Contribution of honeybee drones of different age to colonial thermoregulationHelmut Kovac, Anton Stabentheiner and Robert Brodschneider
Karl-Franzens-Universität Graz, Institut für Zoologie, Universitätsplatz 2, 8010 Graz, Austria
Received 8 May 2008 – Revised 23 October 2008 – Accepted 11 November 2008 - Published online 18 February 2009
Abstract - In addition to honeybee workers, drones also contribute to colonial thermoregulation. We show the drones' contribution to thermoregulation at 5 different experimental temperatures ranging from 15–34 °C. The frequency and the degree of endothermy depended on the drones' local ambient temperature and age. Location on brood or non-brood areas had no influence. The frequency of endothermic drones and the intensity of endothermy increased with decreasing temperature. 30% of drones of 8 days and older heated their thorax by more than 1 °C above the abdomen. The youngest drones (0–2 days) did not exceed this level of endothermy. Though young drones were less often engaged in active heat production, their contribution to brood warming was not insignificant because their abundance on the brood nest was 3.5 times higher than that of the oldest drones (13 days). Results suggest that the stimulus for the drones' increased frequency of heating at low experimental temperatures was their low local ambient air and/or comb temperature.
Key words: Apis mellifera / drone / thermoregulation / thermography
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