Abstract: Aphis gossypii and Acyrthosiphon gossypii are the coexisting species on cotton plant, with their abundance differed within and among years. To explore whether the abundance difference was related to the different responses of the two aphid species to high temperature, a laboratory experiment was conducted to assess the mortality and reproduction of the two aphid species at high temperatures 32, 34, 36 and 38 ℃. With the increasing temperature and prolonged exposure period, the cumulative mortality of the two aphid species increased, and Acyrthosiphon gossypii had a higher cumulative mortality than Aphis gossypii. The daily mortality of the aphids could be well simulated by complementary log-log (CLL) model. The median lethal temperature of the two aphid species estimated by CLL model decreased with prolonged exposure period. Under the same exposure period, the median lethal temperature of Aphis gossypii was higher than that of Acyrthosiphon gossypii. Within the range of 32-38 ℃, the reproduction rate of the two aphid species decreased with increasing temperature, but Aphis gossypii had a significantly higher reproduction rate than Acyrthosiphon gossypii, indicating that at the temperature higher than 32 ℃, Aphis gossypi had higher tolerance against high temperature than Acyrthosiphon gossypii, and consequently, had more competitive advantage under global warming.

Key words: Aphis gossypii, Acyrthosiphon gossypii, high temperature stress, cumulative mortality, reproduction rate, complementary log-log model