Flower visitors in agricultural farms of Nilgiri Biosphere Reserve: Do forests act as pollinator reservoirs?

Abstract

Anthropogenic activities are accelerating the loss of pollinators and the services they provide. Studies have suggested that forests near agricultural farms could serve as pollinator reservoirs. To explore this hypothesis, we examined the relationship between distance to the forest and the number of floral visitors in seven agricultural farms in the Nilgiri Biosphere Reserve in southern India. We used the morphospecies richness of flower visitors as a proxy measure of pollination services provided by forests. We found forty-six flower visitors in total, which included bees, flies, butterflies, moths, earwigs, and beetles. The number of total visitors in farms declined with increasing distance from the forest edge – explaining approximately 63% of the variation in total morphospecies richness – suggesting that natural forests serve as pollinator reservoirs. However, we found no significant relationship between the distance to the forest edge and the species richness of two categories of bees when examined separately, i.e., eusocial and semi-social/solitary bees. We reason that this is because they are likely to inhabit niches that are embedded within the agricultural landscapes. Moreover, we found no relationship between the number of morphospecies and the number of crops at each farm. Since many marginalized farming communities in the region live close to forests and practice pesticide-free, insect-friendly farming, we suggest incentive measures for them. This, in turn, would help conserve forests as pollinator reservoirs, although our findings must be supported by further research.