Behavioural features of a periodic form of massed flight activity in the giant honeybee Apis dorsataG. Kastberger, O. Winder, T. Hoetzl and G. Raspotnig
Department of Neurobiology, Institute of Zoology, Karl-Franzens University Graz, A-8010 Graz, Austria
Abstract - A periodic form of massed flight behaviour in Apis dorsata was studied by video recording and image analysis. Two to three times a day the nest turns from the quiescent state into a high level of commotion for about 5 min. The vertical body orientations of the bees in the curtain then become more and more 'disordered'. In one nest, the total percentage of bees which flew off was less than 20% and the maximum number of hovering bees at a moment was 2-3% of the bee colony. Half of the curtain bees in the surface layer changed their position. The median moving index was below 0.3 mm/s in the quiescent condition and it rose up to 1.0 mm/s during massed flight activity. Our observations indicate that this kind of massed flight is quite different from the great defecation activities reported previously. Although there are diverse forms of massed flight activities in A dorsata, we found that this form of massed flight actitivity causes the periodical rearrangement of the roofing layer of curtain. On a Banyan tree we counted more than 100 nests of A dorsata and observed that nests of different areas of the tree did not supply bees or mass activity simultaneously.
Key words: Apis dorsata / massed flight activity / orientation flight / image analysis / India