[Effects of high temperature on the mortality and fecundity of two co-existing cotton aphid species Aphis gossypii Glover and Acyrthosiphon gossypii Mordvilko].

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 degrees C. 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 degrees C, 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 degrees C, Aphis gossypi had higher tolerance against high temperature than Acyrthosiphon gossypii, and consequently, had more competitive advantage under global warming.