Abstract: 【Aim】 To understand the mutualistic stability in the obligate pollination mutualism between Epicephala ancylopa and host Glochidion sp. in biology and chemical ecology. 【Methods】 Based on the field observation and indoor experiment, we investigated the biological characteristics of Glochidion sp. and E. ancylopa, and the benefits that each species obtains from their obligate nursery pollination mutualism. The dynamic headspace technique and gas chromatography-mass spectrometry (GC-MS) were used to analyze the chemical composition of floral volatiles of both female and male flowers from Glochidion sp. The principal component analysis (PCA) was conducted to assess the compositional differences in  floral scent between the sexes of Glochidion sp. 【Results】 E. ancylopa had only one generation per year in Pu’er Sun River National Park, Yunnan Province, and its adults and larvae were active during March-April and August-October, respectively. For Glochidion sp., the rate of ripening was 44.20%, the rate of consumed fruits was 69.94%, the average number of seeds consumed by each larva was 2.55, and the proportion of intact seeds was 83.06% that could keep the stabilization of mutualism in each population. A total of 24 compounds were detected and identified from the floral scent of Glochidion sp., which were dominated by terpenoids and aliphatics compounds. Among them, (Z)-ocimene and β-elemene were found to have the highest amounts in flowers (47.11% and 22.72%, respectively), and inferred as the major scent components attracting E. ancylopa. The PCA revealed that the chemical compositions of male and female floral scents of Glochidion sp. were distinctly different, which was identified as sexual dimorphism in floral scent. 【Conclusion】 One survival strategy of E. ancylopa is to synchronize eclosion with the flowering season of Glochidion sp. by oversummering in the egg stage and overwintering in the pupal stage. Adult of E. ancylopa is active only at night, whereas the floral scent attracting pollinator is only released obviously at night. Sexual dimorphism in floral scent can help Epicephala moths distinguish floral scents between male and female flowers, mediating behaviors of collecting pollen and pollinating. This study provides a new basis for understanding the mechanism to sustain the stabilization in the Glochidion-Epicephala mutualism and the basic data for further electroantennographic detection and bioassay to identify the compounds with the actual physiological activity to Epicephala moths.

Key words: Epicephala ancylopa, Glochidion, coevolution, morphology, biology, floral scent, sexual dimorphism