Abstract: 【Aim】 The horned gallnut is a closed gall induced by Schlechtendalia chinensis on leaves of its primary host plant Rhus chinensis. It is very important for S. chinensis to clean out its excretion (honeydew) in order to maintain its survival. The study aims to explore the excretion and sugar composition of honeydew produced by S. chinensis fundatrigeniae living in gallnuts. 【Methods】 The honeydew excretion of S. chinensis fundatrigeniae was continuously observed by an inverted fluorescence microscope. Fundatrigeniae were fed with media containing different concentrations of sucrose or starch. Honeydew excretion rates were counted, and the effects of sucrose and starch on the honeydew excretion of fundatrigeniae were analyzed. The composition and contents of sugars in honeydew were detected by liquid chromatography. 【Results】 In gallnuts of S. chinensis, apterous fundatrigeniae were rarely observed to excrete honeydew; however, 35.40%±2.41% of alate fundatrigeniae were observed to excrete honeydew. On agarose media, both apterous and alate fundatrigeniae excreted honeydew, and their honeydew excretion rates were 23.89%±5.58% and 173.96%±28.61%, respectively. On agarose media with different concentrations of sucrose, the honeydew excretion rates of both apterous and alate fundatrigeniae decreased with the increasing of sucrose concentration. On agarose media with different concentrations of starch, the honeydew excretion rate of apterous fundatrigeniae decreased with the increasing of starch concentration. When the starch concentration increased from zero to 2%, the honeydew excretion rate of alate fundatrigeniae increased from 173.96%±28.61% to 236.81%±55.67%, then decreased with the increasing of starch concentration, and decreased to 55.92%±7.22% when the starch concentration was 10%. We detected a total of seven sugars in the honeydew, of which the contents of fructose and glucose were high, accounting for 51.07% and 31.68%, respectively, the sucrose content was very low (only 1.59%), and the contents of the remaining four unknown components were 15.66%. 【Conclusion】 The main components of honeydew produced by S. chinensis fundatrigeniae living in gallnuts are fructose and glucose, and sucrose and starch contents in the diet have an obvious influence on their honeydew excretion.

Key words: Schlechtendalia chinensis, gall, fundatrigeniae, honeydew, sugar composition