Abstract:In order to explore nectar variation and its effect on pollinators of Goodyera foliosa, a nectar rewarding orchid, the nectar volume, total sugar concentration and the composition and content of soluble sugar in single flower in different time within a day were detected by using capillary method, refractometer and high performance liquid-evaporation method. The foraging behavior of pollinators was observed by video camera. The results showed that the volume of single flower nectar reached up to maximum [(7.19±2.29) μL, n=10] at 10:00, and the sugar concentration to maximum [(25.85±1.83)%; n=10] at 16:00. The main soluble sugar in nectar was fructose and sucrose, and the highest content of fructose was 78.310 mg/g at 10:00 am and that of sucrose was 247.600 mg/g at 16:00 pm. The visiting time of Apis cerana was from 9:00 to 15:00 every day, and the peak period was between 10:00 am and 14:00 pm. And the visiting time of Bombus friseanus was from 8:00 to 16:00 every day, and the peak period was from 10:00 to 12:00 and from 16:00 to 18:00. The visiting frequency of the two pollinators was correlated with the changes in nectar volume and sugar concentration of single flower of G. foliosa. They tended to visit flowers with high nectar volume and sugar concentration. Sucrose was the predominant component of nectar in G. foliosa, which can effectively attract all kinds of bees, butterflies and ants to visit flowers with high enthusiasm and access frequency. However, the Apis cerana and Bombus friseanus which could carry the pollen of orchid were major effective pollinators. Therefore, the matching of flower shape and size of visiting insects determined whether they were effective pollinators.
