Abstract:

The reproductive success (Ovule fertilization and the pollen dispersal) of animal-pollinated plants is dependent upon floral visitors and their visiting behavior. The visitor and their behavior are primarily determined by the rewards offered by the plant, mainly nectar secretion and its components. In this study, we linked the floral visitors and their visiting behavior with the fruit and seed siring on a flexistylous ginger, Alpinia blepharocalyx, in Caiyanghe Provincial Natural Reserve (22°30′ N, 101°22′ E), southwest China. The study was carried out from March 16 to April 28,2003. We established 9 plots within 3 noncontiguous patches of a large population of A. blepharocalyx and measured nectar volume and concentration, recorded floral visitor species and their behavior, recorded fruit set and seed production, and measured the effects of a nectar robber, the striped squirrel (Tamiops swinhoei) on reproductive success. Nectar was measured 6 times a day; a micro-capillary tube was used to collect nectar secretions and a refractometer used to analyze sugar concentrations. Visiting frequency and duration were recorded every 2 hours from 7∶30-19∶00 during the entire flowering season. Seventeen species of floral visitors were recorded during the observation period, 8 species of which were pollinators. Of these, Bombus eximius and Bombus richardis were the most effective pollinators due to higher visiting frequencies and apparent well-suited body sizes. The nectar secretion patterns of two phenotypes were opposite: anaflexistylous flower secreted more nectar in the afternoon than that in the morning whereas the cataflexistylous flower showed the reverse pattern. The sugar concentration of both phenotypes declined during the anthesis period from 07∶30 to 20∶00. The visiting frequencies of pollinators were higher in the afternoon than in the morning. Pollinators spent a longer time at the flower during a single visit before 10∶30 A.M. when the visiting frequency was low, but shortened the duration of a visit when the visiting frequencie increased after 11∶30 A.M. The fruit set ratio of A. blepharocalyx was not significantly different between nectar robbed and non-robbed plots, but seed production was greater in the non-robbed plants.

Key words: Zingiberaceae, Pollination biology, Nectar robber, Tamiops swinhoei, Reproductive success, Plant-animal interactions