Diapause and Non-delayed Eusociality in a Univoltine and Basically Solitary Bee, Ceratina japonica (Hymenoptera, Anthophoridae) : II. Non-delayed Eusociality Induced by Juvenile Hormone Analog Treatment

Ceratina japonica is a univoltine and basically solitary bee, but sometimes produces semisocial or delayed eusocial colonies. This study aims at the induction of non-delayed eusociality in this bee, which is adopted by most temperate social insects but is incompatible with the univoltine life cycle. The second brood rearing by the mother was induced by removing her brood of immatures. Juvenile hormone analog was topically applied to pupae and prepupae removed from cells and their growth was accelerated by heating. Daughters who newly emerged were returned to the mother's nests. Diapause termination was confirmed in 6 out of 20 colonies and non-delayed eusociality was formed in 4 colonies. In 2 of these colonies daughters acted as workers, but in the other 2 as queens, showing an epigenetic caste flexibility. Observed behaviors of key tasks were described and discussed.