Some social and dietary prerequisites of oocyte development in Vespa orientalis L. workers

Removal of the queen induced ovarial development in workers of the Oriental hornet, Vespa orientalis L. This occurred in workers kept in groups and mainly during the first five days after removal of the queen. Cooling of the workers or their subjection to a protein-free diet inhibited their ovarial development, but in either case, the inhibition disappeared once normal conditions were restored. For workers living in a group, ovarial development occurred only in workers of high hierarchal rank. However, the ovaries developed in all workers which were isolated singly after having lived in a group. On the other hand, inhibition of ovarial development occurred in about 50% of workers isolated singly from the moment of emergence, which suggests that social contact acts as a releasing stimulus for ovarial development in queenless hornet workers. Development of the ovaries was observed also in worker groups prevented from building, and the connection between building and ovarial development is discussed.