Pollinating Agents of Eucalyptus citriodora Hook. –Insects or Wind?

Abstract

This study was conducted to evaluate the mode of pollination of Eucalyptus citriodora in Santiniketan, West Bengal, India. Ten trees were marked for the present investigation. Visits were made periodically to record various phenological events of the inflorescences and flowers, and the behavioural patterns of insects at the flowers. The rate of anthesis was recorded using tagged inflorescences. E. citriodora flowers from December to January. The tree is self-compatible, apomixis is absent, fruits are set through autogamy and allogamy. Eighteen different insect species were recorded at the flowers foraging for nectar and pollen. All the insect visitors were diurnal in nature. Their visiting time, mode of visit, forage nature, and time spent on flower varied with each other. The inefficiency of the visitors made the plant into anemophilous nature. Fruit set was unaffected when the insects were excluded from visiting the flowers. Flower and pollen anthesis, and pollen release took place during day time. Nocturnal pollen release was not observed. The shifting of the pollination system might be viewed as one of the adaptive mechanisms for tropical conditions.