Abstract: 【Aim】By clarifying the difference in the temperature adaptability of the main biological characters between two closely related species of corn borers, the Asian corn borer (Ostrinia furnacalis) and European corn borer (O. nubilalis)， living in the only one sympatric region in the world and accompanied by fierce interspecific competition， this study aims to reveal the biological driving mechanism of the rapid replacement of O. nubilalis population by O. furnacalis in the sympatric region in Xinjiang, Northwest China.【Methods】 At 15, 20, 25, 30 and 35 ℃, the egg duration, egg mass hatching rates, egg hatching rates per egg mass and mortalities of egg masses of the O. furnacalis and O. nubilalis populations isolated from the same region in Xinjiang, and at 20, 25, 30 and 35 ℃, their adult longevity, pre-oviposition period, oviposition period, numbers of eggs laid per female, larval and pupal duration, larval and pupal weight etc. were measured and compared. 【Results】 The results showed that the mortalities of egg masses of O. nubilalis were significantly higher than those of O. furnacalis at 15, 20, 25 and 35 ℃, and the average egg hatching rates per egg mass of O. nubilalis were significantly lower than those of O. furnacalis at 20, 25, 30 and 35 ℃. Furthermore, the hatching ability of egg masses of O. nubilalis decreased significantly with the increase of temperature, until the temperature increased to 35 ℃, the mortality of egg masses was the highest (73.42%±2.28%) and the average egg hatching rate per egg mass was the lowest (48.46%±2.64%), while those of O. furnacalis were 41.88%±4.33% and 67.99%±2.52%, respectively. At the same temperature, there was no significant difference in the pre-oviposition period, female adult longevity, male adult longevity and oviposition period between sympatric O. furnacalis and O. nubilalis. However, the main fecundity indexes of O. nubilalis, such as the number of egg masses laid per female, average number of eggs per egg mass laid by a single female and average number of eggs laid per female, were significantly lower than those of O. furnacalis. Compared with O. furnacalis, O. nubilalis had significantly heavier 1st-4th instar larval weight at the low temperature of 20 ℃. However, at higher temperatures (30 and 35 ℃), the 2nd and 3rd instar larval weight of O. nubilalis was significantly lighter than that of O. furnacalis and the duration of various instar larvale and pupal duration of O. nubilalis showed no significant difference from those of O. furnacalis. 【Conclusion】Compared with O. nubilalis, O. furnacalis has better temperature adaptability. Especially at high temperatures (30 and 35 ℃), O. furnacalis has higher survival rate of egg masses, better hatching ability, higher fecundity and heavier body weight, showing stronger competitiveness.

Key words: Ostrinia furnacalis, O. nubilalis, related species, biological characteristics, interspecific competition