title: Nectar properties and the role of sunbirds as pollinators of the golden-flowered tea (Camellia petelotii).
abstract: OBJECTIVE
  Properties of floral nectar have been used to predict if a plant species is pollinated by birds. To see whether winter-flowering plants evolve nectar properties corresponding to bird pollinators, nectar properties of severalCamelliaspecies (including the golden-flowered tea), as well as the role of floral visitors as effective pollinators, were examined.
  
  
  METHODS
  Potential pollinators ofCamellia petelotiiwere identified at different times of day and under various weather conditions. A bird exclusion experiment was used to compare the pollination effectiveness of birds and insects. Nectar sugar components (fructose, glucose, and sucrose) fromC. petelotiigrowing wild and another sevenCamelliaspecies and 22 additional cultivars (all in cultivation) were examined by high-performance liquid chromatography (HPLC).
  
  
  RESULTS
  The sunbirdAethopyga siparajaand honeybees were the most frequent floral visitors toC. petelotii. Honeybee visits were significantly reduced in cloudy/rainy weather. The fruit and seed set of flowers with birds excluded were reduced by 64%, indicating that bird pollination is significant. For the wild populations ofC. petelotii, a bagged flower could secrete 157 μL nectar; this nectar has a low sugar concentration (19%) and is sucrose-dominant (87%). The eightCamelliaspecies and 22 cultivars had an average sugar concentration of around 30% and a sucrose concentration of 80%, demonstrating sucrose-dominant nectar inCamelliaspecies.
  
  
  CONCLUSIONS
  The nectar sugar composition ofCamelliaspecies was characterized by sucrose dominance. In addition, the large reduction in seed set when birds are excluded in the golden-flowered tea also supports the suggestion that these winter-flowering plants may have evolved with birds as significant pollinators.
authors.affiliation: Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan 430079, China.
authors.forename: Shi-Guo
authors.initials: SG
authors.lastname: Sun
authors.affiliation: Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region, and Chinese Academy of Sciences, Guilin 541006, China.
authors.forename: Zhi-Huan
authors.initials: ZH
authors.lastname: Huang
authors.affiliation: Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan 430079, China.
authors.forename: Zhi-Bao
authors.initials: ZB
authors.lastname: Chen
authors.affiliation: Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan 430079, China hsq@mail.ccnu.edu.cn.
authors.forename: Shuang-Quan
authors.initials: SQ
authors.lastname: Huang
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology; D028244:Camellia / Q000737:chemistry / Q000502:physiology*; D035264:Flowers / Q000737:chemistry / Q000502:physiology*; D005632:Fructose / Q000032:analysis; D005947:Glucose / Q000032:analysis; D007313:Insecta / Q000502:physiology; D046109:Passeriformes / Q000502:physiology*; D057048:Plant Nectar / Q000737:chemistry / Q000502:physiology*; D054817:Pollination; D012639:Seeds / Q000737:chemistry / Q000502:physiology; D013395:Sucrose / Q000032:analysis
chemical_list: D057048:Plant Nectar; D005632:Fructose; D013395:Sucrose; D005947:Glucose
keywords: Camellia petelotii; Theaceae; bird pollination; effective pollinators; insect pollination; nectar properties; sucrose content; winter flowering