Foraging activity and breeding system of Avicennia officinalis L. (Avicenniaceae) in Kerala, India

Abstract

Field studies were carried out to assess the foraging activity and the breeding system of Avicennia officinalis L. in Chettuwa, Thrissur, India during the two flowering seasons of 2018–2019. A. officinalis, also known as the Indian mangrove is a common mangrove occupying the river banks of the Kerala coast of southern India. The plant blooms massively during the onset of the first summer showers. The flowering to fruiting period lasted from April to July. Bagging experiments revealed that A. officinalis preferred a mixed breeding system though they had a low fruit set recorded in self-pollination experiments. A total of 15 species of foraging insects belonging to three orders, Hymenoptera, Diptera, and Lepidoptera, were observed. The three most abundant insect foragers were Apis florea Fabr., Campsomeriella collaris Fabr., and Chrysomya megacephala Fabr. Among these, A. florea showed a significantly high visitation rate followed by C. collaris and then C. megacephala. C. collaris, however, had the highest and most significant handling time for Avicennia officinalis than A. florea. The peak foraging activity was recorded from 1000h to 1100h and from 1500h to 1700h. These findings emphasize the importance of insect flower visitors in the breeding of A. officinalis, highlighting the need to maintain the plant-pollinator relationships for the protection of mangrove ecosystems.