A study on floral phenology, pollination mechanisms and molecular characterisation of pollinator in Bulbophyllum careyanum (Orchidaceae)

Abstract

The present study focuses on flowering phenology, pollinator intensity in Bulbophyllum careyanum during different times of the day and visitation rates with the number of flowers per inflorescence. The average time taken from bud initiation of inflorescence till its maturity (27.4±0.79 days), flower longevity (15.3±1.09 days) and wilting period (4.2±0.27 days) were almost same during flowering seasons in two consecutive years (2012 and 2013). However, inflorescence bud initiation and flower opening delayed for about three weeks during 2013 as compared to the former. Hand pollination and bagging experiments showed that induced and spontaneous autogamy, agamospermy and geitonogamy failed to produce fruits, but flowers under natural conditions (control) and those introduced to xenogamy produced fruits with 23.3% and 86.7% respectively. Pollinators mostly visited the flowers during morning hours (0615-0645) and evening hours (1645-1710). Pollinator visitation rates were significantly correlated with the number of flowers per inflorescence (r values ranges from 0.84 to 1.00, significant at 0.01). Molecular characterisation of the pollinators were done by Polymerase Chain Reaction (PCR) amplification of four mitochondrial gene fragments (12s rDNA, 16s rDNA, Cytochrome c oxydase I and NADH 4 & 5 dehydrogenase). Different insect species including flies, wasps, grasshoppers and bees visited the B.careyanum flowers, but only Drosophila melanogaster was found to be the real pollinator.