1. The thoracic temperatures (TTh) of captive Bombus edwardsii queens and drones from the current year approached ambient temperatures (TA) at night, but warm-up was frequent throughout the day. 2. A Bombus vosnesenskii queen which had initiated nest building maintained TTh nearly continuously between 37.4 and 38.8 °C at night and in the daytime. On the other hand, the TTh of an overwintered queen which was not "broody" was close to TA (about 22 °C), except when the bee walked from the nest box and fed on sugar syrup, when TTh approached 40 °C. 3. Workers and queens applied themselves closely to cocoons and heated them by body contact. The temperature of the cocoons declined when the attending workers depleted the honey in the nest. 4. Bees achieved a large difference between TTh and TA while being stationary when no wing movements were visible. Thoracic temperature subsequently declined when they were made to fly in place while suspended from the thread-like thermocouple leads. 5. Workers of B. edwardsii maintained a mean TTh of 37.3 °C while foraging for nectar from Arctostaphylos otayensis at dawn when there was frost on the ground and TA near the flowers was 2 to 3 °C. © 1972 Springer-Verlag.