Pollination System of Aucuba japonica: A Pollination Experiment and an Observation of Floral Visitors

We studied the pollination system of a shrub, Aucuba japonica Thunb, by conducting a pollinator exclusion experiment (bagging and artificial pollination) and an observation of floral visitors. The fruit set was lower in the bagging treatments (either 1 mm or 3 mm mesh) than that under natural condition. Artificial pollination treatment with the bagging, however, did not decrease the fruit sets. Moreover, there was no difference in the fruit sets between 1 mm and 3 mm mesh treatments. These results suggest that A. japonica is mainly pollinated by insects. The main floral visitors were Coleoptera, mainly Cantharidae and Curculionoidae, and Nematocera, such as Sciaridae. It is concluded that A. japonica depends on opportunistic visitations by small generalist insects for pollination.