Secondary Metabolites In Nectar And Their Effects On Pollination

Secondary metabolites associated with plant defence to herbivores ubiquitously present in flora nectar. But their ecological significance is poorly understood. The objective of present study aims to reveal the adaptive natuer of these metabolistes in nectar in biocoenosis context by analyzing the behavioral and physiological mechanisms of how bees cope with secondary compounds in nectar. The results are as following.1. The plant, Elsholtzia rugulosa, produces the nectar that contains phenolic compounds. The relative astringency (RA, an indicator of phenolic deterrence to herbivores) of the nectar was averagely 0.1679±0.0467. Colonies' absconding or death indicates phenolics in the nectar are deterrent to honey bees. 2. As compared to gel electrophoresis of proteins from worker bee's hypopharyngeal glands of Apis mellifera, Apis cerana also expresses glucose oxidase (GOX). Consequently, Chinese honey bees exploited the nectar that contains secondary metabolites as their food when few flowers are available.3. GOX was inhibited by phenolics in nectar outside hives. Evolved nest homeostasis, i.e. maintenance of CO2 at desired 35℃, could directly deactivate phenolics, and played a role in the action of GOX as well. Thus, the maintenance of desired nest homeostais is essential for bees to detoxify. 4. During the flowering period of E. rugulosa, minor plant of Eucalyptus globules promoted bee's collecting nectar from E. rugulosa. Bee's visitation to Tripterygium wilfordii with toxic nectar was tightly linked to their visitation to Fragaria nilgerensis and Polygonum multiflorum, which are sympatric and flower synchronically. 5. Secondary metabolites increased in nectar honey bee's food demand, thus promoting bee's visitation to flowers. Simultaneously, secondary metabolites in nectar induced a high biased-female sex ratio in colony. High bee's visitation rate and high biased-female sex ratio indicated a good pollination service provided by honey bees.