Diversity and Ecological Role of Insect Flower Visitors in the Pollination of Mangroves from the Indian Sundarbans

Sundarban Biosphere Reserve is one of the most important mangrove zones with a vast range of floral and faunal diversity. The present study explores the plant-pollinator relationship among four true mangrove plants, viz. Avicennia officinalis, Avicennia marina, Aegiceras corniculatum and Aegialitis rotundifolia, and also includes insect visitor diversity and foraging activities of common insect flower visitors of these plants with their efficiency as pollinators. Though each plant is self-compatible for pollination, the activity of flower visitors helped with superior reproductive success. Among the common five visitors, viz. Apis dorsata, Apis mellifera, Chrysomya megacephala, Danaus chrysippus and Micraspis discolor, A. dorsata showed the highest visitation rate (VR) for each plant and M. discolor showed the lowest VR but highest handling time (HT) in all the four mangrove plants. Each flower visitor showed significantly different VR among the plants. In the case of HT, only A. mellifera showed significant variation among plants. A. dorsata and A. mellifera showed maximum pollen carrying efficiency compared to the others. These findings emphasize the role of insect flower visitors in pollination, leading to the perquisite for the protection of mangroves of the Indian Sundarbans.