Abstract: Epicephala lativalvaris Li, Wang & Zhang has been found obligately pollinating Breynia fruticosa and B. rostrata. Based on the field observation of the flower-visiting behavior of E. lativalvaris, the indoor rearing of the E. lativalvaris larvae and the dissection of the B. fruticosa and B. rostrata fruits, we made a detailed study for the first time on the morphological characters, the habit of each developmental stage and the life history of E. lativalvaris. The results show that the life history of E. lativalvaris varies under different climatic conditions. It has 4-5 generations and 4 emergence peaks annually in Xiamen, Fujian Province, and the emergence peaks occur during the following periods: early to middle May, middle to late June, August and late September to early October, and a small number of adults emerge during middle to late November and overwinter in eggs or pupae during early December to middle April of the following year; while it has 6 generations annually and does not overwinter in Yinggeling, Hainan Province. Adults of E. lativalvaris actively pollinated female flowers of B. fruticosa or B. rostrata and laid eggs into their ovaries; larvae fed on seeds of the host plants and developed to maturity by consuming all six seeds, whereas 20.37%-77.63% intact fruits were left to keep the stabilization of mutualisms in each population. The ripening rate of B. fruticosa was similar to that of B. rostrata, but the consumption frequency of E. lativalvaris on B. fruticosa fruits was 2.05 times as high as that on B. rostrata. The results indicate that in the E. lativalvaris-Breynia fruticosa and B. rostrata obligate pollination mutualism, the two host plants obtain about equal benefits from E. lativalvaris, whereas E. lativalvaris benefits more from B. rostrata than from B. fruticosa. This study provides reference for the biological study of other Epicephala species and lays a basis for understanding the mechanism to sustain the stabilization of the obligate pollination mutualism in E. lativalvaris-Breynia fruticosa and B. rostrata.

Key words: Epicephala, Breynia fruticosa, Breynia rostrata, morphology, biology, obligate pollination mutualism