| Aphis gossypii Glover, Aphis atrata Zhang and Acyrthosiphon gossypii Mordviko are three important aphid species in cotton field of Xinjiang. The A. atrata and Ac. Gossypii as the dominant species played a primary role to damage cotton during seeding stage. After bud stage A. atrata and Ac. Gossypii declined and even disappeard while Ap. Gossypii as the dominant species played the primary role to damage cotton. The cotton aphid life table and interspecific competition were studied from field surveys, temperature and host plants, in order to clarify the population of A. atrata and Ac. gossypii declined in the late were affected by fluctuations in high temperature and the advantages and disadvantages of Ap. gossypii with Ac. gossypii interspecific competition. It can provide a theoretical basis for future global warming and provide technical support for the reasonable control of cotton aphids. The main results are as follows:1.Field survey confirmed that A. atrata and Ac. gossypii were the dominant species in seeding stage of cotton, then replaced by Ap. gossypii became dominant species after bud stage in 2013. And Ap. Gossypii damaged cotton much more than either A. atrata or Ac. Gossypii.2.The effect of higher fluctuated temperature on the biological A. atrata on cotton and soybean and implication for the population dynamics were determined. The fluctuated temperatures significantly affected the development of aphid on cotton and soybean, and made the rapid decline of the longevity of females, number of progeny per female, reproduction rate and intrinsic rate of increase on cotton, but not on soybean. Meanwhile, the intrinsic rate of increase, reproduction rate, progeny per female and longevity of females on soybean were significantly higher than on cotton in the same temperature regimes. Specifically, mortality of A. atrata under the extreme temperatures(maximum temperature more than 34℃) on soybean was less a half than on cotton. So the hosts could mediate the thermal tolerance of insect pests to extreme temperature.3.The effect of frequency and magnitude of extreme temperature on life history traits of the cotton aphid( Ac. gossypii) was determined. The effects of ocillating temperatures were different to the effects from constant temperature even though the average daily temperature was the same. In oscillating temperature regimes, the higher the frequency and amplitude of temperature peaks, the greater was the decrease in survival and reproduction, and thus the greater the reduction in the fitness of A. gossypii.4.The interspecific competition and distribution about Ap. gossypii and Ac. gossypii at different temperature were determined. The result indicate that during the comfort temperature: rm in single species of Ap. gossypii are all larger than that of Ac. gossypii, however the mixture of them have no significant effect of rm to each other, that is, Ap. gossypii have strong internal competitive ability;over 97% species of the Ap. gossypii lived on the leaves, while the living rate of Ac. gossypii positively increase from 55% to 75% with the temperature. In the same temperature, the coexisting of the two species have no significant effect to either on the leaves and stems, they all live at the upward of cotton. With the temperature raise, the single species has no obvious transport, while Ap. gossypii in the coexisting species increasingly moved downward, as to the Ac. gossypii,no matter single or mixture, they all live more at the top of the cotton. Under the same temperature, coexisting have no influence to the distribution of Ap. Gossypii, while the same as Ac. gossypii under 21℃ and 27℃。However under the 24℃, Ap. gossypii prompt Ac. gossypii to move downward; the rate of alatae decline with the increasing temperature, Ap. gossypii are significantly effected by temperature, while Ac. gossypii are not. |
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