Analysis of Plant-Insect Pollination Network—A Case Study on the Exotic Plants as Nectar Resource of Butterflies across Darjeeling District of West Bengal, India

In ecology, a bipartite network involving higher and lower tropic level components are a reflection of community interaction. Interesting studies on the pollinator-nectar plant relationship enlightens their role in the conservation and valuation of the environment. Additionally the contribution of exotic plants as nectar resource of pollinators could prove beneficial for studies on community structure and function. The present investigation on butterflies-exotic nectar plant community across Darjeeling district of West Bengal, India is of paramount importance in generating awareness for protection of such plant communities. Analysis of such bipartite network characterizing butterfly-plant community could help in elaborating the different aspects of species assemblage and interaction. Different indices (based on unweighed links and weighed links) were used for exploration of such network, A total of 28 exotic plant species served as nectaring resource for 44 butterfly species. Some ecologically significant descriptors of this network included network dimension (no. of species in higher trophic level: 44; no. of species in lower trophic level: 28), links per species (1.042),connectance (0.061) and network asymmetry (-0.222). Other indices based on weighed links included generality (3.608), vulnerability (3.166) and Shannon’s evenness of network interaction (0.4407). Thus the above predictions provide a probable clue to the involvement of exotic plant species to the maintenance of community structure. Significantly, exotic plants serve as key service providers to a community’s pollinator assemblages thereby attempting to fill an otherwise “empty coevolutionary niche”.

r