Abstract: 【Aim】 This study aims to evaluate the degrees of differentiation and reproduction isolation in different geographic populations of the tea geometrid, Ectropis obliqua Prout. 【Methods】 Investigations of morphological, biological properties and reciprocal cross experiments were carried out in Hangzhou population (H) and Quzhou population (Q) of E. obliqua, which were collected in the field of Hangzhou and Quzhou, Zhejiang, respectively.【Results】 Morphological and biological observation revealed that individuals of population Q had larger body shape and darker wing color than population H, whereas no observable difference in external morphology, genital structure or female fecundity was found between the two populations. Significantly fewer eggs were laid in the reciprocal cross experiments than in self-cross experiment (control). The F1 generation was always obtained with decreased egg hatching rate. The larval duration of the F1 generation was significantly shortened, the temporal distribution of pupation was irregular and pupal weight became lighter as compared with those of parents. The eclosion rate of F1 generation was reduced and the sex ratio was extremely disordered. 【Conclusion】 The results suggest that reproductive isolation and differentiation exist between population H and Q of E. obliqua, and these two geographic populations should be different species.

Key words:  Ectropis obliqua, geographic population, morphology, population differentiation, reproductive isolation, cross experiment