Abstract: The sibling pests, Ectropis grisescens and Ectropis obliqua, are morphologically similar. However, the potential differences between their biological characteristics especially the body-length, weight, developmental duration and population growth rates of each development stage remains unclear. In the current study, we characterized and compared this issue based on laboratory observation. Firstly, the body-length and weight of the old larvae, pupae and moths were significantly different, with higher levels observed on E. grisescens in comparison to those of E. obliqua. Secondly, the periods of one generation between these two pest species were distinct. E. grisescens needed 36.6 d to complete one generation, whereas E. obliqua required at least 39.7 d. Finally, the generational survival rate and population growth rate in E. obliqua was 0.28 and 24.9, respectively, which was approximately half of that in E. grisescens. Hence, we proposed that E. grisescens had larger body size, faster developmental rate and stronger reproductive capacity than E. obliqua.

Key words: Ectropis grisescens, Ectropis obliqua, body length, body weight, developmental duration, population growth rate