Interactive Effect of Honey Bees [Apis mellifera, Apis cerana (Hymenoptera: Apidae)] and Native Bees for Pollination Services in Radish, Raphanus sativus

Abstract

Radish flowers, being self-incompatible are highly reliant on insect visitors for pollination. Honey bees are effective pollinators of radish. Pollination is influenced by visitation rates, behaviour and pollination effectiveness of pollinators which aid in seedset. We explored bee behaviour known to favour pollination; flowers visited per unit time and time required to process a flower by honey bees and non-Apis bees visiting radish. During our study, 54 species/morphospecies were observed to visit radish flowers, of which Apis cerana indica is predominant. Pollinator effectiveness was measured by means of seed set by flowers receiving a single visit of a specific pollinator as compared to seed set by flowers allowed for open pollination (multiple visits) and was found to be 0.31 and 0.36 for A. cerana and Apis mellifera, respectively. Yield enhancement studies through entomophily showed that, flowers receiving unrestricted visit of pollinators (open control) recorded 265.5% higher yield followed by interaction of two pollinators (A. c. indica + A. mellifera) 198.3%, A. mellifera (163.8%) and A. c. indica (178.3%) with respect to radish flowers allowed only for self-pollination. Pollinator diversity enhanced pollination and seed set in radish. These advantages of pollinator synergies and benefits of biodiversity are increasingly recognized.