Analysis & Studies On The Population Dynamics Of Cotton Aphid Intimidated By Natural Enemy

During the research on the population dynamics of cotton aphid ever, the dynamics modeling of cotton aphid was described with one Logistic curve, and the carrying capacity is a fixed number. This paper took advantage of trend analysis and periodicity analysis for the first time to make research and analysis on population dynamics of cotton aphid intimidated by natural enemy, and showed this view has its limitation through full and accurate date .The result was as follows: (1) The year trend of cotton aphid intimidated by natural enemy is pictured with a three cubed polynomial. This polynomial has two wave crests which the former wave is higher than the latter's, denoting different peak of cotton aphid aspectively.This result showed that population number of cotton aphid took on rising ,ascending state, not a kind of Logistic curve ,i.e., a Sigmoid curve . This made clear that the carrying capacity is a variable, not a constant. (2) The analysis of periodicity on cotton aphid intimidated by natural enemy shows that the cotton aphid's main periodicity is Ï€/4 , and the reason is not understood currently in the paper, which need more research in the future. (3) Cotton's year periodicity can be divided several little periodicities, each of which includes one up-phase and down-phase. The up-phase is described with Logistic curve, but the down-phase with reverse Logistic curve. For the latter periodicities are shorter than the former, and the data is divided into three phases to fit. These models are Statistical tests show that above three models are prominences. (4)From above models ,we can see that in one year life history, the model of aphis gossypii intimidated by natural enemy growth curve is determined by two Logistic Equation one reverse Logistic curve ,rather than one Logistic Equation, i.e., (The damaged phrase of seedling and summer aphid) (The endangered phrase of seedling and summer aphid) and (The ascend phrase of autumn aphid) These parameters, including r₁ , r₂ , r₃ , K₁ , K ₂ ,K ₃,are all greater than zero. From the trend analysis and periodicity analysis, the dynamics model of cotton aphid intimidated by natural enemy is also expressed by the equation as follows:...