Morphological Characterization of Pollen Collected by Apis dorsata from a Tropical Rainforest

Apis dorsata is one of the important honeybee species in tropical and subtropical regions that forage on various plants including herbs, grasses, forest trees and plantation trees. However, information on the favored bee plants in terms of identity and quantity is lacking. The objectives of this study were: (1) to identify the pollen sources of Apis dorsata and (2) to develop a pollen atlas for selected plants foraged by Apis dorsata. Pollen cell samples from twenty one different colonies of Apis dorsata combs were collected, identified and quantified based on several reference materials. A total of twelve different pollen sources were identified in the samples. Pollen sizes were 8-9x38-40 μm, comprising five different shape classes. Inaperturate granulum pollen grains were observed in Ceiba pentandra and Garcinia hombroniana while rugulate grains were found in Mangifera indica. Pantoporate, syncolpate and pericolpate pollen grains with reticulum to microreticulate exine patterns occurred in Acacia auriculiformis, Melaleuca cajuputi and Ixora congesta. Elaeis guineensis showed trichotomosulcate pollen grains with a microreticulate sexine. Pantocolpate areola pollen was found in Mimosa pudica while granulum pollen was observed in Cocos nucifera. Anacardium occidentale showed a disulcate grain with a striate sexine pattern. Pollen grains of Averrhoa carambola and Dimocarpus longan were tricolpate and fossulate perforate to striate perforate. This work shows that Elaeis guineensis and Mimosa pudica were the most commonly found pollen sources. A pollen atlas of selected plants foraged by Apis dorsata in the tropical rainforest of Marang, Terengganu was developed.