[Effects of temperature and density on the mortality and reproduction of cotton aphid Aphis gossypii].

A laboratory cotton leaf disc experiment was conducted to study the effects of different temperature (32, 34, 36, 38, and 40 degrees C) and density (5, 25, 50, and 75 individuals per dish) on the mortality and reproduction of Aphis gossypii. With the increase of temperature, density, and culture duration, the cumulative mortality of A. gossypii presented an increasing trend. The parameters estimated by complementary log-log (CLL) model showed that the beta value decreased with the increase of density, indicating that the effects of temperature weakened with increasing density. The gamma value, a parameter for the time effect of temperature, changed with culture duration, indicating that the morality of A. gossypii was co-affected by the temperature and culture duration. The two-way ANOVA analysis of variance showed that temperature and density had significant effects on the fecundity of A. gossypii, and there existed interactive effect. At 32-36 degrees C, the reproduction rate of A. gossypii decreased with the increase of density, but at 40 degrees C, no significant difference was observed in the reproduction rate under different densities, suggesting that the density effect was weakened with increasing temperature, i. e., the contribution of temperature and density to the survival and reproduction of individual varied with the ranges of the temperature and density. This study could provide reference for the monitoring and forecasting of A. gossypii population and for the improvement of pests control.