Pollinator activity and their role on seed set of medicinal and aromatic Lamiaceae plants

Abstract

Lamiaceae is one of the most economically important plant families based on their aromatic, medicinal, and industrial significance. In the present study three species of the Lamiaceae subfamily, Nepetoideae (Ocimum basillicum, Nepeta cateria, Leucas aspera) and one species from Lamioideae (Rosmarinus officinalis) were selected to document the pollinator bee diversity, foraging behavior, and their role on seed set. Thirty-two species of bees representing three families of Hymenoptera, (Apidae (94.87%) followed by Megachilidae (3.74%) and Halictidae (1.40%) were observed in all four plant species. Non-Apis bees were more abundant (69.35%) than Apis species (30.65%). The species-level variation in pollinator bees was observed in each plant species irrespective of space, time, and environmental conditions. O. basillicum attracted the maximum number of pollinator species (22) followed by R. officinalis (14) and L. aspera (10) and N. cataria (5). In O. basillicum, Ceratina species were major flower visitors, whereas R. officinalis was mainly visited by both Ceratina and Apis sp. L. aspera was dominated by Amegilla species and N. cataria mostly visited by the Apis bee species. However, irrespective of the diversity, the abundance of pollinator activity mainly contributed to enhancing the maximum number of seeds set in each species up to 64% overall increase under open pollination compared to bagged conditions. Also, a significant reduction in the seed set percentage was observed in R. officinalis and L. aspera under bagged pollination conditions. This indicates the high dependency of Lamiaceae plants on bee pollinators to maintain their reproduction and regeneration activities.